CN119029870A

CN119029870A - Multi-source coordinated fault ride-through method and device for isolated power grid

Info

Publication number: CN119029870A
Application number: CN202411161258.XA
Authority: CN
Inventors: 杜善周; 范培育; 许先义; 柴耀军; 黄涌波; 卢国平; 鲁绍杰; 石建川; 袁亮
Original assignee: China Shenhua Energy Co Ltd; Shenhua Zhungeer Energy Co Ltd; Shenhua Zhunneng Resources Development and Utilisation Co Ltd
Current assignee: China Shenhua Energy Co Ltd; Shenhua Zhungeer Energy Co Ltd; Shenhua Zhunneng Resources Development and Utilisation Co Ltd
Priority date: 2024-08-22
Filing date: 2024-08-22
Publication date: 2024-11-26

Abstract

The application provides a multi-source collaborative fault ride-through method and device for an isolated power grid. The method comprises the following steps: acquiring grid-connected point voltage of an isolated power grid at a first moment; judging whether the voltage of the parallel network point is in a preset voltage range or not to obtain a first judging result; under the condition that the first judgment result is negative, performing first excitation control on the synchronous generator in the isolated power grid; acquiring grid-connected point voltage of an isolated power grid at a second moment, judging whether the grid-connected point voltage at the second moment is in a preset voltage range, and obtaining a second judgment result, wherein the grid-connected point voltage at the second moment is the grid-connected point voltage after the first excitation control of the synchronous generator; if the second judgment result is yes, performing second excitation control on the synchronous generator, and controlling a photovoltaic system in the isolated power grid to generate power on the isolated power grid by adopting a first control method; and under the condition that the second judging result indicates no, controlling the photovoltaic system to generate power for the isolated power grid by adopting a second control method.

Description

Multi-source collaborative fault ride-through method and device for isolated power grid

Technical Field

The application relates to the technical field of fault ride-through, in particular to a multi-source collaborative fault ride-through method of an isolated power grid, a multi-source collaborative fault ride-through device of the isolated power grid, a computer readable storage medium and electronic equipment.

Background

In order to achieve the aim of 'future carbon peak carbon neutralization', global climate change is actively dealt with, and the A country proposes to construct a novel power system taking new energy as a main body, accelerate the development of renewable energy sources and promote the electric power cleaning. The novel power system is characterized in that a new energy source is taken as a main body, a conventional synchronous unit is taken as an auxiliary body, the novel power system has the characteristic of 'high-proportion new energy source and high-proportion power electronic equipment', and the new energy source power generation has the characteristics of strong randomness, weak support, low disturbance rejection, low inertia response and the like. Therefore, the novel power system can be caused to have a new complex chain reaction problem in a complex or special scene, and great challenges are brought to the safe operation of the system and the transformation and upgrading of the traditional power system.

Along with the energy-saving index of the fuel unit, auxiliary machines of the thermal power unit in the prior art are driven by frequency converters gradually, however, the overload capacity of the auxiliary machine frequency converters is weak, the problem similar to the weak fault ride-through capacity of the photovoltaic power unit exists, low voltage can occur in the fault ride-through process, the auxiliary machine frequency converters are locked and output, large-scale furnace shutdown occurs, and even tripping of the fuel unit is triggered, so that shutdown accidents are caused. Therefore, for an isolated power system with a new energy photovoltaic generator set and a traditional synchronous generator at the same time, the adaptability of new energy equipment and stations to the traditional power system needs to be considered, wherein the fault ride through capability is a key focusing link in the new energy station involved network.

Disclosure of Invention

The application mainly aims to provide a multi-source collaborative fault ride-through method of an isolated power grid, a multi-source collaborative fault ride-through device of the isolated power grid, a computer readable storage medium and electronic equipment. At least solves the problem that the new energy power generation is difficult to be compatible with the traditional power system during the fault ride-through in the prior art.

To achieve the above object, according to one aspect of the present application, there is provided a multi-source collaborative fault ride-through method of an isolated power grid, including: acquiring grid-connected point voltage of an isolated power grid at a first moment; judging whether the voltage of the parallel network point is in a preset voltage range or not to obtain a first judging result; if the first judgment result indicates no, performing first excitation control on the synchronous generator in the isolated power grid, wherein the first excitation control is used for updating the initial voltage of the synchronous generator to a first preset voltage; acquiring grid-connected point voltage of an isolated power grid at a second moment, judging whether the grid-connected point voltage at the second moment is in a preset voltage range, and obtaining a second judgment result, wherein the second moment is the grid-connected point voltage after the first excitation control of the synchronous generator; if the second judgment result indicates yes, performing second excitation control on the synchronous generator, and controlling a photovoltaic system in the isolated power grid to generate power by adopting a first control method, wherein the second excitation control is used for updating a first preset voltage of the synchronous generator to an initial voltage, the first control method comprises a maximum power point tracking method and a rated power control method, the maximum power point tracking method is used for tracking the maximum power point of the photovoltaic system, and the rated power control method is used for controlling the photovoltaic system to output rated active power and rated reactive power; and under the condition that the second judging result indicates no, controlling the photovoltaic system to generate power on the isolated power grid by adopting a second control method, wherein the second control method comprises a direct-current voltage control method and a first power control method, the direct-current voltage control method is used for stabilizing the direct-current bus voltage of the photovoltaic system, and the first power control method is used for controlling the photovoltaic system to output first active power and first active power.

Optionally, the power generation device of the isolated power grid further includes an auxiliary device, and the multi-source cooperative fault ride-through method further includes, when the second determination result indicates yes: and controlling the auxiliary equipment to supply power to a first load, wherein the first load is all loads which adopt the auxiliary equipment to supply power in the isolated power grid.

Optionally, the power generation device of the isolated power grid further includes an auxiliary device, and the multi-source cooperative fault ride-through method further includes, if the second determination result indicates no: and controlling the auxiliary equipment to supply power to a second load, wherein the second load is part of all loads which adopt the auxiliary equipment to supply power in the isolated power grid.

Optionally, the power generation device of the isolated power grid further comprises auxiliary equipment and a storage battery, and the multi-source cooperative fault ride-through method further comprises, when the first judgment result indicates yes: and controlling the auxiliary equipment to supply power to a third load, wherein the third load is all loads for supplying power by adopting the auxiliary equipment in the isolated power grid, and controlling the auxiliary equipment to charge a storage battery.

Optionally, in the case that the second determination result indicates no, the multi-source cooperative fault ride-through method further includes: judging whether the voltage of a direct current bus of the photovoltaic system is over-voltage or not to obtain a third judging result; under the condition that the third judging result indicates yes, executing the step of controlling the photovoltaic system to generate power on the isolated power grid by adopting a second control method; and under the condition that the third judging result indicates no, controlling the photovoltaic system to generate power on the isolated power grid by adopting a maximum power point tracking method and a second power control method, wherein the second power control method is used for controlling the photovoltaic system to output second active power and second reactive power.

Optionally, the photovoltaic system includes a photovoltaic panel and a two-stage photovoltaic inverter, the two-stage photovoltaic inverter includes a front stage and a rear stage, the front stage is used for boosting dc-dc conversion, the rear stage is used for ac-dc conversion, the synchronous generator is subjected to second excitation control, and the photovoltaic system in the isolated power grid is controlled to generate power by adopting a first control method, and the method includes: performing first preset excitation control on the synchronous generator to update the first preset voltage to the second preset voltage; performing second preset excitation control on the synchronous generator to update the second preset voltage to the initial voltage, wherein the second excitation control comprises first preset excitation control and second preset excitation control; the control front stage adopts a maximum power point tracking control method to track the maximum power point of the photovoltaic cell panel; and the control later stage adopts a rated power control method to output rated active power and rated reactive power of the two-stage photovoltaic inverter so as to generate power for the isolated power grid.

Optionally, the photovoltaic system includes a photovoltaic panel and a two-stage photovoltaic inverter, the structure of the two-stage photovoltaic inverter includes a front stage and a rear stage, the front stage is used for boosting direct current-direct current conversion, the rear stage is used for alternating current-direct current conversion, the photovoltaic system is controlled to generate electricity to an isolated power grid by adopting a second control method, and the method includes: the control front stage adopts a direct-current voltage control method to stabilize the direct-current bus voltage of the photovoltaic system; and the control later stage adopts a first power control method to control the two-stage photovoltaic inverter to output first active power and first active power so as to generate power for the isolated power grid.

According to another aspect of the present application, there is provided a multi-source collaborative fault ride-through device of an isolated power grid, comprising: the acquisition module is used for acquiring grid-connected point voltage of the isolated power grid at a first moment; the first judging module is used for judging whether the grid-connected point voltage is in a preset voltage range or not to obtain a first judging result; the first execution module is used for carrying out first excitation control on the synchronous generator in the isolated power grid under the condition that the first judgment result indicates no, and the first excitation control is used for updating the initial voltage of the synchronous generator to a first preset voltage; the second judging module is used for acquiring the grid-connected point voltage of the isolated power grid at a second moment and judging whether the grid-connected point voltage at the second moment is in a preset voltage range or not to obtain a second judging result, wherein the second moment is the grid-connected point voltage after the synchronous generator is subjected to first excitation control; the second execution module is used for carrying out second excitation control on the synchronous generator and controlling a photovoltaic system in the isolated power grid to generate power by adopting a first control method under the condition that a second judgment result indicates yes, wherein the second excitation control is used for updating a first preset voltage of the synchronous generator to an initial voltage, the first control method comprises a maximum power point tracking method and a rated power control method, the maximum power point tracking method is used for tracking the maximum power point of the photovoltaic system, and the rated power control method is used for controlling the photovoltaic system to output rated active power and rated reactive power; the third execution module is used for controlling the photovoltaic system to generate power for the isolated power grid by adopting a second control method under the condition that the second judgment result indicates no, wherein the second control method comprises a direct-current voltage control method and a first power control method, the direct-current voltage control method is used for stabilizing the direct-current bus voltage of the photovoltaic system, and the first power control method is used for controlling the photovoltaic system to output first active power and first active power.

According to still another aspect of the present application, there is provided a computer readable storage medium, the computer readable storage medium including a stored program, wherein when the program runs, a device on which the computer readable storage medium is controlled to execute the above-mentioned multi-source collaborative fault ride-through method for an isolated power grid.

According to yet another aspect of the application, there is provided: the system comprises one or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, the one or more programs comprising a multi-source collaborative fault ride-through method for performing the isolated power grid described above.

By applying the technical scheme of the application, first, under the condition of acquiring the bus voltage of the grid-connected point of the isolated power grid, a first judgment result can be obtained by judging whether the voltage of the grid-connected point of the isolated power grid is in a preset voltage range, and the voltage of the grid-connected point at the moment can be considered to be acquired at the first moment. In the application, aiming at the condition that the first judgment result indicates no, first excitation control is performed on the synchronous generator in the isolated power grid, and in the step, the first excitation control can be used for updating the initial voltage of the synchronous generator to a first preset voltage. Furthermore, after the synchronous generator performs the first excitation control, the grid-connected point voltage of the isolated power grid is obtained again, and a second judgment result can be obtained by judging whether the obtained grid-connected point voltage is within the preset voltage range, wherein the obtained grid-connected point voltage of the isolated power grid is obtained at the second moment, and the first moment occurs before the second moment. Then, under the condition that the second judgment result indicates yes, the application can carry out second excitation control on the synchronous generator which carries out the first excitation control, and control the photovoltaic system to generate electricity on the isolated power grid by adopting a first control method. In the step, the second excitation control can be used for updating the first preset voltage of the synchronous generator to the initial voltage, so that the problem that the power angle is reversed due to the first preset voltage added by the first excitation control of the synchronous generator is avoided during the fault period, and the positive effect is played on the system recovery; the first control method may include a maximum power point tracking method for tracking a maximum power point of the photovoltaic system to maintain voltage balance of the direct current bus of the photovoltaic system, and a rated power control method for controlling the photovoltaic system to output rated active power and rated reactive power to achieve power balance. In addition, under the condition that the second judging result indicates no, the application can control the photovoltaic system to generate power for the isolated power grid by adopting a second control method. In this step, the second control method may include a direct current voltage control method and a first power control method. In this step, the dc voltage control method may be used to stabilize the dc bus voltage of the photovoltaic system to maintain the dc bus voltage balance of the photovoltaic system, and the first power control method is used to control the photovoltaic system to output the first active power and the first active power, i.e. to implement power balance by recalculating the first active power and the first active power of the photovoltaic system. In summary, the synchronous generator and the photovoltaic system can realize cooperative fault ride-through, so that the problem that the new energy power generation (photovoltaic system) is difficult to be compatible with the traditional power system (synchronous generator) during the fault ride-through in the prior art is solved, and a large-scale off-grid accident in an isolated power grid can be avoided.

Drawings

The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the application. In the drawings:

Fig. 1 is a block diagram of a hardware structure of a mobile terminal for performing a multi-source collaborative fault ride-through method of an isolated power grid according to an embodiment of the present application;

Fig. 2 shows a flow diagram of a multi-source collaborative fault ride-through method for an isolated power grid according to an embodiment of the present application;

Fig. 3 is a schematic circuit diagram of a front-stage circuit and a back-stage circuit of a two-stage photovoltaic inverter in a multi-source collaborative fault ride through method of an isolated power grid according to an embodiment of the present application;

fig. 4 shows a control block diagram of a pre-stage circuit switching process in a multi-source collaborative fault ride-through method of an isolated power grid according to an embodiment of the present application;

Fig. 5 shows a schematic diagram of a control strategy of a later-stage circuit in a multi-source collaborative fault ride-through method of an isolated power grid according to an embodiment of the present application;

fig. 6 shows a control block diagram of a switching process of a later-stage circuit in a multi-source collaborative fault ride-through method of an isolated power grid according to an embodiment of the present application;

fig. 7 shows a control block diagram of a synchronous generator excitation process in a multi-source collaborative fault ride-through method of an isolated power grid according to an embodiment of the present application;

Fig. 8 is a schematic diagram of a compensation device of an auxiliary machine frequency converter with an additional energy storage device in a multi-source collaborative fault ride through method of an isolated power grid according to an embodiment of the present application;

FIG. 9 is a flow chart of a method for multi-source collaborative fault ride-through of a specific isolated power grid provided in accordance with an embodiment of the present application;

fig. 10 is a schematic diagram of a three-phase fault system voltage condition of Case1 in a specific multi-source collaborative fault ride-through method of an isolated power grid according to an embodiment of the present application;

Fig. 11 is a schematic diagram showing reactive power situation of a three-phase fault system of Case1 in a specific multi-source collaborative fault ride-through method of an isolated power grid according to an embodiment of the present application;

Fig. 12 is a schematic diagram showing a three-phase fault system voltage condition of Case2 in a specific multi-source collaborative fault ride-through method of an isolated power grid according to an embodiment of the present application;

fig. 13 is a schematic diagram showing reactive power situation of a three-phase fault system of Case2 in a specific multi-source collaborative fault ride-through method of an isolated power grid according to an embodiment of the present application;

fig. 14 shows a block diagram of a multi-source cooperative fault ride-through device for an isolated power grid according to an embodiment of the present application.

Wherein the above figures include the following reference numerals:

102. A processor; 104. a memory; 106. a transmission device; 108. an input-output device; 10. an acquisition module; 20. a first judgment module; 30. a first execution module; 40. a second judging module; 50. a second execution module; 60. and a third execution module.

Detailed Description

It should be noted that, without conflict, the embodiments of the present application and features of the embodiments may be combined with each other. The application will be described in detail below with reference to the drawings in connection with embodiments.

In order that those skilled in the art will better understand the present application, a technical solution in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in which it is apparent that the described embodiments are only some embodiments of the present application, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present application without making any inventive effort, shall fall within the scope of the present application.

It should be noted that the terms "first," "second," and the like in the description and the claims of the present application and the above figures are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate in order to describe the embodiments of the application herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

As described in the background art, auxiliary machines of a thermal power generating unit in the prior art are driven by frequency converters gradually, however, the overload capacity of the auxiliary machine frequency converters is weak, the problem similar to the weak fault ride-through capacity of a photovoltaic power generating unit exists, low voltage can occur in the fault ride-through process, the auxiliary machine frequency converters are locked and output, and then large-scale furnace shutdown occurs, even tripping of a fuel unit is triggered, so that shutdown accidents are caused.

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

The method embodiments provided in the embodiments of the present application may be performed in a mobile terminal, a computer terminal or similar computing device. Taking the mobile terminal as an example, fig. 1 is a hardware structural block diagram of the mobile terminal of a multi-source collaborative fault ride-through method of an isolated power grid according to an embodiment of the present application. As shown in fig. 1, a mobile terminal may include one or more (only one is shown in fig. 1) processors 102 (the processor 102 may include, but is not limited to, a microprocessor MCU or a processing device such as a programmable logic device FPGA) and a memory 104 for storing data, wherein the mobile terminal may also include a transmission device 106 for communication functions and an input-output device 108. It will be appreciated by those skilled in the art that the structure shown in fig. 1 is merely illustrative and not limiting of the structure of the mobile terminal described above. For example, the mobile terminal may also include more or fewer components than shown in fig. 1, or have a different configuration than shown in fig. 1.

The memory 104 may be used to store a computer program, for example, a software program of application software and a module, such as a computer program corresponding to a multi-source collaborative fault ride-through method of an isolated power grid in an embodiment of the present invention, and the processor 102 executes the computer program stored in the memory 104, thereby performing various functional applications and data processing, that is, implementing the method described above. Memory 104 may include high-speed random access memory, and may also include non-volatile memory, such as one or more magnetic storage devices, flash memory, or other non-volatile solid-state memory. In some examples, the memory 104 may further include memory remotely located relative to the processor 102, which may be connected to the mobile terminal via a network. Examples of such networks include, but are not limited to, the internet, intranets, local area networks, mobile communication networks, and combinations thereof. The transmission device 106 is used to receive or transmit data via a network. Specific examples of the network described above may include a wireless network provided by a communication provider of the mobile terminal. In one example, the transmission device 106 includes a network adapter (Network Interface Controller, simply referred to as a NIC) that can connect to other network devices through a base station to communicate with the internet. In one example, the transmission device 106 may be a Radio Frequency (RF) module, which is configured to communicate with the internet wirelessly.

In this embodiment, a multi-source collaborative fault ride-through method of an isolated power grid operating on a mobile terminal, a computer terminal, or a similar computing device is provided, it being noted that the steps illustrated in the flowchart of the figures may be performed in a computer system such as a set of computer executable instructions, and, although a logical sequence is illustrated in the flowchart, in some cases, the steps illustrated or described may be performed in a different order than that illustrated herein.

Fig. 2 is a flow chart of a multi-source collaborative fault ride-through method for an isolated power grid in accordance with an embodiment of the present application. As shown in fig. 2, the method comprises the steps of:

step S201, grid-connected point voltage of an isolated power grid at a first moment is obtained;

Specifically, under the condition that an alternating current power supply of the isolated power grid fails, voltage dip or power interruption phenomenon can occur to grid connection point voltage of the isolated power grid, and therefore large-scale off-grid accidents can occur in the isolated power grid. Therefore, the grid-connected point voltage of the isolated power grid is obtained, and analysis basis is provided for a fault ride-through method for avoiding large-scale off-grid accidents in the isolated power grid.

Step S202, judging whether the voltage of the grid-connected point is in a preset voltage range or not to obtain a first judging result;

Specifically, the voltage of the grid-connected point in the normal operation of the isolated power grid may be a standard voltage, the minimum voltage in the preset voltage range may be a voltage after the voltage of the grid-connected point is suddenly reduced, and the maximum voltage in the preset voltage range may be the standard voltage. The above-mentioned preset voltage range can be set reasonably by a person skilled in the art according to actual situations, and the present application is not limited in particular.

Optionally, the step of obtaining may further be obtaining a grid-connected point voltage drop depth of the grid-connected point voltage in the isolated power grid; the step of judging can also be to judge whether the voltage drop depth of the grid-connected point is within a preset drop depth range. The preset dropping depth range can be the voltage dropping depth of the grid-connected point allowing the voltage of the grid-connected point to drop, and a person skilled in the art can reasonably select according to actual situations.

Step S203, under the condition that the first judging result indicates no, performing first excitation control on the synchronous generator in the isolated power grid, wherein the first excitation control is used for updating the initial voltage of the synchronous generator to a first preset voltage;

Specifically, the first determination result indicates no condition, that is, the grid-connected point voltage in the isolated power grid is characterized as suddenly dropped.

Optionally, most of the traditional power generation systems have strong disturbance rejection capability and strong supporting capability on an isolated power grid due to the voltage specific and excitation automatic regulation system of the synchronous generator, so that the synchronous generator can provide no-power support in fault ride-through and play a role in inertial support. And unlike new energy generator sets (photovoltaic systems) limited by power electronics, synchronous generators have a greater capacity to withstand short-circuit currents. Therefore, under the condition that the voltage of the grid-connected point suddenly drops, the recovery effect of the excitation regulating process of the synchronous generator after the system (the isolated power grid) fails is considered, the synchronous generator in the isolated power grid can be subjected to first excitation control so as to update the initial voltage of the synchronous generator to a first preset voltage, and therefore the first excitation control of the synchronous generator is realized.

Step S204, grid-connected point voltage of the isolated power grid at a second moment is obtained, whether the grid-connected point voltage at the second moment is in a preset voltage range or not is judged, and a second judgment result is obtained, wherein the grid-connected point voltage at the second moment is the grid-connected point voltage after the first excitation control of the synchronous generator;

Specifically, after the first excitation control is performed on the synchronous generator, the grid-connected point voltage of the isolated power grid, that is, the grid-connected point voltage at the second moment, may be obtained again. And further, whether the grid-connected point voltage at the second moment is in the preset voltage range or not can be judged again, and a second judging result indicating yes or a second judging result indicating no can be obtained.

Step S205, under the condition that the second judging result indicates yes, performing second excitation control on the synchronous generator, and controlling the photovoltaic system to generate power on the isolated power grid by adopting a first control method, wherein the second excitation control is used for updating a first preset voltage of the synchronous generator to an initial voltage, the first control method comprises a maximum power point tracking method and a rated power control method, the maximum power point tracking method is used for tracking the maximum power point of the photovoltaic system, and the rated power control method is used for controlling the photovoltaic system to output rated active power and rated reactive power;

Specifically, in the case that the second determination result indicates yes, it indicates that the fault of the isolated power grid has been cleared, so that the second excitation control may be performed on the synchronous generator, so that the first preset voltage of the synchronous generator is restored to the initial voltage. In addition, because the synchronous generator and the photovoltaic system are adopted to pass through the cooperative fault, the photovoltaic system is required to be controlled to generate power for the isolated power grid by adopting the first control method while the synchronous generator is subjected to second excitation control, wherein the first control method comprises a maximum power point tracking method and a rated power control method, so that the voltage balance and the power balance of a direct current bus of the photovoltaic system are maintained.

Step S206, under the condition that the second judging result indicates no, the photovoltaic system is controlled to generate power for the isolated power grid by adopting a second control method, wherein the second control method comprises a direct-current voltage control method and a first power control method, the direct-current voltage control method is used for stabilizing the direct-current bus voltage of the photovoltaic system, and the first power control method is used for controlling the photovoltaic system to output first active power and first active power.

Specifically, under the condition that the second judging result indicates no, the fault of the isolated power grid is not cleared, so that the application also adopts a fault traversing method for controlling the photovoltaic system to generate power for the isolated power grid by adopting a second control method, thereby realizing the purpose of carrying out cooperative fault traversing on the isolated power grid by the first excitation control of the synchronous generator and the second control method of the photovoltaic system, and further avoiding the occurrence of large-area off-grid accidents.

According to the embodiment, first, under the condition that the bus voltage of the grid connection point of the isolated power grid is obtained, whether the grid connection point voltage is in a preset voltage range or not is judged, and a first judgment result can be obtained. Aiming at the condition that the first judgment result indicates no, the synchronous generator in the isolated power grid is subjected to first excitation control, and a second judgment result can be obtained by judging whether the power generation equipment in the isolated power grid normally operates or not. In this step, the first excitation control may be used to update the initial voltage of the synchronous generator to a first preset voltage. And further, under the condition that the second judgment result indicates yes, the application can carry out second excitation control on the synchronous generator which is subjected to the first excitation control, and control the photovoltaic system to generate power on the isolated power grid by adopting the first control method. In the step, the second excitation control can be used for updating the first preset voltage of the synchronous generator to the initial voltage, so that the problem that the first preset voltage added by the first excitation control of the synchronous generator causes reverse power angle during the fault period is avoided, and the positive effect is played on system recovery; the first control method may include a maximum power point tracking method for tracking a maximum power point of the photovoltaic system to maintain bus voltage balance, and a rated power control method for controlling the photovoltaic system to output rated active power and rated reactive power to achieve power balance. In addition, under the condition that the second judging result indicates no, the application can control the photovoltaic system to generate power for the isolated power grid by adopting a second control method. In this step, the second control method may include the above maximum power point tracking method and the first power control method, and similarly, the maximum power point tracking method is used for tracking a maximum power point of the photovoltaic system to maintain the voltage balance of the dc bus of the photovoltaic system, and the first power control method is used for controlling the photovoltaic system to output the first active power and the first active power, that is, by recalculating the first active power and the first active power of the photovoltaic system, power balance is achieved. The application can cooperate with the fault ride-through of the synchronous generator and the photovoltaic system, and can avoid large-scale off-grid accidents in the isolated power grid, thereby solving the problem that the new energy power generation (photovoltaic system) is difficult to be compatible with the traditional power system (synchronous generator) during the fault ride-through in the prior art.

In one aspect, in some optional embodiments, the power generation device of the isolated power grid further includes an auxiliary device, that is, after the first excitation control is performed on the synchronous generator, in order to improve safe and reliable operation of the isolated power grid, fault ride-through capability of the auxiliary device may also be considered, so that in a case where the second determination result indicates yes, the multi-source collaborative fault ride-through method further includes: and controlling the auxiliary equipment to supply power to a first load, wherein the first load is all loads which adopt the auxiliary equipment to supply power in the isolated power grid.

On the other hand, in some optional embodiments, the power generation device of the isolated power grid further includes an auxiliary device, that is, after the first excitation control is performed on the synchronous generator, in order to improve safe and reliable operation of the isolated power grid, fault ride-through capability of the auxiliary device may also be considered, so that in a case that the second determination result indicates no, the multi-source collaborative fault ride-through method further includes: and controlling the auxiliary equipment to supply power to a second load, wherein the second load is part of all loads which adopt the auxiliary equipment to supply power in the isolated power grid. It can be understood that under the condition that the second judgment result indicates no, the grid-connected point voltage of the isolated power grid is not recovered to the grid-connected point voltage in the normal operation stage of the isolated power grid, so that the grid-connected point voltage at the moment may threaten auxiliary equipment to enable the auxiliary equipment to trip and protect, and therefore, the method adopted in the embodiment cuts out part of loads in the isolated power grid to operate so as to achieve the purpose of improving the safety and stability of the isolated power grid.

It should be noted that, the power generation equipment of the isolated power grid of the application may further include a storage battery, and if the second judgment result indicates no, the grid-connected point voltage of the isolated power grid is not recovered to the grid-connected point voltage of the isolated power grid in the normal operation stage, but the auxiliary equipment is not threatened, so that the auxiliary equipment is trip-protected. At the moment, partial load in the isolated power grid is not required to be cut off, auxiliary equipment can be controlled to supply power to the first load, meanwhile, a storage battery can be controlled to drive the auxiliary equipment, and therefore the purpose of improving safety and stability of the isolated power grid is achieved.

In some optional embodiments, the power generation device of the isolated power grid further includes an auxiliary device and a storage battery, so that, in a case where the voltage of the grid connection point of the isolated power grid is a fault voltage (the voltage of the grid connection point is not within a preset voltage range), the storage battery can have a capability of driving the auxiliary device, so that, in a case where the first determination result indicates yes, the multi-source collaborative fault ride through method further includes: and controlling the auxiliary equipment to supply power to a third load, wherein the third load is all loads for supplying power by adopting the auxiliary equipment in the isolated power grid, and controlling the auxiliary equipment to charge a storage battery.

In some optional embodiments, in a case that the second determination result indicates no, the multi-source collaborative fault ride-through method further includes: judging whether the voltage of a direct current bus of the photovoltaic system is over-voltage or not to obtain a third judging result; under the condition that the third judging result indicates yes, executing the step of controlling the photovoltaic system to generate power on the isolated power grid by adopting a second control method; and under the condition that the third judging result indicates no, controlling the photovoltaic system to generate power for the isolated power grid by adopting a third control method, wherein the third control method comprises a maximum power point tracking method and a second power control method, and the second power control method is used for controlling the photovoltaic system to output second active power and second reactive power.

In the above embodiment, after the step of performing the first excitation control on the synchronous generator, different fault ride-through strategies are adopted for the case that the grid-connected point voltage of the isolated power grid is still the fault voltage, that is, the second judgment result indicates no. Namely, under the condition that the detected direct current bus voltage exceeds the rated voltage which can be borne by an inverter in the photovoltaic system, the direct current bus voltage overvoltage of the photovoltaic system can be considered (namely, the third judgment result indicates yes), and at the moment, the step of controlling the photovoltaic system to generate power for an isolated power grid by adopting a second control method can be executed; and under the condition that the detected direct current bus voltage does not exceed the rated voltage which can be borne by an inverter in the photovoltaic system, the direct current bus voltage of the photovoltaic system can be considered to be not overvoltage (namely, the third judging result indicates no), at the moment, the photovoltaic system can be controlled to generate power for an isolated power grid by adopting a third control method, wherein the third control method can comprise the maximum power point tracking method and a second control method, and the second control method can be used for controlling the photovoltaic system to recalculate and output second active power and second reactive power.

In some alternative embodiments, the photovoltaic system includes a photovoltaic panel and a two-stage photovoltaic inverter, the two-stage photovoltaic inverter including a front stage for boosting dc-dc conversion and a rear stage for ac-dc conversion, the second excitation control of the synchronous generator, and controlling the photovoltaic system in the isolated grid to generate power from the isolated grid using a first control method, comprising: performing first preset excitation control on the synchronous generator to update the first preset voltage to the second preset voltage; performing second preset excitation control on the synchronous generator to update the second preset voltage to the initial voltage, wherein the second excitation control comprises first preset excitation control and second preset excitation control; the control front stage adopts a maximum power point tracking control method to track the maximum power point of the photovoltaic cell panel; and the control later stage adopts a rated power control method to output rated active power and rated reactive power of the two-stage photovoltaic inverter so as to generate power for the isolated power grid.

It is first clear that the first predetermined voltage is a positive reference voltage that the synchronous generator increases in order to increase the voltage supporting effect on the system in case of a fault not cleared, to increase the excitation effect. In the above embodiment, the rear stage circuit can be restored to rated power control since the fault has been cleared, and therefore, the synchronous generator fault is removed to the maximum process of the power angle swing, and the additional forward reference voltage during the fault is maintained first. And further, in the process of the power angle from the maximum value to the minimum value, the positive reference voltage is cleared, and the negative reference voltage is increased to prevent the power angle from reversing, namely, the first preset voltage is updated to the second preset voltage. The subsequent swing and swing rest phases are restored to normal states, and the reference voltage is not added with any value, namely the second preset voltage is updated to the initial voltage.

In some alternative embodiments, the photovoltaic system includes a photovoltaic panel and a two-stage photovoltaic inverter, the two-stage photovoltaic inverter having a structure including a front stage for boosting dc-dc conversion and a rear stage for ac-dc conversion, the photovoltaic system being controlled to generate power from an isolated grid using a second control method, comprising: the control front stage adopts a direct-current voltage control method to stabilize the direct-current bus voltage of the photovoltaic system; and the control later stage adopts a first power control method to control the two-stage photovoltaic inverter to output first active power and first active power so as to generate power for the isolated power grid.

In the above embodiment, the control of the maximum power point tracking method is suspended by controlling the front stage by using the dc voltage control method, so that the dc bus voltage is stabilized. The active power and the reactive power of the two-stage photovoltaic inverter are recalculated by controlling the rear stage by adopting the first power control method, so that the two-stage photovoltaic inverter is switched from rated active power to first active power, and the two-stage photovoltaic inverter is switched from rated reactive power to first active power, thereby achieving the purpose of generating power by utilizing new first active power and first active power sight low-voltage ride through to an isolated power grid.

In order to enable those skilled in the art to more clearly understand the technical solution of the present application, the implementation process of the multi-source collaborative fault ride-through method of the isolated power grid of the present application will be described in detail below with reference to specific embodiments.

The embodiment relates to a specific multi-source collaborative fault ride-through method of an isolated power grid, which comprises the following steps:

Step S1: analyzing the characteristics of the power generation technology of the photovoltaic power generation unit and the fuel unit, and establishing an isolated power grid model containing the photovoltaic power generation unit, the excitation control of the fuel unit, auxiliary machines of the power plant and the power consumption load;

step S2: the method comprises the steps of considering the output characteristics and the requirements on fault ride-through capability of new energy photovoltaic power generation, designing respective fault ride-through methods according to the recovery action of the whole excitation process of a generator after system faults and the requirements on the low-voltage ride-through capability of an auxiliary frequency converter of a power plant;

Step S3: by considering the fault falling depth and the time scale of fault ride-through control strategies of different power generation units and through a multi-source cooperative switching control method, the coordination fault ride-through capability of the new energy power generation unit and the traditional power system is improved, and the safe and reliable operation of the system is ensured.

The photovoltaic power generation system can adopt a two-stage photovoltaic inverter control method in consideration of the fact that the photovoltaic power generation unit is constrained by power electronic devices and has low overcurrent tolerance level. Optionally, the two-stage photovoltaic inverter includes a front stage circuit and a back stage circuit, as shown in fig. 3, where PV is a solar panel in the front stage circuit, g1 is a PWM control signal in the front stage circuit, U _dc is a dc bus voltage, g2 is a PWM control signal in the back stage circuit, L _f is a filter inductance in the back stage circuit, and AC is an alternating current (whose alternating currents are i _a,i_b and i _c, and alternating voltages are V _a,V_b and V _c).

Optionally, the pre-stage circuit adopts a Boost circuit to realize maximum power point tracking method control (MPPT). The front-stage control specifically comprises the following steps: as shown in fig. 4, the output voltage U _pv and the current i _pv of the solar panel are detected, and the voltage U _max of the maximum power point of the solar panel can be gradually approximated to the voltage by using an interference observation method (Perturb & Observe algorithms, P & O) to obtain a duty ratio, and then compared with a triangular carrier wave to obtain a PWM driving signal. The back-stage circuit adopts a virtual synchronous generator control strategy to realize the three-phase grid-connected inverter.

Optionally, under the normal condition (i.e. no voltage drop occurs) of the system, the control strategy is shown in fig. 4, at this time, the control switch is S ₁, the front-stage circuit of the photovoltaic power generation system is used for stabilizing the voltage of the dc bus, and the rear-stage virtual synchronous generator controls the inverter to output active power and reactive power. When the voltage drop occurs in the system, the front-stage Boost circuit also tracks the maximum power point, generates a modulation signal d, and obtains a PWM control signal g1 through comparing the modulation signal d with a carrier wave, wherein the PWM control signal g1 controls the on-off of a thyristor of the front-stage circuit, the output power of the front-stage inverter is unchanged, the voltage drop at the network side causes the power imbalance of the system, the problem of the voltage rise of a direct-current bus occurs, and overcurrent protection or overvoltage protection is caused, so that the photovoltaic inverter is off-network. Furthermore, in order to realize the fault ride-through of the photovoltaic inverter, the fault voltage drop depth U _T and the direct current bus voltage U _dc can be detected, a front-stage circuit switch is dialed to S ₂, the tracking of the maximum power point is firstly suspended, the control of the constant direct current voltage U _{dc_ref} is adopted, and the stability of the direct current bus voltage U _dc is ensured by utilizing a proportional integral controller (PI control) according to the control deviation of U _dc and U _{dc_ref}. After the fault is removed, the maximum power point tracking reference voltage U _max in a normal working state can be adopted for smooth transition; the back-end circuit switches the reference power from the rated value to a new power value by recalculating the active power and reactive power reference values, thereby realizing low-voltage ride through by using the new active and reactive reference powers.

Optionally, as the related photovoltaic grid-connected standard specifies that the inverter needs to absorb or send reactive current to the system as far as possible to meet the specified standard during the fault, so as to support the voltage of the system, and the calculation formula of the reactive current reference value I _Q of the inverter during the fault is as follows:

Where U _N represents a system rated voltage, I _N represents a system rated current, and U _T represents a fault drop voltage.

Optionally, according to the reactive current required to be output by the inverter, the reference value of the reactive power output by the inverter can be recalculated, and meanwhile, the input of active power is ensured as far as possible, and the calculation formulas of the reference value P _ref of the active power and the reference value Q _ref of the reactive power are as follows:

Q_ref＝I_Q×U_T，

Where I _Q denotes the inverter output reactive current during a fault, U _T denotes the fault drop voltage, S denotes the system rated capacity, and P _N denotes the rated active power.

Optionally, under the condition that a new energy generator set of the system is in a normal working condition, the front stage of the photovoltaic inverter can adopt maximum power tracking control, and the rear stage circuit can realize power output change by changing an active power reference value; when the system fails, the switch can be switched from S ₁ to S ₂ to direct-current voltage control as shown in FIG. 4 once the overvoltage condition occurs in the front-stage circuit; the back-stage circuit can calculate an active power reference value and a reactive power reference value according to the fault voltage condition, so that the power balance of the system is maintained as much as possible, the system is enabled to avoid the operation condition of a cutting machine as much as possible, and the fault crossing capability is improved.

Alternatively, as shown in fig. 5, the latter-stage control is specifically: the voltage and current information collection is carried out from an AC end (the alternating currents are i _a,i_b and i _c, the alternating voltages are V _a,V_b and V _c), then the active power P and the reactive power Q are calculated through dq/abc conversion, when the fault voltage U _g is detected through amplitude, no overvoltage condition occurs, the switch is arranged at S ₁, and the output voltage amplitude E and the phase theta are controlled through VSG by utilizing P, Q, f _ref、P_N、Q_N. If the amplitude detection and the overvoltage occur, the switch is switched to S ₂, P, Q, f _ref、P_ref、Q_ref generates new voltage amplitude E and phase theta through VSG control to generate reference voltage, and then the control signal g2 is obtained through inner loop control to realize the switch control of the later-stage circuit.

Specifically, as shown in fig. 6, virtual synchronous generator control is adopted, through simulating synchronous generator frequency modulation and excitation voltage regulation processes, inertial support of a system is enhanced by utilizing a synchronous generator swing equation, wherein the voltage reference phase θ of an inverter is obtained by utilizing the frequency droop characteristic of the inverter and combining with the virtual inertial regulation characteristic of the synchronous generator, and then the voltage reference amplitude E _m of the inverter is generated by utilizing reactive power-voltage droop characteristic, namely, the reference voltage amplitude and the phase of the inverter are obtained by utilizing two formulas of active power-phase and reactive power-voltage to realize control, and the power outer loop is controlled as follows:

E_m＝U_ref+k_q(Q_ref-Q)，

Where f ₀ denotes the system nominal frequency, w ₀ denotes the system nominal angular velocity, k _p denotes the active and frequency droop coefficients, k _q denotes the reactive and voltage droop coefficients, J denotes the virtual inertia constant, The method comprises the steps of representing the actual angular speed change rate of an inverter, P _ref representing the reference active power of the inverter, P representing the actual output active power of the inverter, f representing the actual frequency of the inverter, E _m representing the control voltage amplitude of the inverter, U _ref representing the rated voltage reference value, Q _ref representing the reference reactive power of the inverter and Q representing the actual output reactive power of the inverter.

The synchronous generator can adopt an excitation control method due to the voltage characteristic and the excitation automatic regulation system, so that reactive power support can be provided in fault ride-through, the synchronous generator has strong disturbance rejection capability, and is limited by power electronic devices relative to a new energy generator set, and the synchronous generator has stronger short-circuit current bearing capability and stronger power grid support capability.

Specifically, when the system is in a fault state, the excitation control of the synchronous generator plays a role in regulation, and has stronger voltage stabilizing capability. As shown in fig. 7, fig. 7 is a block diagram of a synchronous generator excitation system control structure, V _a is an additional voltage for fault recovery process excitation control, and reference values are selected according to switching of different fault recovery stages; v _PSS is the additional reference voltage of the power system stabilizer, U _G is the terminal voltage of the generator, and the three voltages are added to form the control system reference voltage V _ref. The method comprises the steps of detecting the machine end voltage U _G of the generator through an excitation controller measuring link G _R(s), comparing the detected voltage with a reference voltage V _ref to obtain a voltage difference (V _ref-U_G), solving the problem that a measuring signal and the reference voltage deviate little and cannot drive a circuit to work through a comprehensive amplifying unit G _A(s), then preventing the driving signal from being overlarge through an amplitude limiting link, and obtaining a control voltage U _C to control an excitation unit G(s) to realize the excitation regulation process of the synchronous generator to obtain a synchronous generator voltage output U _G.

Alternatively, as shown in fig. 7, the synchronous generator excitation system voltage measurement comparing unit generally ignores the delay of the comparing circuit, measures the synchronous generator terminal voltage U _G in real time, compares the deviation thereof from the reference voltage V _ref, and generally has the transfer function as follows:

Where G _R(s) represents a voltage measurement comparison unit transfer function, K _R is a measurement unit scaling factor, T _R is a measurement unit time constant, s represents a sign of a complex frequency, and is an expression after laplace transform.

Because the deviation signal between the measurement signal output by the measurement unit and the reference voltage V _ref is smaller, the power driving signal can be obtained after being amplified by the integrated power amplifying unit, as shown in fig. 7, the output signal of the amplifying unit needs to be subjected to an amplitude limiting link, and the control model is as follows:

Where G _A(s) is a transfer function of the integrated amplifying unit, K _A is a voltage amplifying coefficient, T _A is an amplifier time constant, s represents a sign of complex frequency, and is an expression after laplace transform.

By establishing a simple synchronous generator excitation loop mathematical model, neglecting damping effect in the excitation process, as shown in fig. 7, the transfer function of the excitation unit is obtained:

Wherein G _G(s) is an excitation unit transfer function, K _G is a synchronous motor amplification factor, T _G is a synchronous motor response time constant, s represents a sign of complex frequency, and is an expression after Laplacian transformation.

Optionally, the synchronous generator often uses excitation control to ensure stable operation of the system in the fault crossing process, and in order to improve the capability of maintaining the system stable in the fault process of the synchronous generator, the fault transient process can be divided into five stages according to the power angle relation of the synchronous generator. Different control strategies are respectively carried out according to the characteristics of each stage, so that the fault recovery capability of the system is improved. As shown in fig. 7, V _a is the additional voltage for the fault recovery process excitation control, V _PSS is the additional reference voltage for the power system stabilizer, and the specific switching control process is:

1) The 1 st and 2 nd phases refer to the process from the occurrence of a short-circuit fault to the fault removal, and then to the swing of the power angle to the maximum value, and in the first two phases, in order to enhance the excitation of the synchronous generator as quickly as possible, a proper positive voltage Δv _ref needs to be added to the reference voltage 0 of the automatic voltage regulator (automatic voltage regulation, AVR) in the excitation control system, and at this time, the switch is switched from S ₁ to S ₂.

2) Stage 3 refers to the process of swinging from the maximum value to the minimum value of the power angle of the synchronous generator, in which the positive voltage DeltaV _ref added to the reference voltage of the automatic voltage regulator needs to be removed, the control logic is switched from S ₂ to S ₃, and a negative voltage DeltaV _ref is added to prevent the generator from swinging in the reverse direction of the power angle, and even the step-out phenomenon is caused.

3) The 4 th and 5 th phases refer to the subsequent swing and oscillation rest phases of the power angle, the phases need to be switched back to S ₁ in time for control, the negative reference voltage-DeltaV _ref added in the third phase process is cut off, and meanwhile, the oscillation is stabilized as soon as possible through multi-source collaborative fault ride-through (PSS) of an isolated power grid of a power system stabilizer (power system stabili), so that the function of promoting the whole fault recovery process is achieved.

In the fault process, the excitation process of the synchronous generator needs to be increased by a positive voltage reference value DeltaV _ref as soon as possible to maintain the stability of the system; after the fault is removed, in order to prevent the over-excitation from making a successful angle reverse, a negative voltage reference value-DeltaV _ref is required to be added, and the control is restored to S ₁ in the subsequent oscillation rest stage to promote the normal operation of the system.

In addition, besides providing power support for a power grid, most of important auxiliary equipment (such as coal mills, conveyor belts and other equipment) in the thermal power plant adopts a self-powered mode. In order to achieve the effects of speed regulation and economic operation, auxiliary machines of a thermal power plant mostly adopt a frequency converter driving mode, and meanwhile, strict requirements are placed on fault crossing capacity. Once voltage dip, overvoltage or power interruption occurs, the frequency converter is locked, and important auxiliary equipment trips to cause fire extinguishing protection (MFT) action shutdown of a hearth, even shutdown accidents of a generator set and the like, the stable and safe operation of the system is seriously threatened, and economic loss and personal safety threat are caused. Aiming at the problem of insufficient fault ride-through capability of the frequency converter, auxiliary equipment such as an energy storage unit, a storage battery and the like can be added to maintain stable bus voltage by utilizing an active direct current compensation mode, and an 'uncontrolled rectification+storage battery' structure is adopted, and a schematic diagram of a compensation device is shown in fig. 8.

As shown in fig. 8, the auxiliary equipment operates on the principle that: under normal working conditions or in a voltage drop range of more than 0.9pu, the low-voltage ride through strategy is not started, power is supplied by a power plant (A-phase voltage u _a, B-phase voltage u _b and C-phase voltage u _c) to convert the frequency converter into alternating current to drive the auxiliary machine M to work, and meanwhile, uncontrolled rectification (AC/DC) is converted into direct current to charge the energy storage unit, so that the storage battery is maintained in a saturated charging state. When the AC power supply fails and has voltage dip or power interruption, the power grid voltage drops below 0.9pu, fault ride-through is started, the storage battery is boosted by the voltage dip protector to compensate the DC bus voltage U _dc of the frequency converter, and the voltage is continuously supplied to the frequency converter to drive auxiliary equipment to work. When the system is recovered to be normal, the frequency converter is changed into power supply under normal working conditions, the voltage sag protector automatically recovers to be in a standby state, and meanwhile, the storage battery is charged to be in a saturated state.

Optionally, the multi-source collaborative fault ride through control of the isolated network system can be realized according to the coordination and coordination of different fault ride through strategies of the new energy photovoltaic power generation and the fuel unit in fault ride through, and the photovoltaic power generation system is limited by power electronic devices, so that voltage support is limited to the system when the system is in fault. The synchronous generator has strong capability of bearing short-circuit current due to the adjustment of the excitation system, and the influence of system faults on the synchronous generator set is small. The important auxiliary equipment of the thermal power plant mostly has frequency converter control driving work, and once the fault is serious, the auxiliary equipment can trip and protect actions. The coordinated switching control strategy of the system can be realized by the system fault voltage drop depth and different power generation technology control scales, and when necessary, partial unimportant load can be cut off when the important auxiliary machine is not blocked to cause the shutdown accident of the fuel machine set, and the unloading operation is used for ensuring the safe, continuous and reliable system operation.

In summary, in the case where the isolated power grid system includes the above-mentioned photovoltaic power generation system (control), fuel generator set (control), auxiliary equipment (control) and electric load, as shown in fig. 9, a specific control method for fault ride-through may be:

When the system fails and the fault voltage drops below 0.9pu, and if the direct current bus of the photovoltaic system (photovoltaic power generation system) is overvoltage (overvoltage), the front stage and the circuit are switched to S ₂ (direct current voltage control and new active power and reactive power reference value control are adopted). If the photovoltaic system (photovoltaic power generation system) does not have an overvoltage condition on the dc bus, the front stage remains S ₁ (maximum power point tracking control) and the back stage switches to S ₂ (new active power and reactive power control is used). Meanwhile, in order to increase the voltage supporting effect on the system, the synchronous generator increases a positive reference voltage (namely, the additional voltage +DeltaV _ref of the synchronous generator excitation control (1 stage)) in the excitation control, so that the excitation effect is increased. Then, judging whether the fault voltage endangers the driving of the auxiliary equipment, if the fault voltage does not endanger the driving of the auxiliary equipment (namely, if the fault voltage does not endanger the tripping protection of the auxiliary equipment (NO)), the auxiliary equipment can be temporarily driven by the storage battery (namely, the storage battery supplies power), and once the tripping protection of the auxiliary equipment is endangered (yes), the operation of cutting off partial load is adopted, so that the safety and the stability of the system are ensured.

As shown in fig. 9, it is determined whether the fault is cleared, and if the fault is cleared, both the front stage and the back stage of the photovoltaic system switch back to S ₁ control (the front stage circuit adopts the maximum power fault smooth transition under normal working conditions, and the back stage circuit resumes rated power control). The additional forward reference voltage (namely the additional voltage +DeltaV _ref of synchronous generator excitation control (2 stages)) is maintained during the period from the fault removal of the synchronous generator to the maximum process of the power angle swing; the process of the power angle from the maximum value to the minimum value, the positive reference voltage is cleared, the negative reference voltage is increased to prevent the reverse direction of the power angle (namely, the additional voltage-DeltaV _ref of the excitation control (3 stages) of the synchronous generator); the subsequent swing and swing calm phases are restored to normal states, and no value is added to the reference voltage (namely, the additional voltage of the excitation control (4, 5 phases) of the synchronous generator is 0). And the auxiliary equipment resumes the normal power supply mode after the fault clearing voltage is recovered, and supplies power to the storage battery for charging (the storage battery is charged) for next standby.

In this embodiment, when the system fails and voltage drops, the isolated power grid system including the high-proportion new energy photovoltaic power generation and fuel unit can play a role in supporting voltage for the system according to the fault ride-through control of the photovoltaic system during the failure period, the front-stage circuit switches the maximum power to track to maintain the bus voltage balance, and the rear-stage circuit recalculates the active power reference value and the reactive power reference value to realize power balance. Meanwhile, after the fault is cleared, in order to avoid the problem of reverse power angle caused by exciting additional positive voltage reference of the synchronous generator during the fault, the additional negative voltage needs to be switched and controlled in time, and the subsequent stable oscillation process needs to be switched into a normal working state, thereby playing a positive role in system recovery. The auxiliary machinery of the power plant can be influenced during the fault period, once the voltage is lower than 0.9pu, the energy storage unit supplies power to the frequency converter to maintain the auxiliary machinery to work normally, and once the voltage drops too low, part of non-important load needs to be cut off in order to ensure the stable operation of the system.

By way of example, the system may consist of an auxiliary machine, a synchronous generator, a photovoltaic inverter and a 60MW load, the output voltage of the synchronous generator is 13.8kV, the output voltage of the synchronous generator is increased to 230kV through a step-up transformer, the output voltage of the photovoltaic inverter is 380V, and the fault simulation is carried out on an isolated power grid system through transformer access system.

Case1: the system has three-phase short circuit fault at 5s, the voltage drops to 0.8pu, and the fault of 5.5s is cleared, at this time, the system voltage condition is shown in fig. 10 (including the system voltage under normal control in the prior art corresponding to the dotted line and the system voltage under improved control in the application corresponding to the solid line), and the system power change is shown in fig. 11 (including the system reactive power under normal control in the prior art corresponding to the dotted line and the system reactive power under improved control in the application corresponding to the solid line).

And in Case2, when the system has a three-phase short circuit serious fault in 5s, the fault voltage drops to 0.6pu, the fault of 5.5s is cleared, compared with the fault, in order to prevent the auxiliary machine from tripping, the system voltage under the improved control of the operation of the partial load is shown as a solid line in fig. 12 (the system voltage under the normal control in the prior art is shown as a line required in fig. 12), and the reactive power of the system under the improved control of the operation of the partial load is shown as a solid line in fig. 13 (the reactive power of the system under the normal control in the prior art is shown as a line required in fig. 13).

As can be seen, after the three-phase fault occurs in fig. 10, the voltage drops to 0.8pu, and because the excitation links of the power system stabilizer and the synchronous generator participate in control, the system has larger inertia and strong supporting force on the system voltage, and in order to maintain the voltage stability, the system outputs reactive power, so that the voltage of the isolated grid system does not drop to below 0.9pu, and the stable operation of the system is ensured. When serious three-phase short-circuit fault occurs and voltage drop is serious, in order to ensure stable operation of the system and improve recovery capability after a fault process, load shedding operation is performed, and as can be seen by comparing voltage drop conditions during different control strategy faults through fig. 12 and fig. 13, the voltage supporting effect of the system under multi-source coordinated control fault ride-through control is better.

The embodiment of the application also provides a multi-source cooperative fault ride-through device of the isolated power grid, and the multi-source cooperative fault ride-through device of the isolated power grid can be used for executing the multi-source cooperative fault ride-through method for the isolated power grid. The device is used for realizing the above embodiments and preferred embodiments, and is not described in detail. As used below, the term "module" may be a combination of software and/or hardware that implements a predetermined function. While the means described in the following embodiments are preferably implemented in software, implementation in hardware, or a combination of software and hardware, is also possible and contemplated.

The following describes a multi-source collaborative fault ride-through device for an isolated power grid provided by the embodiment of the application.

Fig. 14 is a schematic diagram of a multi-source coordinated fault ride-through device for an isolated power grid according to an embodiment of the application. As shown in fig. 14, the apparatus includes:

the acquisition module 10 is used for acquiring grid-connected point voltage of the isolated power grid at a first moment;

The first judging module 20 is configured to judge whether the voltage of the point of connection is within a preset voltage range, so as to obtain a first judging result;

The first execution module 30 is configured to perform first excitation control on the synchronous generator in the isolated power grid, where the first judgment result indicates no, and the first excitation control is used to update an initial voltage of the synchronous generator to a first preset voltage;

Optionally, most of the traditional power generation systems have strong disturbance rejection capability and strong supporting capability on an isolated power grid due to the voltage specific and excitation automatic regulation system of the synchronous generator, so that the synchronous generator can provide no-power support in fault ride-through and play a role in inertial support. And unlike new energy generator sets (photovoltaic power generation systems) limited by power electronics, synchronous generators have a greater capacity to withstand short-circuit currents. Therefore, under the condition that the voltage of the grid-connected point suddenly drops, the recovery effect of the excitation regulating process of the synchronous generator after the system (the isolated power grid) fails is considered, the synchronous generator in the isolated power grid can be subjected to first excitation control so as to update the initial voltage of the synchronous generator to a first preset voltage, and therefore the first excitation control of the synchronous generator is realized.

The second judging module 40 is configured to obtain a grid-connected point voltage of the isolated power grid at a second moment, and judge whether the grid-connected point voltage at the second moment is within a preset voltage range, so as to obtain a second judging result, where the grid-connected point voltage at the second moment is the grid-connected point voltage after the first excitation control is performed on the synchronous generator;

The second execution module 50 is configured to perform second excitation control on the synchronous generator and control the photovoltaic system to generate power on the isolated power grid by using a first control method if the second determination result indicates yes, where the second excitation control is used to update a first preset voltage of the synchronous generator to an initial voltage, the first control method includes a maximum power point tracking method and a rated power control method, the maximum power point tracking method is used to track a maximum power point of the photovoltaic system, and the rated power control method is used to control the photovoltaic system to output rated active power and rated reactive power;

The third execution module 60 is configured to control the photovoltaic system to generate power on the isolated power grid by using a second control method if the second determination result indicates no, where the second control method includes a dc voltage control method and a first power control method, the dc voltage control method is used to stabilize a dc bus voltage of the photovoltaic system, and the first power control method is used to control the photovoltaic system to output the first active power and the first active power.

Specifically, under the condition that the second judging result indicates no, the fault of the isolated power grid is not cleared, so that the application also adopts a fault traversing method for controlling the photovoltaic system to generate power for the isolated power grid by adopting a second control method, thereby realizing the purpose of carrying out cooperative fault traversing on the isolated power grid by the first excitation control of the synchronous generator and the second control method of the photovoltaic system, and further avoiding the occurrence of large-area off-grid accidents. Optionally, the power generation device of the isolated power grid further includes an auxiliary device, and the multi-source cooperative fault ride-through device further includes: the first control module is used for controlling the auxiliary equipment to supply power to a first load, wherein the first load is all loads which adopt the auxiliary equipment to supply power in the isolated power grid.

Optionally, the power generation device of the isolated power grid further includes an auxiliary device, and the multi-source cooperative fault ride-through device further includes: and the second control module is used for controlling the auxiliary equipment to supply power to a second load, wherein the second load is part of all loads which adopt the auxiliary equipment to supply power in the isolated power grid.

Optionally, the power generation device of the isolated power grid further includes an auxiliary device and a storage battery, and the multi-source cooperative fault ride-through device further includes: and the third control module is used for controlling the auxiliary equipment to supply power to a third load, wherein the third load is all loads which adopt the auxiliary equipment to supply power in the isolated power grid, and controlling the auxiliary equipment to charge the storage battery.

Optionally, in the case that the second determination result indicates no, the multi-source cooperative fault ride-through device further includes: the third judging module is used for judging whether the direct current bus voltage of the photovoltaic system is overvoltage or not to obtain a third judging result; the fourth control module is used for executing the step of controlling the photovoltaic system to generate power for the isolated power grid by adopting the second control method under the condition that the third judging result indicates yes; and the fourth control module is used for controlling the photovoltaic system to generate power on the isolated power grid by adopting a maximum power point tracking method and a second power control method under the condition that the third judgment result indicates no, and the second power control method is used for controlling the photovoltaic system to output second active power and second reactive power.

Optionally, the photovoltaic system includes a photovoltaic panel and a two-stage photovoltaic inverter, the two-stage photovoltaic inverter includes a front stage and a rear stage, the front stage is used for boosting direct current-direct current conversion, the rear stage is used for alternating current-direct current conversion, and the second execution module includes: the first updating unit is used for carrying out first preset excitation control on the synchronous generator so as to update the first preset voltage to the second preset voltage; a second updating unit, configured to perform a second preset excitation control on the synchronous generator to update a second preset voltage to an initial voltage, where the second excitation control includes a first preset excitation control and a second preset excitation control; the first control unit is used for controlling the front stage to track the maximum power point of the photovoltaic cell panel by adopting a maximum power point tracking control method; and the second control unit is used for controlling the rear stage to output rated active power and rated reactive power by adopting a rated power control method to output the two-stage photovoltaic inverter so as to generate power for the isolated power grid.

Optionally, the photovoltaic system includes a photovoltaic panel and a two-stage photovoltaic inverter, and the structure of the two-stage photovoltaic inverter includes a front stage and a rear stage, the front stage is used for boosting direct current-direct current conversion, the rear stage is used for alternating current-direct current conversion, and the third execution module includes: the third control unit is used for controlling the front stage to stabilize the DC bus voltage of the photovoltaic system by adopting a DC voltage control method; and the fourth control unit is used for controlling the rear stage to adopt a first power control method to control the two-stage photovoltaic inverter to output first active power and first active power so as to generate power for the isolated power grid.

The multi-source collaborative fault ride-through device of the isolated power grid comprises a processor and a memory, wherein the acquisition module, the first judging module, the first executing module, the second judging module, the second executing module, the third executing module and the like are all stored in the memory as program units, and the processor executes the program units stored in the memory to realize corresponding functions. The modules are all located in the same processor; or the above modules may be located in different processors in any combination.

The processor includes a kernel, and the kernel fetches the corresponding program unit from the memory. The core can be provided with one or more cores, and the problem that the new energy power generation (photovoltaic system) is difficult to be compatible with the traditional power system (synchronous generator) during the fault ride-through in the prior art is solved by adjusting the parameters of the core.

The memory may include volatile memory, random Access Memory (RAM), and/or nonvolatile memory, such as Read Only Memory (ROM) or flash memory (flash RAM), among other forms in computer readable media, the memory including at least one memory chip.

The embodiment of the invention provides a computer readable storage medium, which comprises a stored program, wherein when the program runs, equipment where the computer readable storage medium is located is controlled to execute a multi-source collaborative fault ride-through method of an isolated power grid.

The embodiment of the invention provides an electronic device, which comprises a processor, a memory and a program stored on the memory and capable of running on the processor, wherein the processor realizes the steps of the multi-source collaborative fault ride-through method of an isolated power grid when executing the program. The device herein may be a server, PC, PAD, cell phone, etc.

The application also provides a computer program product adapted to perform a program of steps of a multi-source collaborative fault ride-through method initialized with an isolated power grid when executed on a data processing apparatus.

It will be appreciated by those skilled in the art that the modules or steps of the invention described above may be implemented in a general purpose computing device, they may be concentrated on a single computing device, or distributed across a network of computing devices, they may be implemented in program code executable by computing devices, so that they may be stored in a storage device for execution by computing devices, and in some cases, the steps shown or described may be performed in a different order than that shown or described herein, or they may be separately fabricated into individual integrated circuit modules, or multiple modules or steps of them may be fabricated into a single integrated circuit module. Thus, the present invention is not limited to any specific combination of hardware and software.

It will be appreciated by those skilled in the art that embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.

The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

In one typical configuration, a computing device includes one or more processors (CPUs), input/output interfaces, network interfaces, and memory.

The memory may include volatile memory in a computer-readable medium, random Access Memory (RAM) and/or nonvolatile memory, etc., such as Read Only Memory (ROM) or flash RAM. Memory is an example of a computer-readable medium.

Computer readable media, including both non-transitory and non-transitory, removable and non-removable media, may implement information storage by any method or technology. The information may be computer readable instructions, data structures, modules of a program, or other data. Examples of storage media for a computer include, but are not limited to, phase change memory (PRAM), static Random Access Memory (SRAM), dynamic Random Access Memory (DRAM), other types of Random Access Memory (RAM), read Only Memory (ROM), electrically Erasable Programmable Read Only Memory (EEPROM), flash memory or other memory technology, compact disc read only memory (CD-ROM), digital Versatile Discs (DVD) or other optical storage, magnetic cassettes, magnetic tape disk storage or other magnetic storage devices, or any other non-transmission medium, which can be used to store information that can be accessed by a computing device. Computer-readable media, as defined herein, does not include transitory computer-readable media (transmission media), such as modulated data signals and carrier waves.

It should also be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises an element.

From the above description, it can be seen that the above embodiments of the present application achieve the following technical effects:

According to the multi-source collaborative fault ride-through method for the isolated power grid, first, under the condition that the bus voltage of the grid-connected point of the isolated power grid is obtained, a first judgment result can be obtained by judging whether the grid-connected point voltage is in a preset voltage range. Aiming at the condition that the first judgment result indicates no, the synchronous generator in the isolated power grid is subjected to first excitation control, and a second judgment result can be obtained by judging whether the power generation equipment in the isolated power grid normally operates or not. In this step, the first excitation control may be used to update the initial voltage of the synchronous generator to a first preset voltage. And further, under the condition that the second judgment result indicates yes, the application can carry out second excitation control on the synchronous generator which is subjected to the first excitation control, and control the photovoltaic system to generate power on the isolated power grid by adopting the first control method. In the step, the second excitation control can be used for updating the first preset voltage of the synchronous generator to the initial voltage, so that the problem that the first preset voltage added by the first excitation control of the synchronous generator causes reverse power angle during the fault period is avoided, and the positive effect is played on system recovery; the first control method may include a maximum power point tracking method for tracking a maximum power point of the photovoltaic system to maintain bus voltage balance, and a rated power control method for controlling the photovoltaic system to output rated active power and rated reactive power to achieve power balance. In addition, under the condition that the second judging result indicates no, the application can control the photovoltaic system to generate power for the isolated power grid by adopting a second control method. In this step, the second control method may include the above maximum power point tracking method and the first power control method, and similarly, the maximum power point tracking method is used for tracking a maximum power point of the photovoltaic system to maintain the voltage balance of the dc bus of the photovoltaic system, and the first power control method is used for controlling the photovoltaic system to output the first active power and the first active power, that is, by recalculating the first active power and the first active power of the photovoltaic system, power balance is achieved. The application can cooperate with the fault ride-through of the synchronous generator and the photovoltaic system, and can avoid large-scale off-grid accidents in the isolated power grid, thereby solving the problem that the new energy power generation (photovoltaic system) is difficult to be compatible with the traditional power system (synchronous generator) during the fault ride-through in the prior art.

The above description is only of the preferred embodiments of the present application and is not intended to limit the present application, but various modifications and variations can be made to the present application by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A multi-source coordinated fault ride-through method for an isolated power grid, characterized by comprising:

Obtaining the grid connection point voltage of the isolated power grid at a first moment;

Determine whether the grid connection point voltage is within a preset voltage range to obtain a first determination result;

When the first judgment result indicates a negative result, performing a first excitation control on the synchronous generator in the isolated power grid, wherein the first excitation control is used to update the initial voltage of the synchronous generator to a first preset voltage;

Obtaining a grid connection point voltage of the isolated power grid at a second moment, and determining whether the grid connection point voltage at the second moment is within the preset voltage range, to obtain a second determination result, wherein the grid connection point voltage at the second moment is the grid connection point voltage after the first excitation control is performed on the synchronous generator;

In the case where the second judgment result indicates yes, a second excitation control is performed on the synchronous generator, and the photovoltaic system in the isolated power grid is controlled to generate electricity for the isolated power grid using a first control method, wherein the second excitation control is used to update the first preset voltage of the synchronous generator to the initial voltage, and the first control method includes a maximum power point tracking method and a rated power control method, wherein the maximum power point tracking method is used to track the maximum power point of the photovoltaic system, and the rated power control method is used to control the photovoltaic system to output rated active power and rated reactive power;

When the second judgment result indicates no, the photovoltaic system is controlled to generate electricity for the isolated power grid using a second control method, the second control method including a DC voltage control method and a first power control method, the DC voltage control method being used to stabilize the DC bus voltage of the photovoltaic system, and the first power control method being used to control the photovoltaic system to output a first active power and a first reactive power.

2. The multi-source coordinated fault ride-through method according to claim 1, characterized in that the power generation equipment of the isolated power grid further includes auxiliary equipment, and when the second judgment result indicates yes, the multi-source coordinated fault ride-through method further includes:

The auxiliary device is controlled to supply power to a first load, where the first load is all loads in the isolated power grid that are powered by the auxiliary device.

3. The multi-source coordinated fault ride-through method according to claim 1, characterized in that the power generation equipment of the isolated power grid further includes auxiliary equipment, and when the second judgment result indicates no, the multi-source coordinated fault ride-through method further includes:

The auxiliary device is controlled to supply power to a second load, where the second load is a portion of all loads in the isolated power grid that are powered by the auxiliary device.

4. The multi-source coordinated fault ride-through method according to claim 1, characterized in that the power generation equipment of the isolated power grid further includes auxiliary equipment and batteries, and when the first judgment result indicates yes, the multi-source coordinated fault ride-through method further includes:

The auxiliary device is controlled to supply power to a third load, where the third load is all loads in the isolated power grid that are powered by the auxiliary device, and the auxiliary device is controlled to charge the battery.

5. The multi-source coordinated fault traversal method according to any one of claims 1 to 4, characterized in that in the second

When the judgment result indicates no, the multi-source coordinated fault traversal method further includes:

Determine whether a DC bus voltage of the photovoltaic system is overvoltage, and obtain a third determination result;

When the third judgment result indicates yes, executing the step of controlling the photovoltaic system to generate electricity for the isolated power grid using the second control method;

When the third judgment result indicates no, the photovoltaic system is controlled to generate electricity for the isolated power grid using a third control method, the third control method includes the maximum power point tracking method and a second power control method, and the second power control method is used to control the photovoltaic system to output a second active power and a second reactive power.

6. The multi-source coordinated fault ride-through method according to any one of claims 1 to 4, characterized in that the photovoltaic system includes a photovoltaic panel and a two-stage photovoltaic inverter, the two-stage photovoltaic inverter includes a front stage and a rear stage, the front stage is used for boosting DC-DC conversion, and the rear stage is used for AC-DC conversion, the synchronous generator is subjected to a second excitation control, and the photovoltaic system in the isolated power grid is controlled to generate electricity for the isolated power grid using a first control method, comprising:

Performing a first preset excitation control on the synchronous generator to update the first preset voltage to a second preset voltage;

Performing a second preset excitation control on the synchronous generator to update the second preset voltage to the initial voltage, wherein the second excitation control includes the first preset excitation control and the second preset excitation control;

Controlling the front stage to track the maximum power point of the photovoltaic panel using the maximum power point tracking control method;

The rear stage is controlled to output the rated active power and the rated reactive power of the two-stage photovoltaic inverter using the rated power control method, so as to generate electricity for the isolated power grid.

7. The multi-source coordinated fault ride-through method according to any one of claims 1 to 4, characterized in that the photovoltaic system comprises a photovoltaic panel and a two-stage photovoltaic inverter, the structure of the two-stage photovoltaic inverter comprises a front stage and a rear stage, the front stage is used for boosting DC-DC conversion, and the rear stage is used for AC-DC conversion, and controlling the photovoltaic system to generate electricity for the isolated power grid using a second control method comprises:

Controlling the front stage to use the DC voltage control method to stabilize the DC bus voltage of the photovoltaic system;

The latter stage is controlled to adopt the first power control method to control the two-stage photovoltaic inverter to output the first active power and the first reactive power, so as to generate electricity for the isolated power grid.

8. A multi-source coordinated fault ride-through device for an isolated power grid, characterized by comprising:

An acquisition module, used for acquiring the grid connection point voltage of the isolated power grid at a first moment;

A first judgment module, used to judge whether the grid connection point voltage is within a preset voltage range, and obtain a first judgment result;

A first execution module, configured to perform a first excitation control on the synchronous generator in the isolated power grid when the first judgment result indicates a negative value, wherein the first excitation control is used to update an initial voltage of the synchronous generator to a first preset voltage;

a second judgment module, configured to obtain a grid connection point voltage of the isolated power grid at a second moment, and to judge whether the grid connection point voltage at the second moment is within the preset voltage range, to obtain a second judgment result, wherein the second moment is the grid connection point voltage after the first excitation control is performed on the synchronous generator;

a second execution module, configured to, when the second judgment result indicates yes, perform a second excitation control on the synchronous generator, and control the photovoltaic system in the isolated power grid to generate electricity for the isolated power grid using a first control method, wherein the second excitation control is used to update the first preset voltage of the synchronous generator to the initial voltage, the first control method includes a maximum power point tracking method and a rated power control method, the maximum power point tracking method is used to track the maximum power point of the photovoltaic system, and the rated power control method is used to control the photovoltaic system to output rated active power and rated reactive power;

A third execution module is used to control the photovoltaic system to generate electricity for the isolated power grid using a second control method when the second judgment result indicates no, the second control method includes a DC voltage control method and a first power control method, the DC voltage control method is used to stabilize the DC bus voltage of the photovoltaic system, and the first power control method is used to control the photovoltaic system to output a first active power and a first reactive power.

9. A computer-readable storage medium, characterized in that the computer-readable storage medium includes a stored program, wherein when the program is running, the device where the computer-readable storage medium is located is controlled to execute the multi-source collaborative fault crossing method for an isolated power grid as described in any one of claims 1 to 7.

10. An electronic device, characterized in that it comprises: one or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and are configured to be executed by the one or more processors, and the one or more programs include a method for executing a multi-source collaborative fault crossing method of an isolated power grid as described in any one of claims 1 to 7.