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CN119482523A - A fault ride-through method for an inverter and related equipment - Google Patents

A fault ride-through method for an inverter and related equipment Download PDF

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Publication number
CN119482523A
CN119482523A CN202411187026.1A CN202411187026A CN119482523A CN 119482523 A CN119482523 A CN 119482523A CN 202411187026 A CN202411187026 A CN 202411187026A CN 119482523 A CN119482523 A CN 119482523A
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inverter
output voltage
fault
grid
power
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Inventor
张丽
李胜男
蒋陈根
彭俊臻
唐金锐
鲁晓天
许守东
陈勇
奚鑫泽
卢佳
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Electric Power Research Institute of Yunnan Power Grid Co Ltd
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Electric Power Research Institute of Yunnan Power Grid Co Ltd
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Priority to CN202411187026.1A priority Critical patent/CN119482523A/en
Publication of CN119482523A publication Critical patent/CN119482523A/en
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for AC mains or AC distribution networks
    • H02J3/24—Arrangements for preventing or reducing oscillations of power in networks
    • H02J3/241—The oscillation concerning frequency
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F18/00—Pattern recognition
    • G06F18/20—Analysing
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for AC mains or AC distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for AC mains or AC distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
    • H02J3/48—Controlling the sharing of the in-phase component
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for AC mains or AC distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
    • H02J3/50—Controlling the sharing of the out-of-phase component
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
    • H02J2203/10—Power transmission or distribution systems management focussing at grid-level, e.g. load flow analysis, node profile computation, meshed network optimisation, active network management or spinning reserve management
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
    • H02J2203/20—Simulating, e g planning, reliability check, modelling or computer assisted design [CAD]

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
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  • General Engineering & Computer Science (AREA)
  • General Physics & Mathematics (AREA)
  • Artificial Intelligence (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Inverter Devices (AREA)

Abstract

本申请实施例公开了一种逆变器的故障穿越方法及相关设备，通过第一幅值和第一相角、第二幅值和第二相角、逆变器到电网之间滤波回路的总电阻和总电感构建并网系统故障等值模型，并基于并网系统故障等值模型、第三幅值和第三相角、第一阻抗角和第二阻抗角获得逆变器故障期间的第三输出电压，利用第三输出电压和正常情况时逆变器输出的第一有功功率，获得逆变器的第二有功功率，并利用第三输出电压和第二有功功率对逆变器进行控制，从而在进行低压穿越时通过利用第三输出电压和第二有功功率对逆变器进行控制，减少了有功功率和无功功率的耦合问题，以增强逆变器故障穿越的稳定性，确保了电网在低压条件下能够得到足够的无功支撑。

The embodiment of the present application discloses a fault ride-through method for an inverter and related equipment, which constructs a grid-connected system fault equivalent model through a first amplitude and a first phase angle, a second amplitude and a second phase angle, and a total resistance and a total inductance of a filter loop between the inverter and the power grid, and obtains a third output voltage during the inverter fault period based on the grid-connected system fault equivalent model, a third amplitude and a third phase angle, a first impedance angle, and a second impedance angle, and obtains a second active power of the inverter by using the third output voltage and a first active power output by the inverter under normal conditions, and controls the inverter by using the third output voltage and the second active power, thereby reducing the coupling problem of active power and reactive power by controlling the inverter during low voltage ride-through, thereby enhancing the stability of the inverter fault ride-through and ensuring that the power grid can obtain sufficient reactive support under low voltage conditions.

Description

Fault ride-through method of inverter and related equipment
[ Field of technology ]
The present invention relates to the field of inverter fault ride-through technology, and in particular, to a fault ride-through method for an inverter and related devices.
[ Background Art ]
As the proportion of new energy in the power system increases, the stability of the traditional power grid faces new challenges. The new energy grid-connected inverter generally lacks rotational inertia like a conventional synchronous generator, which makes it difficult for the grid to remain stable in the event of frequency fluctuations and short-circuit faults. When the voltage of the power grid fluctuates, the conventional low-voltage ride through strategy is not fully applicable to the power system with high-proportion new energy. Especially when the short-circuit current influence is ignored, the inverter may not be continuously operated in a grid-connected mode under a low-voltage condition, which may not only cause instability of power supply, but also trigger a series of chain reactions to aggravate the fluctuation and instability of the power grid.
The VSG control technology of the virtual synchronous machine is introduced to solve the problem that the new energy grid-connected inverter lacks rotational inertia, and stability of a power grid is enhanced by simulating inertia and damping characteristics of a traditional synchronous generator. However, during the low voltage ride through of the inverter, the operating conditions of the inverter may become more complex, especially when the short circuit current impacts the grid. Conventional VSG control strategies may not adequately address these complications, resulting in difficulty in maintaining grid frequencies and voltages within stable ranges.
[ Invention ]
In view of the above, the present invention provides a fault ride-through method for an inverter and related apparatus.
The specific technical scheme of the first embodiment of the invention is that the fault ride-through method of the inverter is applied to a power system, and comprises the steps of constructing a grid-connected system fault equivalent model by utilizing a first amplitude value and a first phase angle of a first output voltage of the inverter, a second amplitude value and a second phase angle of a second output voltage of a power grid in the power system, and a total resistance and a total inductance of a filter loop between the inverter and the power grid, acquiring a second impedance model between the inverter and the power grid after the fault occurrence based on the grid-connected system fault equivalent model, a third amplitude value and a third phase angle of the power grid output voltage after the fault occurrence, bringing the first impedance angle of the inverter and the second impedance angle of the inverter after the fault occurrence into the second impedance model to obtain a third output voltage during the fault occurrence of the inverter, utilizing the third output voltage and the first active power output by the inverter during the normal occurrence to obtain the second active power of the inverter, and utilizing the third output voltage and the second active power to control the inverter.
Preferably, the grid-connected system fault equivalent model is obtained by adopting the following formula:
Wherein, For the first output voltage, V i is the first magnitude, θ is the first phase angle,For the second output voltage, V g is the second amplitude, δ is the second phase angle, Z L is the total impedance, R i is the equivalent resistance between the inverter outlet and the grid-connected point, L i is the equivalent inductance between the inverter outlet and the grid-connected point, R linel is the equivalent resistance between the left side of the line and the fault point, L linel is the equivalent inductance between the left side of the line and the fault point, R liner is the resistance between the fault point and the right side of the line, L liner is the inductance between the fault point and the right side of the line, R L is the total resistance, L L is the total inductance, ω is the angular speed of the power system, and t is the time of the power system.
Preferably, the second impedance model is obtained by using the following formula:
Wherein Z ' L is the impedance between the inverter and the grid after the fault, R ' L is the total resistance between the inverter and the grid after the fault, L ' L is the total inductance between the inverter and the grid after the fault, V i is the first amplitude, ω is the angular velocity of the power system, t is the time of the power system, V ' g is the amplitude of the output voltage of the grid in the power system after the fault, δ ' is the phase angle of the output voltage of the grid after the fault or the phase angle of the output voltage of the power system after the fault.
Preferably, the step of bringing the first impedance angle of the inverter in the normal condition and the second impedance angle of the inverter after the fault occurs into the second impedance model to obtain a third output voltage during the fault period of the inverter comprises the steps of bringing the first impedance angle of the inverter in the normal condition and the second impedance angle of the inverter after the fault occurs into the second impedance model to obtain an output current model during the fault period of the inverter, obtaining a first power angle of an electric power system in the normal condition and obtaining a second power angle of the electric power system after the fault occurs, and obtaining the third output voltage according to the output current model, the first power angle and the second power angle.
Preferably, after the third output voltage during the inverter fault period is obtained, the method further comprises the step of optimizing the third output voltage by using a preset per unit value to obtain a reference output voltage value of the inverter, and the step of obtaining the second active power of the inverter by using the third output voltage and the first active power output by the inverter under the normal condition comprises the step of obtaining the second active power of the inverter by using the reference output voltage value and the first active power output by the inverter under the normal condition, and the step of controlling the inverter by using the third output voltage and the second active power comprises the step of controlling the inverter by using the reference output voltage value and the second active power.
Preferably, the reference output voltage value is obtained by using the following formula:
Wherein V s is the reference output voltage value, V sn is the amplitude of the inverter output voltage under normal conditions, V i is the first amplitude, V g is the second amplitude, ω is the angular velocity of the power system, L L is the total inductance between the inverter outlet and the grid in normal conditions, I i is the amplitude of the output current of the inverter in normal conditions, V' g is the third amplitude,And k is a preset coefficient for the per unit value of the output voltage of the power grid.
Preferably, the second active power is obtained by the following formula:
Wherein, P ref is the second active power, V sn is the amplitude of the inverter output voltage in the normal condition, V s is the reference output voltage value, and P refn is the active power output by the inverter in the normal condition.
The specific technical scheme of the second embodiment of the invention is that the system comprises a grid-connected system fault equivalent model construction module, a model conversion module, an output voltage acquisition module, an active power acquisition module and a control module, wherein the grid-connected system fault equivalent model construction module is used for constructing a grid-connected system fault equivalent model by utilizing a first amplitude value and a first phase angle of a first output voltage of an inverter, a second amplitude value and a second phase angle of a second output voltage of a power grid in a power system and a total resistance and a total inductance of a filter loop between the inverter and the power grid, the grid-connected system fault equivalent model comprises a first impedance model between the inverter and the power grid, the model conversion module is used for acquiring a second impedance model between the inverter and the power grid after the fault based on the grid-connected system fault equivalent model, a third amplitude value and a third phase angle of the power grid output voltage after the fault, the output voltage acquisition module is used for bringing the first impedance angle of the inverter and the second impedance model after the fault into the second impedance model under normal condition, acquiring a third output voltage of the inverter during the fault period, and the third active power module is used for controlling the first active power output of the inverter and the active power controller under the normal condition.
The specific technical scheme of the third embodiment of the application is that the fault ride-through device of the inverter comprises a memory and a processor, wherein the memory stores a computer program, and the computer program, when executed by the processor, causes the processor to execute the steps of the method according to any one of the first embodiment of the application.
A specific solution of a fourth embodiment of the present application is a computer readable storage medium storing a computer program, which when executed by a processor causes the processor to perform the steps of the method according to any of the first embodiments of the present application.
The implementation of the embodiment of the invention has the following beneficial effects:
According to the invention, a grid-connected system fault equivalent model is constructed through the first amplitude, the first phase angle, the second amplitude and the second phase angle, and the total resistance and total inductance of a filter loop between the inverter and the power grid, and a third output voltage during the fault period of the inverter is obtained based on the grid-connected system fault equivalent model, the third amplitude, the third phase angle, the first impedance angle and the second impedance angle, the third output voltage and the first active power output by the inverter under normal conditions are utilized to obtain a second active power of the inverter, and the third output voltage and the second active power are utilized to control the inverter, so that the coupling problem of the active power and the reactive power is reduced through utilizing the third output voltage and the second active power during low-voltage ride-through, the stability of the fault ride-through of the inverter is enhanced, and the power grid is ensured to obtain enough reactive power support under the low-voltage condition.
[ Description of the drawings ]
In order to more clearly illustrate the embodiments of the application or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a flow chart illustrating steps of a fault ride-through method for an inverter;
FIG. 2 is a schematic structural diagram of a grid-connected system fault equivalence model;
FIG. 3 is a flowchart showing steps for obtaining a third output voltage;
FIG. 4 is a flowchart showing steps for optimizing a third output voltage using per unit values;
FIG. 5 is a schematic diagram of a networked inverter control strategy model;
FIG. 6a is an output current of an inverter employing VSG control during a voltage sag;
FIG. 6b is an output current of a VSG controlled inverter employing low voltage ride through according to the present application during a voltage sag;
FIG. 6c is the output voltage of an inverter employing VSG control during a voltage sag;
FIG. 6d is the output voltage of a VSG controlled inverter employing low voltage ride through according to the present application during a voltage sag;
Fig. 6e is the output power of an inverter employing VSG control during a voltage sag;
FIG. 6f is the output power of a VSG controlled inverter employing low voltage ride through according to the present application during a voltage sag;
fig. 7 is a schematic structural diagram of a fault ride-through system of an inverter;
The system comprises a grid-connected system fault equivalent model construction module 401, a model conversion module 402, an output voltage acquisition module 403, an active power acquisition module 404 and a control module 405.
[ Detailed description ] of the invention
The following description of the embodiments of the present application will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
The terms first, second and the like in the description and in the claims and drawings are used for distinguishing between different objects and not for describing a particular sequential order. Furthermore, the terms "comprise" and "have," as well as any variations thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, system, article, or apparatus that comprises a list of steps or modules is not limited to only those steps or modules but may include other steps or modules not expressly listed or inherent to such process, method, article, or apparatus.
Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Those of skill in the art will explicitly and implicitly appreciate that the embodiments described herein may be combined with other embodiments.
Referring to fig. 1, a flow chart of steps of a fault ride-through method of an inverter in a first embodiment of the present application is provided to ensure that a power grid can be adequately supported under a low-voltage condition, the method includes:
Step 101, constructing a grid-connected system fault equivalent model by using a first amplitude and a first phase angle of a first output voltage of an inverter, a second amplitude and a second phase angle of a second output voltage of a power grid in a power system, and a total resistance and a total inductance of a filter loop between the inverter and the power grid, wherein the grid-connected system fault equivalent model comprises a first impedance model between the inverter and the power grid;
102, acquiring a second impedance model between the inverter and the power grid after the fault based on the grid-connected system fault equivalent model, a third amplitude value and a third phase angle of the power grid output voltage after the fault;
Step 103, bringing a first impedance angle of the inverter in normal condition and a second impedance angle of the inverter after the fault occurs into the second impedance model to obtain a third output voltage during the fault period of the inverter;
104, obtaining a second active power of the inverter by using the third output voltage and the first active power output by the inverter under normal conditions;
Step 105, controlling the inverter by using the third output voltage and the second active power.
Specifically, referring to FIG. 2, the grid-connected system failure equivalence model includes 1) left new energy and grid-connected inverter based on virtual synchronous generator control, wherein vectors of output voltage and current are as follows2) The vector of the output voltage and current of the right power grid system power supply is3) The equivalent resistance and inductance between the inverter outlet and the grid-tie point PCC point is R i、Li. 4) The internal resistance and inductance of the power grid system are R g、Lg. 5) And connecting the grid to a line between the power systems, wherein faults occur on the line, and the fault type is short-circuit faults. After a fault, the resistance and inductance from the left side of the line to the fault point is R linel、Llinel, and the resistance and inductance from the fault point to the right side of the line is R liner、Lliner.
According to the method, a grid-connected system fault equivalent model is built through the first amplitude, the first phase angle, the second amplitude and the second phase angle, and the total resistance and total inductance of a filter loop between the inverter and a power grid, a third output voltage during the fault period of the inverter is obtained based on the grid-connected system fault equivalent model, the third amplitude, the third phase angle, the first impedance angle and the second impedance angle, the third output voltage and the first active power output by the inverter under normal conditions are utilized to obtain the second active power of the inverter, and the third output voltage and the second active power are utilized to control the inverter, so that the coupling problem of the active power and the reactive power is reduced through utilizing the third output voltage and the second active power during low-voltage ride-through, the stability of the fault ride-through of the inverter is enhanced, and the power grid is ensured to obtain enough reactive power under the low-voltage condition.
In a specific embodiment, the grid-connected system fault equivalent model is obtained by adopting the following formula:
Wherein, For the first output voltage, V i is the first magnitude, θ is the first phase angle,For the second output voltage, V g is the second amplitude, δ is the second phase angle, Z L is the total impedance, R i is the equivalent resistance between the inverter outlet and the grid-connected point, L i is the equivalent inductance between the inverter outlet and the grid-connected point, R linel is the equivalent resistance between the left side of the line and the fault point, L linel is the equivalent inductance between the left side of the line and the fault point, R liner is the resistance between the fault point and the right side of the line, L liner is the inductance between the fault point and the right side of the line, R L is the total resistance, L L is the total inductance, ω is the angular speed of the power system, and t is the time of the power system.
In a specific embodiment, the second impedance model is obtained using the following formula:
Wherein Z ' L is the impedance between the inverter and the grid after the fault, R ' L is the total resistance between the inverter and the grid after the fault, L ' L is the total inductance between the inverter and the grid after the fault, V i is the first amplitude, ω is the angular velocity of the power system, t is the time of the power system, V ' g is the amplitude of the output voltage of the grid in the power system after the fault, δ ' is the phase angle of the output voltage of the grid after the fault or the phase angle of the output voltage of the power system after the fault. Specifically, after a fault occurs on the grid-connected line, writing an inverter fault current expression according to the grid-connected equivalent system. At this point the grid voltage amplitude and phase angle become V ' g and delta ', and the impedance between VSG and grid changes from Z L to Z ' L.
In a specific embodiment, referring to fig. 3, the step of bringing the first impedance angle of the inverter in the normal condition and the second impedance angle of the inverter after the fault occurs into the second impedance model to obtain a third output voltage during the fault period of the inverter includes:
Step 201, bringing a first impedance angle of the inverter in normal condition and a second impedance angle of the inverter after the occurrence of faults into the second impedance model to obtain an output current model during the faults of the inverter;
Step 202, acquiring a first power angle of the power system in a normal condition and acquiring a second power angle of the power system after a fault occurs;
and 203, obtaining the third output voltage according to the output current model, the first power angle and the second power angle.
Specifically, the output current model is obtained by adopting the following formula:
Wherein, In order to decay the time constant,AndIs the impedance before failure Z L and the impedance after failure Z' L;
and writing a kirchhoff expression according to a grid-connected equivalent system column under normal conditions:
Wherein, The current vector is output by the power grid during normal operation of the system;
Based on Calculating the power angle theta-delta of the system in normal operation:
Wherein I i is the amplitude of the current vector output by the inverter during normal operation of the system;
Based on the grid-connected equivalent system column writing kirchhoff expression under normal condition
Wherein, For the voltage vector output by the inverter during a system fault,For the voltage vector output by the grid during a system fault, L' L is the total inductance between the inverter and the grid during a system fault,A current vector output by the inverter during a system fault;
Based on And calculating the power angle theta-delta' of the system in normal operation.
V if is the amplitude of the voltage vector output by the inverter during the system fault period, and V' g is the amplitude of the voltage vector output by the power grid during the system fault period;
The simultaneous output current model, the first power angle and the second power angle obtain a third output voltage, and the expression of the third output voltage is as follows:
in the formula, Beta represents the depth of the grid voltage drop.
In a specific embodiment, referring to fig. 4, after the obtaining the third output voltage during the inverter fault period, the method further includes:
Step 301, optimizing the third output voltage by using a preset per unit value to obtain a reference output voltage value of the inverter;
obtaining the second active power of the inverter using the third output voltage and the first active power output by the inverter under normal conditions comprises:
Step 302, obtaining a second active power of the inverter by using the reference output voltage value and the first active power output by the inverter under normal conditions;
the controlling the inverter using the third output voltage and the second active power includes:
step 303, controlling the inverter by using the reference output voltage value and the second active power.
The method specifically refers to the national regulation of new energy grid-connected low-voltage ride through regulations, and takes the fact that the inductance value between the inverter and the power grid is not large into consideration, and replaces L' L with L L. And controlling the fault current of the inverter to be not more than 1.4 times of that of the normal operation, and obtaining the value of the reference output voltage of the inverter. The voltage output by the inverter is changed during the fault.
In a specific embodiment, the reference output voltage value is obtained using the following formula:
Wherein V s is the reference output voltage value, V sn is the amplitude of the inverter output voltage under normal conditions, V i is the first amplitude, V g is the second amplitude, ω is the angular velocity of the power system, L L is the total inductance between the inverter outlet and the grid in normal conditions, I i is the amplitude of the output current of the inverter in normal conditions, V' g is the third amplitude,And k is a preset coefficient for the per unit value of the output voltage of the power grid.
Specifically, the preset coefficient is preferably 7.84, and the formula for obtaining the reference output voltage value is as follows:
in a specific embodiment, the second active power is obtained by adopting the following formula:
Wherein, P ref is the second active power, V sn is the amplitude of the inverter output voltage in the normal condition, V s is the reference output voltage value, and P refn is the active power output by the inverter in the normal condition.
In a specific embodiment, please refer to fig. 5, which is a schematic diagram of a control strategy model of a grid-built inverter applied to virtual synchronous generator control according to the present application, by using the control strategy model shown in fig. 5, specifically, firstly, a power calculation module obtains active power and reactive power of a grid-connected point PCC, secondly, an active power-frequency calculation module sends the active power obtained by the power calculation module to the module to calculate and control the frequency and angular velocity of the inverter, secondly, a reactive power-voltage module sends the reactive power obtained by the power calculation module to the module to calculate and control the voltage amplitude of the inverter, and combines the angular velocity obtained by the active power-frequency calculation module and the voltage amplitude obtained by the reactive power-voltage module into electromotive force. Then, a virtual impedance control module sends the electromotive force into the virtual impedance control module, and the synthesized electromotive force is decoupled to a certain extent to obtain a reference value under a voltage re-dq 0 coordinate system; and finally, the reference value is sent into voltage and current double closed-loop control to control the output voltage and current of the inverter. The voltage reference value of the virtual synchronous generator terminal can be regulated, so that current output during faults is effectively limited, the problem of equipment protection and excision caused by overlarge current is avoided, and the stability and safety of the system can be maintained under the condition of deeper voltage drop. In addition, by increasing the constraint condition that the power angle is unchanged before and after the fault, the method can keep stable operation of the VSG during the fault occurrence period and prevent the system from being unstable, so that the VSG can still provide inertial support and voltage support for the power grid under the fault condition. The strategy not only ensures that the power grid can obtain enough reactive power support under the low-voltage condition and prevents the voltage from further decreasing, but also improves the overall stability of the power grid. The method remarkably improves the application effect of the VSG in the high-proportion new energy access power grid, improves the fault response capability of the VSG, reduces the coupling problem of active power and reactive power, and improves the accuracy of integral control. The VSG inverter without the low voltage ride through strategy fails in the power grid, and the output current is as shown in fig. 6a after the grid-connected point voltage drops to 0.3 pu. When a fault occurs in 1.0s, the amplitude of the output current of the inverter is greatly increased, exceeds a current limit value 490A and reaches more than 550A, and when the power grid fails and the voltage drops, the VSG inverter adopting the low-voltage ride-through strategy outputs current as shown in fig. 6b. The output current amplitude of the inverter is almost unchanged when 1.0s fails, the inverter can be prevented from being cut off by a protection device due to overlarge current, the VSG inverter which does not adopt the low-voltage ride through strategy fails in a power grid, and the output voltage is as shown in figure 6c after the voltage drops by 0.3 pu. When a fault occurs in 1.0s, the output voltage of the inverter is only reduced to 255V, which is about 0.8pu, regulated by the VSG control strategy of the inverter. The VSG inverter adopting the low-voltage ride through strategy has the function of supporting the voltage of the power grid, and the output voltage is shown in fig. 6d after the power grid fails and the voltage drops by 0.3 pu. At 1.0s failure occurs and the output voltage of the inverter drops to 182V, approximately 0.58pu, regulated by the improved VSG control strategy. Still higher than the voltage drop amplitude (0.3 pu), and plays a role in supporting the power grid voltage. The VSG inverter without the low voltage ride through strategy fails in the power grid, and after the voltage drops by 0.3pu, the active power and the reactive power are output as shown in fig. 6e. The active power and reactive power output are disturbed at this time, because the original control link of the inverter is disabled after the voltage drops, the active power and reactive power are coupled and cannot be controlled by the control link, the VSG inverter adopting the low voltage ride through strategy fails in the power grid, and the output active power and reactive power are as shown in fig. 6f after the voltage drops by 0.3 pu. The active power and reactive power outputs remain coupled at the beginning but can already be controlled separately. Finally, after the power grid voltage drops, the inverter can still increase stable reactive power, and the effect of supporting the power grid voltage is achieved.
In a specific embodiment, please refer to fig. 7, which is a schematic structural diagram of a fault ride-through system of an inverter in a second embodiment of the present application, the system includes a grid-connected system fault equivalent model building module 401, a model conversion module 402, an output voltage obtaining module 403, an active power obtaining module 404 and a control module 405;
The grid-connected system fault equivalent model construction module 401 is configured to construct a grid-connected system fault equivalent model by using a first amplitude and a first phase angle of a first output voltage of an inverter, a second amplitude and a second phase angle of a second output voltage of a power grid in a power system, and a total resistance and a total inductance of a filter loop between the inverter and the power grid, wherein the grid-connected system fault equivalent model comprises a first impedance model between the inverter and the power grid, the model conversion module 402 is configured to obtain a second impedance model between the inverter and the power grid after the failure based on the grid-connected system fault equivalent model, a third amplitude and a third phase angle of the output voltage of the power grid after the failure, the output voltage acquisition module 403 is configured to bring the first impedance angle of the inverter and the second impedance angle of the inverter after the failure into the second impedance model to obtain a third output voltage during the failure of the inverter, the active power acquisition module 404 is configured to obtain a second active power of the inverter by using the third output voltage and the third active power output by the inverter under normal conditions, and the control module 405 is configured to control the inverter by using the third output voltage and the third active power.
In a specific embodiment, a fault-ride-through device for an inverter according to the third embodiment of the present application includes a memory and a processor, where the memory stores a computer program, and the computer program when executed by the processor causes the processor to perform the steps of the method according to any one of the first embodiment of the present application.
In a specific embodiment, a computer readable storage medium according to a fourth embodiment of the present application stores a computer program, where the computer program when executed by a processor causes the processor to perform the steps of the method according to any one of the first embodiments of the present application. The technical features of the above embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The foregoing examples illustrate only a few embodiments of the application, which are described in detail and are not to be construed as limiting the scope of the application. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the application, which are all within the scope of the application. Accordingly, the protection scope of the present application should be determined by the appended claims.
The present invention is not limited to the above-mentioned embodiments, and any equivalent embodiments which can be changed or modified by the technical content disclosed above can be applied to other fields, but any simple modification, equivalent changes and modification made to the above-mentioned embodiments according to the technical substance of the present invention without departing from the technical content of the present invention still belong to the protection scope of the technical solution of the present invention.

Claims (10)

1.一种逆变器的故障穿越方法，应用于电力系统，其特征在于，所述方法包括：1. A fault ride-through method for an inverter, applied to a power system, characterized in that the method comprises: 利用逆变器的第一输出电压的第一幅值和第一相角、电力系统中电网的第二输出电压的第二幅值和第二相角、逆变器到电网之间滤波回路的总电阻和总电感构建并网系统故障等值模型；Constructing a grid-connected system fault equivalent model using a first amplitude and a first phase angle of a first output voltage of the inverter, a second amplitude and a second phase angle of a second output voltage of the power grid in the power system, and a total resistance and a total inductance of a filter loop between the inverter and the power grid; 基于所述并网系统故障等值模型、发生故障后的电网输出电压的第三幅值和第三相角，获取发生故障后逆变器与电网之间的第二阻抗模型；Based on the grid-connected system fault equivalent model, a third amplitude and a third phase angle of the grid output voltage after the fault occurs, obtaining a second impedance model between the inverter and the grid after the fault occurs; 将正常情况时逆变器的第一阻抗角和故障发生后逆变器的第二阻抗角带入到所述第二阻抗模型，获得逆变器故障期间的第三输出电压；Substituting a first impedance angle of the inverter in a normal situation and a second impedance angle of the inverter after a fault occurs into the second impedance model to obtain a third output voltage during the inverter fault period; 利用所述第三输出电压和正常情况时逆变器输出的第一有功功率，获得逆变器的第二有功功率；Obtaining a second active power of the inverter by using the third output voltage and a first active power output by the inverter under normal conditions; 利用所述第三输出电压和所述第二有功功率对所述逆变器进行控制。The inverter is controlled by using the third output voltage and the second active power. 2.如权利要求1所述的逆变器的故障穿越方法，其特征在于，所述并网系统故障等值模型采用如下公式获得：2. The inverter fault ride-through method according to claim 1, characterized in that the grid-connected system fault equivalent model is obtained by using the following formula: 其中，为所述第一输出电压，Vi为所述第一幅值，θ为所述第一相角，为所述第二输出电压，Vg为所述第二幅值，δ为所述第二相角，ZL为总阻抗，Ri为逆变器出口到并网点之间的等效电阻，Li为逆变器出口到并网点之间的等效电感，Rlinel为线路左侧到故障点之间的等效电阻，Llinel为线路左侧到故障点之间的等效电感，Rliner为故障点到线路右侧的电阻，Lliner为故障点到线路右侧的电感，RL为所述总电阻，LL为所述总电感，ω为电力系统的角速度，t为电力系统的时间。in, is the first output voltage, V i is the first amplitude, θ is the first phase angle, is the second output voltage, Vg is the second amplitude, δ is the second phase angle, ZL is the total impedance, R i is the equivalent resistance between the inverter outlet and the grid-connected point, L i is the equivalent inductance between the inverter outlet and the grid-connected point, R linel is the equivalent resistance between the left side of the line and the fault point, Llinel is the equivalent inductance between the left side of the line and the fault point, R liner is the resistance from the fault point to the right side of the line, L liner is the inductance from the fault point to the right side of the line, R L is the total resistance, L L is the total inductance, ω is the angular velocity of the power system, and t is the time of the power system. 3.如权利要求1所述的逆变器的故障穿越方法，其特征在于，所述第二阻抗模型采用如下公式获得：3. The fault ride-through method of the inverter according to claim 1, wherein the second impedance model is obtained by using the following formula: 其中，Z'L为发生故障后逆变器与电网之间的阻抗，R'L为发生故障后逆变器到电网之间的总电阻，L'L为发生故障后逆变器到电网之间的总电感，Vi为所述第一幅值，ω为电力系统的角速度，t为电力系统的时间，Vg'为发生故障后电力系统中电网的输出电压的幅值，δ'为发生故障后电网的输出电压的相角或者发生故障后电力系统的输出电压的相角。Among them, Z'L is the impedance between the inverter and the grid after the fault occurs, R'L is the total resistance between the inverter and the grid after the fault occurs, L' L is the total inductance between the inverter and the grid after the fault occurs, Vi is the first amplitude, ω is the angular velocity of the power system, t is the time of the power system, Vg ' is the amplitude of the output voltage of the power grid in the power system after the fault occurs, and δ' is the phase angle of the output voltage of the power grid after the fault occurs or the phase angle of the output voltage of the power system after the fault occurs. 4.如权利要求1所述的逆变器的故障穿越方法，其特征在于，所述将正常情况时逆变器的第一阻抗角和故障发生后逆变器的第二阻抗角带入到所述第二阻抗模型，获得逆变器故障期间的第三输出电压，包括：4. The fault ride-through method of the inverter according to claim 1, characterized in that the step of bringing the first impedance angle of the inverter in a normal situation and the second impedance angle of the inverter after the fault occurs into the second impedance model to obtain the third output voltage during the inverter fault period comprises: 将正常情况时逆变器的第一阻抗角和故障发生后逆变器的第二阻抗角带入到所述第二阻抗模型，获得逆变器故障期间的输出电流模型；Substituting a first impedance angle of the inverter in a normal situation and a second impedance angle of the inverter after a fault occurs into the second impedance model to obtain an output current model during the inverter fault period; 获取正常情况时电力系统的第一功角，及获取发生故障后电力系统的第二功角；Obtaining a first power angle of the power system under normal conditions, and obtaining a second power angle of the power system after a fault occurs; 根据所述输出电流模型、所述第一功角和所述第二功角获得所述第三输出电压。The third output voltage is obtained according to the output current model, the first power angle, and the second power angle. 5.如权利要求1所述的逆变器的故障穿越方法，其特征在于，所述获得逆变器故障期间的第三输出电压之后，还包括：5. The inverter fault ride-through method according to claim 1, characterized in that after obtaining the third output voltage during the inverter fault period, the method further comprises: 利用预设的标幺值对所述第三输出电压进行优化，获得逆变器的参考输出电压值；Optimizing the third output voltage using a preset per-unit value to obtain a reference output voltage value of the inverter; 则利用所述第三输出电压和正常情况时逆变器输出的第一有功功率，获得逆变器的第二有功功率包括：Then, using the third output voltage and the first active power output by the inverter in a normal situation, obtaining the second active power of the inverter comprises: 利用所述参考输出电压值和正常情况时逆变器输出的第一有功功率，获得逆变器的第二有功功率；Obtaining a second active power of the inverter by using the reference output voltage value and a first active power output by the inverter under normal conditions; 所述利用所述第三输出电压和所述第二有功功率对所述逆变器进行控制，包括：The controlling the inverter by using the third output voltage and the second active power comprises: 利用所述参考输出电压值和所述第二有功功率对所述逆变器进行控制。The inverter is controlled using the reference output voltage value and the second active power. 6.如权利要求5所述的逆变器的故障穿越方法，其特征在于，所述参考输出电压值采用如下公式获得：6. The fault ride-through method of the inverter according to claim 5, characterized in that the reference output voltage value is obtained by using the following formula: 其中，Vs为所述参考输出电压值，Vsn为正常情况时逆变器输出电压的幅值，Vi为所述第一幅值，Vg为所述第二幅值，ω为电力系统的角速度，LL为正常情况时逆变器出口到电网之间的总电感，Ii为逆变器正常情况下的输出电流的幅值，Vg'为所述第三幅值，为电网输出电压的标幺值，k为预设系数。Wherein, Vs is the reference output voltage value, Vsn is the amplitude of the inverter output voltage under normal conditions, V i is the first amplitude, V g is the second amplitude, ω is the angular velocity of the power system, L L is the total inductance between the inverter outlet and the power grid under normal conditions, I i is the amplitude of the output current of the inverter under normal conditions, V g 'is the third amplitude, is the per unit value of the grid output voltage, and k is the preset coefficient. 7.如权利要求1所述的逆变器的故障穿越方法，其特征在于，所述第二有功功率采用如下公式获得：7. The fault ride-through method of the inverter according to claim 1, characterized in that the second active power is obtained by using the following formula: 其中，Pref为所述第二有功功率，Vsn为正常情况时逆变器输出电压的幅值，Vs为所述参考输出电压值，Prefn为正常情况时逆变器输出的有功功率。Wherein, Pref is the second active power, Vsn is the amplitude of the inverter output voltage under normal circumstances, Vs is the reference output voltage value, and Prefn is the active power output by the inverter under normal circumstances. 8.一种逆变器的故障穿越系统，其特征在于，所述系统包括：并网系统故障等值模型构建模块、模型转换模块、输出电压获取模块、有功功率获取模块和控制模块；8. A fault ride-through system for an inverter, characterized in that the system comprises: a grid-connected system fault equivalent model building module, a model conversion module, an output voltage acquisition module, an active power acquisition module and a control module; 所述并网系统故障等值模型构建模块用于利用逆变器的第一输出电压的第一幅值和第一相角、电力系统中电网的第二输出电压的第二幅值和第二相角、逆变器到电网之间滤波回路的总电阻和总电感构建并网系统故障等值模型；所述并网系统故障等值模型包括逆变器与电网之间的第一阻抗模型；The grid-connected system fault equivalent model construction module is used to construct a grid-connected system fault equivalent model using a first amplitude and a first phase angle of a first output voltage of an inverter, a second amplitude and a second phase angle of a second output voltage of a power grid in a power system, and a total resistance and a total inductance of a filter loop between an inverter and a power grid; the grid-connected system fault equivalent model includes a first impedance model between an inverter and a power grid; 所述模型转换模块用于基于所述并网系统故障等值模型、发生故障后的电网输出电压的第三幅值和第三相角，获取发生故障后逆变器与电网之间的第二阻抗模型；The model conversion module is used to obtain a second impedance model between the inverter and the grid after the fault occurs based on the grid-connected system fault equivalent model, the third amplitude and the third phase angle of the grid output voltage after the fault occurs; 所述输出电压获取模块用于将正常情况时逆变器的第一阻抗角和故障发生后逆变器的第二阻抗角带入到所述第二阻抗模型，获得逆变器故障期间的第三输出电压；The output voltage acquisition module is used to bring the first impedance angle of the inverter under normal conditions and the second impedance angle of the inverter after a fault occurs into the second impedance model to obtain a third output voltage during the inverter fault period; 所述有功功率获取模块用于利用所述第三输出电压和正常情况时逆变器输出的第一有功功率，获得逆变器的第二有功功率；The active power acquisition module is used to obtain the second active power of the inverter by using the third output voltage and the first active power output by the inverter under normal conditions; 所述控制模块用于利用所述第三输出电压和所述第二有功功率对所述逆变器进行控制。The control module is used to control the inverter using the third output voltage and the second active power. 9.一种逆变器的故障穿越设备，包括存储器和处理器，其特征在于，所述存储器存储有计算机程序，所述计算机程序被所述处理器执行时，使得所述处理器执行如权利要求1至7中任一项所述方法的步骤。9. A fault ride-through device for an inverter, comprising a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the method as claimed in any one of claims 1 to 7. 10.一种计算机可读存储介质，存储有计算机程序，其特征在于，所述计算机程序被处理器执行时，使得所述处理器执行如权利要求1至7中任一项所述方法的步骤。10. A computer-readable storage medium storing a computer program, wherein when the computer program is executed by a processor, the processor is caused to execute the steps of the method according to any one of claims 1 to 7.
CN202411187026.1A 2024-08-28 2024-08-28 A fault ride-through method for an inverter and related equipment Pending CN119482523A (en)

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