CN103825363B - A kind of wind-light storage low pressure micro-capacitance sensor group protection coordination controller - Google Patents

Abstract

The invention relates to a protection coordination controller for wind-solar-storage low-voltage micro-grid group, including a micro-grid group protection controller, a micro-grid group public node switch, a micro-grid group outlet head and end switch, and a micro-grid controller; in the micro-grid group When a fault occurs, the protection controller of the microgrid group and the microgrid controller control the public node switch of the microgrid group, the outlet head and end switches of the microgrid group, so that the relay of the entire microgrid group and the distribution network system connected to it Electric protection devices and safety automatic devices can operate safely and reliably. The wind-solar-storage low-voltage micro-grid group protection coordination controller described in the present invention can be widely used in current distribution network systems and micro-grid groups.

Description

A wind-solar-storage low-voltage microgrid group protection coordination controller

technical field

The invention belongs to the technical field of micro-grids, and in particular relates to a group protection coordination controller for wind-solar-storage low-voltage micro-grids.

Background technique

The power system relay protection device is an important part of the power system, and it plays a very important role in ensuring the safe operation of the system. The relay protection of the traditional distribution network system is usually configured as a three-stage current protection, such as instantaneous current quick-break protection, time-limited current quick-break protection, and time-limited current-limiting protection. In the basic design, the power flow flows in one direction from the power supply to the user. In the design of system protection, a current relay is usually installed at the outgoing line of the substation, and an automatic reclosing device is installed on the main feeder.

However, with the investment of distributed power sources such as photovoltaic power generation, wind power generation, and micro gas turbine power generation in the distribution network system, the original radial passive network has become an active network with small and medium-sized power sources distributed, and the trend is no longer Unidirectional flow from the substation bus to each load, thus changing the short-circuit current distribution of the distribution network system. Changes in the structure of the distribution network system have changed the various protection settings and mechanisms of the distribution network, which may result in reduced sensitivity of relay protection and safety automatic devices, reduced protection range, incorrect actions and even loss of protection devices. selective.

Microgrid refers to a small power generation and distribution system composed of distributed power sources, energy storage devices, energy conversion devices, related loads and monitoring and protection devices. It is an autonomous system that can realize self-control, protection and management. It can be operated in parallel with the large power grid, or it can be operated in isolation. Existing research and practice have shown that it is the most effective way to exert the efficiency of distributed power generation by connecting distributed power generation in the form of a micro-grid to the traditional power grid for grid-connected operation and supporting each other with the large power grid.

Therefore, it is necessary to study a new type of protection coordination control device for the micro-grid group, so that the relay protection devices and safety automatic devices of the entire micro-grid group and the distribution network system connected to it can operate safely and reliably, avoiding the distribution network Changes in the system structure lead to changes in various protection settings and mechanisms of the distribution network, resulting in reduced sensitivity of relay protection and safety automatic devices, reduced protection range, incorrect actions and even loss of selectivity of protection devices.

Contents of the invention

(1) Technical problems to be solved

The technical problem to be solved by the present invention is how to make the relay protection device and the safety automatic device of the microgrid group and the distribution network system connected to it operate safely and reliably.

(2) Technical solution

In order to solve the above technical problems, the present invention provides a wind-solar-storage low-voltage micro-grid group protection coordination controller, including: a micro-grid group protection controller; a micro-grid group public node switch, connected to the upper distribution network and the micro-grid group bus ; The first end switch of the microgrid group outgoing line is connected with the microgrid outgoing line and the microgrid group busbar; the microgrid group outgoing line end switch is connected with the microgrid transmission line and a single microgrid busbar; and the microgrid controller is connected with the microgrid group Outgoing end switch connection.

The microgrid group protection controller is connected with the microgrid group public node switch, the microgrid group outlet head switch, the microgrid group outlet end switch, and the microgrid controller through communication lines.

Wherein the microgrid group protection controller controls the tripping and reclosing actions of the microgrid group public node switch and the microgrid group outlet head end switch.

Wherein the microgrid controller controls the tripping and reclosing actions of the outgoing line end switches of the microgrid group.

Preferably, the micro-grid group protection controller includes a network communication control module and a local device information data processing module, which are used to transmit and receive control and data processing of lower-level data through the network; the micro-grid group protection control central decision-making unit, which according to the Power grid group switch status, load status, distributed power generation status and grid connection status, send control commands to the lower communication module; micro grid power generation calculation module, maximum/minimum load power calculation module, current protection setting value calculation module, time limit Quick-break setting value calculation module, each calculation module combines real-time data and historical data of system operation for calculation, they are connected with the central decision-making unit of microgrid group protection and control, and the calculation results are sent to the central decision-making unit.

Preferably, the public node switch of the microgrid group is a fast switch, which jumps off after receiving the island detection information broadcast by the protection controller of the microgrid group, and executes the reclosing action after receiving the information that the circuit is normal; The switch has the functions of short-circuit protection, time-limited quick-break protection, and over-current protection. It jumps off after receiving the fault trip information broadcast by the protection controller of the microgrid group, and performs reclosing action after receiving the information that the circuit is normal; the switch at the end of the microgrid group outlet is After receiving the island detection information from the control terminal RTU of the energy storage unit in the microgrid to which it belongs, the microgrid controller jumps out according to a given delay, which is set and issued by the microgrid group protection controller.

Preferably, the microgrid group public node switch reclosing action time is set and issued by the microgrid group protection controller, which is less than the tripping time of the head end switch of the microgrid group outgoing line and the tripping time of the microgrid group outgoing line end switch, The purpose is that during the reclosing action of the public node switch, the current quick-break protection of the head-end switch of the micro-grid group outlet and the current quick-break protection of the outlet end switch of the micro-grid group will not operate.

(3) Beneficial effects

The wind-solar-storage low-voltage micro-grid group protection coordination controller of the present invention is based on the electrical information of the local micro-grid, the electrical information of the public node switch of the micro-grid group, and the electrical information of the head-end switch of the micro-grid group. Carry out overall coordinated control. When the microgrid group fails, its microgrid group protection coordination controller can ensure that the relay protection device is disconnected in time to ensure the safety of the lower-level line; , disconnect the connection with the distribution network in time to ensure that the micro-grid group does not generate short-circuit current increments to the fault location of the upper level, and ensure the safety of the distribution network system; through the electrical information of the outlet terminal switch of the micro-grid group, ensure the internal safety and stability of a single micro-grid run. Therefore, on the whole, the relay protection devices and safety automatic devices of the microgrid group and the distribution network system connected to it can operate safely and reliably.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. Those skilled in the art can also obtain other drawings based on these drawings without creative work.

Figure 1: A block diagram of the structure and principle of a wind-solar-storage low-voltage microgrid group protection coordination controller provided by the present invention;

Figure 2: Block diagram of the module structure of the microgrid group protection controller;

Figure 3: A structural diagram of a typical working scenario 1 of a wind-solar-storage low-voltage microgrid group protection coordination controller provided by the present invention;

Figure 4: A structural diagram of a typical working scenario 2 of a wind-solar-storage low-voltage microgrid group protection coordination controller provided by the present invention;

Detailed ways

Embodiments of the present invention will be further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but should not be used to limit the scope of the present invention.

As shown in Figure 1, this embodiment discloses a wind-solar-storage low-voltage microgrid group protection coordination controller, including: a microgrid group protection controller _MGSC ; Group busbar connection; microgrid group outlet head-end switch K _Ln , connected with microgrid outlet line and microgrid group bus; microgrid group outlet end switch K _{PCC_MGn} , connected with microgrid transmission line and single microgrid busbar; and microgrid Controller MGC _n .

Among them, the microgrid group protection controller MGSC is connected with the microgrid group public node switch K _PCCG , the microgrid group outlet head-end switch K _Ln , the end switch K _{PCC_MGn} , and the microgrid controller MGC _n through communication lines to control Switching of relay protection devices of microgrid group.

In Figure 1, K _PCCG is the public node switch of the microgrid group. It is a fast switch controlled by the microgrid group protection controller. The issued command executes the reclosing operation. The microgrid group public node switch K _PCCG reclosing action time is set and delivered by the microgrid group protection controller.

In Figure 1, K _Ln is the head-end switch connecting the nth microgrid to the outgoing line of the microgrid group. It has short-circuit protection, time-limited quick-break protection, and overcurrent protection. It can accept the fault trip information broadcast by the microgrid group protection controller, and according to The microgrid group protection controller MGSC issues commands to execute the reclosing operation.

In the figure, K _{PCC_MGn} is the end switch connecting the nth microgrid to the outgoing line of the microgrid group. This fast switch is controlled by the microgrid controller MGC _n , and also has the function of local island protection in the microgrid. After the internal energy storage unit controls the island detection information sent by the terminal RTU, the microgrid controller MGC _n jumps away according to a given delay. The delay is set and issued by the microgrid group protection controller MGSC, in order to avoid the reclosing action time of the microgrid group protection controller MGSC.

The reclosing action time of the public node switch K _PCCG of the microgrid group is shorter than the current quick-break action time of the head-end switch K _Ln of the _microgrid group. The current quick-break protection of _Ln will not operate.

The microgrid group protection controller MGSC, as shown in Figure 2, includes a network communication control module and a microgrid group local device information data processing module for sending and receiving control and data processing of lower-level data through the network; microgrid group protection control The central decision-making unit, which sends control commands to the lower-level communication module according to the switch state, load state, distributed power generation state, and grid-connected state of the microgrid group; the microgrid power generation power calculation module, the maximum/minimum load power calculation module, the current The calculation module of protection setting value and the calculation module of time-limited quick-break setting value, each calculation module combines the real-time data and historical data of system operation for calculation, they are connected with the central decision-making unit of microgrid group protection control, and transmit the calculation results to the central decision-making unit.

When the transmission line in the micro-grid group fails, the wind-solar-storage low-voltage micro-grid protection coordination controller can ensure that the relay protection device is disconnected in time to ensure the safety of the lower-level line; Disconnect the connection with the upper-level distribution network to ensure that the micro-grid group does not generate short-circuit current increments to the upper-level fault location, and ensure the safety of the upper-level distribution network system. The wind-solar-storage low-voltage micro-grid protection coordination controller adopts efficient and flexible network communication methods to realize rapid data exchange between micro-grid groups, optimize the operating status of micro-grids, and improve the reliability of the distribution network system.

The microgrid group protection coordination control scheme proposed by the present invention will be described below with reference to the accompanying drawings, and the specific implementation manner will be described through two typical fault scenarios.

Typical working scenario 1 of protection coordination controller for wind-solar-storage low-voltage microgrid group:

As shown in Figure 3, when a short circuit or a ground fault occurs in the outgoing line of the microgrid 1, the short circuit current of the transmission line increases rapidly.

Step 1, the microgrid controller MGC ₁ detects that the transmission line of the outgoing line of the _microgrid 1 is abnormal, and the discharge power of the energy storage device increases rapidly. Reduce the short-circuit current increment.

Step 2: The microgrid group protection controller MGSC activates the instantaneous current quick-break protection and the time-limited current quick-break protection at the outgoing line of the microgrid, and disconnects the first-end switch K _L1 of the outgoing line of the microgrid 1 .

Step 3: The microgrid group protection controller MGSC monitors the current at the outlet switches of each route. If the current of each line returns to normal, start the microgrid 1 outgoing end switch K _L1 to reclose; if it still does not operate normally, disconnect the microgrid group common Node switch K _PCCG .

Step 4: If the first-end switch K _L1 of the outgoing line of the microgrid 1 is reclosed successfully, the end switch K _{PCC_MG1} of the outgoing line of the microgrid 1 will delay the grid connection. The delay is set by the microgrid group protection controller MGSC to avoid the protection of the microgrid group. The reclosing action time of the controller MGSC; if the reclosing of the head-end switch K _L1 of the microgrid 1 outlet fails, the microgrid 1 operates in an isolated island.

Typical working scenario 2 of protection coordination controller for wind-solar-storage low-voltage microgrid group:

As shown in Figure 4, when a short circuit or ground fault occurs in the upper distribution line of the microgrid group, the short circuit current of the distribution transmission line increases rapidly.

Step 1, the microgrid group protection controller MGSC detects that the current of the transmission line on the distribution network side is abnormal, the power fed by the microgrid group to the distribution network side increases rapidly, and the microgrid group protection controller MGSC quickly disconnects the public node switch of the microgrid group K _PCCG , eliminate the reverse boost current generated by the microgrid group at the short-circuit fault, and avoid the refusal of the upper-level line protection device.

Step 2: The microgrid group protection controller MGSC monitors the outgoing current of the microgrid. If the outgoing current of each channel returns to normal, start the microgrid group public node switch K _PCCG to reclose; if it still does not operate normally, the microgrid group protection controller MGSC shuts off Turn on the head-end switches K _L1 ~ K _Ln of the microgrid group outlets, and the microgrid controllers MGC ₁ ~ MGC _n turn off the end switches K _{PCC_MG1} ~ K _{PCC_MGn} of the microgrid group outlets, and each microgrid operates independently.

Step 3: The microgrid group common node switch K _{PCCG recloses} successfully, and the microgrid group and the distribution network run in parallel; if K _{PCCG recloses} unsuccessfully, the microgrid group operates in an isolated island. The reclosing action time of the public node switch K _PCCG of the microgrid group is set by the microgrid group protection controller MGSC, and its value is smaller than the current quick-break action time of the outlet head switch K _Ln of the microgrid group.

Compared with a single micro-grid protection controller, the protection coordination controller designed for the wind-solar-storage low-voltage micro-grid group in this embodiment has a larger protection range, a larger power supply capacity in the group, and the output of micro-grids is easy to form mutual support. More flexible and more reliable power supply.

In the wind-solar-storage low-voltage micro-grid group, three-level protection devices including public node switch, micro-grid outgoing line head-end switch and outgoing line end switch are set, and the micro-grid group protection coordination controller is used for unified control, which solves the problem of bidirectional current flow on the transmission line of the micro-grid. And the problem of incorrect action of the protection device generated.

The wind-solar-storage low-voltage micro-grid protection coordination controller adopts a flexible communication system and a reliable control structure, which reduces the control complexity of the protection device.

The above embodiments are only used to illustrate the present invention, but not to limit the present invention. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art should understand that various combinations, modifications or equivalent replacements of the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention, and all should cover Within the scope of the claims of the present invention.

Claims (4)

1. A wind-solar-storage low-voltage micro-grid group protection coordination controller is characterized in that it includes: a micro-grid group protection controller; a micro-grid group public node switch, connected to a superior distribution network and a micro-grid group bus; a micro-grid group The outgoing line head switch is connected with the microgrid outgoing line and the microgrid group busbar; the microgrid group outgoing line end switch is connected with the microgrid transmission line and a single microgrid busbar; and the microgrid controller is connected with the microgrid group outgoing line end switch ; The microgrid group protection controller is connected to the microgrid group public node switch, the microgrid group outlet head switch, the microgrid group outlet end switch, and the microgrid controller through a communication line; The micro-grid group protection controller controls the tripping and reclosing actions of the micro-grid group public node switch and the micro-grid group outlet head-end switch; The micro-grid controller controls the tripping and reclosing actions of the outlet terminal switches of the micro-grid group. 2. The wind-solar-storage low-voltage micro-grid group protection coordination controller according to claim 1, wherein the micro-grid group protection controller includes a network communication control module and a local device information data processing module for Lower-level data sending and receiving control and data processing; microgrid group protection control central decision-making unit, which sends control instructions to lower-level communication modules according to microgrid group switch status, load status, distributed power generation status, and grid connection status; microgrid Generated power calculation module, maximum/minimum load power calculation module, current protection setting value calculation module, and time-limited quick-break setting value calculation module. The decision-making units are connected and the calculation results are transmitted to the central decision-making unit. 3. The wind-solar-storage low-voltage micro-grid group protection coordination controller according to claim 1, wherein the micro-grid group public node switch jumps off after receiving the island detection information broadcast by the micro-grid group protection controller, and receives After receiving the normal information of the circuit, the reclosing action is executed; the switch at the head end of the microgrid group outgoing line jumps off after receiving the fault trip information broadcast by the microgrid group protection controller, and executes the reclosing action after receiving the normal information of the circuit; the terminal of the microgrid group outgoing line After the switch receives the island detection information from the control terminal RTU of the energy storage unit in the microgrid to which it belongs, the microgrid controller jumps off according to a given delay, which is set and issued by the microgrid group protection controller . 4. The wind-solar-storage low-voltage micro-grid group protection coordination controller according to claim 3, characterized in that, the reclosing action time of the public node switch of the micro-grid group is less than the tripping time of the head-end switch of the micro-grid group outlet and the micro-grid Delay tripping time of the end switch of the group outgoing line.