WO2022199173A1

WO2022199173A1 - Alternating current/direct current microgrid control method and device

Info

Publication number: WO2022199173A1
Application number: PCT/CN2021/141325
Authority: WO
Inventors: 周强; 张亚平; 付勇
Original assignee: 西安领充创享新能源科技有限公司
Priority date: 2021-03-22
Filing date: 2021-12-24
Publication date: 2022-09-29
Also published as: CN113036804A; DE112021007351T5; CN113036804B

Abstract

The present application is suitable for the technical field of microgrids, and provides an alternating current/direct current microgrid control method and device. The method is applied to an alternating current/direct current microgrid; the alternating current/direct current microgrid comprises an alternating current microgrid, a direct current microgrid, and a bidirectional converter, wherein the alternating current microgrid is connected to a power distribution network by means of a grid connection point, and the bidirectional converter is electrically connected between the alternating current microgrid and the direct current microgrid. The method comprises: detecting the power of a grid connection point in real time; and if the power of the grid connection point satisfies a preset anti-countercurrent protection trigger condition, controlling to disconnect the electrical connection between the alternating current microgrid and the bidirectional converter. The alternating current-direct current microgrid control method provided in the present application can improve the reliability of supplying power to loads.

Description

AC/DC microgrid control method and device

This application claims the priority of the Chinese patent application with the application number 202110303508.9 and the application name "AC/DC microgrid control method and device", which was submitted to the State Intellectual Property Office on March 22, 2021, the entire contents of which are incorporated herein by reference Applying.

technical field

The present application relates to the field of microgrids, and in particular, to a control method and device for an AC/DC microgrid.

Background technique

In recent years, Distributed Generation (DG) has gradually attracted widespread attention as an emerging power generation mode. The proposal of Micro-Grid aims to realize the flexible and efficient application of distributed power, and solve the problem of grid connection of a large number and various forms of distributed power. As a beneficial supplement to centralized power generation, the access location of microgrid is mainly near the distribution network users. However, in actual use, due to the volatility and instability of distributed power generation, the magnitude and direction of the power flow in the distribution network on the user side will change, and the microgrid may transmit power to the upper-level distribution network, causing distribution problems. The voltage distribution of the grid itself has changed. Therefore, various places have successively issued regulations on the management of grid connection of distributed power systems. Among them, some places have proposed that users of energy storage power stations are not allowed to send electricity back to the grid (that is, not connected to the grid).

In view of the above policies and technical status, the microgrid control method proposed by related research mainly monitors the power of the grid connection point in real time. When the power of the grid connection point and the anti-backflow protection threshold meet the preset relationship, the microgrid is controlled to work in the island mode. Otherwise, Control the microgrid to work in grid-connected mode.

However, under this microgrid control method, the microgrid system frequently switches between grid-connected mode and island mode, which reduces the reliability of load power supply.

SUMMARY OF THE INVENTION

The embodiments of the present application provide an AC/DC microgrid control method and device, which can solve the problem of low reliability of load power supply.

In a first aspect, an embodiment of the present application provides an AC/DC microgrid control method, which is applied to an AC/DC microgrid. The AC/DC microgrid includes an AC microgrid, a DC microgrid, and a bidirectional converter, wherein the AC microgrid passes through the The grid connection point is connected to the distribution network, and the bidirectional converter is electrically connected between the AC microgrid and the DC microgrid, and the method includes:

Real-time detection of the power of the grid-connected point;

If the power of the grid-connected point satisfies the preset anti-backflow protection trigger condition, the control is to disconnect the electrical connection between the AC microgrid and the bidirectional converter.

In one embodiment, taking the current flowing from the distribution network to the AC/DC microgrid as the positive direction, the triggering condition for the anti-reverse current protection includes: the power of the grid-connected point is less than or equal to the first anti-reverse current protection threshold, wherein the first anti-reverse current protection Threshold is greater than or equal to 0.

In one embodiment, the triggering condition of the anti-reverse flow protection further includes: the duration for which the power of the grid-connected point is less than or equal to the first anti-reverse flow protection threshold is greater than the preset anti-reverse flow protection duration.

In one of the embodiments, after controlling the disconnection of the electrical connection between the AC microgrid and the bidirectional converter, the method further includes:

The power of the bidirectional converter is adjusted to a preset power value, wherein, under the preset power value, after the AC microgrid is connected to the bidirectional converter, the power of the grid connection point is greater than the first anti-backflow protection threshold.

If the power of the grid-connected point satisfies the preset anti-backflow protection stop condition, the control will restore the electrical connection between the AC microgrid and the bidirectional converter; the anti-backflow protection stop condition includes: the power of the grid-connected point is greater than or equal to the second anti-backflow protection threshold , wherein the second anti-reverse flow protection threshold is greater than the first anti-reverse flow protection threshold.

In one embodiment, the method further includes:

If the AC microgrid is electrically connected to the bidirectional converter, and the power of the grid connection point is greater than the first anti-reverse current protection threshold and smaller than the second anti-reverse current protection threshold, the bidirectional converter is adjusted according to the second anti-reverse current protection threshold and the power of the grid connection point. of power.

In one embodiment, the method further includes:

If the power of the grid-connected point does not meet the triggering conditions of the anti-reverse current protection, the AC/DC microgrid is controlled to operate according to the preset energy storage power generation plan.

In one of the embodiments, the AC microgrid includes an AC load electrically connected to the grid connection point, the DC microgrid includes a power generation system, an energy storage system and a DC load that are electrically connected to the bidirectional converters, respectively, and the AC/DC microgrid is controlled according to the preset The developed energy storage power generation plan runs, including:

According to the energy storage power generation plan, if the current moment is in the energy storage charging period and the power of the energy storage system is less than the first preset power threshold, the output power of the power generation system is gradually adjusted according to the first preset step size until it reaches the maximum power generation power. And according to the output power of the power generation system and the power of the DC load, the power of the bidirectional converter is adjusted, so that the energy storage system is charged according to the planned charging power in the energy storage power generation plan;

If the current moment is in the energy storage charging period, and the power of the energy storage system is greater than or equal to the first preset power threshold, the output power of the power generation system is adjusted to be equal to the sum of the power of the DC load and the power of the AC load, and the bidirectional converter is adjusted. The power of the transformer is equal to the inverse of the power of the AC load.

In one embodiment, the method further includes:

According to the energy storage power generation plan, if the current moment is in the energy storage discharge period and the power of the energy storage system is greater than the second preset power threshold, the output power of the power generation system is gradually adjusted according to the second preset step size until the maximum power generation power is reached, And according to the output power of the power generation system and the power of the DC load, the power of the bidirectional converter is gradually adjusted according to the third preset step size, so that the energy storage system discharges the power according to the plan in the energy storage power generation plan;

If the current moment is in the energy storage discharge period, and the power of the energy storage system is less than or equal to the second preset power threshold, the output power of the power generation system is gradually adjusted according to the second preset step size until it reaches the maximum power generation power, and according to the power generation system The output power of the energy storage system and the power of the DC load are adjusted, and the power of the bidirectional converter is adjusted so that the discharge power of the energy storage system is 0.

In one embodiment, the method further includes:

According to the energy storage power generation plan, if the current moment is in the static energy storage period and the power of the energy storage system is less than the first preset power threshold, the output power of the power generation system is gradually adjusted according to the first preset step size until it reaches the maximum power generation power , and adjust the power of the bidirectional converter to be equal to the inverse of the power of the AC load;

If the current moment is in the static energy storage period, and the power of the energy storage system is greater than or equal to the first preset power threshold, the output power of the power generation system is adjusted to be equal to the sum of the power of the DC load and the power of the AC load, and the two-way transformer is adjusted. The power of the current transformer is equal to the inverse of the power of the AC load.

In a second aspect, an embodiment of the present application provides an AC/DC microgrid control device, which is applied to an AC/DC microgrid. The AC/DC microgrid includes an AC microgrid, a DC microgrid, and a bidirectional converter, wherein the AC microgrid passes through the The grid connection point is connected to the distribution network, and the bidirectional converter is electrically connected between the AC microgrid and the DC microgrid. The AC/DC microgrid control device includes:

The detection module is used to detect the power of the grid connection point in real time;

The protection module is used to control the disconnection of the electrical connection between the AC microgrid and the bidirectional converter if the power of the grid-connected point satisfies the preset anti-backflow protection trigger condition.

In a third aspect, an embodiment of the present application provides an AC/DC microgrid control device, including: a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, the above-mentioned first The AC/DC microgrid control method of any one of one aspect.

The AC/DC microgrid control method and device provided by the embodiments of the present application control the disconnection of the electrical connection between the AC microgrid and the bidirectional converter when the power of the grid-connected point meets the preset anti-reverse current protection trigger condition, thereby preventing reverse power The emergence of the system eliminates the need to set up a reverse power protector, which reduces the cost of system construction. Moreover, the DC microgrid can supply power to the DC load normally through the internal energy storage system and power generation system, and the AC microgrid continues to provide power to the AC load from the distribution network. Therefore, the AC/DC microgrid control method and device provided by the embodiments of the present application are provided. , while preventing reverse current protection, it will not affect the power supply of AC load and DC load, which improves the reliability of load power supply. In addition, for the distribution network, when the anti-reverse power is protected, the AC load continues to take power, the distribution network will not be suddenly unloaded, and it will not cause excessive impact on the distribution network, which improves the stability of the distribution network.

Description of drawings

1 is a schematic structural diagram of an AC/DC microgrid provided by an embodiment of the present application;

FIG. 2 is a schematic flowchart of an AC/DC microgrid control method provided by an embodiment of the present application;

3 is a schematic diagram of the principle of adjusting the power of the bidirectional converter according to the second anti-backflow protection threshold and the power of the grid connection point provided by an embodiment of the present application;

4 is a schematic flowchart of a method for controlling an AC/DC microgrid during an energy storage charging period provided by an embodiment of the present application;

5 is a schematic flowchart of a method for controlling an AC/DC microgrid during an energy storage discharge period provided by an embodiment of the present application;

FIG. 6 is a schematic flowchart of a method for controlling an AC/DC microgrid during an energy storage standstill period provided by an embodiment of the present application;

FIG. 7 is a schematic structural diagram of an AC/DC microgrid control device provided by an embodiment of the present application.

Description of reference numbers:

AC and DC Microgrid 10

AC Microgrid 110

AC load 111

Second sampling device 112

DC Microgrid 120

DC bus 121

Power generation system 122

Photovoltaic power generation device 1221

Photovoltaic DC/DC 1222

The third sampling device 1223

Energy Storage System 123

Energy storage device 1231

Energy storage DC/DC 1232

Fourth sampling device 1233

DC load 124

Fifth sampling device 1241

Bidirectional converter 130

Microgrid control device 140

Distribution network 20

Step-down transformer 201

The first sampling device 202

High voltage AC bus 203

Low voltage AC bus 204

Detailed ways

In order to make the purpose, technical solutions and advantages of the present application more clearly understood, the present application will be described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, but not to limit the present application.

It can be understood that the terms "first", "second", "third", "fourth", etc. (if any) in the embodiments of the present application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence.

It will be understood that, as used herein, the term "and/or" refers to and including any and all possible combinations of one or more of the associated listed items.

In the traditional technology, the reverse current phenomenon of the AC and DC microgrid is mainly prevented in the following two ways:

The first is to set up a reverse power protector between the AC and DC microgrid and the grid connection point. Although this method can prevent backflow, the system cost is relatively high.

The second is to prevent backflow by controlling the AC and DC microgrids. Specifically, by monitoring the power of the grid-connected point in real time, when the power of the grid-connected point triggers the anti-backflow protection threshold, the control switches the microgrid to the island mode, and vice versa, controls the microgrid to work in the grid-connected mode. There are two main problems with this AC/DC microgrid control method:

1) The microgrid frequently switches between grid-connected mode and island mode, which reduces the reliability of load power supply;

2) The microgrid frequently switches between the grid-connected mode and the island mode, which is the frequent sudden loading and sudden unloading of the distribution network, which has a greater impact on the distribution network.

The AC/DC microgrid control method and device provided by the embodiments of the present application aim to solve the above problems.

The technical solutions in the present application will be described in detail below with reference to the accompanying drawings. It should be noted that different technical features in this application may be combined with each other without conflict.

The AC/DC microgrid control method provided by the embodiments of the present application can be applied to the AC/DC microgrid shown in FIG. 1 to control the AC/DC microgrid, prevent reverse current (ie, reverse power), and realize grid connection without grid connection. As shown in FIG. 1 , the AC/DC microgrid 10 includes an AC microgrid 110 , a DC microgrid 120 , a bidirectional converter 130 and an AC/DC microgrid control device (hereinafter referred to as a microgrid control device) 140 . The AC microgrid 110 is connected to the distribution network 20 through the grid connection point PCC, and the bidirectional converter 130 is electrically connected between the AC microgrid 110 and the DC microgrid 120 . Among them, the grid connection point PCC is also called the common connection point and so on.

Specifically, a step-down transformer 201 , a first sampling device 202 and a circuit breaker QF1 may also be arranged in sequence between the distribution network 20 and the grid connection point PCC. The distribution network 20 and the step-down transformer 201 are connected by a high-voltage AC bus 203 . The distribution network 20 outputs 10kV or 35kV high-voltage AC through the high-voltage AC bus 203 , and the step-down transformer 201 steps down the high-voltage AC output from the distribution network 20 to 400V AC, and outputs it through the low-voltage AC bus 204 . The first sampling device 202 and the circuit breaker QF1 are connected in series on the low-voltage AC bus 204 between the step-down transformer 201 and the grid connection point PCC. The first sampling device 202 is used to collect signals such as voltage, current or power on the low-voltage AC bus 204 between the step-down transformer 201 and the grid connection point PCC. The first sampling device 202 can be signal-connected with the microgrid control device 140 through a measurement signal line, and transmit the collected measurement signal to the microgrid control device 140 . The circuit breaker QF1 is used to control the on-off between the step-down transformer 201 and the grid connection point PCC. The circuit breaker QF1 can be connected to the microgrid control device 140 through a switch signal line. The circuit breaker QF1 is controlled by the microgrid control device 140 and can receive switching signals sent by the microgrid control device 140 to realize closing and opening.

The AC microgrid 110 may include AC loads 111 electrically connected to the low voltage AC bus 204 . Optionally, the AC microgrid 110 may further include a second sampling device 112 and a circuit breaker QF2. The second sampling device 112 and the circuit breaker QF2 are connected between the AC load 111 and the low-voltage AC bus 204 . The second sampling device 112 is used to collect signals such as voltage, current or power on the line between the low-voltage AC bus 204 and the AC load 111 . The second sampling device 112 may be signal-connected with the microgrid control device 140 through a measurement signal line, and transmit the collected measurement signal to the microgrid control device 140 . The circuit breaker QF2 is used to control the on-off between the low-voltage AC bus 204 and the AC load 111 . The circuit breaker QF2 can be connected to the microgrid control device 140 through a switch signal line. The circuit breaker QF2 is controlled by the microgrid control device 140 and can receive the switch signal sent by the microgrid control device 140 to realize closing and opening.

The bidirectional converter 130 may be an AC/DC converter, which is a voltage conversion device between an AC bus and a DC bus, and can realize bidirectional flow of AC and DC energy. That is, the bidirectional converter 130 can not only convert the alternating current on the low-voltage alternating current bus 204 into direct current and output it to the direct current bus (DC BUS) 121, but also can convert the direct current on the direct current bus 121 into alternating current and output it to the low-voltage direct current bus 204. The bidirectional converter 130 operates in a constant power mode. The bidirectional converter 130 can be connected to the microgrid control device 140 through a communication signal line, so as to realize the interaction of communication signals with the microgrid control device 140 .

Exemplarily, a circuit breaker QF3 may be provided between the AC microgrid 110 and the bidirectional converter 130 . Specifically, the circuit breaker QF3 is provided between the low-voltage AC bus 204 and the bidirectional converter 130 in the AC microgrid 110 . The circuit breaker QF3 is used to control the on-off between the low-voltage AC bus 204 and the bidirectional converter 130 . The circuit breaker QF3 can be connected to the microgrid control device 140 through a switch signal line. The circuit breaker QF3 is controlled by the microgrid control device 140 and can receive the switch signal sent by the microgrid control device 140 to realize closing and opening.

Optionally, the DC microgrid 120 may include a power generation system 122 , an energy storage system 123 and a DC load 124 that are electrically connected to the DC load 121 , respectively. Specifically, the power generation system 122 may be a photovoltaic power generation system or a wind power power generation system, and may also include both a photovoltaic power generation system and a wind power power generation system. The embodiments of the present application are described by taking the power generation system 122 as a photovoltaic power generation system as an example. The power generation system 122 may include a photovoltaic power generation (PV) device 1221 and a photovoltaic DC/DC 1222 connected to the photovoltaic power generation device 1221 . The photovoltaic DC/DC 1222 is a voltage conversion device between the DC bus 121 and the photovoltaic power generation device 1221 , and can realize the bidirectional flow of energy between the photovoltaic power generation device 1221 and the DC bus 121 . The photovoltaic DC/DC 1222 works in the maximum power point tracking (Maximum Power Point Tracking, MPPT) mode. The photovoltaic DC/DC 1222 can be connected to the microgrid control device 140 through a communication signal line, and the maximum output power of the photovoltaic DC/DC 1222 is regulated and controlled by the microgrid control device 140. The energy storage system 123 may include an energy storage system (ESS) device 1231 and an energy storage DC/DC 1232 connected to the energy storage device 1231 . The energy storage DC/DC 1232 can be connected to the microgrid control device 140 through a communication signal line. The energy storage DC/DC 1232 is a voltage conversion device between the DC bus 121 and the energy storage device 1231 , and can realize the bidirectional flow of energy between the energy storage device 1231 and the DC bus 121 . The energy storage DC/DC 1232 works in the DC bus voltage regulation mode.

Optionally, a third sampling device 1223 and a circuit breaker QF4 may be provided between the photovoltaic DC/DC 1222 and the DC bus 121 . The third sampling device 1223 is used to collect signals such as voltage, current or power on the line between the photovoltaic DC/DC 1222 and the DC bus 121. The third sampling device 1223 may be connected to the microgrid control device 140 through a signal line of the measurement signal, and transmit the collected measurement signal to the microgrid control device 140 . The circuit breaker QF4 is used to control the on-off between the photovoltaic DC/DC 1222 and the DC bus 121. The circuit breaker QF4 can be connected to the microgrid control device 140 through a switch signal line. The circuit breaker QF4 is controlled by the microgrid control device 140 and can receive the switch signal sent by the microgrid control device 140 to realize closing and opening.

Optionally, a fourth sampling device 1233 and a circuit breaker QF5 may be provided between the energy storage DC/DC 1232 and the DC bus 121 . The fourth sampling device 1233 is used to collect signals such as voltage, current or power on the line between the energy storage DC/DC 1232 and the DC bus 121. The fourth sampling device 1233 can be signal-connected with the microgrid control device 140 through a measurement signal line, and transmit the collected measurement signal to the microgrid control device 140 . The circuit breaker QF5 is used to control the on-off between the energy storage DC/DC 1232 and the DC bus 121. The circuit breaker QF5 can be connected to the microgrid control device 140 through a switch signal line. The circuit breaker QF5 is controlled by the microgrid control device 140 and can receive the switch signal sent by the microgrid control device 140 to realize closing and opening.

Optionally, a fifth sampling device 1241 and a circuit breaker QF6 may be provided between the DC load 124 and the DC bus 121 . The fifth sampling device 1241 is used to collect signals such as voltage, current or power on the line between the DC load 124 and the DC bus 121 . The fifth sampling device 1241 can be signal-connected with the microgrid control device 140 through a measurement signal line, and transmit the collected measurement signal to the microgrid control device 140 . The circuit breaker QF6 is used to control the on-off between the DC load 124 and the DC bus 121 . The circuit breaker QF6 can be connected to the microgrid control device 140 through a switch signal line. The circuit breaker QF6 is controlled by the microgrid control device 140 and can receive the switch signal sent by the microgrid control device 140 to realize closing and opening.

The microgrid control device 140 is the “brain” of the AC/DC microgrid 10 . The microgrid control device 140 collects data such as voltage, current, or power at each sampling point through the first sampling device 202, the second sampling device 112, the third sampling device 1223, the fourth sampling device 1233, and the fifth sampling device 1241. These data are used for remote control, remote adjustment and remote signaling of the bidirectional converter 130 , the power generation system 122 and the energy storage system 123 . Meanwhile, the microgrid control device 140 controls the circuit breaker QF1, circuit breaker QF2, circuit breaker QF3, circuit breaker QF4, circuit breaker QF5 or circuit breaker QF6 to open or close according to the data.

It should be noted that the embodiments of the present application do not limit the structures of each module, device, device, etc. in the AC/DC microgrid 10, and can be selected according to actual needs. The microgrid control device 140 may be a computer device, a host computer, a programmable logic controller (Programmable Logic Controller, PLC) or a microprocessor, or the like. The piconet control device 140 may include a memory, a processor, and a computer program stored in the memory and executable on the processor.

FIG. 2 shows a schematic flowchart of the AC/DC microgrid control method provided by the present application. The embodiments of the present application are described by taking the method applied to the microgrid control device 140 in FIG. 1 as an example. As shown in FIG. 2 , the AC/DC microgrid control method provided in this embodiment may include:

S201. Detect the power P _pcc of the grid-connected point in real time.

Optionally, the current and voltage of the sampling point may be collected by the first sampling device, and the microgrid control device calculates and obtains the power P _pcc of the grid-connected point according to the current and voltage of the sampling point.

S202 , if the power P _pcc of the grid-connected point satisfies a preset trigger condition for anti-backflow protection, control to disconnect the electrical connection between the AC microgrid and the bidirectional converter.

The anti-reverse flow protection trigger condition refers to the preset triggering condition of the anti-reverse flow protection. Optionally, a critical state where reverse power occurs may be determined as the trigger condition for anti-backflow protection, or a certain safety value may be reserved on the basis of the critical state of reverse power to determine the trigger condition for anti-backflow protection.

When the power P _pcc of the grid connection point does not meet the preset anti-reverse current protection triggering conditions, it is considered that there is no reverse power in the AC/DC microgrid at the current moment, no need to take anti-reverse current protection, and the AC/DC microgrid works in the grid-connected state.

When the power P _pcc of the grid-connected point satisfies the preset trigger condition of anti-reverse current protection, it is considered that there is a reverse power risk in the AC-DC microgrid at the current moment. The microgrid control device controls the circuit breaker QF3 to be disconnected, thereby disconnecting the electrical connection between the AC microgrid and the bidirectional converter. At this time, the DC microgrid is disconnected from the AC microgrid, the DC microgrid will no longer output power to the grid connection point, and the power at the grid connection point will not have reverse power, so there will be no online phenomenon, preventing the occurrence of reverse current phenomenon.

At the same time, the DC microgrid is disconnected from the AC microgrid. The power generation system and the energy storage system in the DC microgrid jointly provide the energy required by the DC load and can supply power to the DC load normally. On the other hand, after the DC microgrid is disconnected from the AC microgrid, the DC microgrid can maintain its own balance. Specifically, when the DC load increases, the microgrid control device controls the output power of the power generation system, and supplements the power on the DC bus through the energy storage system. When the output of the power generation system is greater than the DC load demand, the energy storage system absorbs the excess power generation. When the DC load is reduced or suddenly unloaded, the short-term imbalance in the DC microgrid can be supplemented by the energy storage system.

The DC microgrid is disconnected from the AC microgrid, the AC microgrid is still connected to the grid connection point, and the distribution network continues to provide power to the AC load, so the AC load can maintain normal operation. For the distribution network, the AC load continues to take power, and the distribution network is not unloaded, which will not cause excessive impact on the distribution network.

It should be noted that, in the traditional technology, when the power at the grid connection point triggers the anti-reverse current protection threshold, the microgrid is switched to the island mode by disconnecting the circuit breaker at the grid connection point, namely the circuit breaker QF1. At this time, the power supply of the AC microgrid is Can not guarantee. And disconnecting the circuit breaker QF1, the distribution network is suddenly unloaded, causing a greater impact on the distribution network. However, in the AC/DC microgrid control method provided by this embodiment, when the power P _pcc of the grid-connected point satisfies the preset anti-reverse current protection trigger condition, the electrical connection between the AC microgrid and the bidirectional converter is controlled to be disconnected, thereby preventing reverse power The emergence of the system eliminates the need to set up a reverse power protector, which reduces the cost of system construction. Moreover, the DC microgrid can supply power to the DC load normally through the internal energy storage system and power generation system, and the AC microgrid can continue to provide power to the AC load from the distribution network. Therefore, the AC/DC microgrid control method provided in this embodiment can prevent reverse current flow. At the same time of protection, it will not affect the power supply of AC load and DC load, which improves the reliability of load power supply. In addition, for the distribution network, during the anti-reverse current protection, the AC load continues to take power, the distribution network will not be suddenly unloaded, and it will not cause excessive impact on the distribution network, which improves the stability of the distribution network.

The trigger condition of the anti-backflow protection can be a preset power threshold. It can be understood that when the positive direction of the setting is different, the triggering conditions of the anti-backflow protection are different. The following embodiments take the direction of current flowing from the distribution network in FIG. 1 to the AC/DC microgrid (that is, the direction indicated by the arrow in FIG. 1 ) as the positive direction, and describe the triggering conditions of the anti-reverse current protection and the specific method for controlling the DC microgrid.

In one embodiment, taking the direction of current flowing from the distribution network to the AC/DC microgrid as the positive direction, the anti-reverse current protection triggering condition may include: the power P _pcc of the grid connection point is less than or equal to the first anti-reverse current protection threshold P ₁ . The first anti-backflow protection threshold P ₁ is a preset fixed power value and has a direction. In one embodiment, the anti-backflow protection threshold may be zero. In another embodiment, the anti-backflow protection threshold may also be a value greater than 0. The method of judging whether to trigger the anti-reverse flow protection through the anti-reverse flow protection threshold is simple and reliable, and can improve the efficiency of the anti-reverse flow protection.

Further, in one embodiment, the anti-reverse flow protection trigger condition may further include: the power P _pcc of the grid-connected point is less than or equal to the first anti-reverse flow protection threshold P ₁ for a duration greater than a preset anti-reverse flow protection duration. That is to say, when the power of the grid-connected point is less than or equal to the first anti-reverse current protection threshold P ₁ , and the duration is greater than the anti-reverse current protection time period, the anti-reverse current protection action is triggered, and the power of the AC microgrid and the bidirectional converter is controlled to be disconnected. connect. The anti-backflow protection duration can be set according to the actual situation, for example, it can be 5s, 10s or 20s, etc. In this embodiment, by setting the duration factor in the trigger condition of the anti-reverse flow protection, it can effectively prevent the occasional fluctuation of the power P _pcc of the grid connection point caused by the abnormality of the microgrid from being misjudged as the reverse flow, and the anti-reverse flow protection is triggered by mistake, so that the micro-grid can be improved. The accuracy and safety of grid anti-reverse current protection.

In one embodiment, after step S202, the above method further includes: adjusting the power of the bidirectional converter to a preset power value, wherein, under the preset power value, after the AC microgrid is connected to the bidirectional converter, the grid connection point The power P _pcc is greater than the first anti-backflow protection threshold P ₁ . Optionally, the preset power value may be 0. In this way, when the circuit breaker QF3 is closed again and the AC microgrid is reconnected to the bidirectional converter, the DC microgrid will not output negative power to the grid connection point, nor will it consume the power output by the grid connection point. The power P _pcc of the grid-connected point is the power output by the distribution network minus the power of the AC load. Therefore, it can be ensured that the reverse current phenomenon does not occur after the AC microgrid and the bidirectional converter are electrically reconnected, thereby ensuring the safety of the distribution network. Moreover, the preset power value is a fixed value, and the bidirectional converter, as a controlled power source, works in constant power mode, and its power is not affected by fluctuations of other loads, so it will not cause sudden changes in the power of the grid connection point, ensuring the microgrid and the stability of the distribution network.

In one embodiment, after step S202, the above method further includes:

If the power P _pcc of the grid-connected point satisfies the preset anti-backflow protection stop condition, the control is to restore the electrical connection between the AC microgrid and the bidirectional converter.

Specifically, after disconnecting the circuit breaker QF3, the bidirectional converter will no longer consume the power of the grid connection point, nor will it transmit power in the negative direction to the grid connection point, so the power P _pcc of the grid connection point will gradually recover. When the power P _pcc of the grid-connected point recovers to meet the preset anti-reverse current protection stop condition, the micro-grid control device controls to close the circuit breaker QF3 to restore the electrical connection between the AC micro-grid and the bidirectional converter, thus ensuring that the grid-connected power is met when the power P pcc is restored. When conditions are met, the grid is connected in time, which further improves the stability and reliability of the AC/DC microgrid.

Optionally, the stop condition of the anti-backflow protection may correspond to the trigger condition of the anti-backflow protection, for example, the power P _pcc of the grid connection point may be greater than the first anti-backflow protection threshold P ₁ . Optionally, the condition for stopping the anti-reverse flow protection may also be: the power P _pcc of the grid connection point is greater than or equal to the second anti-reverse flow protection threshold P ₂ , wherein the second anti-reverse flow protection threshold P ₂ is greater than the first anti-reverse flow protection threshold P ₁ . In other words, the stop condition of the anti-reverse flow protection is: on the basis of the _first anti-reverse flow protection threshold P1, a certain safety range is set (that is, the difference between the _second anti-reverse flow protection threshold P2 and the _first anti-reverse flow protection threshold P1), In this way, the risk of reverse power occurring after the AC/DC microgrid is reconnected to the grid can be reduced, and the stability of the AC/DC microgrid can be further improved.

In one embodiment, when the AC microgrid is electrically connected to the bidirectional converter, that is, when the AC/DC microgrid is in a grid-connected state, if the power P _pcc of the grid-connected point satisfies the preset anti-reverse current protection boundary condition, the The anti-backflow protection boundary condition and the power P _pcc of the grid connection point regulate the power P _ACDC of the bidirectional converter. Among them, the anti-backflow protection boundary condition is used to define and screen the situations where the trigger condition of the anti-backflow protection is not triggered, but the stop condition of the anti-backflow protection is not satisfied. That is, the backflow prevention protection boundary condition is a condition between the backflow prevention protection trigger condition and the backflow prevention protection stop condition. In a specific embodiment, the boundary condition for preventing backflow is: the power P _pcc of the grid connection point is greater than the first protection threshold P ₁ and less than the second protection threshold P ₂ .

Since P _PCC =P _{AC_Load} +P _ACDC , and the bidirectional converter is used as the controlled power source, when the power P _pcc of the grid-connected point satisfies the boundary condition of anti-backflow protection, according to the second anti-backflow protection threshold P ₂ and the power of the grid-connected point The power P _PCC regulates the power P _ACDC of the bidirectional converter. By adjusting the power P _ACDC of the bidirectional converter, the power P _{pcc of the grid-connected point can be quickly adjusted to ensure the stability of the power P pcc} _of the grid-connected point, and greatly reduce the risk of reverse power in the AC/DC microgrid.

Specifically, FIG. 3 shows a schematic diagram of the principle of adjusting the power P _ACDC of the bidirectional converter according to the second anti-backflow protection threshold P ₂ and the power P _pcc of the grid connection point in an embodiment. As shown in Figure 3, the second anti-backflow protection threshold P ₂ is used as a given value, and the power P _PCC of the grid-connected point at the current moment is used as a feedback. Limiting, P _{ACDC_Set} as the set value of the power P _ACDC of the bidirectional converter. Through PI adjustment, in the first aspect, fast adjustment of the power P _pcc of the grid-connected point can be achieved. In the second aspect, since the power of the bidirectional converter is equal to the sum of the power P _PV of the DC load, the power P _ESS of the energy storage system and the output power P _PV of the power generation system, that is, P _ACDC =P _{DC_Load} +P _ESS +P _PV , By adjusting the output power P _ACDC of the bidirectional converter, the DC microgrid can achieve power self-balancing without affecting the power generation output of the power generation system. Compared with the traditional method in which the energy storage system and the power generation system adjust the power through separate converters, the method provided in this embodiment does not need to take into account the power adjustment of the energy storage system and the power generation system. The power regulation of the outlets can also not be affected by the power generation output, giving full play to the advantages of the energy storage system as a voltage source.

It can be understood that when the power P _pcc of the grid-connected point is greater than or equal to the second anti-reverse flow protection threshold P ₂ , the adjustment mode is exited; when the power P _pcc of the grid-connected point is less than or equal to the first anti-reverse flow protection threshold P ₁ , exit the adjustment mode. Adjust the mode, and repeat step S202.

The AC/DC microgrid control method provided by the embodiment of the present application further includes a process of controlling the operation of the AC/DC microgrid according to the energy storage power generation plan, which will be described in detail below with reference to the embodiment.

In one embodiment, the above method further includes:

If the power P _pcc of the grid-connected point does not meet the preset triggering conditions for anti-reverse current protection, the AC/DC microgrid is controlled to operate according to the preset energy storage power generation plan.

Specifically, when the power P _pcc of the grid-connected point is greater than the second anti-reverse current protection threshold P ₂ , that is, when the AC-DC micro-grid is in the grid-connected state and there is no reverse power risk, the AC-DC micro-grid can be controlled to store according to the preset storage capacity. The power generation plan can be operated. The energy storage power generation plan can be formulated in advance according to the set peak and valley period, electricity price and other source-load-storage data. In the energy storage power generation plan, according to the time period, it can include the energy storage charging period, the energy storage discharging period and the energy storage resting period. The AC/DC microgrid control at each time period will be further described below in conjunction with the accompanying drawings:

1) Energy storage charging period

FIG. 4 is a schematic flowchart of a method for controlling an AC/DC microgrid during an energy storage charging period according to an embodiment of the present application. As shown in Figure 4, the above steps control the AC/DC microgrid to operate according to the preset energy storage power generation plan, which may include:

According to the energy storage power generation plan, if the current moment is in the energy storage charging period, step S401 is executed.

S401. Determine whether the power of the energy storage system is less than a first preset power threshold.

The first preset power threshold is used to represent whether the current battery power is close to full power. If the power of the energy storage system is greater than or equal to the first preset power threshold, it indicates that the current battery power is relatively large and close to full power. If the power of the energy storage system is less than the first preset power threshold, it indicates that the current power is low and not close to full power.

If the power of the energy storage system is less than the first preset power threshold, step S402 is performed; otherwise, step S403 is performed.

S402 , gradually adjust the output power P _PV of the power generation system according to the first preset step size ΔP _PV1 until reaching the maximum power generation power, and adjust the power of the bidirectional converter according to the output power P _PV of the power generation system and the power P _{DC_Load} of the DC load P _ACDC , so that the energy storage system is charged according to the planned charging power P _{ESS_Plan1} in the energy storage power generation plan.

According to the first preset step size ΔP _PV1 , the output power P _PV of the power generation system is gradually adjusted until the maximum power generation power is reached, which can prevent the sudden change of the output power P _PV of the power generation system from causing the sudden change of the power P _pcc of the grid connection point to trigger the anti-backflow protection, thus ensuring that the anti-backflow protection is triggered. Stability of AC and DC Microgrids. It should be noted that, for photovoltaic power generation systems, the maximum power limit of photovoltaics can be gradually increased until the maximum power tracking point is reached.

Since P _ACDC =P _{DC_Load} +P _ESS +P _PV , according to the output power P _PV of the power generation system and the power P _{DC_Load} of the DC load, the power P _ACDC of the bidirectional converter is adjusted in real time, so that P _ESS =P _{ESS_Plan1} .

S403. Adjust the output power P _PV of the power generation system to be equal to the sum of the power P _{DC_Load} of the DC load and the power P _{AC_Load} of the AC load, and adjust the power of the bidirectional converter to be equal to the opposite of the power P _{AC_Load} of the AC load.

That is, if the current moment is in the energy storage charging period, and the power of the energy storage system is greater than or equal to the first preset power threshold, the microgrid control device adjusts the output power of the power generation system P _PV =P _{AC_Load} +P _{DC_Load} . For the photovoltaic power generation system, the maximum photovoltaic power limit can be limited to perform photovoltaic tracking load output. At the same time, the microgrid control device adjusts the power of the bidirectional converter P _ACDC =-P _{AC_Load} in real time, that is, the bidirectional converter tracks the output of the AC load.

2) Energy storage discharge period

FIG. 5 is a schematic flowchart of a method for controlling an AC/DC microgrid during an energy storage discharge period according to an embodiment of the present application. As shown in Figure 5, the above steps control the AC/DC microgrid to operate according to the preset energy storage power generation plan, which may include:

According to the energy storage power generation plan, if the current moment is in the energy storage discharge period, step S501 is performed;

S501. Determine whether the power of the energy storage system is greater than a second preset power threshold. If the power of the energy storage system is greater than the second preset power threshold, perform S502; otherwise, perform S503.

The second preset power threshold is used to represent whether the current battery power is close to emptying. The power of the energy storage system is less than the second preset power threshold, indicating that the current battery power is low and close to emptying. The power of the energy storage system is greater than or equal to the second preset power threshold, indicating that the current power is large and not close to emptying.

S502 , gradually adjust the output power P _PV of the power generation system according to the second preset step size ΔP _PV2 until reaching the maximum power generation power, and according to the output power P _PV of the power generation system and the power P _{DC_Load} of the DC load, according to the third preset step size ΔP _ACDC gradually adjusts the power P _ACDC of the bidirectional converter, so that the energy storage system discharges according to the planned discharge power P _{ESS_Plan2} in the energy storage power generation plan.

The specific process and beneficial effects of gradually adjusting the output power P _PV of the power generation system according to the second preset step size ΔP _PV2 until reaching the maximum power generation power, etc., refer to the above step S402, which will not be repeated here. Wherein, the second preset step size ΔP _PV2 may be the same as the first preset step size ΔP _PV1 , or may be different.

Since P _ACDC =P _{DC_Load} +P _ESS +P _PV , the power P _ACDC of the bidirectional converter is gradually adjusted according to the third preset step size ΔP _ACDC , so that P _ESS =P _{ESS_Plan2} can be achieved. Here, the power P _ACDC of the bidirectional converter is gradually adjusted according to the third preset step size ΔP _ACDC , which can prevent the power P _ESS of the energy storage system from suddenly changing or changing too fast, causing the sudden change of the power P _PCC of the grid connection point to trigger the reverse power protection, so that the reverse power protection can be prevented. Ensure the stability of AC and DC microgrids.

S503 , gradually adjust the output power P _PV of the power generation system according to the second preset step size ΔP _PV2 until reaching the maximum power generation power, and adjust the power of the bidirectional converter according to the output power P _PV of the power generation system and the power P _{DC_Load} of the DC load P _ACDC , so that the discharge power of the energy storage system is 0.

In this step, the principles and beneficial effects of adjusting the output power P _PV of the power generation system are similar to those in step S502, the difference is that the goal of adjusting the power P _ACDC of the bidirectional converter in step S502 is to make P _ESS =P _{ESS_Plan2} , while this In the step, the goal of adjusting the power P _ACDC of the bidirectional converter is to make P _ESS =0.

3) Energy storage rest period

FIG. 6 is a schematic flowchart of a method for controlling an AC/DC microgrid during an energy storage standstill period according to an embodiment of the present application. As shown in Figure 6, the above steps control the AC/DC microgrid to operate according to the preset energy storage power generation plan, which may include:

According to the energy storage power generation plan, if the current moment is in the energy storage rest period, step S601 is performed.

S601. Determine that the power of the energy storage system is less than a first preset power threshold, if the power of the energy storage system is less than the first preset power threshold, perform step S602, otherwise, perform step S603.

This step is the same as step S401 and will not be repeated here.

S602 , gradually adjust the output power P _PV of the power generation system according to the first preset step size ΔP _PV1 until reaching the maximum power generation power, and adjust the power P _ACDC of the bidirectional converter to be equal to the opposite of the power P _{AC_Load} of the AC load.

The specific process and beneficial effects of gradually adjusting the output power P _PV of the power generation system according to the first preset step size ΔP _PV1 until reaching the maximum power generation power refer to step S402, which will not be repeated here.

Adjust P _ACDC so that P _{ACDC_Set} = -P _{AC_Load} , that is, the bidirectional converter tracks the output of the AC load.

S603. Adjust the output power P _PV of the power generation system to be equal to the sum of the power P _{DC_Load} of the DC load and the power P _{AC_Load} of the AC load, and adjust the power of the bidirectional converter to be equal to the power of the AC load.

The process and beneficial effects of this step are the same as those of step S403, and are not repeated here.

In this embodiment, by controlling the AC/DC microgrid to operate according to the preset energy storage power generation plan, the energy time shift and distribution capacity expansion of the energy storage system can be fully utilized, and the utilization rate of the energy storage system can be improved. At the same time, the utilization value of AC and DC microgrids can be improved by shaving peaks and filling valleys.

It should be understood that although the steps in the flowcharts of FIGS. 2 and 4-6 are sequentially displayed according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, the execution of these steps is not strictly limited to the order, and the steps may be executed in other orders. Moreover, at least a part of the steps in FIGS. 2 and 4-6 may include multiple sub-steps or multiple stages, and these sub-steps or stages are not necessarily executed at the same time, but may be executed at different times. The order of execution of the steps or phases is not necessarily sequential, but may be performed alternately or alternately with other steps or at least a portion of sub-steps of other steps or phases.

FIG. 7 shows a structural block diagram of an AC/DC microgrid control device provided by an embodiment of the present application. As shown in FIG. 7 , the AC/DC microgrid control device provided in this embodiment may include:

A detection module 701, used for real-time detection of the power of the grid-connected point;

The protection module 702 is configured to control disconnection of the electrical connection between the AC microgrid and the bidirectional converter if the power of the grid-connected point satisfies a preset trigger condition for anti-backflow protection.

In one embodiment, the protection module 702 is further configured to adjust the power of the bidirectional converter to a preset power value, wherein, under the preset power value, after the AC microgrid is connected to the bidirectional converter, the power of the grid connection point is greater than An anti-backflow protection threshold.

In one embodiment, the AC/DC microgrid control device further includes a restoration module 703, configured to control and restore the electrical connection between the AC microgrid and the bidirectional converter if the power of the grid-connected point satisfies the preset anti-reverse current protection stop condition; The stop condition of the anti-backflow protection includes: the power of the grid connection point is greater than or equal to the second anti-backflow protection threshold, wherein the second anti-backflow protection threshold is greater than the first anti-backflow protection threshold.

In one embodiment, the AC/DC microgrid control device further includes a regulation module 704, for if the AC microgrid is electrically connected to the bidirectional converter, the power of the grid connection point is greater than the first anti-reverse current protection threshold and less than the second anti-reverse current protection threshold threshold, the power of the bidirectional converter is adjusted according to the second anti-backflow protection threshold and the power of the grid connection point.

In one embodiment, the AC/DC microgrid control device further includes an energy storage plan module 705, configured to control the AC/DC microgrid to operate according to a preset energy storage power generation plan if the power of the grid-connected point does not meet the trigger condition of the anti-reverse current protection .

In one embodiment, the energy storage planning module 705 is specifically configured to, according to the energy storage power generation plan, if the current moment is in the energy storage charging period and the power of the energy storage system is less than the first preset power threshold, the first preset step The output power of the power generation system is adjusted gradually until the maximum power generation power is reached, and the power of the bidirectional converter is adjusted according to the output power of the power generation system and the power of the DC load, so that the energy storage system can be charged according to the planned charging power in the energy storage power generation plan. Charging; if the current moment is in the energy storage charging period, and the power of the energy storage system is greater than or equal to the first preset power threshold, adjust the output power of the power generation system to be equal to the sum of the power of the DC load and the power of the AC load, and adjust the bidirectional power The power of the converter is equal to the inverse of the power of the AC load.

In one embodiment, the energy storage plan module 705 is specifically configured to, according to the energy storage power generation plan, if the current moment is in the energy storage discharge period, and the power of the energy storage system is greater than the second preset power threshold, the second preset step Adjust the output power of the power generation system step by step until it reaches the maximum power generation power, and gradually adjust the power of the bidirectional converter according to the third preset step size according to the output power of the power generation system and the power of the DC load, so that the energy storage system can meet the storage requirements. The planned discharge power in the power generation plan can be discharged; if the current moment is in the energy storage discharge period, and the power of the energy storage system is less than or equal to the second preset power threshold, the output power of the power generation system is gradually adjusted according to the second preset step size. Until the maximum generating power is reached, and according to the output power of the power generation system and the power of the DC load, the power of the bidirectional converter is adjusted so that the discharge power of the energy storage system is 0.

In one embodiment, the energy storage planning module 705 is specifically configured to, according to the energy storage power generation plan, if the current moment is in the energy storage rest period and the power of the energy storage system is less than the first preset power threshold, the first preset power The step size gradually adjusts the output power of the power generation system until it reaches the maximum power generation power, and adjusts the power of the bidirectional converter to be equal to the opposite number of the power of the AC load; is equal to the first preset power threshold, the output power of the power generation system is adjusted to be equal to the sum of the power of the DC load and the power of the AC load, and the power of the bidirectional converter is adjusted to be equal to the inverse of the power of the AC load.

The AC/DC microgrid control device provided in this embodiment is used to execute the AC/DC microgrid control method provided by the method embodiment of the present application, and the technical principle and technical effect are similar.

Those skilled in the art can clearly understand that, for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example. Module completion, that is, dividing the internal structure of the above device into different functional units or modules to complete all or part of the functions described above. Each functional unit and module in the embodiment may be integrated in one processing unit, or each unit may exist physically alone, or two or more units may be integrated in one unit, and the above-mentioned integrated units may adopt hardware. It can also be realized in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing from each other, and are not used to limit the protection scope of the present application. For the specific working processes of the units and modules in the above-mentioned system, reference may be made to the corresponding processes in the foregoing method embodiments, which will not be repeated here.

The embodiment of the present application also provides an AC/DC microgrid control device, the AC/DC microgrid control device includes: a processor, a memory, and a computer program stored in the memory and running on the processor, the processor The steps in any of the above method embodiments are implemented when the computer program is executed.

It should be clear that the process, principle, and beneficial effects of the processor executing the computer program in the embodiment of the present application are consistent with the execution process of each step in the above method, and details can be found in the above description.

Embodiments of the present application further provide a computer-readable storage medium, where a computer program is stored in the computer-readable storage medium, and when the computer program is executed by a processor, the steps in any of the foregoing method embodiments can be implemented.

Those skilled in the art will appreciate that any reference to memory, storage, database or other medium used in the various embodiments provided in this application may include non-volatile and/or volatile memory. Nonvolatile memory may include read only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous chain Road (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

The technical features of the above embodiments can be combined arbitrarily. In order to make the description simple, all possible combinations of the technical features in the above embodiments are not described. However, as long as there is no contradiction in the combination of these technical features It is considered to be the range described in this specification.

The above-mentioned embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the above-mentioned embodiments, those of ordinary skill in the art should understand that: it can still be used for the above-mentioned implementations. The technical solutions described in the examples are modified, or some technical features thereof are equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions in the embodiments of the application, and should be included in the within the scope of protection of this application.

Claims

An AC/DC microgrid control method, characterized in that it is applied to an AC/DC microgrid, the AC/DC microgrid includes an AC microgrid, a DC microgrid and a bidirectional converter, wherein the AC microgrid passes through a grid connection point Connecting to a distribution network, the bidirectional converter is electrically connected between the AC microgrid and the DC microgrid, and the method includes:

Real-time detection of the power of the grid-connected point;

If the power of the grid-connected point satisfies a preset trigger condition for anti-backflow protection, the control is to disconnect the electrical connection between the AC microgrid and the bidirectional converter.
The method according to claim 1, wherein, taking the current flowing from the distribution network to the AC-DC microgrid as a positive direction, the triggering condition of the anti-reverse current protection comprises: the power of the grid-connected point is less than or equal to The first anti-backflow protection threshold, wherein the first anti-backflow protection threshold is greater than or equal to 0.
The method according to claim 2, wherein the triggering condition of the anti-backflow protection further comprises: the duration of the power of the grid-connected point being less than or equal to the first anti-backflow protection threshold is greater than a preset anti-backflow protection duration.
The method according to claim 2, wherein after the controlling disconnects the electrical connection between the AC microgrid and the bidirectional converter, the method further comprises:

Adjust the power of the bidirectional converter to a preset power value, wherein, under the preset power value, after the AC microgrid is connected to the bidirectional converter, the power of the grid connection point is greater than that of the first power grid. An anti-backflow protection threshold.
The method according to any one of claims 2 to 4, wherein after the controlling disconnection of the electrical connection between the AC microgrid and the bidirectional converter, the method further comprises:

If the power of the grid-connected point satisfies the preset anti-reverse-current protection stop condition, control to restore the electrical connection between the AC microgrid and the bidirectional converter; the anti-reverse-current protection stop condition includes: the power of the grid-connected point The power is greater than or equal to a second anti-reverse flow protection threshold, wherein the second anti-reverse flow protection threshold is greater than the first anti-reverse flow protection threshold.
The method according to claim 5, wherein the method further comprises:

If the AC microgrid is electrically connected to the bidirectional converter, and the power of the grid-connected point is greater than the first anti-reverse flow protection threshold and smaller than the second anti-reverse flow protection threshold, according to the second anti-reverse flow protection threshold The protection threshold and the power of the grid connection point regulate the power of the bidirectional converter.
The method according to any one of claims 1 to 4 and 6, wherein the method further comprises:

If the power of the grid-connected point does not meet the triggering condition of the anti-backflow protection, the AC-DC microgrid is controlled to operate according to a preset energy storage power generation plan.
The method according to claim 7, wherein the AC microgrid comprises an AC load electrically connected to the grid connection point, and the DC microgrid comprises a power generation system, An energy storage system and a DC load, the controlling the AC/DC microgrid to operate according to a pre-established energy storage power generation plan, including:

According to the energy storage power generation plan, if the current moment is in the energy storage charging period and the power of the energy storage system is less than the first preset power threshold, the output power of the power generation system is gradually adjusted according to the first preset step size Until the maximum power generation is reached, and according to the output power of the power generation system and the power of the DC load, the power of the bidirectional converter is adjusted, so that the energy storage system is in accordance with the plan in the energy storage power generation plan charging power charging;

If the current moment is in the energy storage charging period, and the power of the energy storage system is greater than or equal to the first preset power threshold, adjust the output power of the power generation system to be equal to the power of the DC load and the AC load and adjust the power of the bidirectional converter to be equal to the inverse of the power of the AC load.
The method according to claim 8, wherein the method further comprises:

According to the energy storage power generation plan, if the current moment is in the energy storage discharge period and the power of the energy storage system is greater than the second preset power threshold, the output power of the power generation system is gradually adjusted according to the second preset step size until the maximum power generation power is reached, and according to the output power of the power generation system and the power of the DC load, the power of the bidirectional converter is gradually adjusted according to the third preset step size, so that the energy storage system can The planned discharge power discharge in the energy storage power generation plan;

If the current moment is in the energy storage discharge period, and the power of the energy storage system is less than or equal to the second preset power threshold, the output power of the power generation system is gradually adjusted according to the second preset step size until it reaches maximum generating power, and adjust the power of the bidirectional converter according to the output power of the power generation system and the power of the DC load, so that the discharge power of the energy storage system is 0.
The method according to claim 8, wherein the method further comprises:

According to the energy storage power generation plan, if the current moment is in the energy storage rest period, and the power of the energy storage system is less than the first preset power threshold, then gradually adjust the power according to the first preset step size until the output power of the power generation system reaches the maximum power generation power, and adjust the power of the bidirectional converter to be equal to the inverse of the power of the AC load;

If the current moment is in the energy storage rest period, and the power of the energy storage system is greater than or equal to the first preset power threshold, adjust the output power of the power generation system to be equal to the power of the DC load and the AC power The sum of the power of the load, and adjust the power of the bidirectional converter to be equal to the inverse of the power of the AC load.
An AC/DC microgrid control device, characterized in that it is applied to an AC/DC microgrid, the AC/DC microgrid includes an AC microgrid, a DC microgrid and a bidirectional converter, wherein the AC microgrid passes through a grid connection point Connected to the distribution network, the bidirectional converter is electrically connected between the AC microgrid and the DC microgrid, and the AC/DC microgrid control device includes:

a detection module, used for real-time detection of the power of the grid-connected point;

The protection module is configured to control disconnection of the electrical connection between the AC microgrid and the bidirectional converter if the power of the grid-connected point satisfies a preset trigger condition for anti-backflow protection.
The device according to claim 11, wherein, taking the current flowing from the power distribution network to the AC/DC microgrid as a positive direction, the triggering condition for the anti-reverse current protection comprises: the power of the grid connection point is less than or equal to The first anti-backflow protection threshold, wherein the first anti-backflow protection threshold is greater than or equal to 0.
The device according to claim 12, wherein the triggering condition of the anti-backflow protection further comprises: the duration of the power of the grid-connected point being less than or equal to the first anti-backflow protection threshold value is greater than a preset anti-backflow protection duration.
The device according to claim 12, wherein the protection module is further configured to adjust the power of the bidirectional converter to a preset power value, wherein, under the preset power value, the AC microgrid After being connected to the bidirectional converter, the power of the grid connection point is greater than the first anti-backflow protection threshold.
The device according to any one of claims 12 to 14, wherein the DC microgrid control device further comprises:

A recovery module, configured to control and restore the electrical connection between the AC microgrid and the bidirectional converter if the power of the grid-connected point satisfies a preset anti-backflow protection stop condition; the anti-backflow protection stop condition includes: The power of the grid connection point is greater than or equal to a second anti-reverse flow protection threshold, wherein the second anti-reverse flow protection threshold is greater than the first anti-reverse flow protection threshold.
The device according to claim 15, wherein the DC microgrid control further comprises:

A regulation module, configured to, if the AC microgrid is electrically connected to the bidirectional converter, the power of the grid connection point is greater than the first anti-reverse current protection threshold and less than the second anti-reverse current protection threshold, according to the The second anti-backflow protection threshold and the power of the grid connection point adjust the power of the bidirectional converter.
The device according to any one of claims 11 to 14 and 16, wherein the DC microgrid control further comprises:

An energy storage planning module, configured to control the AC/DC microgrid to operate according to a preset energy storage power generation plan if the power of the grid-connected point does not meet the triggering condition of the anti-reverse current protection.
An AC/DC microgrid control device, characterized in that it includes a memory, a processor, and a computer program stored in the memory and running on the processor, and the processor implements the following when executing the computer program. The method of any one of claims 1 to 10.