A method for controlling operation of a microgrid

Abstract

The present invention discloses a microgrid operation control method for tracking and processing photovoltaic surplus power reverse grid connection and transformer overload problems in the microgrid. The microgrid includes a mains power supply, an energy storage device and a control module. If the current time is within the peak time period, the control module determines whether the mains power value at the current time is greater than the preset photovoltaic surplus power tracking threshold. If not, the control module obtains the working mode of the energy storage inverter and the charge state of the energy storage battery, and determines whether the mains power value at the current time is less than the preset transformer maximum load value. If it is less than the preset transformer maximum load value, the control module controls the energy storage inverter to charge the energy storage device. The technical solution provided by the present invention will not affect the normal operation of the photovoltaic device and the energy storage device in the microgrid, that is, peak shaving and valley filling, and can effectively avoid the reverse grid connection of photovoltaic surplus power or the electric energy of the energy storage device or the overload operation of the user's transformer.

Description

Technical Field

[0001] The present invention relates to the field of electric power, and in particular to an operation control method of a microgrid. Background Art

[0002] As an important support for "Internet +" smart energy and a technical means of friendly interaction with large power grids, microgrids can improve the safety and reliability of power systems, promote the access and local consumption of clean energy, improve energy utilization efficiency, play an important role in energy conservation and emission reduction, and are conducive to building a conservation-oriented society.

[0003] On August 27, 2020, the National Development and Reform Commission and the National Energy Administration publicly solicited opinions on the "Guiding Opinions of the National Development and Reform Commission and the National Energy Administration on Carrying out "Integration of Wind, Solar, Water, Fire and Storage" and "Integration of Source, Grid, Load and Storage" (Draft for Comments). The "Guiding Opinions" pointed out that "the overall efficiency of my country's power system is low, the coordination of sources, grids and loads is insufficient, and the complementary and mutual assistance of various power sources is insufficient. Deep-seated contradictions such as the lack of mutual assistance and mutual assistance of various power sources are becoming increasingly prominent, and they urgently need to be coordinated and optimized." It clearly proposed to carry out the construction of "park-level source, grid, load and storage integration". Relying on modern information and communication technology, big data, artificial intelligence, energy storage and other new technologies, fully mobilize the regulation and response capabilities of the load side. In urban commercial areas and commercial complexes, relying on photovoltaic power generation, grid-connected microgrids and electric vehicle charging infrastructure construction, carry out park-level source, grid, load and storage integration that combines distributed power generation with flexible charging and discharging of electric vehicles; in areas with large industrial loads and good new energy resources, support the development and construction of distributed power sources and nearby access and consumption, and combine incremental distribution networks and other work to carry out the construction of green power supply industrial parks with integrated source, grid, load and storage. Research the comprehensive optimization configuration plan of sources, networks, loads and storage, promote the integrated development with multi-energy complementary demonstration parks and smart integrated energy services, improve self-balancing capabilities under economically feasible conditions, and reduce the demand for peak regulation and capacity reserve of large power grids.

[0004] Microgrid refers to a small power distribution system consisting of distributed power sources, power loads, distribution facilities, monitoring and protection devices, etc. Microgrids are divided into grid-connected microgrids and independent microgrids, which can achieve self-control and autonomous management. Grid-connected microgrids can be connected to the external grid or run independently; independent microgrids are not connected to the external grid, and the power is self-balanced.

[0005] Photovoltaic storage is "photovoltaic + energy storage". Photovoltaic storage integrated microgrid is a typical microgrid networking form. During the low electricity price period, users give priority to photovoltaic power supply and charge energy storage at the same time. When photovoltaic power is insufficient, it is supplemented by the mains. During the peak electricity price period, energy storage and photovoltaic power are used together to supply power to users, and the insufficient part is supplemented by the mains. It not only achieves peak shaving and valley filling, but also realizes green substitution of electricity and reduces carbon emissions.

[0006] However, the photovoltaic and energy storage integrated microgrid may encounter the following problems during operation:

[0007] (1) When the energy storage device is performing peak load shaving (discharging), if the total power consumption of the user minus the power generation power of the photovoltaic power generation device is less than the discharge power of the energy storage device, the power of the energy storage device will flow back to the upper-level power grid connected to the user, resulting in a reduction in the peak load shaving income of the energy storage device;

[0008] (2) During the power generation process of a photovoltaic power generation device, the photovoltaic power generation power may be greater than the total power consumption of the user. The excess power of the photovoltaic power generation device will flow back to the upper-level power grid connected to the user, resulting in a decrease in photovoltaic power generation income;

[0009] (3) When the energy storage device is valley filling (charging), if the charging power of the energy storage device is too high, resulting in the user's total power consumption being too high, it may cause the user's transformer to overload or even trip, affecting the transformer's efficiency, life, and the user's power safety.

[0010] The mainstream energy storage devices on the market currently generally achieve peak shaving and valley filling operation by pre-setting the charging and discharging power of the energy storage device in each time period (such as setting the energy storage device to discharge from 8:00 to 12:00 with a discharge power of 200kW, and setting the energy storage device to charge from 0:00 to 8:00 with a charging power of 100kW). The microgrid is not designed with a control method to prevent reverse flow and transformer overload. The energy storage device will not adjust the charging and discharging power in real time according to the user's power consumption and photovoltaic power generation. Therefore, it is easy for the photovoltaic surplus power or the energy storage device's power to be reversely connected to the grid or the user's transformer to be overloaded.

[0011] In addition, the prior art also pre-sets the minimum chargeable power and maximum dischargeable power of the energy storage device in each power consumption period according to the user's historical power consumption data and future power consumption plan (if the photovoltaic power generation device is also newly built, it is also necessary to predict the future power generation data of the photovoltaic power generation device), and then sets the charge and discharge power of the energy storage device in each power consumption period. There are many problems in this mode:

[0012] (1) The workload is large and requires statistics on a large amount of users’ historical electricity consumption data;

[0013] (2) Poor timeliness: when unexpected changes occur in the user's electricity consumption, the operating parameters of the energy storage device cannot be adjusted in advance;

[0014] (3) The prediction accuracy of photovoltaic power generation is poor. The prediction of photovoltaic power generation data is difficult and photovoltaic power generation is unstable, resulting in poor accuracy of the pre-set charging and discharging power of the energy storage device. Summary of the invention

[0015] In view of the above, it is necessary to provide an operation control method of a microgrid, which can enable the energy storage device to absorb the excess electric energy generated by the photovoltaic device while operating in peak shaving and valley filling, so as to avoid the situation where the surplus power of the photovoltaic device or the electric energy of the energy storage device is reversely connected to the grid or the user's transformer is overloaded.

[0016] The technical solution provided by the present invention is as follows:

[0017] The present invention provides an operation control method of a microgrid, which is used to track and handle the problems of photovoltaic surplus power reverse flow to the grid and transformer overload in the microgrid. The microgrid includes a mains power supply, an energy storage device and a control module, wherein the energy storage device includes an energy storage battery and an energy storage converter matched with the energy storage battery, the energy storage converter has a charging mode and a discharging mode, in which the energy storage converter controls the charging of the energy storage battery in the charging mode, and in the discharging mode, the energy storage converter controls the discharging of the energy storage battery; the control module can obtain the charge state of the energy storage battery, the working mode and working power of the energy storage converter, and the mains power value of the mains power supply in real time, and the operation control method of the microgrid includes:

[0018] If the current time is within the peak time period, the control module determines whether the current mains power value is greater than the preset photovoltaic surplus power tracking threshold value. If not, the control module obtains the working mode of the energy storage inverter and the charge state of the energy storage battery, and determines whether the current mains power value is less than the preset transformer maximum load value. If the current mains power value is less than the preset transformer maximum load value, the control module controls the energy storage inverter to operate so that the energy storage device is charged.

[0019] Furthermore, the control module obtains the working mode of the energy storage converter and the state of charge of the energy storage battery, including:

[0020] When the energy storage inverter is in the shutdown state, if the charge state of the energy storage battery is less than the preset energy storage battery charging depth, and the current mains power value is less than the preset transformer maximum load value, the control module controls the energy storage inverter to start up and switch to the charging mode, and adjusts the charging power of the energy storage inverter to the maximum charging power of the energy storage inverter.

[0021] Furthermore, the control module acquires the working mode of the energy storage converter and the state of charge of the energy storage battery and further includes:

[0022] When the energy storage converter is in the power-on state and in the charging mode, if the state of charge of the energy storage battery is less than the preset energy storage battery charging depth, the control module determines whether the current mains power value is less than the preset transformer maximum load value. If so, and the charging power of the energy storage converter is less than the maximum charging power of the energy storage converter, the control module increases the charging power of the energy storage converter; if not, the control module reduces the charging power of the energy storage converter;

[0023] If the state of charge of the energy storage battery is greater than a preset depth of charge of the energy storage battery, the control module controls the energy storage converter to shut down.

[0024] Furthermore, the control module acquires the working mode of the energy storage converter and the state of charge of the energy storage battery and further includes:

[0025] When the energy storage converter is in the on state and in the discharge mode, the control module controls the energy storage converter to shut down.

[0026] Furthermore, the charging power of the energy storage converter is obtained by the following formula:

[0027] P i =P′ i ×I i

[0028] Where P i is the charging power of the energy storage converter, P′ i is the maximum charging power of the energy storage battery, I i The charging power growth coefficient of the energy storage battery.

[0029] Furthermore, the operation control method of the microgrid also includes:

[0030] If the current time is within the peak time period, the control module determines whether the mains power value at the current time is greater than the preset photovoltaic surplus power tracking threshold. If so, the control module obtains the working mode of the energy storage inverter and the charge state of the energy storage battery, and determines whether the mains power value at the current time is greater than the preset mains power backflow prevention threshold. If the mains power value at the current time is greater than the preset mains power backflow prevention threshold, the control module controls the energy storage inverter to operate so that the energy storage device discharges.

[0031] Furthermore, the control module obtains the working mode of the energy storage converter and the state of charge of the energy storage battery, including:

[0032] When the energy storage inverter is in the shutdown state, if the charge state of the energy storage battery is greater than the preset energy storage battery discharge depth, and the mains power value at the current time is greater than the preset mains power backflow prevention threshold, the control module controls the energy storage inverter to start up and switch to the discharge mode, and adjusts the discharge power of the energy storage inverter to the maximum discharge power of the energy storage inverter.

[0033] Furthermore, the control module acquires the working mode of the energy storage converter and the state of charge of the energy storage battery and further includes:

[0034] When the energy storage converter is in the power-on state and in the discharge mode, if the state of charge of the energy storage battery is greater than the preset energy storage battery discharge depth, the control module determines whether the current mains power value is greater than the preset mains power reverse flow prevention threshold value. If so, and the discharge power of the energy storage converter is less than the maximum discharge power of the energy storage converter, the control module increases the discharge power of the energy storage converter; if not, the control module reduces the discharge power of the energy storage converter;

[0035] If the state of charge of the energy storage battery is less than a preset discharge depth of the energy storage battery, the control module controls the energy storage converter to shut down.

[0036] Furthermore, the control module acquires the working mode of the energy storage converter and the state of charge of the energy storage battery and further includes:

[0037] When the energy storage converter is in the on state and in the charging mode, the control module controls the energy storage converter to shut down.

[0038] Furthermore, the discharge power of the energy storage converter is obtained by the following formula:

[0039] P o =P′ o ×I o

[0040] Where P o The discharge power of the energy storage converter, P′ o is the maximum discharge power of the energy storage battery, I o is the discharge power growth coefficient of the energy storage battery.

[0041] Furthermore, the operation control method of the microgrid also includes:

[0042] If the current time is in normal or off-peak time period, the control module obtains the working mode of the energy storage inverter and the charge state of the energy storage battery, and determines whether the current mains power value is less than the preset transformer maximum load value. If so, the control module controls the energy storage inverter to operate so that the energy storage device is charged.

[0043] The present invention has the following advantages:

[0044] a) It will not affect the normal operation of the photovoltaic device and energy storage device in the microgrid, that is, peak shaving and valley filling. At the same time, it can effectively avoid the reverse grid connection of photovoltaic surplus power or energy storage device power or the overload operation of the user's transformer;

[0045] b) Adjust the charging and discharging power of the energy storage device in real time according to the user's power consumption and the power generation power of the photovoltaic device;

[0046] c) There is no need to collect a large amount of user historical data or perform frequent manual operations. The microgrid can be automatically controlled by simply setting the operating parameters in advance. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0048] Figure 1 A schematic diagram of a flow chart of a microgrid operation control method provided by an embodiment of the present invention;

[0049] Figure 2 A schematic diagram of the structure of a microgrid provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0050] In order to enable those skilled in the art to better understand the scheme of the present invention, and to more clearly understand the purpose, technical scheme and advantages of the present invention, the technical scheme in the embodiment of the present invention is clearly and completely described below in conjunction with specific embodiments and with reference to the accompanying drawings. It should be noted that the implementation methods not shown or described in the accompanying drawings are forms known to those skilled in the art. In addition, although demonstrations of parameters containing specific values ​​may be provided herein, it should be understood that the parameters do not need to be exactly equal to the corresponding values, but may be approximated to the corresponding values ​​within an acceptable error tolerance or design constraint. Obviously, the described embodiments are only embodiments of a part of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work should belong to the scope of protection of the present invention. In addition, the terms "including" and "having" in the specification and claims of the present invention and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, device, product or equipment containing a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or equipment.

[0051] In one embodiment of the present invention, a microgrid operation control method is provided for tracking and processing the photovoltaic surplus power reverse flow to the grid and transformer overload problems in the microgrid.

[0052] like Figure 2 As shown, the microgrid includes a mains power supply, a photovoltaic device, an energy storage device and a control module. The photovoltaic device is a general term for all devices used to realize photovoltaic power generation in a photovoltaic power generation system. The energy storage device is a general term for all devices used to realize the charging and discharging of energy storage batteries in an energy storage system.

[0053] The energy storage device includes an energy storage battery and an energy storage converter (PCS) matched with the energy storage battery. The energy storage converter is a converter that realizes bidirectional conversion of electric energy and is connected between the battery system and the power grid (and / or load) in the electrochemical energy storage system. The energy storage converter has a charging mode and a discharging mode. In the charging mode, the energy storage converter controls the charging of the energy storage battery, and in the discharging mode, the energy storage converter controls the discharging of the energy storage battery.

[0054] The control module is connected to the mains power supply and the energy storage device respectively, and the control module can obtain the state of charge of the energy storage battery, the working mode and working power of the energy storage converter, and the mains power value of the mains power supply in real time. Among them, the state of charge (SOC) refers to the ratio of the remaining capacity of the battery to the battery capacity. SOC is used to reflect the remaining capacity of the battery, and its value range is 0 to 1. When SOC=0, it means that the battery is fully discharged; when SOC=1, it means that the battery is fully charged.

[0055] like Figure 1 As shown, the operation control method of the microgrid includes:

[0056] If the current time is within the peak time period, the control module determines whether the current mains power value is greater than the preset photovoltaic surplus power tracking threshold:

[0057] (1) If there is a risk of reverse grid connection in the photovoltaic device, the control module obtains the working mode of the energy storage inverter and the charge state of the energy storage battery, and determines whether the current mains power value is less than the preset transformer maximum load value. If the current mains power value is less than the preset transformer maximum load value, the control module controls the energy storage inverter to operate so that the energy storage device is charged.

[0058] The control module acquires the working mode of the energy storage converter and the state of charge of the energy storage battery, including:

[0059] a. When the energy storage inverter is in the shutdown state, if the charge state of the energy storage battery is less than the preset energy storage battery charging depth, and the current mains power value is less than the preset transformer maximum load value, the control module controls the energy storage inverter to start up and switch to the charging mode, and adjusts the charging power of the energy storage inverter to the maximum charging power of the energy storage inverter.

[0060] b. When the energy storage converter is in the on state and in the charging mode, the state of charge of the energy storage battery is compared with the preset depth of charge of the energy storage battery:

[0061] If the state of charge of the energy storage battery is less than the preset energy storage battery charging depth, the control module determines whether the current mains power value is less than the preset transformer maximum load value. If so, and the charging power of the energy storage inverter is less than the maximum charging power of the energy storage inverter, the control module increases the charging power of the energy storage inverter; if not, the control module reduces the charging power of the energy storage inverter.

[0062] If the state of charge of the energy storage battery is greater than a preset depth of charge of the energy storage battery, the control module controls the energy storage converter to shut down.

[0063] c. When the energy storage converter is in the on state and in the discharge mode, the control module controls the energy storage converter to shut down.

[0064] (2) If no, that is, the photovoltaic device does not have the risk of reverse grid connection, the control module obtains the working mode of the energy storage inverter and the charge state of the energy storage battery, and determines whether the mains power value at the current time is greater than the preset mains power backflow prevention threshold. If the mains power value at the current time is greater than the preset mains power backflow prevention threshold, the control module controls the energy storage inverter to operate so that the energy storage device discharges.

[0065] The control module acquires the working mode of the energy storage converter and the state of charge of the energy storage battery, including:

[0066] a. When the energy storage inverter is in the shutdown state, if the charge state of the energy storage battery is greater than the preset energy storage battery discharge depth, and the mains power value at the current time is greater than the preset mains power backflow prevention threshold, the control module controls the energy storage inverter to start up and switch to the discharge mode, and adjusts the discharge power of the energy storage inverter to the maximum discharge power of the energy storage inverter.

[0067] b. When the energy storage converter is in the on state and in the discharge mode, the state of charge of the energy storage battery is compared with the preset energy storage battery discharge depth:

[0068] If the state of charge of the energy storage battery is greater than the preset energy storage battery discharge depth, the control module determines whether the current mains power value is greater than the preset mains power backflow prevention threshold. If so, and the discharge power of the energy storage inverter is less than the maximum discharge power of the energy storage inverter, the control module increases the discharge power of the energy storage inverter; if not, the control module reduces the discharge power of the energy storage inverter.

[0069] If the state of charge of the energy storage battery is less than a preset discharge depth of the energy storage battery, the control module controls the energy storage converter to shut down.

[0070] c. When the energy storage converter is in the on state and in the charging mode, the control module controls the energy storage converter to shut down.

[0071] It should be noted that the purpose of comparing the mains power and the PV surplus power tracking threshold is to determine whether there is a possibility of PV reverse grid access, and to compare the mains power and the mains power reverse flow prevention threshold, especially when the mains power is ≤ the mains power reverse flow prevention threshold. This means that once the energy storage battery is discharged, it is possible to reverse grid access, so the energy storage battery cannot be discharged.

[0072] The charging depth of the energy storage battery is the maximum SOC that can be reached during the battery charging process. If the state of charge of the energy storage battery is less than the preset charging depth of the energy storage battery, it means that the energy storage battery has charging capability and the energy storage battery can be controlled to be charged. Otherwise, it means that the energy storage battery can no longer be charged.

[0073] The energy storage battery discharge depth is the minimum SOC that can be reached during the battery discharge process. If the state of charge of the energy storage battery is greater than the preset energy storage battery discharge depth, it means that the energy storage battery has discharge capability and the energy storage battery can be controlled to discharge. Otherwise, it means that the energy storage battery can no longer discharge.

[0074] In one embodiment of the present invention, a method for calculating the charging power of the energy storage converter is provided, which is obtained by the following formula:

[0075] P i =P′ i ×I i

[0076] Where P i is the charging power of the energy storage converter, P′ i is the maximum charging power of the energy storage battery, I i The charging power growth coefficient of the energy storage battery.

[0077] It should be noted that in the scenarios where the user's power consumption is normal, the user's power consumption is too low but the photovoltaic device is still generating electricity or the energy storage device is still discharging, and the user's power consumption is too high but the energy storage device is still charging, the charging power of the energy storage inverter needs to be adjusted, and the specific values ​​may be different or equal, and this does not limit the scope of protection of the present invention.

[0078] In one embodiment of the present invention, a method for calculating the discharge power of the energy storage converter is provided, which is obtained by the following formula:

[0079] P o =P′ o ×I o

[0080] Where P o The discharge power of the energy storage converter, P′ o is the maximum discharge power of the energy storage battery, I o is the discharge power growth coefficient of the energy storage battery.

[0081] It should be noted that in the scenarios where the user's power consumption is normal, the user's power consumption is too low but the photovoltaic device is still generating electricity or the energy storage device is still discharging, and the user's power consumption is too high but the energy storage device is still charging, the discharge power of the energy storage inverter needs to be adjusted, and the specific values ​​may be different or equal, and this does not limit the scope of protection of the present invention.

[0082] In one embodiment of the present invention, a microgrid operation control method is provided, such as Figure 1 As shown, the operation control method of the microgrid also includes:

[0083] If the current time is in normal or off-peak time period, the control module obtains the working mode of the energy storage inverter and the charge state of the energy storage battery, and determines whether the current mains power value is less than the preset transformer maximum load value. If so, the control module controls the energy storage inverter to operate so that the energy storage device is charged.

[0084] The control module acquires the working mode of the energy storage converter and the state of charge of the energy storage battery, including:

[0085] a. When the energy storage inverter is in the shutdown state, if the charge state of the energy storage battery is less than the preset energy storage battery charging depth, and the current mains power value is less than the preset transformer maximum load value, the control module controls the energy storage inverter to start up and switch to the charging mode, and adjusts the charging power of the energy storage inverter to the maximum charging power of the energy storage inverter.

[0086] b. When the energy storage converter is in the on state and in the charging mode, the state of charge of the energy storage battery is compared with the preset depth of charge of the energy storage battery:

[0087] If the state of charge of the energy storage battery is less than the preset energy storage battery charging depth, the control module determines whether the current mains power value is less than the preset transformer maximum load value. If so, and the charging power of the energy storage inverter is less than the maximum charging power of the energy storage inverter, the control module increases the charging power of the energy storage inverter; if not, the control module reduces the charging power of the energy storage inverter.

[0088] If the state of charge of the energy storage battery is greater than a preset depth of charge of the energy storage battery, the control module controls the energy storage converter to shut down.

[0089] c. When the energy storage converter is in the on state and in the discharge mode, the control module controls the energy storage converter to shut down.

[0090] In one embodiment of the present invention, a motion control system of a microgrid is provided, and the system operates based on the operation control method of the microgrid described in the above embodiment.

[0091] In one embodiment of the present invention, a motion control system for a microgrid is provided, and its related configuration parameters are shown in Table 1:

[0092] Table 1. Configuration parameters

[0093]

[0094]

[0095] It should be noted that the PV surplus power tracking threshold in the above table is 0, which means that the tolerance for PV reverse grid connection is relatively high, and there is no need to let the energy storage device respond in advance. If this value is increased, the more it is increased, the lower the tolerance for PV reverse grid connection.

[0096] Specifically, this embodiment includes the following processes and steps:

[0097] (1) Collect information on users’ electricity consumption periods, energy storage devices, and transformer rated parameters.

[0098] (2) Enter the collected information in the configuration table as the judgment conditions for each process during runtime.

[0099] (3) In the configuration table, enter the battery charging power growth coefficient and the battery discharging power growth coefficient. These two items are key parameters for the operation of this system. They specify the specific values ​​that need to be adjusted for the charging and discharging power of the energy storage device when the user's power consumption is normal, the user's power consumption is too low but the photovoltaic power generation device is still generating power or the energy storage device is still discharging, and the user's power consumption is too high but the energy storage device is still charging. Through these two parameters, this system realizes the charging and discharging power adjustment of the energy storage device without manual operation during the residual power tracking process.

[0100] (4) In the configuration table, the maximum load rate of the input transformer, the AC power reverse flow prevention threshold and the photovoltaic surplus power tracking threshold are input. These three items are also the key parameters for the operation of this system. They specify when the system needs to adjust the charging and discharging power of the energy storage device and the direction of the adjustment (increase or decrease).

[0101] (5) The microgrid adjusts the charging and discharging power of the energy storage device according to the output instructions.

[0102] The idea of ​​this motion control system embodiment is the same as the working process of the operation control method in the above embodiment. The entire content of the above operation control method embodiment is incorporated into this motion control system embodiment by full reference and will not be repeated here.

[0103] The present invention focuses on improving the existing solution in the microgrid, which does not design a photovoltaic surplus power tracking strategy to prevent reverse flow and transformer overload, resulting in the energy storage device not adjusting the charging and discharging power in real time according to the user's power consumption and photovoltaic power generation. Therefore, it is easy to cause the photovoltaic surplus power or the power storage device's power to be reversely connected to the grid or the user's transformer to be overloaded. The present invention provides an operation control method for a microgrid, which does not require frequent manual operation, and can automatically operate after the operating conditions are pre-set. After operation, it will not affect the operation of the photovoltaic power generation device and the peak-shaving and valley-filling operation of the energy storage device in the microgrid, and can effectively prevent the photovoltaic surplus power or the power storage device's power from being reversely connected to the grid or the user's transformer from being overloaded.

[0104] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope thereof. Any equivalent structure or equivalent process transformation made by using the contents of the present invention specification and drawings, directly or indirectly applied in other related technical fields, is also included in the patent protection scope of the present invention.

Claims

1. A microgrid operation control method, characterized in that: Used to track and handle the problems of photovoltaic surplus power reverse flow to the grid and transformer overload in a microgrid, the microgrid includes a mains power supply, an energy storage device and a control module, wherein the energy storage device includes an energy storage battery and an energy storage converter matched with the energy storage battery, the energy storage converter has a charging mode and a discharging mode, in the charging mode, the energy storage converter controls the charging of the energy storage battery, in the discharging mode, the energy storage converter controls the discharging of the energy storage battery; the control module can obtain the charge state of the energy storage battery, the working mode and working power of the energy storage converter, and the mains power value of the mains power supply in real time, and the operation control method of the microgrid includes: If the current time is within the peak time period, the control module determines whether the mains power value at the current time is greater than the preset photovoltaic surplus power tracking threshold value. If so, the control module obtains the working mode of the energy storage inverter and the charge state of the energy storage battery, and determines whether the mains power value at the current time is greater than the preset mains power backflow prevention threshold value. If the mains power value at the current time is greater than the preset mains power backflow prevention threshold value, the control module controls the energy storage inverter to work so that the energy storage device discharges; If the current time is in the normal or off-peak time period, the control module obtains the working mode of the energy storage inverter and the charge state of the energy storage battery, and determines whether the mains power value at the current time is less than the preset transformer maximum load value. If the mains power value at the current time is less than the preset transformer maximum load value, the control module controls the energy storage inverter to operate so that the energy storage device is charged.

2. The microgrid operation control method according to claim 1, characterized in that: The control module acquires the working mode of the energy storage converter and the state of charge of the energy storage battery, including: When the energy storage inverter is in the shutdown state, if the charge state of the energy storage battery is less than the preset energy storage battery charging depth, and the current mains power value is less than the preset transformer maximum load value, the control module controls the energy storage inverter to start up and switch to the charging mode, and adjusts the charging power of the energy storage inverter to the maximum charging power of the energy storage inverter.

3. The microgrid operation control method according to claim 1, characterized in that: The control module acquiring the working mode of the energy storage converter and the state of charge of the energy storage battery also includes: When the energy storage converter is in the power-on state and in the charging mode, if the state of charge of the energy storage battery is less than the preset energy storage battery charging depth, the control module determines whether the current mains power value is less than the preset transformer maximum load value. If so, and the charging power of the energy storage converter is less than the maximum charging power of the energy storage converter, the control module increases the charging power of the energy storage converter; if not, the control module reduces the charging power of the energy storage converter; If the state of charge of the energy storage battery is greater than a preset depth of charge of the energy storage battery, the control module controls the energy storage converter to shut down.

4. The operation control method of the microgrid according to claim 1, characterized in that: The control module acquiring the working mode of the energy storage converter and the state of charge of the energy storage battery also includes: When the energy storage converter is in the on state and in the discharge mode, the control module controls the energy storage converter to shut down.

5. The operation control method of the microgrid according to claim 2 or 3, characterized in that: The charging power of the energy storage converter is obtained by the following formula: Pi=P' i ×I i Where P i is the charging power of the energy storage converter, P' i is the maximum charging power of the energy storage battery, I i The charging power growth coefficient of the energy storage battery.

6. The microgrid operation control method according to claim 1, characterized in that: The control module acquires the working mode of the energy storage converter and the state of charge of the energy storage battery, including: When the energy storage inverter is in the shutdown state, if the charge state of the energy storage battery is greater than the preset energy storage battery discharge depth, and the mains power value at the current time is greater than the preset mains power backflow prevention threshold, the control module controls the energy storage inverter to start up and switch to the discharge mode, and adjusts the discharge power of the energy storage inverter to the maximum discharge power of the energy storage inverter.

7. The microgrid operation control method according to claim 1, characterized in that: The control module acquiring the working mode of the energy storage converter and the state of charge of the energy storage battery also includes: When the energy storage converter is in the power-on state and in the discharge mode, if the state of charge of the energy storage battery is greater than the preset energy storage battery discharge depth, the control module determines whether the current mains power value is greater than the preset mains power reverse flow prevention threshold value. If so, and the discharge power of the energy storage converter is less than the maximum discharge power of the energy storage converter, the control module increases the discharge power of the energy storage converter; if not, the control module reduces the discharge power of the energy storage converter; If the state of charge of the energy storage battery is less than a preset discharge depth of the energy storage battery, the control module controls the energy storage converter to shut down.

8. The microgrid operation control method according to claim 1, characterized in that: The control module acquiring the working mode of the energy storage converter and the state of charge of the energy storage battery also includes: When the energy storage converter is in the on state and in the charging mode, the control module controls the energy storage converter to shut down.

9. The microgrid operation control method according to claim 6 or 7, characterized in that: The discharge power of the energy storage converter is obtained by the following formula: P o =P' o ×I o Where P o The discharge power of the energy storage converter, P' o is the maximum discharge power of the energy storage battery, I o is the discharge power growth coefficient of the energy storage battery.

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