Method and system for controlling energy storage battery under alternating current and direct current hybrid micro-grid

Abstract

The invention discloses a control method and system for an energy storage battery under an AC / DC hybrid microgrid. The method comprises the following steps: controlling local equipment of the AC / DC hybrid microgrid in an interconnection grid-connected operation mode to adopt a master-slave control strategy; according to the actual energy storage capacity of the energy storage battery and the power surplus or defect condition of the direct current sub micro-grid, determining a switching strategy among a plurality of preset power modes: when the energy storage capacity of the energy storage battery is greater than 20% and less than 80%, the energy storage battery works in a charging and discharging mode; when the energy storage capacity of the energy storage battery is larger than or equal to 80% and the wind power and photovoltaic maximum power output power is smaller than the direct-current load, the energy storage battery only discharges without charging and is used for supplementing the power vacancy in the alternating-current and direct-current hybrid micro-grid; when the energy storage capacity of the energy storage battery is smaller than or equal to 20% and the wind power and photovoltaic maximum power output power is larger than the direct-current load, the energy storage battery works in the mode of only charging but not discharging and is used for absorbing surplus power in the alternating-current and direct-current hybrid micro-grid.

Description

Technical Field

[0001] The present application relates to the field of power balance control, and in particular to a control method, system, electronic device and computer-readable storage medium for energy storage batteries in an AC / DC hybrid microgrid. Background Art

[0002] As a complex microgrid including AC and DC sub-microgrids, it is more difficult for AC / DC hybrid microgrid to achieve internal autonomy of each sub-microgrid, power mutual assistance between sub-microgrids and maintain coordinated control of the entire system compared with a single microgrid. Based on the local control layer of the AC / DC hybrid microgrid under different operating modes, MGCC is built to collect information such as voltage, frequency, SOC and power surplus and shortage of AC / DC sub-microgrids for power coordinated control to improve the dynamic performance of the AC / DC hybrid microgrid system, achieve the maximum consumption of distributed renewable energy, enhance the power support between AC / DC sub-microgrids, and ensure the stability of the operation of the AC / DC hybrid microgrid.

[0003] In the interconnected grid-connected operation mode, the local device control of the AC / DC hybrid microgrid adopts a master-slave control strategy. At this time, the voltage and frequency of the AC sub-microgrid are supported by the large grid, and there is no need to consider the power flow inside the AC sub-microgrid. The bus voltage of the DC sub-microgrid is jointly controlled by the energy storage unit and the bidirectional AC / DC converter. The energy storage adopts a constant voltage control strategy, and the bidirectional AC / DC converter adopts a constant DC bus voltage control strategy. In the interconnected grid-connected operation, the maximum consumption of renewable energy is the first priority, so the photovoltaic and wind units adopt MPPT control. According to the actual requirements of the microgrid operation, the maximum limit of the energy storage SOC is set to 80%, and the minimum limit of the energy storage SOC is set to 20%. When 20%≤SOC<80%, the energy storage works in the charge and discharge mode: when SOC≥80%, the energy storage only discharges and does not charge; when SOC≤20%, the energy storage only charges and does not discharge.

[0004] In order to avoid the impact of deep charging and discharging of energy storage batteries on their life and the loss of AC / DC hybrid microgrid systems caused by frequent starting of bidirectional AC / DC converters, it is very important to formulate a power coordination control strategy for AC / DC hybrid microgrids under the interconnected grid-connected operation mode. Summary of the invention

[0005] The purpose of this application is to provide a control method, system, electronic device and computer-readable storage medium for an energy storage battery in an AC / DC hybrid microgrid.

[0006] To achieve the above objectives, the present application provides, in a first aspect, a control method for an energy storage battery in an AC / DC hybrid microgrid, comprising the following steps:

[0007] A master-slave control strategy is adopted to control the local equipment of the AC / DC hybrid microgrid in the interconnected grid-connected operation mode; wherein, under the control of the master-slave control strategy, the voltage and frequency of the AC sub-microgrid are supported by the large power grid, and the bus voltage of the DC sub-microgrid is jointly controlled by the energy storage battery and the bidirectional AC / DC converter, the energy storage battery adopts a constant voltage control strategy, and the bidirectional AC / DC converter adopts a constant DC bus voltage control strategy;

[0008] According to the actual energy storage of the energy storage battery and the power surplus or deficiency of the DC sub-microgrid, a switching strategy between the preset multiple power modes is determined:

[0009] In response to the energy storage capacity of the energy storage battery being greater than 20% and less than 80%, controlling the energy storage battery to operate in a charge and discharge mode;

[0010] In response to the energy storage capacity of the energy storage battery being greater than or equal to 80% and the maximum power output of wind power and photovoltaic power being less than the DC load, the energy storage battery is controlled to operate in a discharge mode of only discharging but not charging, so as to supplement the power shortage in the AC / DC hybrid microgrid;

[0011] In response to the energy storage capacity of the energy storage battery being less than or equal to 20% and the maximum power output of wind power and photovoltaic power being greater than the DC load, the energy storage battery is controlled to operate in a charging mode of only charging but not discharging to absorb surplus power in the AC / DC hybrid microgrid.

[0012] In response to the energy storage capacity of the energy storage battery being greater than 20% and less than 80%, controlling the energy storage battery to operate in a charge and discharge mode is specifically:

[0013] In response to the energy storage capacity of the energy storage battery being greater than 20% and less than 80%, and the maximum power output of wind power and photovoltaic power being greater than the DC load, the energy storage battery is controlled to operate in a charge and discharge mode of primary charging and secondary discharging to absorb surplus power in the AC / DC hybrid microgrid;

[0014] In response to the energy storage capacity of the energy storage battery being greater than 20% and less than 80%, and the maximum power output of wind power and photovoltaic power being less than the DC load, the energy storage battery is controlled to operate in a charge and discharge mode of main discharge and secondary charge to supplement the power shortage in the AC / DC hybrid microgrid.

[0015] Also includes:

[0016] In response to the output of the wind power and photovoltaic units when the energy storage battery operates in the main charging and secondary discharging charging and discharging mode being greater than a preset level, resulting in the storage energy of the energy storage battery being greater than or equal to 80%, in order to avoid deep charging of the energy storage battery, the energy storage battery is controlled to switch to standby mode, and the bidirectional AC / DC converter is controlled to operate in an inverter state, and the surplus electric energy in the AC / DC hybrid microgrid is transmitted to the power grid.

[0017] Also includes:

[0018] In response to the output of the wind power and photovoltaic units when the energy storage battery operates in the main discharge and secondary charge charging and discharging mode being less than a preset level, resulting in the storage energy of the energy storage battery being less than or equal to 80%, in order to avoid deep discharge of the energy storage battery, the energy storage battery is controlled to switch to standby mode, and the bidirectional AC / DC converter is controlled to operate in a rectification state, and the AC sub-microgrid provides power support for the AC / DC hybrid microgrid.

[0019] Also includes:

[0020] According to the influence of line parameters on the operating power distribution of the DC sub-microgrid and the AC sub-microgrid in the interconnected grid-connected operation mode, a power integral droop control strategy that adjusts the virtual resistance from the frequency domain perspective is adopted to distribute the system fluctuating power; wherein, the droop control part in the power integral droop control strategy enables the inverter to simulate the characteristics of the synchronous generator, automatically adjust the output power size according to the system operation status, and provide frequency and voltage support for the AC bus, and the power integral part in the power integral droop control strategy refers to obtaining the frequency domain parameters by integration so as to adjust the virtual resistance according to the frequency domain parameters.

[0021] Also includes:

[0022] The virtual inertia control strategy of the interconnected converter is adopted to control the power flow and the inertia of the sub-microgrid between the AC sub-microgrid and the DC sub-microgrid.

[0023] To achieve the above objectives, the present application provides, in a second aspect, a control system for an energy storage battery in an AC / DC hybrid microgrid, comprising:

[0024] The first unit is used to control the local equipment of the AC / DC hybrid microgrid in the interconnected grid-connected operation mode to adopt a master-slave control strategy; wherein, under the control of the master-slave control strategy, the voltage and frequency of the AC sub-microgrid are supported by the large power grid, and the bus voltage of the DC sub-microgrid is jointly controlled by the energy storage battery and the bidirectional AC / DC converter, the energy storage battery adopts a constant voltage control strategy, and the bidirectional AC / DC converter adopts a constant DC bus voltage control strategy;

[0025] The second unit is used to determine a switching strategy between the preset multiple power modes according to the actual storage energy of the energy storage battery and the power surplus or deficiency of the DC sub-microgrid:

[0026] In response to the energy storage capacity of the energy storage battery being greater than 20% and less than 80%, controlling the energy storage battery to operate in a charge and discharge mode;

[0027] In response to the energy storage capacity of the energy storage battery being greater than or equal to 80% and the maximum power output of wind power and photovoltaic power being less than the DC load, the energy storage battery is controlled to operate in a discharge mode of only discharging but not charging, so as to supplement the power shortage in the AC / DC hybrid microgrid;

[0028] In response to the energy storage capacity of the energy storage battery being less than or equal to 20% and the maximum power output of wind power and photovoltaic power being greater than the DC load, the energy storage battery is controlled to operate in a charging mode of only charging but not discharging to absorb surplus power in the AC / DC hybrid microgrid.

[0029] The second unit is also used for:

[0030] In response to the energy storage capacity of the energy storage battery being greater than 20% and less than 80%, and the maximum power output of wind power and photovoltaic power being greater than the DC load, the energy storage battery is controlled to operate in a charge and discharge mode of primary charging and secondary discharging to absorb surplus power in the AC / DC hybrid microgrid;

[0031] In response to the energy storage capacity of the energy storage battery being greater than 20% and less than 80%, and the maximum power output of wind power and photovoltaic power being less than the DC load, the energy storage battery is controlled to operate in a charge and discharge mode of main discharge and secondary charge to supplement the power shortage in the AC / DC hybrid microgrid.

[0032] To achieve the above-mentioned purpose, the present application provides an electronic device in a third aspect, the electronic device comprising:

[0033] Memory for storing computer programs;

[0034] A processor is used to implement the steps of the control method of the energy storage battery in the AC / DC hybrid microgrid as described in any embodiment of the first aspect when executing the computer program stored in the memory.

[0035] To achieve the above-mentioned objectives, the present application provides in a fourth aspect a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, each step of controlling the energy storage battery in the AC / DC hybrid microgrid as described in any embodiment of the first aspect above is implemented.

[0036] The control scheme of the energy storage battery under the AC / DC hybrid microgrid provided in the present application, in order to avoid the influence of deep charge and discharge of the energy storage battery on the life and the loss of the AC / DC hybrid microgrid system caused by the frequent start of the bidirectional AC / DC converter, firstly puts the local equipment of the AC / DC hybrid microgrid in the interconnected grid-connected operation mode under the master-slave control strategy, and then formulates the switching strategy between different power modes according to the SOC of the energy storage battery and the power surplus or deficiency of the DC sub-microgrid, so as to provide an effective processing strategy for each situation as much as possible, thereby minimizing the impact on the life of the energy storage battery and the loss of the system. The present application also provides a control system, electronic equipment and computer-readable storage medium for the energy storage battery under the AC / DC hybrid microgrid, which have the above-mentioned beneficial effects and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0038] Figure 1 A flow chart of a control method for an energy storage battery in an AC / DC hybrid microgrid provided in an embodiment of the present application;

[0039] Figure 2 It is a structural diagram of an AC / DC hybrid microgrid system in an interconnected grid-connected operation mode;

[0040] Figure 3 A branch schematic diagram of two different charging and discharging modes in a control method for an energy storage battery in an AC / DC hybrid microgrid provided in an embodiment of the present application;

[0041] Figure 4 A schematic diagram of branches of two other switching strategies provided in the embodiment of the present application;

[0042] Figure 5 A structural block diagram of a control system for an energy storage battery in an AC / DC hybrid microgrid provided in an embodiment of the present application. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0044] See also Figure 1 , Figure 1 A flow chart of a control method for an energy storage battery in an AC / DC hybrid microgrid provided in an embodiment of the present application, for an AC / DC hybrid microgrid including an AC sub-microgrid and a DC sub-microgrid, comprising the following steps:

[0045] Step 101: Control local devices of an AC / DC hybrid microgrid in an interconnected grid-connected operation mode to adopt a master-slave control strategy;

[0046] This step is intended to be performed by an execution subject (such as a local server or cloud server for data processing and analysis) suitable for executing the control method of the energy storage battery under the AC / DC hybrid microgrid provided by this application. In the interconnected grid-connected operation mode, the local device control of the AC / DC hybrid microgrid adopts a master-slave control strategy. At this time, the voltage and frequency of the AC sub-microgrid are supported by the large power grid, and there is no need to consider the power flow inside the AC sub-microgrid. The bus voltage of the DC sub-microgrid is jointly controlled by the energy storage unit and the bidirectional AC / DC converter. The energy storage adopts a constant voltage control strategy, and the bidirectional AC / DC converter adopts a constant DC bus voltage control strategy. Figure 2 The structure diagram of an AC / DC hybrid microgrid system in an interconnected grid-connected operation mode is shown. It is connected to the grid through the AC side, and the AC side contains a wind turbine, while the DC is connected to the photovoltaic and energy storage units. The AC load and DC load are connected to the AC bus and DC bus respectively, and the AC and DC buses are connected through a converter for power exchange. During the stable operation of the system, the wind turbine provides power for the AC load, the DC side load is met by photovoltaic power generation, and the battery is used to smooth fluctuations and cut peaks and fill valleys.

[0047] In the interconnected grid-connected operation mode, the maximum consumption of renewable energy is the first priority, so the photovoltaic and wind units adopt MPPT control. According to the actual requirements of microgrid operation, the maximum limit of energy storage SOC is set to 80%, and the minimum limit of energy storage SOC is set to 20%. When 20% ≤ SOC < 80%, the energy storage works in the charge and discharge mode: when SOC ≥ 80%, the energy storage only discharges but does not charge; when SOC ≤ 20%, the energy storage only charges but does not discharge.

[0048] Step 102: Determine a switching strategy between multiple preset power modes according to the actual energy storage of the energy storage battery and the power surplus or deficiency of the DC sub-microgrid;

[0049] On the basis of step 101, this step aims at the execution subject to formulate multiple power mode switching strategies according to the actual energy output of the energy storage battery and the power surplus or deficiency of the DC sub-microgrid, which may include a power autonomous mode.

[0050] Switching strategies include:

[0051] In response to the energy storage capacity of the energy storage battery being greater than 20% and less than 80%, controlling the energy storage battery to operate in a charge and discharge mode;

[0052] For details, please refer to Figure 3 The schematic diagram of the two branches under the subdivision shown in the figure, in response to the energy storage of the energy storage battery being greater than 20% and less than 80%, and the maximum power output of wind power and photovoltaic power being greater than the DC load, the energy storage battery is controlled to work in the charging and discharging mode of main charging and secondary discharging to absorb the surplus power in the AC / DC hybrid microgrid. At this time, the system power balance expression is: P wing +P pv -P bat =P load , Pwind represents wind power, Ppv represents photovoltaic power, Pbat represents the power of energy storage battery, and Pload represents the load power. This mode can be named power autonomous mode 1; when the storage capacity of the energy storage battery is greater than 20% and less than 80%, and the maximum power output of wind power and photovoltaic power is less than the DC load, the energy storage battery is controlled to work in the main discharge and secondary charge mode to supplement the power shortage in the AC / DC hybrid microgrid. At this time, the system power balance expression is: P wind +P pv +P bat =P load , this mode can be named as power autonomy mode 2.

[0053] In response to the energy storage capacity of the energy storage battery being greater than or equal to 80% and the maximum power output of wind power and photovoltaic power being less than the DC load, the energy storage battery is controlled to operate in a discharge mode of only discharging but not charging, so as to supplement the power shortage in the AC / DC hybrid microgrid;

[0054] When the energy storage state of charge SOC ≥ 80%, the battery is only discharged but not charged. The maximum power output of wind power and photovoltaic power is less than the DC load. At this time, the battery works in the discharge mode to supplement the power shortage. At this time, the system power balance expression is: P wind +P pv +P bat =P load , this mode can be named as power autonomy mode three.

[0055] In response to the energy storage capacity of the energy storage battery being less than or equal to 20% and the maximum power output of wind power and photovoltaic power being greater than the DC load, the energy storage battery is controlled to operate in a charging mode of only charging but not discharging to absorb surplus power in the AC / DC hybrid microgrid.

[0056] When the energy storage state of charge SOC ≤ 20%, the battery is only charged but not discharged. When the maximum power output of wind power and photovoltaic power is greater than the DC load, the battery works in charging mode and absorbs surplus power. At this time, the system power balance expression is: P wind +P pv -P bat =P load .

[0057] The control method of the energy storage battery in the AC / DC hybrid microgrid provided in the present application, in order to avoid the influence of deep charge and discharge of the energy storage battery on the life and the loss of the AC / DC hybrid microgrid system caused by the frequent startup of the bidirectional AC / DC converter, firstly puts the local equipment of the AC / DC hybrid microgrid in the interconnected grid-connected operation mode under the master-slave control strategy, and then formulates the switching strategy between different power modes according to the SOC of the energy storage battery and the power surplus or deficiency of the DC sub-microgrid, so as to provide an effective processing strategy for each situation as much as possible, thereby minimizing the impact on the life of the energy storage battery and the loss of the system.

[0058] exist Figure 1 and Figure 3 In addition to the four power autonomy modes shown in FIG. Figure 4 Two other modes are further provided:

[0059] Power mutual assistance mode 1: In response to the wind power and photovoltaic unit output being greater than the preset level when the energy storage battery is working in the main charging and secondary discharging charging and discharging mode, resulting in the energy storage battery having a storage capacity greater than or equal to 80%, in order to avoid deep charging of the energy storage battery, the energy storage battery is controlled to switch to the standby mode, and the bidirectional AC / DC converter is controlled to work in the inverter state, and the surplus electric energy in the AC / DC hybrid microgrid is transmitted to the grid. At this time, the system power balance expression is: P wind +P pv -P ILC =P load ;

[0060] Power mutual assistance mode 1: In response to the wind power and photovoltaic unit output being less than the preset level when the energy storage battery is working in the main discharge and secondary charge charging mode, resulting in the energy storage battery having a storage capacity less than or equal to 80%, in order to avoid deep discharge of the energy storage battery, the energy storage battery is controlled to switch to standby mode, and the bidirectional AC / DC converter is controlled to work in the rectification state, and the AC sub-microgrid provides power support for the AC / DC hybrid microgrid. At this time, the system power balance expression is: P wind +P pv +P ILC =P load , P ILC Indicates the power of the bidirectional AC / DC converter.

[0061] When DC micro-sources or AC micro-sources are operated in parallel under traditional droop control, due to differences in export line parameters, circulating current problems occur between micro-sources, that is, it is impossible to reasonably share the system load power among micro-sources. In this regard, this application also analyzes and studies the impact of line parameters on the power distribution of parallel micro-source operation, and proposes an improved droop control strategy for DC micro-sources and AC micro-sources:

[0062] That is, in order to coordinate the batteries and supercapacitors of the hybrid energy storage system in the DC microgrid to reasonably distribute the system fluctuation power during normal operation, so as to give full play to their respective advantages, a power integral droop control strategy is proposed to adjust the virtual resistance from the perspective of frequency domain. Among them, the droop control part of the power integral droop control strategy enables the inverter to simulate the basic characteristics of the synchronous generator and automatically adjust the output power according to the system operation status, which can provide frequency and voltage support for the AC bus. The droop control belongs to the non-interconnected communication control method, which is suitable for the parallel operation of multiple AC micro-sources. Under ideal conditions, it can achieve reasonable power distribution between micro-sources; and the power integral part of the power integral droop control strategy can also adjust the virtual resistance from the perspective of frequency domain by obtaining frequency domain parameters in an integral manner.

[0063] Furthermore, the coordinated control strategy of the interconnected converter is also deeply explored. In order to realize the reasonable power flow of the sub-microgrids on both sides and improve the inertia of the sub-grids on both sides, the principle of virtual synchronous generator is applied to propose a virtual inertia control strategy for the interconnected converter, which can be specifically divided into a control strategy for the AC micro-source interface converter and a control strategy for the DC micro-source interface converter. Among them, the control strategy of the AC micro-source interface converter is similar to the control strategy of the DC micro-source interface converter according to its control target classification. Since the bus voltage and frequency need to be stable during the operation of the AC microgrid, it is essentially necessary to consider the control of the active power and reactive power output of the interface converter. The AC micro-source interface converter is generally a three-phase voltage source inverter, which adopts a double closed-loop control structure. The outer loop is responsible for tracking the control target, and the inner loop is the current loop, which is used to fine-tune and improve the output power quality of the inverter.

[0064] Because the situation is complicated, it is impossible to list them one by one for explanation. Those skilled in the art should be aware that there may be many examples based on the basic method principles provided by this application combined with actual conditions, and all of them should be within the scope of protection of this application without sufficient creative work.

[0065] See below Figure 5 , Figure 5 This is a structural block diagram of a control system 500 for an energy storage battery in an AC / DC hybrid microgrid provided in an embodiment of the present application. This embodiment exists as a system embodiment corresponding to the above method embodiment. The control system 500 for an energy storage battery in an AC / DC hybrid microgrid may include:

[0066] The first unit 501 is used to control the local equipment of the AC / DC hybrid microgrid in the interconnected grid-connected operation mode to adopt a master-slave control strategy; wherein, under the control of the master-slave control strategy, the voltage and frequency of the AC sub-microgrid are supported by the large power grid, and the bus voltage of the DC sub-microgrid is jointly controlled by the energy storage battery and the bidirectional AC / DC converter, the energy storage battery adopts a constant voltage control strategy, and the bidirectional AC / DC converter adopts a constant DC bus voltage control strategy;

[0067] The second unit 502 is used to determine a switching strategy between the preset multiple power modes according to the actual storage energy of the energy storage battery and the power surplus or deficiency of the DC sub-microgrid:

[0068] In response to the energy storage capacity of the energy storage battery being greater than 20% and less than 80%, controlling the energy storage battery to operate in a charge and discharge mode;

[0069] In response to the energy storage capacity of the energy storage battery being greater than or equal to 80% and the maximum power output of wind power and photovoltaic power being less than the DC load, the energy storage battery is controlled to operate in a discharge mode of only discharging but not charging, so as to supplement the power shortage in the AC / DC hybrid microgrid;

[0070] In response to the energy storage capacity of the energy storage battery being less than or equal to 20% and the maximum power output of wind power and photovoltaic power being greater than the DC load, the energy storage battery is controlled to operate in a charging mode of only charging but not discharging to absorb surplus power in the AC / DC hybrid microgrid.

[0071] In some other implementations of this embodiment, the second unit 502 is further configured to:

[0072] In response to the energy storage capacity of the energy storage battery being greater than 20% and less than 80%, and the maximum power output of wind power and photovoltaic power being greater than the DC load, the energy storage battery is controlled to operate in a charging and discharging mode of primary charging and secondary discharging to absorb surplus power in the AC / DC hybrid microgrid;

[0073] In response to the energy storage capacity of the energy storage battery being greater than 20% and less than 80%, and the maximum power output of wind power and photovoltaic power being less than the DC load, the energy storage battery is controlled to operate in a charge and discharge mode of main discharge and secondary charge to supplement the power shortage in the AC / DC hybrid microgrid.

[0074] In some other implementations of this embodiment, the second unit 502 is further configured to:

[0075] In response to the output of wind power and photovoltaic units being greater than a preset level when the energy storage battery is operating in a main charging and secondary discharging charging and discharging mode, resulting in the storage energy of the energy storage battery being greater than or equal to 80%, in order to avoid deep charging of the energy storage battery, the energy storage battery is controlled to switch to standby mode, and the bidirectional AC / DC converter is controlled to operate in an inverter state, and the surplus electric energy in the AC / DC hybrid microgrid is transmitted to the power grid.

[0076] In response to the output of wind power and photovoltaic units being less than a preset level when the energy storage battery is operating in a main discharge and secondary charge charging mode, resulting in the storage energy of the energy storage battery being less than or equal to 80%, in order to avoid deep discharge of the energy storage battery, the energy storage battery is controlled to switch to standby mode, and the bidirectional AC / DC converter is controlled to operate in a rectification state, and the AC sub-microgrid provides power support for the AC / DC hybrid microgrid.

[0077] In some other implementations of this embodiment, the system may further include:

[0078] The third unit 503 is used to distribute the system fluctuating power according to the influence of line parameters on the operating power distribution of the DC sub-microgrid and the AC sub-microgrid in the interconnected grid-connected operation mode, and adopts a power integral droop control strategy that adjusts the virtual resistance from the frequency domain perspective; wherein the droop control part of the power integral droop control strategy enables the inverter to simulate the characteristics of the synchronous generator, automatically adjust the output power size according to the system operation status, and provide frequency and voltage support for the AC bus, and the power integral part of the power integral droop control strategy refers to obtaining frequency domain parameters by integration to adjust the virtual resistance according to the frequency domain parameters.

[0079] In some other implementations of this embodiment, the system may further include:

[0080] The fourth unit 504 is used to control the power flow and sub-microgrid inertia between the AC sub-microgrid and the DC sub-microgrid by adopting the virtual inertia control strategy of the interconnected converter; wherein the virtual inertia control strategy of the interconnected converter is constructed by combining the interconnected converter coordination control strategy with the principle of the virtual synchronous generator.

[0081] This embodiment exists as a system embodiment corresponding to the above method embodiment. Compared with the prior art, the control system of the energy storage battery under the AC / DC hybrid microgrid provided by this embodiment, in order to avoid the influence of deep charging and discharging of the energy storage battery on the life and the loss of the AC / DC hybrid microgrid system caused by the frequent startup of the bidirectional AC / DC converter, firstly puts the local equipment of the AC / DC hybrid microgrid in the interconnected grid-connected operation mode under the master-slave control strategy, and then formulates the switching strategy between different power modes according to the SOC of the energy storage battery and the power surplus or deficiency of the DC sub-microgrid, so as to provide an effective processing strategy for each situation as much as possible, thereby minimizing the impact on the life of the energy storage battery and the loss of the system.

[0082] Based on the above embodiments, the present application further provides an electronic device, which may include a memory and a processor, wherein a computer program is stored in the memory, and when the processor calls the computer program in the memory, the steps provided in the above embodiments may be implemented. Of course, the electronic device may also include various necessary network interfaces, power supplies, and other components.

[0083] The present application also provides a computer-readable storage medium on which a computer program is stored, and when the computer program is executed by an execution terminal or a processor, the steps provided in the above embodiment can be implemented. The storage medium may include: a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, and other media that can store program codes.

[0084] The various embodiments in the specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other. For the system disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0085] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0086] Specific examples are used herein to illustrate the principles and implementation methods of the present application, and the description of the above embodiments is only used to help understand the method and core ideas of the present application. For ordinary technicians in this technical field, without departing from the principles of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall within the scope of protection of the claims of the present application.

[0087] It should also be noted that, in this specification, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or equipment. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or equipment including the elements.

Claims

1. A control method for energy storage battery in AC / DC hybrid microgrid, characterized in that: The following steps are involved: A master-slave control strategy is adopted to control the local equipment of the AC / DC hybrid microgrid in the interconnected grid-connected operation mode; wherein, under the control of the master-slave control strategy, the voltage and frequency of the AC sub-microgrid are supported by the large power grid, and the bus voltage of the DC sub-microgrid is jointly controlled by the energy storage battery and the bidirectional AC / DC converter, the energy storage battery adopts a constant voltage control strategy, and the bidirectional AC / DC converter adopts a constant DC bus voltage control strategy; According to the actual energy storage of the energy storage battery and the power surplus or deficiency of the DC sub-microgrid, a switching strategy between the preset multiple power modes is determined: In response to the energy storage capacity of the energy storage battery being greater than 20% and less than 80%, controlling the energy storage battery to operate in a charge and discharge mode; In response to the energy storage capacity of the energy storage battery being greater than or equal to 80% and the maximum power output of wind power and photovoltaic power being less than the DC load, the energy storage battery is controlled to operate in a discharge mode of only discharging but not charging, so as to supplement the power shortage in the AC / DC hybrid microgrid; In response to the energy storage capacity of the energy storage battery being less than or equal to 20% and the maximum power output of wind power and photovoltaic power being greater than the DC load, the energy storage battery is controlled to operate in a charging mode of only charging but not discharging, so as to absorb surplus power in the AC / DC hybrid microgrid.

2. The control method of energy storage battery in AC / DC hybrid microgrid according to claim 1 is characterized in that: In response to the energy storage capacity of the energy storage battery being greater than 20% and less than 80%, controlling the energy storage battery to operate in a charge and discharge mode is specifically: In response to the energy storage capacity of the energy storage battery being greater than 20% and less than 80%, and the maximum power output of wind power and photovoltaic power being greater than the DC load, the energy storage battery is controlled to operate in a charge and discharge mode of primary charging and secondary discharging to absorb surplus power in the AC / DC hybrid microgrid; In response to the energy storage capacity of the energy storage battery being greater than 20% and less than 80% and the maximum power output of wind power and photovoltaic power being less than the DC load, the energy storage battery is controlled to operate in a charge and discharge mode of main discharge and secondary charge to supplement the power shortage in the AC / DC hybrid microgrid.

3. The control method of energy storage battery in AC / DC hybrid microgrid according to claim 2 is characterized in that: Also includes: In response to the output of the wind power and photovoltaic units when the energy storage battery operates in the main charging and secondary discharging charging and discharging mode being greater than a preset level, resulting in the storage energy of the energy storage battery being greater than or equal to 80%, in order to avoid deep charging of the energy storage battery, the energy storage battery is controlled to switch to standby mode, and the bidirectional AC / DC converter is controlled to operate in an inverter state, and the surplus electric energy in the AC / DC hybrid microgrid is transmitted to the power grid.

4. The control method of energy storage battery in AC / DC hybrid microgrid according to claim 2 is characterized in that: Also includes: In response to the output of the wind power and photovoltaic units when the energy storage battery operates in the main discharge and secondary charge charging and discharging mode being less than a preset level, resulting in the storage energy of the energy storage battery being less than or equal to 80%, in order to avoid deep discharge of the energy storage battery, the energy storage battery is controlled to switch to standby mode, and the bidirectional AC / DC converter is controlled to operate in a rectification state, and the AC sub-microgrid provides power support for the AC / DC hybrid microgrid.

5. The control method of energy storage battery in AC / DC hybrid microgrid according to any one of claims 1 to 4, characterized in that: Also includes: According to the influence of line parameters on the operating power distribution of the DC sub-microgrid and the AC sub-microgrid in the interconnected grid-connected operation mode, a power integral droop control strategy that adjusts the virtual resistance from the frequency domain perspective is adopted to distribute the system fluctuating power; wherein, the droop control part in the power integral droop control strategy enables the inverter to simulate the characteristics of the synchronous generator, automatically adjust the output power size according to the system operation status, and provide frequency and voltage support for the AC bus, and the power integral part in the power integral droop control strategy refers to obtaining the frequency domain parameters by integration so as to adjust the virtual resistance according to the frequency domain parameters.

6. The control method of energy storage battery in AC / DC hybrid microgrid according to any one of claims 1 to 4, characterized in that: Also includes: The virtual inertia control strategy of the interconnected converter is adopted to control the power flow and the inertia of the sub-microgrid between the AC sub-microgrid and the DC sub-microgrid.

7. A control system for energy storage batteries in an AC / DC hybrid microgrid, characterized in that: include: The first unit is used to control the local equipment of the AC / DC hybrid microgrid in the interconnected grid-connected operation mode to adopt a master-slave control strategy; wherein, under the control of the master-slave control strategy, the voltage and frequency of the AC sub-microgrid are supported by the large power grid, and the bus voltage of the DC sub-microgrid is jointly controlled by the energy storage battery and the bidirectional AC / DC converter, the energy storage battery adopts a constant voltage control strategy, and the bidirectional AC / DC converter adopts a constant DC bus voltage control strategy; The second unit is used to determine a switching strategy between the preset multiple power modes according to the actual storage energy of the energy storage battery and the power surplus or deficiency of the DC sub-microgrid: In response to the energy storage capacity of the energy storage battery being greater than 20% and less than 80%, controlling the energy storage battery to operate in a charge and discharge mode; In response to the energy storage capacity of the energy storage battery being greater than or equal to 80% and the maximum power output of wind power and photovoltaic power being less than the DC load, the energy storage battery is controlled to operate in a discharge mode of only discharging but not charging, so as to supplement the power shortage in the AC / DC hybrid microgrid; In response to the energy storage capacity of the energy storage battery being less than or equal to 20% and the maximum power output of wind power and photovoltaic power being greater than the DC load, the energy storage battery is controlled to operate in a charging mode of only charging but not discharging, so as to absorb surplus power in the AC / DC hybrid microgrid.

8. The control system of the energy storage battery in the AC / DC hybrid microgrid according to claim 7 is characterized in that: The second unit is also used for: In response to the energy storage capacity of the energy storage battery being greater than 20% and less than 80%, and the maximum power output of wind power and photovoltaic power being greater than the DC load, the energy storage battery is controlled to operate in a charge and discharge mode of primary charging and secondary discharging to absorb surplus power in the AC / DC hybrid microgrid; In response to the energy storage capacity of the energy storage battery being greater than 20% and less than 80% and the maximum power output of wind power and photovoltaic power being less than the DC load, the energy storage battery is controlled to operate in a charge and discharge mode of main discharge and secondary charge to supplement the power shortage in the AC / DC hybrid microgrid.

9. An electronic device, characterized in that: include: Memory, for computer programs; A processor, configured to implement the steps of the method for controlling an energy storage battery in an AC / DC hybrid microgrid as claimed in any one of claims 1 to 6 when executing a computer program stored in the memory.

10. A readable storage medium, characterized in that: The readable storage medium stores a computer program, and after being executed by a processor, the computer program can implement each step of the control method of the energy storage battery in the AC / DC hybrid microgrid as described in any one of claims 1 to 6.

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