Photovoltaic storage and charging system and control method and control device thereof

Abstract

The present invention provides a photovoltaic storage and charging system and a control method and control device thereof, the method comprising: obtaining the SOC and PCS output power of each energy storage cabinet energy storage battery in the system; obtaining the maximum SOC deviation according to the maximum and minimum SOC values, and judging whether the maximum SOC deviation exceeds the power regulation threshold; if yes, controlling the PCS to execute the SOC balancing strategy; if no, obtaining the maximum power deviation according to the maximum power value and the minimum power value; judging whether the maximum power deviation exceeds the power regulation threshold; if yes, controlling the PCS to execute the power balancing strategy. The present invention uses SOC regulation as an outer loop and power regulation as an inner loop to perform SOC balancing or power balancing on the photovoltaic storage and charging system energy storage battery, so as to solve the problem of increasing SOC deviation that may be caused by the long-term operation of a pure off-grid system, and the realization of balancing regulation does not require additional electrical wiring and construction, and is easy to implement and apply in existing photovoltaic storage and charging systems.

Description

Technical Field

[0001] The present invention relates to the field of new energy technology, and in particular to a control method of a photovoltaic storage and charging system, a control device of the photovoltaic storage and charging system, and a photovoltaic storage and charging system. Background Art

[0002] At present, for the solar-storage-charging system, the off-grid operation of a single PCS (Power Conversion System) is in VF (Voltage / Frequency) mode, and the off-grid parallel operation of multiple PCSs adopts a non-communication droop solution.

[0003] When the PCS is off-grid and in parallel operation, the power allocated to each PCS is significantly affected by the line impedance, and different internal control parameters need to be matched under different load conditions to achieve a better power sharing effect. Even if a better power sharing effect can be achieved, the SOC between energy storage systems will gradually widen during long-term off-grid applications.

[0004] Therefore, how to ensure the SOC balance of the off-grid parallel system in long-term operation has become a key issue restricting the operating reliability and operating income of the solar-storage-charging system. Summary of the invention

[0005] In order to solve the above technical problems, the first purpose of the present invention is to provide a control method for a solar storage and charging system.

[0006] The second objective of the present invention is to provide a control device for a solar storage and charging system.

[0007] The third objective of the present invention is to provide a solar storage and charging system.

[0008] The technical solution adopted by the present invention is as follows:

[0009] An embodiment of the first aspect of the present invention proposes a control method for a photovoltaic storage and charging system, wherein the photovoltaic storage and charging system includes a plurality of energy storage cabinets connected in parallel on the same AC bus, the energy storage cabinets include a PCS and an energy storage battery, and when the PCS is in an off-grid state, the method includes the following steps: obtaining the energy storage battery SOC and PCS output power of each energy storage cabinet in the photovoltaic storage and charging system; obtaining a maximum SOC deviation according to a maximum SOC value and a minimum SOC value, and judging whether the maximum SOC deviation exceeds a power regulation threshold; if the maximum SOC deviation exceeds the power regulation threshold, controlling the PCS to execute a SOC balancing strategy; if the maximum SOC deviation does not exceed the power regulation threshold, further obtaining a maximum power deviation according to a maximum output power value and a minimum output power value; judging whether the maximum power deviation exceeds the power regulation threshold; if the maximum power deviation exceeds the power regulation threshold, controlling the PCS to execute a power balancing strategy.

[0010] The control method of the solar energy storage and charging system proposed in the present invention may also have the following additional technical features:

[0011] According to one embodiment of the present invention, the power balancing strategy includes the following steps: obtaining the PCS with the highest power and the PCS with the lowest power; controlling the PCS with the highest power to reduce output power by adjusting the off-grid control parameters; and controlling the PCS with the lowest power to increase output power by adjusting the off-grid control parameters.

[0012] According to one embodiment of the present invention, the SOC balancing strategy includes the following steps: calculating the total load power of the photovoltaic energy storage system based on the output power of all PCSs, judging the charging and discharging direction of the load based on the total load power, wherein the total load power is the sum of the photovoltaic output power and the power consumed by the electrical load; calculating the maximum allowable power deviation ΔPmax based on the maximum SOC deviation; and adjusting the power of the PCS of the maximum SOC energy storage cabinet and the PCS of the minimum SOC energy storage cabinet based on the charging and discharging direction of the load and the maximum allowable power deviation ΔPmax.

[0013] According to one embodiment of the present invention, power regulation is performed on the PCS of the maximum SOC energy storage cabinet and the PCS of the minimum SOC energy storage cabinet according to the charge and discharge direction of the load and the maximum allowable power deviation ΔPmax, specifically including: if it is determined that the PCS is discharging the load, it is determined whether the discharge power of the PCS of the maximum SOC energy storage cabinet exceeds the discharge power threshold; if it does not exceed the discharge power threshold, it is further determined whether the power deviation between the PCS of the maximum SOC energy storage cabinet and the PCS of the minimum SOC energy storage cabinet exceeds the maximum allowable power deviation ΔPmax; if it does not exceed the maximum allowable power deviation ΔPmax, the virtual impedance of the PCS of the maximum SOC energy storage cabinet is reduced and the virtual impedance is limited. , and increase the virtual impedance of the PCS of the minimum SOC energy storage cabinet and perform virtual impedance limiting; if it is determined that the PCS is charging the load, determine whether the power of the PCS of the minimum SOC energy storage cabinet exceeds the charging power threshold, if the power of the PCS of the minimum SOC energy storage cabinet does not exceed the charging power threshold, then further determine whether the power deviation between the PCS of the maximum SOC energy storage cabinet and the PCS of the minimum SOC energy storage cabinet exceeds the maximum allowable power deviation ΔPmax, if it does not exceed the maximum allowable power deviation ΔPmax, then increase the virtual impedance of the PCS of the maximum SOC energy storage cabinet and perform virtual impedance limiting, and reduce the virtual impedance of the PCS of the minimum SOC energy storage cabinet and perform virtual impedance limiting.

[0014] An embodiment of the second aspect of the present invention proposes a control device for a photoelectric storage and charging system, wherein the photoelectric storage and charging system includes a plurality of energy storage cabinets connected in parallel on the same AC bus, wherein the energy storage cabinets include a PCS and an energy storage battery, and the control device includes: a first acquisition module, wherein the first acquisition module is used to obtain the energy storage battery SOC and PCS output power of each energy storage cabinet in the photoelectric storage and charging system when the PCS is in an off-grid state; a first judgment module, wherein the first judgment module is used to obtain a maximum SOC deviation according to a maximum SOC value and a minimum SOC value, and to determine whether the maximum SOC deviation exceeds a power regulation threshold; a first execution module, wherein the first execution module is used to control the PCS to execute a SOC balancing strategy when the maximum SOC deviation exceeds the power regulation threshold; a second acquisition module, wherein the second acquisition module is used to further obtain a maximum power deviation according to a maximum output power value and a minimum output power value when the maximum SOC deviation does not exceed the power regulation threshold; a second judgment module, wherein the second judgment module is used to determine whether the maximum power deviation exceeds the power regulation threshold; and a second execution module, wherein the second execution module is used to control the PCS to execute a power balancing strategy when the maximum power deviation exceeds the power regulation threshold.

[0015] The control device of the above-mentioned solar storage and charging system of the present invention also has the following additional technical features:

[0016] According to one embodiment of the present invention, the second execution module implements the power balancing strategy by the following steps: obtaining the PCS with the highest power and the PCS with the lowest power; controlling the PCS with the highest power to reduce output power by adjusting the off-grid control parameters; and controlling the PCS with the lowest power to increase output power by adjusting the off-grid control parameters.

[0017] According to one embodiment of the present invention, the first execution module adopts the following steps to execute the SOC balancing strategy: the total load power of the photovoltaic storage and charging system is calculated according to the output power of all PCSs, and the charging and discharging direction of the load is determined according to the total load power, and the total load power is the sum of the photovoltaic output power and the power consumed by the electrical load; the maximum allowable power deviation ΔPmax is calculated according to the maximum SOC deviation; the power of the PCS of the maximum SOC energy storage cabinet and the PCS of the minimum SOC energy storage cabinet is adjusted according to the charging and discharging direction of the load and the maximum allowable power deviation ΔPmax.

[0018] According to one embodiment of the present invention, the first execution module is further used to: if it is determined that the PCS discharges the load, determine whether the discharge power of the PCS of the maximum SOC energy storage cabinet exceeds the discharge power threshold; if it does not exceed the discharge power threshold, further determine whether the power deviation between the PCS of the maximum SOC energy storage cabinet and the PCS of the minimum SOC energy storage cabinet exceeds the maximum allowable power deviation ΔPmax; if it does not exceed the maximum allowable power deviation ΔPmax, reduce the virtual impedance of the PCS of the maximum SOC energy storage cabinet and perform virtual impedance limiting, and increase the virtual impedance of the PCS of the minimum SOC energy storage cabinet and perform Perform virtual impedance limiting; if it is determined that the PCS is charging the load, determine whether the power of the PCS of the minimum SOC energy storage cabinet exceeds the charging power threshold; if the power of the PCS of the minimum SOC energy storage cabinet does not exceed the charging power threshold, further determine whether the power deviation between the PCS of the maximum SOC energy storage cabinet and the PCS of the minimum SOC energy storage cabinet exceeds the maximum allowable power deviation ΔPmax; if it does not exceed the maximum allowable power deviation ΔPmax, increase the virtual impedance of the PCS of the maximum SOC energy storage cabinet and perform virtual impedance limiting, and reduce the virtual impedance of the PCS of the minimum SOC energy storage cabinet and perform virtual impedance limiting.

[0019] A third aspect of the present invention provides a photovoltaic storage and charging system, including the control device of the photovoltaic storage and charging system described in the second aspect of the present invention.

[0020] Beneficial effects of the present invention:

[0021] The present invention uses SOC regulation as the outer loop and power regulation as the inner loop to perform SOC balancing or power balancing on the energy storage batteries of the photovoltaic storage and charging system, so as to solve the problem of increasing SOC deviation that may be caused by long-term operation of a pure off-grid system, improve the reliability of off-grid operation of the photovoltaic storage and charging system, increase operational benefits, and the implementation of balanced regulation does not require mutual communication between PCSs, does not require additional electrical wiring and construction, and is easy to implement and apply in existing photovoltaic storage and charging systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a flow chart of a control method of a photovoltaic storage and charging system according to a first embodiment of the present invention;

[0023] Figure 2 is a schematic structural diagram of a light storage and charging system according to an embodiment of the present invention;

[0024] Figure 3 is a flow chart of a control method of a solar storage and charging system according to a second embodiment of the present invention;

[0025] Figure 4 is a flow chart of a control method of a solar storage and charging system according to a third embodiment of the present invention;

[0026] Figure 5 is a flow chart of a control method of a solar storage and charging system according to a fourth embodiment of the present invention;

[0027] Figure 6 4 is a block diagram of a control device of a solar storage and charging system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] Figure 1 is a flow chart of a control method of a photovoltaic storage and charging system according to a first embodiment of the present invention. Figure 2 As shown in the figure, the photovoltaic storage and charging system includes: multiple energy storage cabinets ESS Cabinet connected in parallel on the same AC bus AC BUS, loads mounted on the AC bus AC BUS and EMS (Energy Management System). The loads include power load Load and photovoltaic array PV Panel. The photovoltaic array PV Panel is mounted on the AC bus AC BUS through the photovoltaic inverter PV Inverter. The energy storage cabinet ESS Cabinet consists of energy storage batteries, energy storage inverter PCS and local controller LC. LC is a data forwarding unit. On the one hand, it is responsible for forwarding the data reported by PCS to EMS, and on the other hand, it is responsible for forwarding the data or instructions sent by EMS to PCS. EMS is a data converging unit, which is responsible for collecting key information such as SOC percentage and PCS output power reported by each ESS Cabinet, and then uniformly sending it to all energy storage cabinets ESS Cabinet. LC in the energy storage cabinet can also be omitted, and PCS communicates directly with EMS. If LC is omitted, EMS will also play the role of LC.

[0030] According to one embodiment of the present invention, Figure 1 As shown, the EMS can implement the control method of the solar storage charging system by taking the following steps:

[0031] S1, obtain the energy storage battery SOC and PCS output power of each energy storage cabinet in the solar storage and charging system.

[0032] S2, obtaining a maximum SOC deviation according to the maximum SOC value and the minimum SOC value, and determining whether the maximum SOC deviation exceeds a power regulation threshold.

[0033] Specifically, the SOCs of the energy storage batteries of all energy storage cabinets can be sorted, the maximum and minimum values ​​can be screened out, the energy storage cabinet numbers corresponding to the maximum and minimum values ​​can be recorded, and the difference between the maximum SOC and the minimum SOC can be calculated as the maximum SOC deviation.

[0034] S3: If the maximum SOC deviation exceeds the power regulation threshold, the PCS is controlled to execute the SOC balancing strategy.

[0035] S4: If the maximum SOC deviation does not exceed the power regulation threshold, further obtaining the maximum power deviation according to the maximum output power and the minimum output power.

[0036] Specifically, the PCS output powers of all energy storage cabinets can be sorted, the maximum and minimum values ​​can be screened out, the energy storage cabinet numbers corresponding to the maximum and minimum values ​​can be recorded, and the difference between the maximum output power and the minimum output power can be calculated as the maximum power deviation.

[0037] S5, determining whether the maximum power deviation exceeds a power regulation threshold.

[0038] S6: If the maximum power deviation exceeds the power regulation threshold, the PCS is controlled to execute a power balancing strategy.

[0039] Specifically, SOC balancing is first performed according to the actual SOC, and then power balancing is performed according to the actual output power. Thus, SOC regulation is used as the outer loop and power regulation is used as the inner loop to perform SOC balancing or power balancing on the energy storage batteries of the photovoltaic storage and charging system, so as to solve the problem of increasing SOC deviation that may be caused by long-term operation of a pure off-grid system, thereby improving the reliability of off-grid operation of the photovoltaic storage and charging system and increasing operational efficiency. Moreover, the implementation of balancing regulation does not require mutual communication between PCSs, and does not require additional electrical wiring and construction, and is easy to implement and apply in existing photovoltaic storage and charging systems.

[0040] As a specific example of the present invention, Figure 3 As shown, the power balancing strategy includes the following steps:

[0041] S11, obtaining a PCS with the largest power and a PCS with the smallest power.

[0042] S12, by adjusting the off-grid control parameters, the PCS with the largest power is controlled to reduce the output power.

[0043] S13, by adjusting the off-grid control parameters, the PCS with the smallest power is controlled to increase the output power.

[0044] Specifically, the power of the two PCSs with the maximum power and the minimum power is adjusted simultaneously, with the aim of making the output power of the two PCSs substantially equal. Off-grid control parameters may include virtual impedance. The output power of the PCS with the maximum control power may be reduced by increasing the virtual impedance and performing virtual impedance limiting. The output power of the PCS with the minimum control power may be increased by reducing the virtual impedance and performing virtual impedance limiting. Virtual impedance limiting is to limit the amplitude of the virtual impedance. When increasing the virtual impedance, if it increases to the maximum virtual impedance amplitude threshold, it stops. When reducing the virtual impedance, if it decreases to the minimum virtual impedance amplitude threshold, it stops.

[0045] As a specific example of the present invention, Figure 4 As shown, the SOC balancing strategy includes the following steps:

[0046] S21, calculate the total load power of the photovoltaic storage and charging system according to the output power of all PCSs, and determine the charging and discharging direction of the load according to the total load power. The total load power is the sum of the photovoltaic output power and the power consumed by the electrical load.

[0047] S22, calculating a maximum allowable power deviation ΔPmax according to the maximum SOC deviation.

[0048] S23, power adjustment is performed on the PCS of the maximum SOC energy storage cabinet and the PCS of the minimum SOC energy storage cabinet according to the charge and discharge direction of the load and the maximum allowable power deviation ΔPmax.

[0049] Further, according to one embodiment of the present invention, Figure 5 As shown, according to the charge and discharge direction of the load and the maximum allowable power deviation ΔPmax, the power of the PCS of the maximum SOC energy storage cabinet and the PCS of the minimum SOC energy storage cabinet are adjusted, specifically including:

[0050] If it is determined that the PCS discharges the load, it is determined whether the discharge power of the PCS of the energy storage cabinet with the maximum SOC exceeds the discharge power threshold (S231-S232). If it does not exceed the discharge power threshold, it is further determined whether the power deviation between the PCS of the energy storage cabinet with the maximum SOC and the PCS of the energy storage cabinet with the minimum SOC exceeds the maximum allowable power deviation ΔPmax (S233). If it does not exceed the maximum allowable power deviation ΔPmax, the virtual impedance of the PCS of the energy storage cabinet with the maximum SOC is reduced and the virtual impedance is limited, and the virtual impedance of the PCS of the energy storage cabinet with the minimum SOC is increased and the virtual impedance is limited (S234).

[0051] If it is determined that the PCS is charging the load, determine whether the power of the PCS of the minimum SOC energy storage cabinet exceeds the charging power threshold (S235-S236). If the power of the PCS of the minimum SOC energy storage cabinet does not exceed the charging power threshold, further determine whether the power deviation between the PCS of the maximum SOC energy storage cabinet and the PCS of the minimum SOC energy storage cabinet exceeds the maximum allowable power deviation ΔPmax (S237). If it does not exceed the maximum allowable power deviation ΔPmax, increase the virtual impedance of the PCS of the maximum SOC energy storage cabinet and perform virtual impedance limiting, and reduce the virtual impedance of the PCS of the minimum SOC energy storage cabinet and perform virtual impedance limiting (S238).

[0052] Specifically, the power of the two energy storage cabinets with the maximum SOC and the minimum SOC is adjusted simultaneously, with the aim of charging the energy storage cabinet with the maximum SOC less and charging the energy storage cabinet with the minimum SOC more. For equipment that needs to increase the charging power, it is necessary to determine whether its output power reaches the charging power threshold and whether its power deviation reaches the maximum allowable power deviation. If the charging power threshold is not reached and the maximum allowable power deviation ΔPmax is not exceeded, the virtual impedance of the PCS of the energy storage cabinet with the maximum SOC is increased, and the virtual impedance of the PCS of the energy storage cabinet with the minimum SOC is reduced. In this way, the SOC balance of the energy storage cabinets can be achieved.

[0053] In summary, according to the control method of the photovoltaic storage and charging system in the embodiment of the present invention, SOC regulation is used as the outer loop and power regulation is used as the inner loop to perform SOC balancing or power balancing on the energy storage batteries of the photovoltaic storage and charging system, so as to solve the problem of increasing SOC deviation that may be caused by long-term operation of a pure off-grid system, thereby improving the reliability of off-grid operation of the photovoltaic storage and charging system and increasing operational benefits. The implementation of balanced regulation does not require mutual communication between PCSs, does not require additional electrical wiring and construction, and is easy to implement and apply in existing photovoltaic storage and charging systems.

[0054] Corresponding to the control method of the above-mentioned photovoltaic storage and charging system, the present invention also provides a control device of the photovoltaic storage and charging system. Since the device embodiment of the present invention corresponds to the above-mentioned method embodiment, the details not disclosed in the device embodiment can be referred to the above-mentioned method embodiment, and the present invention will not repeat them.

[0055] Figure 6 is a block diagram of a control device of a photovoltaic storage and charging system according to an embodiment of the present invention, wherein the photovoltaic storage and charging system comprises a plurality of energy storage cabinets connected in parallel to the same AC bus, wherein the energy storage cabinets comprise a PCS and an energy storage battery, such as Figure 6 As shown, the device includes: a first acquisition module 100, a first judgment module 200, a first execution module 300, a second acquisition module 400, a second judgment module 500 and a second execution module 600.

[0056] Among them, the first acquisition module 100 is used to obtain the SOC of the energy storage battery and the PCS output power of each energy storage cabinet in the solar storage and charging system when the PCS is in an off-grid state; the first judgment module 200 is used to obtain the maximum SOC deviation according to the maximum SOC value and the minimum SOC value, and judge whether the maximum SOC deviation exceeds the power regulation threshold; the first execution module 300 is used to control the PCS to execute the SOC balancing strategy when the maximum SOC deviation exceeds the power regulation threshold; the second acquisition module 400 is used to further obtain the maximum power deviation according to the maximum output power value and the minimum output power value when the maximum SOC deviation does not exceed the power regulation threshold; the second judgment module 500 is used to judge whether the maximum power deviation exceeds the power regulation threshold; the second execution module 600 is used to control the PCS to execute the power balancing strategy when the maximum power deviation exceeds the power regulation threshold.

[0057] According to one embodiment of the present invention, the second execution module 600 adopts the following steps to execute the power balancing strategy: obtain the PCS with the highest power and the PCS with the lowest power; control the PCS with the highest power to reduce output power by adjusting the off-grid control parameters; control the PCS with the lowest power to increase output power by adjusting the off-grid control parameters.

[0058] According to one embodiment of the present invention, the first execution module 300 adopts the following steps to execute the SOC balancing strategy: the total load power of the photovoltaic storage and charging system is calculated based on the output power of all PCSs, and the charging and discharging direction of the load is determined based on the total load power, where the total load power is the sum of the photovoltaic output power and the power consumed by the electrical load; the maximum allowable power deviation ΔPmax is calculated based on the maximum SOC deviation; the power of the PCS of the maximum SOC energy storage cabinet and the PCS of the minimum SOC energy storage cabinet is adjusted according to the charging and discharging direction of the load and the maximum allowable power deviation ΔPmax.

[0059] According to one embodiment of the present invention, the first execution module 300 is further used to: if it is determined that the PCS discharges the load, determine whether the discharge power of the PCS of the maximum SOC energy storage cabinet exceeds the discharge power threshold; if it does not exceed the discharge power threshold, further determine whether the power deviation between the PCS of the maximum SOC energy storage cabinet and the PCS of the minimum SOC energy storage cabinet exceeds the maximum allowable power deviation ΔPmax; if it does not exceed the maximum allowable power deviation ΔPmax, reduce the virtual impedance of the PCS of the maximum SOC energy storage cabinet and perform virtual impedance limiting, and increase the virtual impedance of the PCS of the minimum SOC energy storage cabinet and perform Virtual impedance limiting; if it is determined that the PCS is charging the load, determine whether the power of the PCS of the minimum SOC energy storage cabinet exceeds the charging power threshold. If the power of the PCS of the minimum SOC energy storage cabinet does not exceed the charging power threshold, further determine whether the power deviation between the PCS of the maximum SOC energy storage cabinet and the PCS of the minimum SOC energy storage cabinet exceeds the maximum allowable power deviation ΔPmax. If it does not exceed the maximum allowable power deviation ΔPmax, increase the virtual impedance of the PCS of the maximum SOC energy storage cabinet and perform virtual impedance limiting, and reduce the virtual impedance of the PCS of the minimum SOC energy storage cabinet and perform virtual impedance limiting.

[0060] In summary, according to the control device of the photovoltaic storage and charging system in the embodiment of the present invention, SOC regulation is used as the outer loop and power regulation is used as the inner loop to perform SOC balancing or power balancing on the energy storage battery of the photovoltaic storage and charging system, so as to solve the problem of increasing SOC deviation that may be caused by long-term operation of a pure off-grid system, thereby improving the reliability of off-grid operation of the photovoltaic storage and charging system and increasing operational efficiency. The implementation of balanced regulation does not require mutual communication between PCSs, does not require additional electrical wiring and construction, and is easy to implement and apply in existing photovoltaic storage and charging systems.

[0061] In the description of the present invention, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms are not necessarily for the same embodiment or example. Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, fragment or portion of a code including one or more executable instructions for implementing the steps of a custom logical function or process, and the scope of the preferred embodiments of the present invention includes additional implementations, in which functions may be performed in a non-sequential order as shown or discussed, including in a substantially simultaneous manner or in reverse order according to the functions involved, which should be understood by a technician in the technical field to which the embodiments of the present invention belong.

[0062] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0063] A person skilled in the art may understand that all or part of the steps in the method for implementing the above-mentioned embodiment may be completed by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, which, when executed, includes one or a combination of the steps of the method embodiment.

[0064] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A control method for a solar storage and charging system, characterized in that: The photovoltaic storage and charging system includes a plurality of energy storage cabinets connected in parallel to the same AC bus, the energy storage cabinets include a PCS and an energy storage battery, and when the PCS is in an off-grid state, the method includes the following steps: Obtain the energy storage battery SOC and PCS output power of each energy storage cabinet in the solar energy storage and charging system; Obtaining a maximum SOC deviation according to a maximum SOC value and a minimum SOC value, and determining whether the maximum SOC deviation exceeds a power regulation threshold; If the maximum SOC deviation exceeds the power regulation threshold, controlling the PCS to execute the SOC balancing strategy; If the maximum SOC deviation does not exceed the power regulation threshold, further obtaining a maximum power deviation according to the maximum output power and the minimum output power; Determining whether the maximum power deviation exceeds a power regulation threshold; If the maximum power deviation exceeds the power adjustment threshold, controlling the PCS to execute a power balancing strategy; The SOC balancing strategy includes the following steps: The total load power of the photovoltaic storage and charging system is calculated based on the output power of all PCSs, and the charging and discharging direction of the load is determined based on the total load power. The total load power is the sum of the photovoltaic output power and the power consumed by the electrical load; Calculate the maximum allowable power deviation ΔPmax according to the maximum SOC deviation; According to the charge and discharge direction of the load and the maximum allowable power deviation ΔPmax, the power of the PCS of the maximum SOC energy storage cabinet and the PCS of the minimum SOC energy storage cabinet are adjusted; According to the charge and discharge direction of the load and the maximum allowable power deviation ΔPmax, the power of the PCS of the maximum SOC energy storage cabinet and the PCS of the minimum SOC energy storage cabinet are adjusted, including: If it is determined that the PCS discharges the load, it is determined whether the discharge power of the PCS of the maximum SOC energy storage cabinet exceeds the discharge power threshold; if it does not exceed the discharge power threshold, it is further determined whether the power deviation between the PCS of the maximum SOC energy storage cabinet and the PCS of the minimum SOC energy storage cabinet exceeds the maximum allowable power deviation ΔPmax; if it does not exceed the maximum allowable power deviation ΔPmax, the virtual impedance of the PCS of the maximum SOC energy storage cabinet is reduced and the virtual impedance is limited, and the virtual impedance of the PCS of the minimum SOC energy storage cabinet is increased and the virtual impedance is limited; If it is determined that the PCS is charging the load, it is determined whether the power of the PCS of the minimum SOC energy storage cabinet exceeds the charging power threshold; if the power of the PCS of the minimum SOC energy storage cabinet does not exceed the charging power threshold, it is further determined whether the power deviation between the PCS of the maximum SOC energy storage cabinet and the PCS of the minimum SOC energy storage cabinet exceeds the maximum allowable power deviation ΔPmax; if it does not exceed the maximum allowable power deviation ΔPmax, the virtual impedance of the PCS of the maximum SOC energy storage cabinet is increased and the virtual impedance is limited, and the virtual impedance of the PCS of the minimum SOC energy storage cabinet is reduced and the virtual impedance is limited.

2. The control method of the photovoltaic storage and charging system according to claim 1, characterized in that: The power balancing strategy includes the following steps: Get the PCS with the largest power and the PCS with the smallest power; By adjusting the off-grid control parameters, the PCS with the largest control power can reduce its output power; By adjusting the off-grid control parameters, the PCS with the smallest power is controlled to increase its output power.

3. A control device for a light storage and charging system, characterized in that: The solar energy storage and charging system includes a plurality of energy storage cabinets connected in parallel on the same AC bus, the energy storage cabinets include a PCS and an energy storage battery, and the control device includes: A first acquisition module, wherein the first acquisition module is used to acquire the energy storage battery SOC and PCS output power of each energy storage cabinet in the solar energy storage system when the PCS is in an off-grid state; A first judgment module, the first judgment module is used to obtain a maximum SOC deviation according to a maximum SOC value and a minimum SOC value, and judge whether the maximum SOC deviation exceeds a power regulation threshold; A first execution module, wherein the first execution module is used to control the PCS to execute the SOC balancing strategy when the maximum SOC deviation exceeds the power regulation threshold; A second acquisition module, the second acquisition module is used to further acquire a maximum power deviation according to a maximum output power value and a minimum output power value when the maximum SOC deviation does not exceed the power regulation threshold; A second judgment module, the second judgment module is used to judge whether the maximum power deviation exceeds the power adjustment threshold; A second execution module, wherein the second execution module is used to control the PCS to execute a power balancing strategy when the maximum power deviation exceeds the power adjustment threshold; The first execution module executes the SOC balancing strategy by the following steps: the total load power of the photovoltaic storage and charging system is calculated according to the output power of all PCSs, and the charge and discharge direction of the load is determined according to the total load power, wherein the total load power is the sum of the photovoltaic output power and the power consumed by the power load; the maximum allowable power deviation ΔPmax is calculated according to the maximum SOC deviation; the power of the PCS of the maximum SOC energy storage cabinet and the PCS of the minimum SOC energy storage cabinet is adjusted according to the charge and discharge direction of the load and the maximum allowable power deviation ΔPmax; The first execution module is further used for: If it is determined that the PCS discharges the load, it is determined whether the discharge power of the PCS of the maximum SOC energy storage cabinet exceeds the discharge power threshold; if it does not exceed the discharge power threshold, it is further determined whether the power deviation between the PCS of the maximum SOC energy storage cabinet and the PCS of the minimum SOC energy storage cabinet exceeds the maximum allowable power deviation ΔPmax; if it does not exceed the maximum allowable power deviation ΔPmax, the virtual impedance of the PCS of the maximum SOC energy storage cabinet is reduced and the virtual impedance is limited, and the virtual impedance of the PCS of the minimum SOC energy storage cabinet is increased and the virtual impedance is limited; If it is determined that the PCS is charging the load, it is determined whether the power of the PCS of the minimum SOC energy storage cabinet exceeds the charging power threshold; if the power of the PCS of the minimum SOC energy storage cabinet does not exceed the charging power threshold, it is further determined whether the power deviation between the PCS of the maximum SOC energy storage cabinet and the PCS of the minimum SOC energy storage cabinet exceeds the maximum allowable power deviation ΔPmax; if it does not exceed the maximum allowable power deviation ΔPmax, the virtual impedance of the PCS of the maximum SOC energy storage cabinet is increased and the virtual impedance is limited, and the virtual impedance of the PCS of the minimum SOC energy storage cabinet is reduced and the virtual impedance is limited.

4. The control device of the light storage and charging system according to claim 3, characterized in that: The second execution module executes the power balancing strategy by using the following steps: Get the PCS with the largest power and the PCS with the smallest power; By adjusting the off-grid control parameters, the PCS with the largest control power can reduce its output power; By adjusting the off-grid control parameters, the PCS with the smallest power is controlled to increase its output power.

5. A light storage and charging system, characterized in that: It comprises a control device for the light storage and charging system according to claim 3 or 4.

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