Energy storage system SOC balance control method and device and computer equipment

Abstract

The invention relates to the technical field of photovoltaic energy storage, and discloses an energy storage system SOC balance control method and device and computer equipment, an energy storage system comprises a plurality of energy storage inverters, and the method comprises the steps that when the load power of the energy storage system is stable, the battery charging and discharging proportion of each energy storage inverter and the sum of the battery output or input power of the energy storage system are calculated; distributing the sum of the output or input power of the battery to each energy storage inverter based on the charge-discharge ratio of the battery; and performing charging mode SOC balance control or discharging mode SOC balance control on each energy storage inverter based on the distributed battery output or input power. According to the invention, two-way SOC equalization is carried out according to the battery charging and discharging proportion of a single machine. On the premise that the maximum charging and discharging capacity of the battery is guaranteed, double-channel SOC balanced release in a parallel system and a single machine is guaranteed, power dispatching is preferentially guaranteed when the maximum capacity of the single circuit is exceeded, the service life of the battery is guaranteed, the phenomenon that a power grid buys electricity is avoided, and expenses are reduced.

Description

Technical Field

[0001] The present invention relates to the field of photovoltaic energy storage technology, and in particular to a method, device and computer equipment for SOC balancing control of an energy storage system. Background Art

[0002] Currently, for energy storage grid-connected inverters, whether for stand-alone or parallel systems, the DC side of the energy storage inverter is a dual-channel battery. During the grid-connected process, energy is provided to the load, and excess PV (photovoltaic) energy is used to charge the battery. The difference in the state of charge (SOC) of the two channels on the DC side is increasing, which may have significant impacts, such as shortened battery life, reduced battery capacity utilization, and safety hazards.

[0003] These impacts are specifically reflected in: 1. The battery capacity utilization rate decreases. When charging, the high SOC battery will trigger the overvoltage protection in advance, resulting in the low SOC battery unable to be fully charged. When discharging, the low SOC battery will trigger the undervoltage protection in advance, making it impossible to release the remaining power of the high SOC battery; 2. Accelerated battery decay and reduced lifespan. Long-term overcharge and over-discharge will cause its performance to decay; 3. Increased safety hazards. Long-term imbalance will lead to local overheating, thermal runaway and even explosion of a single battery; 4. Circulation and energy loss. The SOC difference of the parallel dual batteries will cause circulation, resulting in ineffective energy flow between the batteries, increasing system losses and reducing overall efficiency; 5. Further deterioration of electrochemical performance: Long-term inconsistent charge and discharge currents will aggravate the differences in the degree of SEI film aging, leading to differentiation of the chemical reaction rates inside the battery cell, and further widening the SOC deviation.

[0004] Most existing energy storage inverters with dual-path batteries primarily guarantee power scheduling, but ignore the impact of the SOC differences between the dual-path batteries on the battery life itself, resulting in shortened battery life, reduced capacity utilization, and potential safety hazards. Summary of the Invention

[0005] In view of this, the present invention provides an energy storage system SOC balancing control method, device and computer equipment to solve the problem in the prior art that only power scheduling is considered in the energy storage system while ignoring battery SOC balancing, resulting in shortened battery life.

[0006] In a first aspect, the present invention provides a method for SOC balancing control of an energy storage system, wherein the energy storage system includes multiple energy storage inverters. The method includes:

[0007] When the load power of the energy storage system is stable, calculate the battery charge and discharge ratio of each energy storage inverter and the total battery output or input power of the energy storage system;

[0008] Allocate the total battery output or input power to each energy storage inverter based on the battery charge and discharge ratio;

[0009] Based on the allocated battery output or input power, the battery of each energy storage inverter is subjected to SOC balancing control in charging mode or SOC balancing control in discharging mode.

[0010] The present invention provides a method for controlling the SOC balancing of an energy storage system. When the load power is stable, the method first calculates the battery charge and discharge ratio and the total output or input power of the battery of each energy storage inverter, and then distributes power based on the ratio to ensure that the output power of each inverter accurately matches the system demand, thereby avoiding energy waste due to unreasonable power distribution, improving the energy utilization rate of the energy storage system, and making the system run more efficiently. Dual-channel SOC balancing is performed according to the battery charge and discharge ratio of a single machine. Under the premise of the maximum charge and discharge capacity of the battery, the balanced release of the dual-channel SOC in the parallel system and the single machine is guaranteed. When the maximum capacity of a single channel is exceeded, power scheduling is prioritized to ensure battery life, avoid the phenomenon of grid purchase of electricity, reduce cost expenditure, and solve the problem in the prior art that only power scheduling is considered in the energy storage system while ignoring battery SOC balancing, resulting in shortened battery life.

[0011] In an optional embodiment, the energy storage system SOC balancing control method further includes: determining whether the load power of the energy storage system is stable in the following manner:

[0012] When the load power of the energy storage system is not stable, the meter power is distributed according to the rated power of each energy storage inverter until the meter stabilizes at the preset value and there is no meter buying phenomenon. The load power of the energy storage system is then determined to be stable.

[0013] This invention provides a method for SOC balancing control of an energy storage system. This method uses the stability of the meter at a preset value and the absence of meter-buying as the criteria for determining load power stability, providing a clear basis for determining system stability. Compared to fuzzy judgment, this approach can accurately locate system stability nodes, ensuring that subsequent power allocation and SOC balancing control are carried out based on system stability, thereby improving the effectiveness and accuracy of the control strategy.

[0014] In an optional embodiment, calculating the battery charge and discharge ratio of each energy storage inverter includes:

[0015] Obtain the battery capacity, current battery SOC, battery voltage, and battery SOC protection value of each energy storage inverter;

[0016] The battery charge and discharge ratio of each energy storage inverter is calculated based on the battery capacity, current battery SOC, battery voltage and battery SOC protection value of each energy storage inverter.

[0017] The present invention provides a method for controlling the SOC balance of an energy storage system. This method calculates the battery charge and discharge ratio based on parameters such as the battery capacity and current battery SOC of each energy storage inverter. This method fully considers the actual energy storage capacity and status of each inverter battery. The calculation incorporates battery voltage and SOC protection values, effectively preventing battery damage due to overcharging, overdischarging, or voltage anomalies. Calculating the battery charge and discharge ratio is a crucial step in achieving SOC balance and helps narrow the SOC differences between the batteries in each inverter.

[0018] In an optional embodiment, the battery charge and discharge ratio of each energy storage inverter is calculated based on the battery capacity, current battery SOC, battery voltage, and battery SOC protection value of each energy storage inverter, including:

[0019] Designate one energy storage inverter as the master and other energy storage inverters as slaves;

[0020] Calculate the master battery charge and discharge capacity based on the master's battery capacity, current battery SOC, battery voltage, and battery SOC protection value, and calculate each slave battery charge and discharge capacity based on each slave's battery capacity, current battery SOC, battery voltage, and battery SOC protection value;

[0021] Calculate the sum of the master battery charge and discharge capacity and all slave battery charge and discharge capacities;

[0022] The charge and discharge ratio of the master battery is calculated based on the charge and discharge capacity and the sum value of the master battery, and the charge and discharge ratio of each slave battery is calculated based on the charge and discharge capacity and the sum value of each slave battery.

[0023] The present invention provides a method for SOC balancing control of energy storage systems. This method designates a master as the decision-making core, responsible for aggregating global information and calculating battery charge and discharge ratios, thus avoiding coordination delays and conflicts in distributed architectures. The master can make optimal decisions based on more comprehensive data, improving system response speed. The charge and discharge capacities of the master and slave devices are calculated separately, taking into account hardware differences between different inverters. The ratio is calculated based on the sum of the charge and discharge capacities, ensuring that power allocation matches the actual capabilities of the devices. The master can dynamically adjust the master and slave battery charge and discharge ratios based on real-time load changes.

[0024] In an optional embodiment, the total output or input power of the battery is distributed to each energy storage inverter based on the battery charge and discharge ratio, including:

[0025] Calculate the product of the host battery charge and discharge ratio and the total battery output or input power as the host battery allocated power, and distribute the host battery allocated power to the host;

[0026] The product of the charge and discharge ratio of each slave battery and the total output or input power of the battery is calculated as the allocated power of each slave battery, and the allocated power of each slave battery is distributed to the corresponding slave.

[0027] This invention provides a method for SOC balancing control of energy storage systems. By directly multiplying the battery charge-discharge ratio by the total power, the allocation results are consistent with the previously calculated strategy. When changes in battery parameters such as SOC and voltage cause the battery charge-discharge ratio to adjust, the allocated power is dynamically updated.

[0028] In an optional embodiment, each energy storage inverter includes at least two batteries; the energy storage system also includes a photovoltaic circuit board;

[0029] Based on the allocated battery output or input power, each energy storage inverter is subjected to SOC balancing control in charging mode or SOC balancing control in discharging mode, including:

[0030] When the energy storage system meets the preset charging conditions, the initial dual-battery charging power setpoint in each energy storage inverter is calculated based on whether the zero-backflow protection function is enabled. Based on the initial dual-battery charging power setpoint, the charging mode SOC balancing control is performed on the dual-battery in each energy storage inverter under the conditions of no zero-backflow protection, zero-backflow protection, limited battery charging power, and meter abnormality.

[0031] When the energy storage system meets the preset discharge conditions, the initial dual-path battery discharge power setpoint in each energy storage inverter is calculated based on the presence of photovoltaic circuit boards and load power demand. Based on the initial dual-path battery discharge power setpoint, the discharge mode SOC balancing control of the dual-path batteries in each energy storage inverter is performed in the event of sudden load changes, limited battery discharge power, energy storage inverter self-loss, and meter abnormalities.

[0032] The present invention provides a method for SOC balancing control of an energy storage system, which distinguishes between charging and discharging modes, and formulates exclusive control strategies for different working conditions in each mode. During charging, the initial charging power set value is calculated based on whether the 0 anti-backflow function is enabled, and the situations of no 0 anti-backflow, 0 anti-backflow, power limitation and meter abnormality are handled separately; during discharging, the initial discharge power set value is calculated based on the presence of the photovoltaic circuit board and the load power demand, and then adjusted for load mutations, power limitation and other situations, to ensure that accurate SOC balancing control can be achieved in all scenarios, and to improve the adaptability and effectiveness of the control strategy. The dual-channel batteries in each energy storage inverter are controlled independently and collaboratively. Taking into account the possible performance differences of the dual-channel batteries, the dynamic balancing of the SOC of the dual-channel batteries is achieved by separately calculating and adjusting their charging and discharging power set values, thereby avoiding the degradation of system performance due to battery imbalance.

[0033] In an optional embodiment, the energy storage inverter includes an ARM controller;

[0034] Based on the initial dual-battery charging power given value, the charging mode SOC balancing control is performed on the dual batteries in each energy storage inverter under the conditions of no 0 backflow prevention, 0 backflow prevention, battery charging power limitation, and meter abnormality, including:

[0035] In the absence of zero backflow protection, the ARM controller sends the dual battery charging ratio and calculates the initial dual battery charging power set value based on the dual battery charging ratio. It also determines whether the charging power set value of each battery exceeds its own maximum charging power. If it exceeds, the excess is added to the other battery until the load and battery charging power are stable.

[0036] When the load and battery charging power are running stably, it is determined whether the actual charging power of each battery is less than the preset battery charging power setting value. If so, the charging ratio of the two batteries is switched, and it is determined whether the difference between the SOC values ​​of the two batteries is greater than a first preset value. If so, the dual battery charging power given value is recalculated as the battery charging power given target value, and the secondary battery charging power is distributed based on the sum of the actual charging power of the two batteries, so that the initial dual battery charging power given value is close to the battery charging power given target value;

[0037] When the battery charging power is limited, determining a battery charging power limit value, and when the battery charging power limit value is less than a given battery charging power target value, adjusting the given battery charging power target value to the battery charging power limit value;

[0038] In the case of zero backflow prevention, the battery charging power set value is cyclically increased according to the first preset step size in each charging cycle until the actual battery charging power is less than the preset battery charging power set value. At this time, it is determined that the photovoltaic circuit board outputs the maximum power, and the battery maximum charging power value does not exceed the battery's own maximum charging power value;

[0039] When the electric meter is abnormal and there is no 0 backflow prevention, the dual-channel battery charging power setting value is set to the battery maximum charging power value, and the initial dual-channel battery charging power setting value does not exceed the battery maximum charging power value.

[0040] The present invention provides a method for SOC balancing control of an energy storage system. In the absence of 0 backflow protection, when the given value of the charging power of a battery exceeds its maximum charging power, the excess portion is automatically added to the other battery to avoid damage to the battery due to overcharging and ensure charging safety. When the battery charging power is limited, the given target value is adjusted to the limited power value to prevent the battery from being subjected to excessive power under abnormal conditions, thereby extending the battery life. When the load is stable but the actual charging power is insufficient, the SOC balancing is accelerated by switching the charging ratio of the two batteries. A secondary distribution is performed based on the sum of the actual charging power, so that the initial given value gradually approaches the target value, achieving a smooth transition and avoiding the impact of power mutations on the system. In the 0 backflow protection mode, the maximum power point of the photovoltaic power generation is accurately identified by cyclically increasing the given value and monitoring the actual power. In abnormal situations such as the loss of the electric meter, the given charging power value is automatically set to the maximum charging power of the battery to ensure that the system continues to operate.

[0041] In an optional embodiment, the energy storage inverter includes an ARM controller;

[0042] Based on the initial dual-battery discharge power given value, discharge mode SOC balancing control is performed on the dual batteries in each energy storage inverter under conditions of sudden load change, battery discharge power limitation, energy storage inverter self-loss, and meter abnormality, including:

[0043] When the load suddenly changes, the ARM controller is used to send the dual-battery discharge ratio and calculate the initial dual-battery discharge power setpoints for the case where the energy storage system only has batteries and no photovoltaic circuit boards, and the case where the energy storage system has batteries and photovoltaic circuit boards.

[0044] In the case of battery discharge power restrictions, when one of the battery lines is restricted, the restriction on the other battery line is lifted, and the unrestricted battery line is given priority to output power to meet the load demand. When the discharge power of both batteries is restricted and the restricted battery discharge power does not meet the load demand, the meter is allowed to purchase electricity.

[0045] When calculating the energy storage inverter's own loss, the energy storage inverter's own loss is cyclically increased according to a second preset step length until the meter value is greater than the second preset value, so that the energy storage system operates stably. When the meter value is greater than the second preset value and the actual output power of any of the dual-path batteries is less than the preset battery discharge power setting value, the energy storage inverter's own loss is cyclically reduced according to a third preset step length until the energy storage inverter's own loss threshold range is met.

[0046] In the case of an abnormality of the electric meter, the dual-channel battery discharge power given value is set to the battery maximum discharge power value, and the initial dual-channel battery discharge power given value does not exceed the battery maximum discharge power value.

[0047] The present invention provides a method for SOC balancing control of an energy storage system. When the load suddenly changes, it distinguishes between "battery-only, no photovoltaic" and "battery + photovoltaic" scenarios, calculating discharge power setpoints for each scenario to ensure power distribution more closely matches actual energy supply and demand. An ARM controller issues discharge ratios for both battery paths, prioritizing the output power of the battery with the higher SOC, achieving efficient energy output while accelerating SOC balancing. When the power of a single battery path is limited (e.g., due to overtemperature load reduction), the restriction on the other path is automatically released, allowing the unrestricted battery to take on more load, protecting the battery while meeting load demand. The meter is only allowed to purchase electricity when both battery paths are limited, prioritizing battery energy depletion, reducing electricity purchase costs while ensuring power continuity. By cyclically increasing and decreasing the system's own loss value, the system finds the optimal loss parameters under different operating conditions, ensuring that power calculations are closer to actual losses. In abnormal situations such as meter loss, the discharge power setpoint is automatically set to the battery's maximum discharge power, ensuring continued system operation. This discharge-mode SOC balancing control ensures battery safety while meeting load demand. Through dynamic loss compensation and fault tolerance mechanisms, the energy storage system can maintain efficient operation under complex operating conditions.

[0048] In a second aspect, the present invention provides a SOC balancing control device for an energy storage system, wherein the energy storage system includes a plurality of energy storage inverters, and the device includes:

[0049] The battery charge-discharge ratio and battery output or input power calculation module is used to calculate the battery charge-discharge ratio of each energy storage inverter and the total battery output or input power of the energy storage system when the load power of the energy storage system is stable;

[0050] A battery output or input power distribution module is used to distribute the total battery output or input power to each energy storage inverter based on the battery charge and discharge ratio;

[0051] The SOC balancing control module is used to perform SOC balancing control in charging mode or SOC balancing control in discharging mode on each energy storage inverter based on the allocated battery output or input power.

[0052] In a third aspect, the present invention provides a computer device comprising: a memory and a processor, the memory and the processor being communicatively connected to each other, the memory storing computer instructions, and the processor executing the computer instructions to thereby execute the energy storage system SOC balancing control method of the first aspect or any corresponding embodiment thereof.

[0053] In a fourth aspect, the present invention provides a computer-readable storage medium having computer instructions stored thereon, the computer instructions being used to enable a computer to execute the energy storage system SOC balancing control method of the first aspect or any corresponding embodiment thereof.

[0054] In a fifth aspect, the present invention provides a computer program product comprising computer instructions for causing a computer to execute the energy storage system SOC balancing control method of the first aspect or any corresponding embodiment thereof. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0056] Figure 1 is a flow chart of a method for SOC balancing control of an energy storage system according to an embodiment of the present invention;

[0057] Figure 2 is a flow chart of another SOC balancing control method for an energy storage system according to an embodiment of the present invention;

[0058] Figure 3 is a flow chart of another SOC balancing control method for an energy storage system according to an embodiment of the present invention;

[0059] Figure 4 1 is a flow chart of SOC balancing control in a charging mode in an energy storage system SOC balancing control method according to an embodiment of the present invention;

[0060] Figure 5 1. It is a flow chart of SOC balancing control in discharge mode of an energy storage system SOC balancing control method according to an embodiment of the present invention;

[0061] Figure 6 2 is a structural block diagram of an energy storage system SOC balancing control device according to an embodiment of the present invention;

[0062] Figure 7 Schematic diagram of the hardware structure of a computer device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0063] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are 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 those skilled in the art without making creative efforts shall fall within the scope of protection of the present invention.

[0064] Most existing energy storage inverter solutions simply ensure that grid-connected batteries have sufficient energy to support the load, eliminating the need to purchase electricity from the grid to support the load and reducing customer expenses. They charge the battery when PV energy is high, disregarding SOC balancing. Assuming the current battery SOC value is within the grid-connected minimum SOC protection point, the battery can continue to operate and discharge power. However, these solutions fail to consider the significant impacts that can arise as the SOC gap widens, including shortened battery life, reduced capacity utilization, and potential safety hazards.

[0065] An embodiment of the present invention provides a method for controlling SOC balancing of an energy storage system. By first ensuring power scheduling and then dynamically adjusting the dual-path SOC balancing, the SOC balancing of the dual-path batteries in a parallel system and a single-machine system is achieved under the premise of the maximum charge and discharge capacity of the battery, thereby ensuring the battery life.

[0066] According to an embodiment of the present invention, an embodiment of a SOC balancing control method for an energy storage system is provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0067] In this embodiment, a SOC balancing control method for an energy storage system is provided, which can be used in an energy storage system including multiple energy storage inverters. Figure 1 FIG. 1 is a flow chart of a method for controlling SOC balancing of an energy storage system according to an embodiment of the present invention. Figure 1 As shown, the process includes the following steps:

[0068] Step S101 , when the load power of the energy storage system is stable, the battery charge and discharge ratio of each energy storage inverter and the total output or input power of the batteries of the energy storage system are calculated.

[0069] Specifically, load power stability generally means that the fluctuation range of the load power value within a certain period of time is within a preset small range. For example, if the power fluctuation threshold is set to ±5%, when the power variation of the load carried by the energy storage system remains within the range of ±5% of the current average power for 10 consecutive minutes, the load power can be preliminarily determined to be stable. Load power stability is also related to meter data and the energy balance status of the system. When the meter data is stable at the preset value and there is no meter buying phenomenon, it can serve as an important basis for load power stability.

[0070] When the energy storage system includes one energy storage inverter, it is a stand-alone system; when the energy storage system includes at least two energy storage inverters, it is a parallel system.

[0071] The energy storage system captures several key parameters for each energy storage inverter, including battery capacity, current state of charge (SOC), battery voltage, and battery SOC protection value. These parameters reflect the battery's current energy storage capacity, health status, and safe operating limits. For example, battery capacity determines the maximum amount of charge a battery can theoretically store, while the current SOC indicates the percentage of charge currently stored. Based on these captured parameters, the system calculates the battery charge and discharge ratio for each energy storage inverter.

[0072] The calculation takes into account both battery capacity and current SOC. Batteries with larger capacity and higher SOC can handle more power during the charge and discharge process. For example, if an inverter has a large battery capacity and a higher SOC, its battery charge and discharge ratio in the entire system will be relatively high, meaning it will shoulder a larger share of the subsequent power distribution. Battery voltage and SOC protection levels are also considered to ensure the calculated ratio is within a safe range and prevent overcharging or over-discharging.

[0073] After calculating the battery charge and discharge ratios for each inverter, the system calculates the total output or input power of the energy storage system's batteries. This value combines the total power that all batteries can output in their current state, reflecting the power output capacity of the entire energy storage system under stable load.

[0074] Step S102 : Allocate the total output or input power of the battery to each energy storage inverter based on the battery charge and discharge ratio.

[0075] Specifically, after obtaining the battery charge-discharge ratio and the total battery output or input power, the system distributes the total battery output or input power to each energy storage inverter according to the battery charge-discharge ratio. Specifically, the power allocated to each inverter is equal to its battery charge-discharge ratio multiplied by the total battery output or input power. For example, if the battery charge-discharge ratio of an inverter is 0.3 and the total battery output or input power is 100kW, then the power allocated to the inverter is 100×0.3=30kW. Through this proportional distribution method, it is ensured that the power borne by each inverter matches the performance and status of its battery, achieving reasonable power distribution and avoiding overloading or underloading of some inverters.

[0076] Step S103 : Based on the allocated battery output or input power, the battery of each energy storage inverter is subjected to SOC balancing control in a charging mode or SOC balancing control in a discharging mode.

[0077] Specifically, after completing power allocation, the system determines whether the energy storage system is in charging or discharging mode based on the current energy supply and demand. If the photovoltaic (PV) panel energy exceeds the load energy, the battery needs to be charged, and the energy storage system enters charging mode. Conversely, if the PV panel energy is less than the load energy, the battery needs to release energy, and the energy storage system enters discharging mode.

[0078] SOC represents the percentage of a battery's current stored charge to its total capacity, reflecting the battery's energy storage status. In energy storage systems consisting of multiple energy storage inverters and dual-channel batteries, differences in initial capacity, charge and discharge rates, and aging levels among battery cells can gradually lead to imbalanced SOCs if left uncontrolled. SOC balancing control aims to eliminate or minimize these differences, aligning the SOCs of all batteries. During charging, power distribution is adjusted according to regulations to avoid overcharging, while during discharging, power supply is guaranteed in response to load changes and battery limitations, thereby achieving dynamic balancing of the dual-channel battery SOCs.

[0079] The energy storage system SOC balancing control method provided in this embodiment first calculates the battery charge and discharge ratio and the total battery output or input power of each energy storage inverter when the load power is stable, and then distributes power based on the ratio to ensure that the output power of each inverter accurately matches the system demand, avoids energy waste due to unreasonable power distribution, improves the energy utilization rate of the energy storage system, and makes the system run more efficiently. Dual-channel battery SOC balancing is performed according to the charge and discharge ratio of a single-machine battery. Under the premise of the maximum charge and discharge capacity of the battery, the SOC of the dual-channel batteries in the parallel system and the single-machine system is guaranteed to be released evenly. When the maximum capacity of a single-channel battery is exceeded, power scheduling is prioritized to ensure battery life, avoid the phenomenon of grid purchase of electricity, reduce cost expenditure, and solve the problem in the prior art that the energy storage system only considers power scheduling and ignores battery SOC balancing, resulting in shortened battery life.

[0080] In this embodiment, a SOC balancing control method for an energy storage system is provided, which can be used in an energy storage system including multiple energy storage inverters. Figure 2 FIG. 1 is a flow chart of a method for controlling SOC balancing of an energy storage system according to an embodiment of the present invention. Figure 2 As shown, the process includes the following steps:

[0081] Step S201 , determining whether the load power of the energy storage system is stable is performed as follows: when the load power of the energy storage system is not stable, the meter power is distributed according to the rated power of each energy storage inverter until the meter stabilizes at a preset value and there is no meter buying phenomenon, then the load power of the energy storage system is determined to be stable.

[0082] Specifically, load power stability is also related to meter data and the system's energy balance. When meter data is stable at a preset value and there is no meter-purchased electricity, it can serve as an important indicator of load power stability. For example, if the power value displayed by the meter remains within a certain stable range and the system does not need to purchase large amounts of electricity from the grid to meet load demand, it indicates that the energy supply and demand relationship within the system is relatively balanced and the load power is stable. This judgment, combined with the interaction of the grid, further confirms the stable operation of the system from the perspective of energy flow.

[0083] Furthermore, if the load suddenly changes, the electricity meter is allocated according to the rated power. Assuming that the parallel system consists of two energy storage inverters, the energy storage inverter will continue to purchase electricity after limiting the load power allocation due to its own discharge logic. The load power is continuously allocated, so that the energy storage inverter with output capacity outputs more, and the energy storage inverter without output capacity maintains the maximum output until the electricity meter is close to 0.

[0084] It should be noted that determining the load power stability of an energy storage system requires not only the status of the electric meter but also the comprehensive consideration of the operating status of each component within the energy storage system. When the operating parameters (such as voltage, current, and temperature) of key equipment such as the inverter and battery are within the normal range and do not fluctuate abnormally, and the system does not provide any fault alarm information, it can assist in determining that the load power is stable. For example, if the battery temperature remains stable within the normal operating temperature range and the inverter output voltage and frequency fluctuate slightly, these all indicate that the system is operating smoothly under the current load and the load power is stable.

[0085] Step S202 : When the load power of the energy storage system is stable, the battery charge and discharge ratio of each energy storage inverter and the total output or input power of the batteries of the energy storage system are calculated.

[0086] Specifically, after the load power of the energy storage system is stabilized, the parallel system SOC balancing logic processing is started. The above step S202 includes:

[0087] Step S2021: Obtain the battery capacity, current battery SOC, battery voltage, and battery SOC protection value of each energy storage inverter.

[0088] Specifically, battery capacity refers to the maximum amount of electricity a battery can theoretically store when fully charged. It is a fundamental indicator of a battery's energy storage capacity and is typically measured in ampere-hours (Ah) or watt-hours (Wh). For example, a battery labeled 50Ah can ideally discharge at a current of 1A for 50 hours. In an energy storage system, battery capacity determines the maximum energy available to the inverter, impacting both charge and discharge power distribution and the overall energy storage strategy.

[0089] The current battery SOC (State of Charge) indicates the percentage of the battery's total capacity that is currently stored, providing a direct reflection of the battery's current energy storage level. For example, a current battery SOC of 60% means the battery is currently at 60% of its full capacity. It is a core parameter for power scheduling and SOC balancing in energy storage systems. During charging, SOC is used to determine whether the battery is nearly fully charged and adjust the charging strategy. During discharging, SOC is used to assess whether the battery's remaining charge can meet load demand. It is also used to distribute power between the two battery paths to achieve SOC balancing.

[0090] Battery voltage is an important parameter that characterizes the working state of the battery, reflecting the electrochemical reaction and energy state inside the battery. During normal operation, the battery voltage is within a specific range. The standard voltage range of different types of batteries varies. For example, the normal voltage range of lithium-ion battery cells is generally 2.75V-4.2V. By monitoring the battery voltage, the battery performance and health status can be evaluated. Abnormal voltage (too high or too low) may indicate that the battery has problems such as overcharging, over-discharging, internal short circuit or aging. During the charging and discharging process, the battery voltage directly affects the charge and discharge current and power control. When charging, the voltage approaches the full charge voltage and the battery will switch to trickle charging. When discharging, the voltage reaches the discharge cut-off voltage and the discharge stops.

[0091] Battery SOC protection values ​​include an upper charge limit and a lower discharge limit, setting safety boundaries for the battery's charge and discharge processes. The upper charge limit prevents overcharging, which can lead to performance degradation, shortened lifespan, and even safety incidents. The lower discharge limit prevents overdischarge, which can irreversibly damage the battery's internal chemical substances. During energy storage system operation, when the battery SOC reaches or approaches the protection value, the system automatically adjusts the charge and discharge strategy, such as limiting charging power or stopping discharge, to ensure that the battery always operates within a safe SOC range, ensuring battery safety and extending its service life.

[0092] Step S2022 , calculating the battery charge and discharge ratio of each energy storage inverter based on the battery capacity, current battery SOC, battery voltage, and battery SOC protection value of each energy storage inverter.

[0093] In some optional implementations, the above step S2022 includes:

[0094] In step a1, one energy storage inverter is designated as the master, and the other energy storage inverters except the master are designated as slaves.

[0095] Specifically, taking a parallel system consisting of two energy storage inverters as an example, during the system initialization or configuration phase, one energy storage inverter is designated as the master through specific setup instructions or hardware identification, while the others automatically become slaves. For example, you can manually select a specific inverter as the master in the system management interface, or assign a specific inverter master status through hardware DIP or IP address settings, clearly defining its dominant position in the system.

[0096] Step a2, calculate the host battery charge and discharge capacity based on the host's battery capacity, current battery SOC, battery voltage and battery SOC protection value, and calculate the battery charge and discharge capacity of each slave based on the battery capacity, current battery SOC, battery voltage and battery SOC protection value of each slave.

[0097] Specifically, each energy storage inverter includes an ARM controller, a DSP controller, and at least two batteries. In this embodiment, a dual-battery system is used as an example.

[0098] The host ARM controller calculates the host's battery charge and discharge power given value A1 and the slave's battery charge and discharge power given value A2 respectively; the host calculates the sum of the charge and discharge capacity of the dual batteries in the single-machine system (host) based on the battery capacity, current SOC, battery voltage, and SOC protection value; the slave calculates the sum of the charge and discharge capacity of the dual batteries in the single-machine system (slave) based on the battery capacity, current SOC, battery voltage, and SOC protection value.

[0099] Step a3: Calculate the sum of the charge and discharge capacity of the master battery and the charge and discharge capacity of all slave batteries.

[0100] Specifically, in the entire parallel system, the charge and discharge capacity of a single machine battery or the sum of the charge and discharge capacity of the master machine battery and the charge and discharge capacity of the slave machine battery is calculated.

[0101] Step a4: Calculate the charge and discharge ratio of the master battery based on the charge and discharge capacity and the sum of the master battery, and calculate the charge and discharge ratio of each slave battery based on the charge and discharge capacity and the sum of the slave battery.

[0102] Specifically, the charge-discharge ratio of the host battery=the charge-discharge capacity of the host battery / (the charge-discharge capacity of the host battery+the charge-discharge capacity of the slave battery).

[0103] Slave battery charge and discharge ratio = slave battery charge and discharge capacity / (host battery charge and discharge capacity + slave battery charge and discharge capacity).

[0104] The energy storage system SOC balancing control method provided in this embodiment designates the master as the decision-making core, responsible for aggregating global information and calculating the battery charge and discharge ratio, thus avoiding coordination delays and conflicts in distributed architectures. The master can make optimal decisions based on more comprehensive data, improving system response speed. The battery charge and discharge capacity of the master and slave devices is calculated separately, taking into account the hardware differences between different inverters. The ratio is calculated based on the sum of the battery charge and discharge capacities to ensure that power distribution matches the actual capabilities of the equipment. The master can dynamically adjust the battery charge and discharge ratio of the master and slave devices based on real-time load changes.

[0105] Step S203 : Allocate the total output or input power of the battery to each energy storage inverter based on the battery charge and discharge ratio.

[0106] Specifically, the above step S203 includes:

[0107] Step S2031 : Calculate the product of the host battery charge-discharge ratio and the total battery output or input power as the host battery allocated power, and distribute the host battery allocated power to the host.

[0108] Step S2032 : Calculate the product of the charge-discharge ratio of each slave battery and the total output or input power of the battery as the allocated power of each slave battery, and distribute the allocated power of each slave battery to the corresponding slave.

[0109] Specifically, in steps S2031 and S2032, when the load power is stable, the total output or input power of the batteries in the parallel system is calculated, and power is distributed to each energy storage inverter (master or slave) based on the calculated charge and discharge ratios of the master battery and the slave battery in the parallel system. The SOC balancing logic of the DSP controller inside the single-machine system is then used.

[0110] It should be noted that, by superimposing disturbances on the electric meter, since inverter power - electric meter power = load power, the electric meter value is gradually increased or decreased according to the electric meter disturbance, thereby changing the load power.

[0111] Parallel system SOC balancing control: When adjusting the power output between different energy storage inverters, it is possible that a certain energy storage inverter will limit its power, resulting in the phenomenon of electricity purchase by the meter. As long as there is electricity purchase, the meter power will be distributed to make the parallel system SOC balancing control stable. Load power distribution and parallel system SOC balancing are a dynamic adjustment process.

[0112] Step S204: Based on the allocated battery output or input power, perform SOC balancing control in charging mode or SOC balancing control in discharging mode on each energy storage inverter. Figure 1 Step S103 of the illustrated embodiment will not be described in detail here.

[0113] The energy storage system SOC balancing control method provided in this embodiment calculates the battery charge and discharge ratio based on parameters such as the battery capacity and current battery SOC of each energy storage inverter. This fully considers the actual energy storage capacity and status of each inverter battery. The calculation incorporates battery voltage and SOC protection values, effectively preventing battery damage due to overcharging, overdischarging, or voltage anomalies. Calculating the battery charge and discharge ratio is a crucial step in achieving SOC balancing, helping to narrow the SOC differences between batteries in each inverter. By directly multiplying the battery charge and discharge ratio by the total power, the allocation results are consistent with the previous calculation strategy. When changes in parameters such as battery SOC and voltage cause the battery charge and discharge ratio to adjust, the allocated power is dynamically updated.

[0114] In this embodiment, a SOC balancing control method for an energy storage system is provided, which can be used in an energy storage system including multiple energy storage inverters. Figure 3 FIG. 1 is a flow chart of a method for controlling SOC balancing of an energy storage system according to an embodiment of the present invention. Figure 3 As shown, the process includes the following steps:

[0115] Step S301: When the load power of the energy storage system is stable, calculate the battery charge and discharge ratio of each energy storage inverter and the total battery output or input power of the energy storage system. Figure 2 Step S202 of the illustrated embodiment will not be described in detail here.

[0116] Step S302: Allocate the total output or input power of the battery to each energy storage inverter based on the battery charge and discharge ratio. Figure 2 Step S203 of the illustrated embodiment will not be described in detail here.

[0117] Step S303 : Based on the allocated battery output or input power, SOC balancing control in charging mode or SOC balancing control in discharging mode is performed on each energy storage inverter.

[0118] Specifically, each energy storage inverter includes at least two batteries; the energy storage system also includes a photovoltaic circuit board PV; the above step S303 includes:

[0119] Step S3031: When the energy storage system meets the preset charging conditions, the initial dual-path battery charging power set value in each energy storage inverter is calculated based on whether the 0% backflow prevention function is enabled in the energy storage system. Based on the initial dual-path battery charging power set value, charging mode SOC balancing control is performed on the dual-path batteries in each energy storage inverter under the conditions of no 0% backflow prevention, 0% backflow prevention, limited battery charging power, and meter abnormality.

[0120] Specifically, there are three conditions when charging:

[0121] First: When PV energy > load energy, the battery needs to be charged, and the energy storage system is determined to enter charging mode.

[0122] Second: The battery charging power in the energy storage system is limited due to logic such as over-temperature load reduction and bus voltage level load reduction.

[0123] Third: The meter itself has poor contact, resulting in no meter status.

[0124] like Figure 4 As shown, the system determines whether it is a dual-battery system. If not, it defaults to the battery's maximum charging power. If so, it determines whether the meter is functioning properly. If so, it determines whether to perform zero reverse flow prevention. If not, it sets the battery charging power to exactly equal the maximum battery charge and discharge power, and does not perform SOC balancing control.

[0125] In some optional embodiments, such as Figure 4 As shown, the energy storage inverter includes an ARM controller; the above step S3031 includes:

[0126] Step b1: In the absence of zero backflow protection, the dual-battery charging ratio is issued through the ARM controller, and the initial dual-battery charging power set value is calculated based on the dual-battery charging ratio. It is determined whether the charging power set value of each battery exceeds the maximum charging power of its own battery. If it exceeds, the excess is added to the other battery until the load and battery charging power are stable.

[0127] Specifically, the dual-battery charging ratios are delivered via the ARM controller, and the charging ratios of battery 1 and battery 2 are calculated based on the dual-battery charging ratios.

[0128] In the absence of zero backflow protection, the initial battery charging power setpoint = (PV power - inverter power + meter power (positive)) * battery charging ratio (battery 1 charging ratio, battery 2 charging ratio) / (battery 1 charging ratio + battery 2 charging ratio). If the charging power setpoint allocated to battery 1 is greater than the battery's maximum charging power, the excess is added to battery 2, and battery 2 is treated similarly.

[0129] Step b2: When the load and battery charging power are running stably, determine whether the actual charging power of each battery is less than the preset battery charging power setting value. If so, the charging ratio of the two batteries is switched, and determine whether the difference between the SOC values ​​of the two batteries is greater than a first preset value. If so, recalculate the dual battery charging power given value as the battery charging power given target value, and distribute the secondary battery charging power based on the sum of the actual charging power of the two batteries, so that the initial dual battery charging power given value approaches the battery charging power given target value.

[0130] Specifically, the preset battery charging power setting value = the battery charging power given value - 100. Because the difference between the value of 100 and the actual value is relatively small through experiments, 100 is used as the setting value.

[0131] The first preset value is set to 3.

[0132] When the load and battery charging power are stable, the actual battery charging power is less than (the battery charging power setting value - 100), the charging ratio of battery 1 and battery 2 switches, and the difference in the SOC of the two batteries jumps to greater than 3. The battery charging power setting value calculation is then re-executed to obtain the battery charging power setting target value. When the load and battery charging power are stable, the sum of the actual charging power of the two batteries is used for secondary power allocation, slowly adjusting the initial battery charging power setting value closer to the recalculated battery charging power setting target value.

[0133] It should be noted that when the battery is charged according to the allocated charging ratio, the SOC calculation on the battery side is sometimes inaccurate, resulting in SOC jumps, so the charging ratio also changes. The prerequisite for calculating the battery charging power set value is that it is consistent with the power change situation before entering this statement judgment. Therefore, a link is added to determine whether the SOC difference is greater than 3. When it is greater than 3, the battery charging power set value allocation operation will be executed again.

[0134] Step b3: When the battery charging power is limited, determine the battery charging limit power value; when the battery charging limit power value is less than the battery charging power given target value, adjust the battery charging power given target value to the battery charging limit power value.

[0135] Specifically, when the battery charging power is limited due to over-temperature charging power limit or bus voltage difference charging power drop, and when the limited power value is less than the battery charging power given target value, the battery charging power given target value is set to be equal to the limited power value.

[0136] Step b4, under the condition of 0 backflow prevention, the battery charging power set value is cyclically increased according to the first preset step size in each charging cycle until the actual charging power of the battery is less than the preset battery charging power setting value. At this time, it is determined that the photovoltaic circuit board outputs the maximum power, and the battery maximum charging power value does not exceed the battery's own maximum charging power value.

[0137] Specifically, the first preset step size is set to 500.

[0138] Since the battery charging power is the meter's positive value + its own charging power value as the charging target, in the case of 0 backflow prevention, the meter is close to 0. Assume that the value of PV power - inverter power + meter power (positive) is A. Initialize A = 1000 and increase it by 500 each cycle. The battery charging power set value is recalculated using the formula: Battery charging power set value = A * battery charging ratio (battery 1 charging ratio, battery 2 charging ratio) / (battery 1 charging ratio + battery 2 charging ratio). When the battery's actual charging power is less than (battery charging power set value - 100), A stops increasing. At this point, it is considered that the PV has delivered maximum power and the battery's maximum charging power is less than or equal to the battery's own maximum charging power value.

[0139] Step b5: When the electric meter is abnormal and there is no 0 backflow prevention, the dual-way battery charging power setting value is set to the battery maximum charging power value, and the initial dual-way battery charging power setting value does not exceed the battery maximum charging power value.

[0140] Specifically, when the energy storage inverter is connected to the grid, the electric meter is lost and the backflow prevention function is not turned on, the battery charging power set value defaults to the battery maximum charging power value. At the same time, the calculated initial battery charging power set value cannot exceed the battery maximum charging power value.

[0141] The energy storage system SOC balancing control method provided in this embodiment, in the absence of 0 backflow protection, when the given value of the charging power of a battery exceeds its maximum charging power, the excess portion is automatically added to the other battery to avoid damage to the battery due to overcharging and ensure charging safety. When the battery charging power is limited, the given target value is adjusted to the limited power value to prevent the battery from being subjected to excessive power under abnormal conditions, thereby extending the battery life. When the load is stable but the actual charging power is insufficient, the SOC balancing is accelerated by switching the charging ratio of the two batteries. A secondary distribution is performed based on the sum of the actual charging power, so that the initial given value gradually approaches the target value, achieving a smooth transition and avoiding the impact of power mutations on the system. In the 0 backflow protection mode, the maximum power point of the photovoltaic power generation is accurately identified by cyclically increasing the given value and monitoring the actual power. In abnormal situations such as the loss of the electric meter, the charging power given value is automatically set to the maximum charging power of the battery to ensure that the system continues to operate.

[0142] Step S3032: When the energy storage system meets the preset discharge conditions, the initial dual-path battery discharge power setpoint in each energy storage inverter is calculated based on the presence of photovoltaic circuit boards and the load power demand. Based on the initial dual-path battery discharge power setpoint, discharge mode SOC balancing control is performed on the dual-path batteries in each energy storage inverter under conditions of sudden load changes, limited battery discharge power, energy storage inverter losses, and meter anomalies.

[0143] Specifically, if Figure 5As shown, there are three conditions during discharge:

[0144] First: When PV energy < load energy, the battery needs to release energy, and the energy storage system is determined to enter discharge mode.

[0145] Second: The battery discharge power in the energy storage system is limited due to logic such as over-temperature discharge and load reduction, bus voltage-battery voltage difference discharge and load reduction.

[0146] Third: The meter itself has poor contact, resulting in no meter status.

[0147] In some optional implementations, the energy storage inverter includes an ARM controller; the above step S3012 includes:

[0148] In step c1, when the load suddenly changes, the ARM controller is used to send the dual-path battery discharge ratio, and the initial dual-path battery discharge power given value is calculated respectively when the energy storage system has only batteries and no photovoltaic circuit board and when the energy storage system has batteries and photovoltaic circuit board.

[0149] Specifically, power distribution and load mutation response: When the load suddenly changes, the ARM controller determines the total load size through the difference between the total inverter power and the total meter power. The DSP controller uses the total load as the release power target value and performs power distribution calculation according to the following formula.

[0150] Determine the initial calculation method: Select different initial calculation logics based on the PV presence and load requirements:

[0151] For batteries only and no PV: Use the formula "Dual-battery discharge power setting value = (load + machine loss X) × battery discharge ratio (calculated separately for battery 1 and battery 2) / (battery 1 discharge ratio + battery 2 discharge ratio)" to calculate.

[0152] When PV and batteries coexist and PV power is less than load power, use the formula "Battery discharge power setting value = (absolute value (PV - load) + machine internal loss X) × battery discharge ratio (calculated separately for battery 1 and battery 2) / (battery 1 discharge ratio + battery 2 discharge ratio)".

[0153] The machine's own loss X is the energy storage inverter's own loss X.

[0154] In step c2, when the battery discharge power is limited, if the discharge power of one battery is limited, the discharge power limit of the other battery is released, and the unrestricted battery is given priority to output power to meet the load demand; when the discharge power of both batteries is limited and the limited battery discharge power does not meet the load demand, the electric meter is allowed to purchase electricity.

[0155] Specifically, as shown in the logic of step c1, long-term stable load operation may cause the machine to overheat and discharge, especially the DC-side battery. Due to different configurations, the discharge power of one of the two batteries may be limited, resulting in the meter purchasing one power level. At this point, the restriction on the other battery is lifted, and it will discharge according to the load demand, thus meeting the customer's need to not purchase electricity from the grid. Considering safety and long-term equipment operation, the meter is allowed to purchase electricity only when both batteries are limited and the limited power value is insufficient to meet the load.

[0156] In step c3, when calculating the energy storage inverter's own loss, the energy storage inverter's own loss is cyclically increased according to a second preset step size until the meter value is greater than the second preset value, enabling the energy storage system to operate stably. When the meter value is greater than the second preset value and the actual output power of any of the two-way batteries is less than the preset battery discharge power setting value, the energy storage inverter's own loss is cyclically decreased according to a third preset step size until the energy storage inverter's own loss threshold range is met.

[0157] Specifically, the second preset value is set to 50, the second preset step is set to 50, and the third preset step is set to 5.

[0158] When calculating the energy storage inverter's own loss X in step c1, X is gradually increased by 50 in a cycle. Since the loss of each machine is different, the system is considered stable when the meter value is greater than or equal to -10. At this time, X may be a very large number. If X is not processed, the battery discharge power setting value may be incorrect during the next cycle download, and the amount of electricity sold will increase. That is, when the meter value is greater than or equal to -10 and the actual output battery power of any dual battery is less than (battery set discharge power - 30), the value of X is slowly reduced in a 5-step cycle, maintaining a minimum of X = 10. The maximum value cannot exceed 6% of the rated power, according to the minimum conversion efficiency limit.

[0159] Step c4: When the electric meter is abnormal, the dual-path battery discharge power given value is set to the battery maximum discharge power value, and the initial dual-path battery discharge power given value does not exceed the battery maximum discharge power value.

[0160] Specifically, when the energy storage inverter is grid-connected and the meter is lost, the battery discharge power setpoint defaults to the battery's maximum discharge value. Furthermore, the battery discharge power setpoint calculated in step c1 cannot exceed the battery's maximum discharge power value. The energy storage system SOC balancing control method provided in this embodiment distinguishes between "battery-only, no photovoltaic" and "battery + photovoltaic" scenarios when the load changes suddenly, calculating the discharge power setpoint separately to ensure that power distribution more closely matches actual energy supply and demand. The ARM controller issues the discharge ratios of the two batteries, prioritizing the output power of the battery with the higher SOC, achieving efficient energy output while accelerating SOC balancing. When the power of a single battery is limited (e.g., due to overtemperature load reduction), the restriction on the other battery is automatically released, allowing the unrestricted battery to take on more load, both protecting the battery and meeting load demand. The meter is only allowed to purchase electricity when both batteries are limited, and the battery energy is depleted first, reducing electricity purchase costs while ensuring power continuity. By cyclically increasing and decreasing the system's own loss value, the system finds the optimal loss parameters under different operating conditions, ensuring that power calculations more closely approximate actual losses. In abnormal situations such as meter loss, the system automatically sets the discharge power setpoint to the maximum battery discharge power to ensure continued system operation. Discharge mode SOC balancing control ensures battery safety while meeting load requirements. Through dynamic loss compensation and fault tolerance mechanisms, the energy storage system can continue to operate efficiently under complex operating conditions.

[0161] The energy storage system SOC balancing control method provided by this embodiment distinguishes between charging and discharging modes, and formulates exclusive control strategies for different working conditions in each mode. When charging, the initial charging power set value is calculated based on whether the 0 anti-backflow function is enabled, and the situations of no 0 anti-backflow, 0 anti-backflow, power limitation and meter abnormality are handled separately; when discharging, the initial discharge power set value is calculated based on the presence of the photovoltaic circuit board and the load power demand, and then adjusted for load mutations, power limitation and other situations to ensure accurate SOC balancing control in all scenarios and improve the adaptability and effectiveness of the control strategy. The dual-channel batteries in each energy storage inverter are controlled independently and collaboratively. Taking into account the possible performance differences of the dual-channel batteries, the dynamic balancing of the SOC of the dual-channel batteries is achieved by separately calculating and adjusting their charging and discharging power set values, thereby avoiding the degradation of system performance due to battery imbalance. As one or more specific application embodiments of the embodiments of the present invention, combined with Figure 4 and Figure 5 The energy storage system SOC balancing control method provided by the present invention is further described in detail, specifically including:

[0162] The SOC balancing control strategy of the dual-channel energy storage inverter is mainly explained from the two directions of charging and discharging. Figure 4 It is the balancing strategy in the single-machine charging mode of the energy storage system. Figure 5It is a balancing strategy for the energy storage system in single-machine discharge mode. The overall control concept is to first ensure power scheduling and then dynamically adjust the dual-path SOC balance. It is necessary to ensure that the battery discharges as much as possible without buying electricity, and to ensure that the PV energy charges the battery as much as possible without selling electricity, thus ensuring battery life and customer benefits.

[0163] In a parallel system, the power scheduling processing logic of the DSP controller and the ARM controller is as follows:

[0164] 1. When the load suddenly changes, the meter is allocated according to the rated power. Assume that the parallel system consists of two energy storage inverters.

[0165] 2. After the energy storage inverter limits the load power distribution due to its own discharge logic, the phenomenon of buying electricity continues to exist. The load power is continuously distributed, so that the machines with output capacity output more, and the energy storage inverter without output capacity maintains the maximum output until the meter is near 0.

[0166] 3. When the load power is stable, start the parallel system SOC balancing logic processing.

[0167] 4. The host ARM calculates the master's battery charge and discharge power setpoint A1 and the slave's battery charge and discharge power setpoint A2. The master calculates the sum of the charge and discharge capacities of the two batteries in the single-machine system (master) based on the battery capacity, current SOC, battery voltage, and SOC protection value. The slave calculates the sum of the charge and discharge capacities of the two batteries in the single-machine system (slave) based on the battery capacity, current SOC, battery voltage, and SOC protection value. Within the parallel system, the battery charge and discharge ratio of each machine is calculated based on the single-machine battery charge and discharge capacity divided by the sum of the master and slave battery capacities (i.e., master battery charge and discharge capacity / (master battery charge and discharge capacity + slave battery charge and discharge capacity)), or alternatively, the slave battery charge and discharge capacity / (master battery charge and discharge capacity + slave battery charge and discharge capacity).

[0168] 5. When the load power is stable, calculate the total output or input power of the batteries in the parallel system. Based on the battery charge and discharge ratios of the master and slave units in the parallel system calculated in step 4, distribute the power to each unit (master or slave). Then, use the SOC balancing logic of the DSP controller inside the single unit.

[0169] 6. Use the meter to superimpose disturbances. Since inverter power - meter power = load power, gradually increase or decrease the meter value according to the meter disturbance, thereby changing the load power.

[0170] 7. Parallel system SOC balancing: When adjusting the output between different machines, it's possible that one machine may limit its power, causing the meter to buy electricity. Whenever there's electricity being bought, meter power is distributed to stabilize the parallel system's SOC balancing. Load power distribution and parallel system SOC balancing are dynamic adjustments. The following describes the SOC balancing strategy within a single-machine system.

[0171] 1. Based on Figure 4 The dual-channel SOC charging mode balancing strategy is as follows:

[0172] (1) There are three conditions when charging:

[0173] First: When PV energy > load energy, the battery needs to be charged.

[0174] Second: The battery charging power in the energy storage system is limited due to logic such as over-temperature load reduction and bus voltage level load reduction.

[0175] Third: The meter itself has poor contact, resulting in no meter status.

[0176] (2) In the absence of zero backflow protection, the battery charging power set value = (PV power - inverter power + meter power (positive)) * battery charging ratio (battery 1 charging ratio, battery 2 charging ratio) / (battery 1 charging ratio + battery 2 charging ratio). If the charging power set value allocated to battery 1 is greater than the maximum charging power of the battery itself, the greater part is added to battery 2, and battery 2 is treated similarly.

[0177] (3) When the load and battery charging power are running stably, the actual battery charging power is less than (the battery charging power given value - 100), the charging ratio of battery 1 and the charging ratio of battery 2 are switched, and the SOC difference between the two batteries is greater than 3 due to the jump, then the given power calculation in (2) is re-executed to obtain the battery charging power given target value.

[0178] (4) When the load and battery charging power are running stably, the sum of the actual charging power of the two batteries is used to perform secondary power distribution, and the battery charging power setting value in (2) is slowly adjusted to approach the battery charging power setting target value recalculated in (3).

[0179] (5) When the over-temperature charging power is limited and the bus voltage difference reduces the charging power, and when the limited power value is less than the battery charging power given target value in (3), the battery charging power given target value in (3) = the limited power value.

[0180] (6) Since the battery charging power takes the positive value of the meter + its own charging power value as the charging target, in the case of 0 anti-backflow, the meter is equal to near 0. The PV power - inverter power + meter power (positive) value in (2) is assumed to be A, initialize A = 1000, and increase by 500 per cycle. The battery charging power given value is calculated by the formula: battery charging power given value = A * battery charging ratio (battery 1 charging ratio, battery 2 charging ratio) / (battery 1 charging ratio + battery 2 charging ratio). When the actual battery charging power is less than (battery charging power given value - 100), A no longer increases. At this time, it is considered that PV has emitted the maximum power, and the battery maximum charging power is less than or equal to the battery's own maximum charging power value.

[0181] (7) When the machine mentioned in (1) is connected to the grid, the electric meter is lost and the backflow protection is not turned on, the battery charging power setting value defaults to the battery maximum charging power value. At the same time, the battery charging power setting value calculated in (2) cannot exceed the battery maximum charging power value.

[0182] 2. Based on Figure 2 The dual-channel SOC discharge mode balancing strategy is as follows:

[0183] (1) There are three conditions under discharge:

[0184] First: When PV energy < load energy, the battery needs to release energy.

[0185] Second: The battery discharge power in the energy storage system is limited due to logic such as over-temperature discharge and load reduction, bus voltage-battery voltage difference discharge and load reduction.

[0186] Third: The meter itself has poor contact, resulting in no meter status.

[0187] (2) When the load changes suddenly, the ARM controller will obtain the total load size at that time based on the total inverter-total electricity meter, and the DSP uses the total load as the target value for releasing power.

[0188] When there are only batteries but no PV, the dual-battery discharge power setting value = (load + machine self-loss X) * battery discharge ratio (calculated separately for battery 1 and battery 2) / (battery 1 discharge ratio + battery 2 discharge ratio).

[0189] When both PV and battery are present and PV power is less than load power, battery discharge is required. The given battery discharge power value = (absolute value (PV - load) + machine loss X) * battery discharge ratio (calculated separately for battery 1 and battery 2) / (battery 1 discharge ratio + battery 2 discharge ratio).

[0190] (3) As in (2), long-term stable operation of the load may cause the machine to overheat and discharge, especially the DC-side battery to overheat and discharge. Due to the different configurations of the dual-path batteries, the discharge power of one of the batteries may be limited. In this way, the meter will have a purchase power limit. At this time, the limit of the other battery is released, and the battery on that path will discharge according to the load demand, so as to meet the customer's demand for not buying electricity from the grid. Considering safety and long-term operation of the equipment, the meter is allowed to purchase electricity only when both batteries are limited and the limited power value is insufficient to meet the load.

[0191] (4) Regarding the machine's own loss X in the calculation formula in (2), X is gradually increased by 50 in the cycle. Since the loss of each machine is different, the system is considered stable when the meter value is greater than >-10. At this time, X may be a very large number. If X is not processed, it may cause the battery discharge power setting value to be incorrect when downloading in the next cycle, increasing the amount of electricity sold. That is, when the meter value is greater than >-10 and the actual output battery power of any of the dual batteries is < (battery set discharge power-30), the X value is slowly reduced in the cycle, and the minimum is maintained at X=10. The maximum cannot exceed 6% of the rated power, according to the minimum conversion efficiency limit.

[0192] (5) When the machine mentioned in (1) is connected to the grid and the electric meter is lost, the battery discharge power setting value defaults to the battery maximum discharge value. At the same time, the battery discharge power setting value calculated in (2) cannot exceed the battery maximum discharge power value.

[0193] The energy storage system SOC balancing control method provided in this embodiment enables effective on-site operation of dual-channel energy storage inverter SOC balancing control in both single-unit and parallel systems. Under zero reverse current protection, the PV outputs maximum power to charge the battery while simultaneously balancing the SOC. Under normal power scheduling, balanced SOC discharge is ensured in both channels, while power scheduling is prioritized under extreme discharge conditions.

[0194] This embodiment also provides an energy storage system SOC balancing control device for implementing the above-mentioned embodiments and preferred implementations. Details already described will not be repeated. As used below, the term "module" may refer to a combination of software and / or hardware that implements a predetermined function. Although the devices described in the following embodiments are preferably implemented in software, implementation in hardware, or a combination of software and hardware, is also possible and contemplated.

[0195] This embodiment provides a SOC balancing control device for an energy storage system, such as Figure 6 Shown, including:

[0196] The battery charge-discharge ratio and battery output or input power calculation module 601 is used to calculate the battery charge-discharge ratio of each energy storage inverter and the total battery output or input power of the energy storage system when the load power of the energy storage system is stable.

[0197] The battery output or input power distribution module 602 is used to distribute the total battery output or input power to each energy storage inverter based on the battery charge and discharge ratio.

[0198] The SOC balancing control module 603 is configured to perform SOC balancing control in a charging mode or SOC balancing control in a discharging mode on each energy storage inverter based on the allocated battery output or input power.

[0199] In some optional embodiments, the energy storage system SOC balancing control device further includes:

[0200] The load power stability judgment module is used to determine the load power stability of the energy storage system in the following manner: when the load power of the energy storage system is not stable, the meter power is distributed according to the rated power of each energy storage inverter until the meter stabilizes at a preset value and there is no meter buying power phenomenon, then the load power of the energy storage system is determined to be stable.

[0201] In some optional embodiments, the battery charge-discharge ratio and battery output or input power calculation module 601 includes:

[0202] The data acquisition unit is used to obtain the battery capacity, current battery SOC, battery voltage and battery SOC protection value of each energy storage inverter.

[0203] The battery charge and discharge ratio calculation unit is used to calculate the battery charge and discharge ratio of each energy storage inverter based on the battery capacity, current battery SOC, battery voltage and battery SOC protection value of each energy storage inverter.

[0204] In some optional embodiments, the battery charge and discharge ratio calculation unit includes:

[0205] The master-slave setting subunit is used to designate one energy storage inverter as the master and other energy storage inverters except the master as slaves.

[0206] The battery charge and discharge capacity calculation subunit is used to calculate the host battery charge and discharge capacity based on the host's battery capacity, current battery SOC, battery voltage and battery SOC protection value, and to calculate the battery charge and discharge capacity of each slave based on the battery capacity, current battery SOC, battery voltage and battery SOC protection value of each slave.

[0207] The sum calculation subunit is used to calculate the sum of the charge and discharge capacity of the host battery and the charge and discharge capacity of all slave batteries.

[0208] The battery charge and discharge ratio calculation subunit is used to calculate the master battery charge and discharge ratio based on the master battery charge and discharge capacity and the sum value, and to calculate the charge and discharge ratio of each slave battery based on the charge and discharge capacity and the sum value of each slave battery.

[0209] In some optional embodiments, the battery output or input power distribution module 602 includes:

[0210] The host battery power distribution unit is used to calculate the product of the host battery charge and discharge ratio and the total battery output or input power as the host battery power distribution, and distribute the host battery power distribution to the host.

[0211] The slave battery power distribution unit is used to calculate the product of the charge and discharge ratio of each slave battery and the total output or input power of the battery as the power distribution of each slave battery, and distribute the power distribution of each slave battery to the corresponding slave.

[0212] In some optional embodiments, each energy storage inverter includes at least two batteries; the energy storage system also includes a photovoltaic circuit board; and the SOC balancing control module 603 includes:

[0213] The charging mode SOC balancing control unit is used to calculate the initial dual-channel battery charging power set value in each energy storage inverter based on whether the 0 backflow prevention function is enabled in the energy storage system when the energy storage system meets the preset charging conditions. Based on the initial dual-channel battery charging power set value, the charging mode SOC balancing control is performed on the dual-channel batteries in each energy storage inverter under the conditions of no 0 backflow prevention, 0 backflow prevention, limited battery charging power, and meter abnormality.

[0214] The discharge mode SOC balancing control unit is used to calculate the initial dual-path battery discharge power set value in each energy storage inverter based on the presence of photovoltaic circuit boards and load power requirements when the energy storage system meets the preset discharge conditions. Based on the initial dual-path battery discharge power set value, the system performs discharge mode SOC balancing control on the dual-path batteries in each energy storage inverter in the event of sudden load changes, limited battery discharge power, energy storage inverter self-loss, and meter abnormalities.

[0215] In some optional embodiments, the energy storage inverter includes an ARM controller; the charging mode SOC balancing control unit includes:

[0216] The power allocation and limitation processing subunit is used to send the dual-battery charging ratio through the ARM controller in the absence of zero backflow protection, calculate the initial dual-battery charging power set value based on the dual-battery charging ratio, and determine whether the charging power set value of each battery exceeds the maximum charging power of its own battery. If it exceeds, the excess will be added to the other battery until the load and battery charging power are stable.

[0217] The ratio switching and secondary distribution subunit is used to determine whether the actual charging power of each battery is less than the preset battery charging power setting value when the load and battery charging power are running stably. If so, the charging ratio of the two batteries is switched, and it is determined whether the difference between the SOC values ​​of the two batteries is greater than a first preset value. If so, the dual battery charging power given value is recalculated as the battery charging power given target value, and the secondary battery charging power is distributed based on the sum of the actual charging power of the two batteries, so that the initial dual battery charging power given value is close to the battery charging power given target value.

[0218] The first limited processing subunit is configured to determine a battery charging limited power value when the battery charging power is limited, and adjust the battery charging power given target value to the battery charging limited power value when the battery charging limited power value is less than the battery charging power given target value.

[0219] The 0 anti-backflow calculation and adjustment subunit is used to cyclically increase the battery charging power set value according to the first preset step size in each charging cycle under the 0 anti-backflow condition until the actual charging power of the battery is less than the preset battery charging power set value. At this time, it is determined that the photovoltaic circuit board outputs the maximum power and the battery maximum charging power value does not exceed the battery's own maximum charging power value.

[0220] The first electric meter abnormality processing subunit is used to set the dual-way battery charging power given value to the maximum charging power value of the battery when the electric meter is abnormal and there is no 0 backflow protection, and the initial dual-way battery charging power given value does not exceed the maximum charging power value of the battery.

[0221] In some optional embodiments, the energy storage inverter includes an ARM controller, and the discharge mode SOC balancing control unit includes:

[0222] The initial calculation subunit is used to use the ARM controller to send the dual-path battery discharge ratio when the load suddenly changes, and to calculate the initial dual-path battery discharge power given value when the energy storage system has only batteries and no photovoltaic circuit board and when the energy storage system has batteries and photovoltaic circuit board.

[0223] The second restricted processing subunit is used to, when the battery discharge power is limited, release the discharge power restriction of the other battery when the discharge power of one battery is limited, and give priority to the unrestricted battery for power output to meet the load demand; when the discharge power of both batteries is limited and the restricted battery discharge power does not meet the load demand, allow the electric meter to purchase electricity.

[0224] The self-loss calculation subunit is used to cyclically increase the self-loss of the energy storage inverter according to a second preset step size when calculating the self-loss of the energy storage inverter until the meter value is greater than the second preset value so that the energy storage system operates stably; when the meter value is greater than the second preset value and the actual output power of any battery in the dual-path battery is less than the preset battery discharge power setting value, cyclically reduce the self-loss of the energy storage inverter according to a third preset step size until the self-loss threshold range of the energy storage inverter is met.

[0225] The second electric meter abnormality processing subunit is used to set the dual-path battery discharge power given value to the battery maximum discharge power value when the electric meter is abnormal, and the initial dual-path battery discharge power given value does not exceed the battery maximum discharge power value.

[0226] The further functional description of each of the above modules and units is the same as that of the above corresponding embodiments and will not be repeated here.

[0227] The energy storage system SOC balancing control device in this embodiment is presented in the form of a functional unit, where the unit refers to an ASIC (Application Specific Integrated Circuit) circuit, a processor and memory that executes one or more software or fixed programs, and / or other devices that can provide the above functions.

[0228] The embodiment of the present invention also provides a computer device having the above Figure 6 The energy storage system SOC balancing control device shown.

[0229] See also Figure 7 , Figure 7 is a structural diagram of a computer device provided by an optional embodiment of the present invention, such as Figure 7 As shown, the computer device includes: one or more processors 10, memory 20, and interfaces for connecting various components, including high-speed interfaces and low-speed interfaces. Various components utilize different buses to communicate with each other and can be installed on a common mainboard or installed in other ways as needed. The processor can process the instructions executed in the computer device, including instructions stored in the memory or on the memory to display the graphical information of the GUI on an external input / output device (such as, a display device coupled to the interface). In some optional embodiments, if necessary, multiple processors and / or multiple buses can be used together with multiple memories and multiple memories. Equally, multiple computer devices can be connected, and each device provides part of the necessary operations (for example, as a server array, a group of blade servers, or a multi-processor system). Figure 7 A processor 10 is taken as an example.

[0230] The processor 10 may be a central processing unit, a network processor, or a combination thereof. The processor 10 may further include a hardware chip. The hardware chip may be an application-specific integrated circuit, a programmable logic device, or a combination thereof. The programmable logic device may be a complex programmable logic device, a field programmable gate array, a general purpose array logic, or any combination thereof.

[0231] The memory 20 stores instructions that can be executed by at least one processor 10, so that the at least one processor 10 executes the method shown in the above embodiment.

[0232] The memory 20 may include a program storage area and a data storage area, wherein the program storage area may store an operating system and application programs required for at least one function; the data storage area may store data created based on the use of the computer device, etc. In addition, the memory 20 may include a high-speed random access memory, and may also include a non-transient memory, such as at least one disk storage device, a flash memory device, or other non-transient solid-state storage device. In some optional embodiments, the memory 20 may optionally include a memory remotely located relative to the processor 10, and these remote memories may be connected to the computer device via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0233] The memory 20 may include a volatile memory, such as a random access memory; the memory may also include a non-volatile memory, such as a flash memory, a hard disk or a solid-state drive; the memory 20 may also include a combination of the above types of memory.

[0234] The computer device further includes an input device 30 and an output device 40. The processor 10, the memory 20, the input device 30 and the output device 40 may be connected via a bus or other means. Figure 7 The bus connection is taken as an example.

[0235] The input device 30 can receive input digital or character information and generate key signal input related to user settings and function control of the computer device, such as a touch screen, a keypad, a mouse, a trackpad, a touch pad, an indicator stick, one or more mouse buttons, a trackball, a joystick, etc. The output device 40 can include a display device, an auxiliary lighting device (e.g., an LED), and a tactile feedback device (e.g., a vibration motor). The above-mentioned display device includes but is not limited to a liquid crystal display, a light emitting diode, a display, and a plasma display. In some optional embodiments, the display device can be a touch screen.

[0236] The embodiment of the present invention also provides a computer-readable storage medium. The above-mentioned method according to the embodiment of the present invention can be implemented in hardware, firmware, or implemented as a computer code that can be recorded in a storage medium, or implemented as a computer code that is originally stored in a remote storage medium or a non-temporary machine-readable storage medium and downloaded through a network and will be stored in a local storage medium, so that the method described herein can be stored in such software processing on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. Among them, the storage medium can be a magnetic disk, an optical disk, a read-only storage memory, a random access memory, a flash memory, a hard disk or a solid-state drive, etc.; further, the storage medium can also include a combination of the above-mentioned types of memory. It can be understood that a computer, a processor, a microprocessor controller or programmable hardware includes a storage component that can store or receive software or computer code. When the software or computer code is accessed and executed by a computer, a processor or hardware, the method shown in the above embodiment is implemented.

[0237] A portion of the present invention may be applied as a computer program product, such as a computer program instruction, which, when executed by a computer, can call or provide the method and / or technical solution according to the present invention through the operation of the computer. Those skilled in the art should understand that the form in which the computer program instruction exists in a computer-readable medium includes, but is not limited to, a source file, an executable file, an installation package file, etc. Accordingly, the way in which the computer program instruction is executed by the computer includes, but is not limited to: the computer directly executes the instruction, or the computer compiles the instruction and then executes the corresponding compiled program, or the computer reads and executes the instruction, or the computer reads and installs the instruction and then executes the corresponding installed program. Here, the computer-readable medium may be any available computer-readable storage medium or communication medium that can be accessed by the computer.

[0238] Although the embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention. Such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A SOC balancing control method for an energy storage system, characterized in that: The energy storage system includes a plurality of energy storage inverters, and the method includes: When the load power of the energy storage system is stable, calculate the battery charge and discharge ratio of each energy storage inverter and the total battery output or input power of the energy storage system; Allocating the total output or input power of the battery to each energy storage inverter based on the battery charge and discharge ratio; Based on the allocated battery output or input power, the battery of each energy storage inverter is subjected to SOC balancing control in charging mode or SOC balancing control in discharging mode.

2. The method according to claim 1, characterized in that The method further includes: determining the load power stability of the energy storage system in the following manner: When the load power of the energy storage system is not stable, the meter power is distributed according to the rated power of each energy storage inverter until the meter stabilizes at the preset value and there is no meter buying phenomenon. The load power of the energy storage system is then determined to be stable.

3. The method according to claim 1, characterized in that The calculation of the battery charge and discharge ratio of each energy storage inverter includes: Obtain the battery capacity, current battery SOC, battery voltage, and battery SOC protection value of each energy storage inverter; The battery charge and discharge ratio of each energy storage inverter is calculated based on the battery capacity, current battery SOC, battery voltage and battery SOC protection value of each energy storage inverter.

4. The method according to claim 3, characterized in that The calculation of the battery charge and discharge ratio of each energy storage inverter based on the battery capacity, current battery SOC, battery voltage, and battery SOC protection value of each energy storage inverter includes: Designate one energy storage inverter as the master and other energy storage inverters as slaves; Calculate the master battery charge and discharge capacity based on the master's battery capacity, current battery SOC, battery voltage, and battery SOC protection value, and calculate each slave battery charge and discharge capacity based on each slave's battery capacity, current battery SOC, battery voltage, and battery SOC protection value; Calculate the sum of the master battery charge and discharge capacity and all slave battery charge and discharge capacities; The charge and discharge ratio of the master battery is calculated based on the charge and discharge capacity and the sum value of the master battery, and the charge and discharge ratio of each slave battery is calculated based on the charge and discharge capacity and the sum value of each slave battery.

5. The method according to claim 4, characterized in that The allocating the total battery output or input power to each energy storage inverter based on the battery charge and discharge ratio includes: Calculate the product of the host battery charge and discharge ratio and the total battery output or input power as the host battery allocated power, and distribute the host battery allocated power to the host; The product of the charge and discharge ratio of each slave battery and the total output or input power of the battery is calculated as the allocated power of each slave battery, and the allocated power of each slave battery is distributed to the corresponding slave.

6. The method according to claim 1, characterized in that Each energy storage inverter includes at least two batteries; the energy storage system also includes a photovoltaic circuit board; The method of performing charging mode SOC balancing control or discharging mode SOC balancing control on each energy storage inverter based on the allocated battery output or input power includes: When the energy storage system meets the preset charging conditions, the initial dual-battery charging power setpoint in each energy storage inverter is calculated based on whether the zero-backflow protection function is enabled. Based on the initial dual-battery charging power setpoint, the charging mode SOC balancing control is performed on the dual-battery in each energy storage inverter under the conditions of no zero-backflow protection, zero-backflow protection, limited battery charging power, and meter abnormality. When the energy storage system meets the preset discharge conditions, the initial dual-path battery discharge power setpoint in each energy storage inverter is calculated based on the presence of photovoltaic circuit boards and load power demand. Based on the initial dual-path battery discharge power setpoint, the discharge mode SOC balancing control of the dual-path batteries in each energy storage inverter is performed in the event of sudden load changes, limited battery discharge power, energy storage inverter self-loss, and meter abnormalities.

7. The method according to claim 6, characterized in that The energy storage inverter includes an ARM controller; Based on the initial dual-battery charging power given value, the charging mode SOC balancing control of the dual batteries in each energy storage inverter is performed under the conditions of no 0 backflow prevention, 0 backflow prevention, battery charging power limitation, and meter abnormality, including: In the absence of zero backflow protection, the ARM controller sends the dual battery charging ratio and calculates the initial dual battery charging power set value based on the dual battery charging ratio. It also determines whether the charging power set value of each battery exceeds its own maximum charging power. If it exceeds, the excess is added to the other battery until the load and battery charging power are stable. When the load and battery charging power are running stably, it is determined whether the actual charging power of each battery is less than the preset battery charging power setting value. If so, the charging ratio of the two batteries is switched, and it is determined whether the difference between the SOC values ​​of the two batteries is greater than a first preset value. If so, the dual battery charging power given value is recalculated as the battery charging power given target value, and the secondary battery charging power is distributed based on the sum of the actual charging power of the two batteries, so that the initial dual battery charging power given value is close to the battery charging power given target value; When the battery charging power is limited, determining a battery charging power limit value, and when the battery charging power limit value is less than the battery charging power given target value, adjusting the battery charging power given target value to the battery charging power limit value; In the case of zero backflow prevention, the battery charging power set value is cyclically increased according to the first preset step size in each charging cycle until the actual battery charging power is less than the preset battery charging power set value. At this time, it is determined that the photovoltaic circuit board outputs the maximum power, and the battery maximum charging power value does not exceed the battery's own maximum charging power value; When the electric meter is abnormal and there is no 0 backflow prevention, the dual-channel battery charging power setting value is set to the battery maximum charging power value, and the initial dual-channel battery charging power setting value does not exceed the battery maximum charging power value.

8. The method according to claim 6, characterized in that The energy storage inverter includes an ARM controller; Based on the initial dual-battery discharge power given value, the discharge mode SOC balancing control of the dual batteries in each energy storage inverter is performed under the conditions of sudden load change, battery discharge power limitation, energy storage inverter self-loss, and meter abnormality, including: When the load suddenly changes, the ARM controller is used to send the dual-battery discharge ratio and calculate the initial dual-battery discharge power setpoints for the case where the energy storage system only has batteries and no photovoltaic circuit boards, and the case where the energy storage system has batteries and photovoltaic circuit boards. In the case of battery discharge power restrictions, when one of the battery lines is restricted, the restriction on the other battery line is lifted, and the unrestricted battery line is given priority to output power to meet the load demand. When the discharge power of both batteries is restricted and the restricted battery discharge power does not meet the load demand, the meter is allowed to purchase electricity. When calculating the energy storage inverter's own loss, the energy storage inverter's own loss is cyclically increased according to a second preset step length until the meter value is greater than the second preset value, so that the energy storage system operates stably. When the meter value is greater than the second preset value and the actual output power of any of the dual-path batteries is less than the preset battery discharge power setting value, the energy storage inverter's own loss is cyclically reduced according to a third preset step length until the energy storage inverter's own loss threshold range is met. In the case of an abnormality of the electric meter, the dual-channel battery discharge power given value is set to the battery maximum discharge power value, and the initial dual-channel battery discharge power given value does not exceed the battery maximum discharge power value.

9. A SOC balancing control device for an energy storage system, characterized in that: The energy storage system includes multiple energy storage inverters, and the device includes: The battery charge-discharge ratio and battery output or input power calculation module is used to calculate the battery charge-discharge ratio of each energy storage inverter and the total battery output or input power of the energy storage system when the load power of the energy storage system is stable; A battery output or input power distribution module, configured to distribute the total battery output or input power to each energy storage inverter based on the battery charge and discharge ratio; The SOC balancing control module is used to perform SOC balancing control in charging mode or SOC balancing control in discharging mode on each energy storage inverter based on the allocated battery output or input power.

10. A computer device, characterized in that: include: A memory and a processor, wherein the memory and the processor are communicatively connected to each other, the memory stores computer instructions, and the processor executes the energy storage system SOC balancing control method according to any one of claims 1 to 8 by executing the computer instructions.

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