Grid connection method and device of energy storage system, electronic equipment and medium

Abstract

The invention provides a grid connection method and device of an energy storage system, electronic equipment and a medium. The grid connection method comprises the following steps: determining a current limiting and voltage regulating range of bus voltage in the energy storage system; the current-limiting and voltage-regulating range is the maximum voltage-regulating range adjusted by adjusting the bus current of the combined battery clusters; based on the current-limiting voltage-regulating range and the boosting range of the DC / DC module connected in series with the battery cluster to be connected in parallel, determining a cabinet-combining voltage-regulating range; based on the terminal voltage of the to-be-combined battery cluster and the bus voltage of the combined battery cluster, the voltage difference between the to-be-combined battery cluster and the bus is determined; when it is determined that voltage regulation and cabinet combination are allowed based on the voltage difference and the cabinet combination voltage regulation range, the bus voltage and / or the voltage output value of the DC / DC module are / is adjusted, and the to-be-combined battery clusters are controlled to be combined into the cabinet; based on DC / DC module adjustment and DC bus current limiting adjustment, the purpose of bidirectional voltage adjustment is achieved, the inter-cluster grid-connected voltage difference range is widened, and the availability and the discharge depth of the system are increased.

Description

Technical Field

[0001] The present application relates to the field of energy storage systems, and more particularly, to a grid connection method, device, and medium for an energy storage system. Background Art

[0002] Due to the directionality of the open-circuit voltage and DC internal resistance voltage of the battery, when the battery operates dynamically, the discharge dynamic terminal voltage is often lower than the static voltage, and the charging dynamic terminal voltage is often higher than the static voltage, making the DC grid connection of the energy storage system during cluster-deficient operation a core issue.

[0003] The DC grid connection result of the energy storage system determines the number of operable clusters of the system and the DOD of the system. The traditional battery cluster powers on and first reduces the pressure difference across the relay through a pre-charge circuit for DC grid connection. This solution is limited by the system pre-charge time, pre-charge resistance power, etc. At the same time, the pre-charge resistance value also determines the size of the pre-charge current, restricting the selection of the pre-charge relay; currently, there is also a DC / DC DC converter used to step up or step down the battery cluster for DC grid connection to improve the system utilization rate; however, it can only control the voltage of the battery cluster to be grid-connected. If the pressure difference between the battery clusters is too large and exceeds the DC / DC voltage regulation range or power output range, it is impossible to effectively regulate the voltage through the DC / DC for grid connection, resulting in a small number of operable clusters of the system during grid connection and poor system utilization rate. Summary of the Invention

[0004] In view of this, the purpose of the present application is to provide a grid connection method, device, electronic device, and medium for an energy storage system, which realizes dual-terminal voltage regulation grid connection through the bus voltage and the DC / DC voltage regulation of the battery cluster to be grid-connected, and broadens the grid connection pressure difference range between clusters.

[0005] A grid connection method for an energy storage system provided by an embodiment of the present application, the grid connection method includes:

[0006] Based on the operating parameters of the energy storage system, determine the current-limiting voltage regulation range of the bus voltage in the energy storage system; the current-limiting voltage regulation range is the maximum voltage regulation range adjusted by adjusting the bus current of the battery clusters already in the cabinet;

[0007] Based on the current-limiting voltage regulation range and the boost range of the DC / DC module connected in series with the battery cluster to be grid-connected, determine the cabinet connection voltage regulation range for the battery cluster to be grid-connected under different operating conditions; the operating conditions include discharge and charge;

[0008] Based on the terminal voltage of the battery cluster to be grid-connected and the bus voltage of the battery clusters already in the cabinet under the target operating condition, determine the pressure difference between the battery cluster to be grid-connected and the bus;

[0009] When it is determined that voltage regulation and cabinet connection are allowed based on the pressure difference and the cabinet connection voltage regulation range, adjust the bus voltage and / or the voltage output value of the DC / DC module, and control the battery cluster to be grid-connected when the pressure difference between the battery cluster to be grid-connected and the bus meets the preset cabinet connection pressure difference condition.

[0010] In some embodiments, in the grid connection method of the energy storage system, before determining that voltage regulation and cabinet connection are allowed based on the pressure difference and the cabinet connection voltage regulation range, the grid connection method further includes:

[0011] Determining a cabinet connection duration threshold based on the circuit structure of the energy storage system; the cabinet connection duration threshold is used to limit the cabinet connection duration of the battery cluster to be connected;

[0012] Narrowing the cabinet connection voltage regulation range based on the cabinet connection duration threshold to obtain an updated cabinet connection voltage regulation range, so that the battery cluster to be connected completes cabinet connection within the cabinet connection duration threshold;

[0013] Judging whether voltage regulation and cabinet connection are allowed based on the pressure difference and the updated cabinet connection voltage regulation range.

[0014] In some embodiments, in the grid connection method of the energy storage system, judging whether voltage regulation and cabinet connection are allowed based on the pressure difference and the updated cabinet connection voltage regulation range includes:

[0015] If the pressure difference conforms to the updated cabinet connection voltage regulation range, it is determined that cabinet connection is allowed;

[0016] If the pressure difference does not conform to the updated cabinet connection voltage regulation range, it is determined that cabinet connection is not allowed.

[0017] In some embodiments, in the grid connection method of the energy storage system, adjusting the bus voltage and / or the voltage output value of the DC / DC module includes:

[0018] When the pressure difference is within the boost range of the DC / DC module, adjusting the voltage output value of the DC / DC module so that the pressure difference between the battery cluster to be connected and the bus voltage conforms to the preset cabinet connection pressure difference condition;

[0019] When the pressure difference is outside the boost range of the DC / DC module, adjusting the bus voltage and the DC / DC module so that the pressure difference between the battery cluster to be connected and the bus voltage conforms to the preset cabinet connection pressure difference condition.

[0020] In some embodiments, in the grid connection method of the energy storage system, the adjusting the bus voltage and the voltage output value of the DC / DC module includes:

[0021] Determining the voltage output value of the DC / DC module; wherein, in the discharging condition, the DC / DC module maintains the minimum voltage output, and in the charging condition, the DC / DC module maintains the maximum voltage output;

[0022] Adjusting the bus voltage by adjusting the bus current; wherein, in the discharging condition, the lower the bus current, the higher the bus voltage; in the charging condition, the lower the bus current, the lower the bus voltage.

[0023] In some embodiments, in the grid connection method of the energy storage system, adjusting the bus voltage by adjusting the bus current includes:

[0024] Calculating the target current limiting value of the bus based on the pressure difference between the battery cluster to be connected and the bus and the dynamic internal resistance during the operation of the energy storage system; the pressure difference between the target current limiting voltage corresponding to the target current limiting value of the bus and the terminal voltage of the battery cluster to be connected meets the preset cabinet connection pressure difference condition;

[0025] Reducing the bus current to the target current limiting value to adjust the bus voltage to the target current limiting voltage.

[0026] In some embodiments, in the grid connection method of the energy storage system, adjusting the bus voltage and controlling the connection of the battery cluster to be connected to the cabinet when the pressure difference between the battery cluster to be connected and the bus meets the preset cabinet connection pressure difference condition includes:

[0027] Maintaining the bus to operate at the target current limiting value within a preset current limiting duration, and determining whether the pressure difference between the battery cluster to be connected and the bus within the preset current limiting duration meets the preset cabinet connection pressure difference condition;

[0028] If it meets the condition, controlling the connection of the battery cluster to be connected to the cabinet when the preset cabinet connection pressure difference condition is met;

[0029] If it does not meet the condition, controlling the bus to resume the rated current.

[0030] In some embodiments, in the grid connection method of the energy storage system, determining the current limiting and voltage regulating range of the bus voltage in the energy storage system based on the operating parameters of the energy storage system includes:

[0031] Calculating the maximum current limiting value of the bus based on the minimum operating ratio, the current operating ratio, and the rated capacity of the energy storage system;

[0032] Calculating the current limiting and voltage regulating range of the bus voltage based on the maximum current limiting value of the bus and the dynamic internal resistance during the operation of the energy storage system.

[0033] In some embodiments, in the grid connection method of the energy storage system, determining the minimum operating ratio, the current operating ratio, and the rated capacity of the energy storage system, and calculating the maximum current limiting value of the bus includes:

[0034] Calculating the maximum current limiting ratio based on the minimum operating ratio and the current operating ratio of the energy storage system;

[0035] Calculating the maximum current limiting value of the bus based on the maximum current limiting ratio and the rated capacity.

[0036] In some embodiments, in the grid connection method of the energy storage system, based on the current limiting and voltage regulating range and the boost range of the DC / DC module connected in series with the battery cluster to be connected, determining the cabinet connection and voltage regulating range for the battery cluster to be connected under different working conditions includes:

[0037] Determine the maximum current limiting and voltage regulating value in the current limiting and voltage regulating range and the maximum voltage boosting value in the voltage boosting range;

[0038] Based on the variation relationship between the bus current and the bus voltage under different working conditions, the maximum current limiting and voltage regulating value, and the maximum voltage boosting value, determine the cabinet connection voltage regulating range for the battery cluster to be paralleled under different working conditions.

[0039] In some embodiments, in the grid connection method of the energy storage system, under the discharging working condition, the cabinet connection voltage regulating range is: greater than or equal to the negative maximum current limiting and voltage regulating value and less than or equal to the maximum voltage boosting value;

[0040] Under the charging working condition, the cabinet connection voltage regulating range is: greater than or equal to 0 and less than or equal to the sum of the maximum voltage boosting value and the maximum current limiting and voltage regulating value.

[0041] In some embodiments, in the grid connection method of the energy storage system, based on the pressure difference between the battery cluster to be paralleled and the bus and the dynamic internal resistance during the operation of the energy storage system, calculate the target current limiting current and the target current limiting voltage of the bus, including:

[0042] According to the variation relationship between the bus current and the bus voltage under different working conditions, based on the pressure difference between the battery cluster to be paralleled and the bus, the maximum voltage boosting value of the boosting range of the DC / DC module, and the dynamic internal resistance during the operation of the energy storage system, calculate the target change amount of the bus current under different working conditions;

[0043] Based on the bus current and the target change amount, determine the target current limiting current of the bus under different working conditions.

[0044] In some embodiments, in the grid connection method of the energy storage system, based on the pressure difference between the battery cluster to be paralleled and the bus, the maximum voltage boosting value of the boosting range of the DC / DC module, and the dynamic internal resistance during the operation of the energy storage system, calculate the target change amount of the bus current under different working conditions; including:

[0045] Under the discharging working condition, based on the sum value of the pressure difference and the maximum voltage boosting value and the dynamic internal resistance, calculate the target change amount of the bus current;

[0046] Under the charging working condition, based on the difference value of the pressure difference and the maximum voltage boosting value and the dynamic internal resistance, calculate the target change amount of the bus current.

[0047] In some embodiments, there is also provided a grid connection device for an energy storage system, and the grid connection device includes:

[0048] A first determination module, configured to determine the current limiting and voltage regulating range of the bus voltage in the energy storage system based on the operating parameters of the energy storage system; the current limiting and voltage regulating range is the maximum voltage regulating range adjusted by adjusting the bus current of the paralleled cabinet battery clusters;

[0049] A second determination module, configured to determine a cabinet connection voltage regulation range for the battery cluster to be connected under different working conditions based on the current limiting and voltage regulation range and the boost range of the DC / DC module connected in series with the battery cluster to be connected; the working conditions include discharging and charging;

[0050] A third determination module, configured to determine the pressure difference between the battery cluster to be connected and the bus based on the terminal voltage of the battery cluster to be connected and the bus voltage of the battery clusters already connected in the cabinet under the target working condition;

[0051] An adjustment module, configured to adjust the bus voltage and / or the voltage output value of the DC / DC module when it is determined that voltage regulation and cabinet connection are allowed based on the pressure difference and the cabinet connection voltage regulation range, and control the battery cluster to be connected to be connected to the cabinet when the pressure difference between the battery cluster to be connected and the bus meets the preset cabinet connection pressure difference condition.

[0052] In some embodiments, an electronic device is further provided, including: a processor, a memory, and a bus, where the memory stores machine-readable instructions executable by the processor. When the electronic device runs, the processor communicates with the memory through the bus. When the machine-readable instructions are executed by the processor, the steps of the grid connection method of the energy storage system are executed.

[0053] In some embodiments, a computer-readable storage medium is further provided. A computer program is stored on the computer-readable storage medium. When the computer program is run by a processor, the steps of the grid connection method of the energy storage system are executed.

[0054] An on-grid connection method, device, electronic device, and medium for an energy storage system are provided in an embodiment of the present application. The on-grid connection method includes: determining a current-limiting voltage regulation range of a bus voltage in the energy storage system based on operating parameters of the energy storage system; the current-limiting voltage regulation range is the maximum voltage regulation range adjusted by adjusting the bus current of the already-connected battery cluster; determining an on-grid voltage regulation range for a to-be-connected battery cluster under different working conditions based on the current-limiting voltage regulation range and the boost range of the DC / DC module connected in series with the to-be-connected battery cluster; the working conditions include discharging and charging; determining the voltage difference between the to-be-connected battery cluster and the bus based on the terminal voltage of the to-be-connected battery cluster and the bus voltage of the already-connected battery cluster under the target working condition; when it is determined that on-grid voltage regulation and connection are allowed based on the voltage difference and the on-grid voltage regulation range, adjusting the bus voltage and / or the voltage output value of the DC / DC module, and controlling the to-be-connected battery cluster to be connected to the grid when the voltage difference between the to-be-connected battery cluster and the bus meets a preset on-grid connection voltage difference condition; the on-grid connection method not only adjusts the terminal voltage of the to-be-connected battery cluster through the DC / DC module, but also performs current-limiting regulation on the DC bus voltage, achieving the purpose of bidirectional voltage regulation, broadening the on-grid voltage difference range between clusters, increasing the system availability and its discharge depth; at the same time, the voltage regulation requirement for the DC / DC is reduced, and the reduction of the DC / DC output power requirement results in a lower design cost and a further reduction in volume; due to the voltage regulation, the actual voltage difference range between the to-be-connected battery cluster and the bus is broadened, the Δsoc at the current allowable power-on is smaller, and the consistency of the energy storage system is better. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present application and should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0056] Figure 1 The flowchart of the on-grid connection method for the energy storage system described in the embodiment of the present application is shown;

[0057] Figure 2 The flowchart of the method for determining the current-limiting voltage regulation range of the bus voltage in the energy storage system described in the embodiment of the present application is shown;

[0058] Figure 3 The flowchart of the method for determining the on-grid voltage regulation range for the to-be-connected battery cluster under different working conditions described in the embodiment of the present application is shown;

[0059] Figure 4 The flowchart of the method for adjusting the bus voltage and / or the voltage output value of the DC / DC module described in the embodiment of the present application is shown;

[0060] Figure 5Shows the schematic diagram of the boost range of the DC / DC and the current-limiting and voltage-regulating range described in the embodiments of the present application;

[0061] Figure 6 Shows the simulation result diagram only considering the 5V voltage difference range on both sides of the main relay of the battery cluster described in the embodiments of the present application;

[0062] Figure 7 Shows the simulation result diagram considering the boost range of the DC / DC module described in the embodiments of the present application;

[0063] Figure 8 Shows the simulation result diagram of the current-limiting and voltage-regulating range determined by the DC / DC module and the bus current regulation described in the embodiments of the present application;

[0064] Figure 9 Shows the schematic diagram of the result of the grid connection device of the energy storage system described in the embodiments of the present application;

[0065] Figure 10 Shows the schematic diagram of the structure of the electronic device described in the embodiments of the present application. Detailed implementation manners

[0066] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. It should be understood that the accompanying drawings in the present application only serve the purpose of illustration and description, and are not used to limit the protection scope of the present application. Additionally, it should be understood that the schematic drawings are not drawn to actual scale. The flowcharts used in the present application illustrate the operations implemented according to some embodiments of the present application. It should be understood that the operations in the flowchart may not be implemented in sequence, and steps without logical context relationships may be reversed or implemented simultaneously. In addition, those skilled in the art can add one or more other operations to the flowchart or remove one or more operations from the flowchart under the guidance of the content of the present application.

[0067] In addition, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. The components of the embodiments of the present application usually described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application claimed, but only represents the selected embodiments of the present application. All other embodiments obtained by those skilled in the art based on the embodiments of the present application without creative efforts belong to the scope of protection of the present application.

[0068] It should be noted that the term "including" will be used in the embodiments of the present application to indicate the existence of the features stated hereinafter, but does not exclude the addition of other features.

[0069] Due to the directionality of the open-circuit voltage and DC internal resistance voltage of the battery, when the battery operates dynamically, the discharge dynamic terminal voltage is often lower than the static voltage, and the charge dynamic terminal voltage is often higher than the static voltage, making the DC grid connection of the energy storage system during cluster shortage operation a core issue.

[0070] The DC grid connection result of the energy storage system determines the number of operable clusters of the system and the DOD of the system. The traditional battery cluster powers on and first reduces the voltage difference across the relay through a pre-charge circuit for DC grid connection. This scheme is limited by the system pre-charge time, pre-charge resistance power, etc. At the same time, the pre-charge resistance value also determines the size of the pre-charge current, restricting the selection of the pre-charge relay; currently, there is also a method of using a DC / DC DC converter to step up or step down the battery cluster and then perform DC grid connection to improve the system availability; however, it can only control the voltage of the battery cluster to be grid-connected. If the voltage difference between the battery clusters is too large and exceeds the voltage regulation range or power output range of the DC / DC, it cannot effectively regulate the voltage through the DC / DC for grid connection.

[0071] Based on this, in the embodiments of the present application, a grid connection method, device, electronic device, and medium for an energy storage system are provided. The grid connection method includes: determining the current-limiting voltage regulation range of the bus voltage in the energy storage system based on the operating parameters of the energy storage system; the current-limiting voltage regulation range is the maximum voltage regulation range adjusted by adjusting the bus current of the already connected battery clusters; determining the grid connection voltage regulation range for the battery cluster to be connected under different working conditions based on the current-limiting voltage regulation range and the boost range of the DC / DC module connected in series with the battery cluster to be connected; the working conditions include discharge and charge; determining the voltage difference between the battery cluster to be connected and the bus based on the terminal voltage of the battery cluster to be connected and the bus voltage of the already connected battery clusters under the target working condition; when it is determined that voltage regulation and grid connection are allowed based on the voltage difference and the grid connection voltage regulation range, adjusting the bus voltage and / or the voltage output value of the DC / DC module, and controlling the battery cluster to be connected to be grid-connected when the voltage difference between the battery cluster to be connected and the bus meets the preset grid connection voltage difference condition; the grid connection method not only adjusts the terminal voltage of the battery cluster to be connected through the DC / DC module, but also performs current-limiting regulation on the DC bus voltage, achieving the purpose of bidirectional voltage regulation, broadening the grid connection voltage difference range between clusters, increasing the system availability and its depth of discharge; at the same time, reducing the voltage regulation requirements for the DC / DC, reducing the DC / DC output power requirements, resulting in a lower design cost and further reducing the volume; due to the voltage regulation effect, the actual voltage difference range between the battery cluster to be connected and the bus is broadened, and the Δsoc at the current allowable power-on is smaller, and the consistency of the energy storage system is better.

[0072] SOC is the State of Charge in the energy storage system, which represents the remaining capacity of the energy storage system that can still provide electrical energy, usually expressed as a percentage.

[0073] Please refer to Figure 1 , Figure 1The figure shows a flowchart of the grid connection method of the energy storage system described in the embodiments of the present application; as Figure 1 shown, the grid connection method includes the following steps S101 - S104:

[0074] S101. Based on the operating parameters of the energy storage system, determine the current-limiting and voltage-regulating range of the bus voltage in the energy storage system; the current-limiting and voltage-regulating range is the maximum voltage-regulating range adjusted by adjusting the bus current of the already-connected battery cluster;

[0075] S102. Based on the current-limiting and voltage-regulating range and the boost range of the DC / DC module connected in series with the battery cluster to be connected, determine the cabinet connection voltage-regulating range for the battery cluster to be connected under different working conditions; the working conditions include discharging and charging;

[0076] S103. Based on the terminal voltage of the battery cluster to be connected and the bus voltage of the already-connected battery cluster under the target working condition, determine the voltage difference between the battery cluster to be connected and the bus;

[0077] S104. When it is determined that voltage regulation and cabinet connection are allowed based on the voltage difference and the cabinet connection voltage-regulating range, adjust the bus voltage and / or the voltage output value of the DC / DC module, and control the battery cluster to be connected to be connected to the cabinet when the voltage difference between the battery cluster to be connected and the bus meets the preset cabinet connection voltage difference condition.

[0078] In step S101, based on the operating parameters of the energy storage system, determine the current-limiting and voltage-regulating range of the bus voltage in the energy storage system; the current-limiting and voltage-regulating range is the maximum voltage-regulating range adjusted by adjusting the bus current of the already-connected battery cluster;

[0079] The operating parameters include: the minimum operating multiple C min of the system, the current operating multiple C current of the system, the dynamic terminal voltage U T of the system, the static voltage ocv, the dynamic internal resistance R rack of the system, the dynamic current I, and the rated capacity rated_Cap.

[0080] Specifically, the dynamic terminal voltage during system discharge is U T，DCH , and the dynamic terminal voltage during system charging is U T，CH .

[0081] The current-limiting and voltage-regulating range is the maximum voltage-regulating range adjusted by adjusting the bus current of the already-connected battery cluster. That is to say, the current-limiting and voltage-regulating range is determined based on the current adjustment range of the bus, or rather, it is determined based on the maximum current-limiting value of the bus.

[0082] The maximum current-limiting value of the bus is determined based on the minimum operating multiple and the current operating multiple of the system. That is to say, when limiting the current of the bus to adjust the bus voltage, it is necessary to ensure that the operating multiple of the system is greater than the minimum operating multiple.

[0083] Based on this, in the embodiments of the present application, please refer to Figure 2 , determining the current-limiting voltage regulation range of the bus voltage in the energy storage system based on the operating parameters of the energy storage system includes the following steps S201 - S202:

[0084] S201. Calculate the maximum current-limiting value of the bus based on the minimum operating multiple, the current operating multiple, and the rated capacity of the energy storage system;

[0085] S202. Calculate the current-limiting voltage regulation range of the bus voltage based on the maximum current-limiting value of the bus and the dynamic internal resistance during the operation of the energy storage system.

[0086] Specifically, determining the minimum operating multiple, the current operating multiple, and the rated capacity of the energy storage system and calculating the maximum current-limiting value of the bus includes:

[0087] Calculate the maximum current-limiting multiple based on the minimum operating multiple and the current operating multiple of the energy storage system;

[0088] Calculate the maximum current-limiting value of the bus based on the maximum current-limiting multiple and the rated capacity.

[0089] Specifically, in the embodiments of the present application, the minimum operating multiple is Cmin, the current operating multiple is Ccurrent, then the current maximum current-limiting multiple ΔC max is calculated by the following formula (1):

[0090] ΔC mnax = C current - C mmin ; (1)

[0091] Calculate the current maximum current-limiting value ΔI according to the rated capacity rated_Cap through the following formula 2 max :

[0092] ΔI max = ΔC max *rated_Cap; (2)

[0093] The dynamic internal resistance during the operation of the energy storage system is calculated in the following manner:

[0094] When the system discharges, the battery internal resistance voltage is in the opposite direction to the open-circuit voltage, that is, at the same soc, the dynamic terminal voltage is less than the static voltage. The relationship between the dynamic terminal voltage U T，DCH , the static voltage ocv, the dynamic current I, and the dynamic internal resistance R rack is as shown in the following formula 3:

[0095] U T，DCH = ocv - |I * R rack |; (3)

[0096] When the system is charging, the internal resistance voltage of the battery is in the same direction as the open-circuit voltage, that is, at the same state of charge (SOC), the dynamic terminal voltage is greater than the static voltage; the dynamic terminal voltage U T，CH , the static voltage ocv, the dynamic current I, and the dynamic internal resistance R rack are related as shown in the following formula (4):

[0097] U T，CH = ocv + |I * R rack |; (4)

[0098] For an operating energy storage system (10% ≤ SOC ≤ 90%), its dynamic internal resistance Rrack is calculated in real time according to Ohm's law.

[0099] It should be noted that the dynamic internal resistance of each paralleled battery cluster in the energy storage system also conforms to the above formulas (3) and (4).

[0100] Specifically, according to the operating conditions of the energy storage system and the corresponding formula (3) or (4), the dynamic internal resistance of each paralleled battery cluster in the energy storage system is calculated.

[0101] Based on the dynamic internal resistance of each paralleled battery cluster, the dynamic internal resistance of the energy storage system is calculated.

[0102] Suppose there are n paralleled battery clusters, and the dynamic internal resistances of the n paralleled battery clusters are R rack1 、R rack2 、... R rackn ; Based on the following formula (5), the dynamic internal resistance R of the energy storage system after the equivalent internal resistances of all paralleled clusters are connected in parallel is calculated rack :

[0103] R rack = 1 / (1 / R rack1 + 1 / R rack2 +... + 1 / R rackn ) (5)

[0104] Based on the maximum current limiting value of the busbar and the dynamic internal resistance during the operation of the energy storage system, the current limiting and voltage regulating range of the busbar voltage is calculated. Specifically, the current limiting and voltage regulating range ΔV is calculated through the following formula (6) max ;

[0105] ΔV max = |ΔI max * R rack | (6)

[0106] In the step S102, based on the current limiting and voltage regulating range and the boosting range of the DC / DC module connected in series with the battery cluster to be paralleled, the paralleling voltage regulating range for the battery cluster to be paralleled under different operating conditions is determined; the operating conditions include discharging and charging.

[0107] Please refer to Figure 3 , based on the current-limiting voltage regulation range and the boost range of the DC / DC module connected in series with the battery cluster to be paralleled, determine the cabinet voltage regulation range for the battery cluster to be paralleled under different working conditions, including the following steps S301 - S302:

[0108] S301. Determine the maximum current-limiting voltage regulation value in the current-limiting voltage regulation range and the maximum boost value in the boost range;

[0109] S302. Based on the variation relationship between the bus current and the bus voltage under different working conditions, the maximum current-limiting voltage regulation value, and the maximum boost value, determine the cabinet voltage regulation range for the battery cluster to be paralleled under different working conditions.

[0110] Among them, the variation relationship between the bus current and the bus voltage under different working conditions is as follows: during the discharge process, the bus voltage can be increased by current limiting. Or rather, in the discharge working condition, the lower the bus current, the higher the bus voltage; during the charging process, current limiting reduces the bus voltage. That is to say, in the charging working condition, the lower the bus current, the lower the bus voltage.

[0111] This is because the relationship between the internal resistance voltage of the charging and discharging battery and the open-circuit voltage is different in direction. When the system discharges, the internal resistance voltage of the battery is opposite to the open-circuit voltage in direction; when the system charges, the internal resistance voltage of the battery is the same as the open-circuit voltage in direction.

[0112] Therefore, in the discharge working condition, the cabinet voltage regulation range is: greater than or equal to the negative maximum current-limiting voltage regulation value and less than or equal to the maximum boost value.

[0113] In the charging working condition, the cabinet voltage regulation range is: greater than or equal to 0 and less than or equal to the sum of the maximum boost value and the maximum current-limiting voltage regulation value.

[0114] Specifically, set the maximum boost value of the DC / DC module as VDC / DCmax. According to the direction relationship between the internal resistance voltage of the charging and discharging battery and the open-circuit voltage, during the discharge process, the bus voltage can be increased by current limiting. Then the allowable voltage difference range for discharge grid connection is:

[0115] -ΔV max ≤ΔU≤V DC / DCmax ;

[0116] During the charging process, current limiting reduces the bus voltage. Then the allowable voltage difference range for charging grid connection is:

[0117] 0≤ΔU≤ΔV max +V DC / DCmax ;

[0118] Among them, ΔU represents the voltage difference between the battery cluster to be paralleled and the bus.

[0119] In the step S103, based on the terminal voltage of the battery cluster to be paralleled and the bus voltage of the paralleled cabinet battery cluster under the target working condition, determine the pressure difference between the battery cluster to be paralleled and the bus.

[0120] Specifically, the bus voltage is the dynamic terminal voltage U bus，动 , and the terminal voltage of the cluster to be paralleled is the static voltage U rack，静 , then calculate the pressure difference ΔU between the battery cluster to be paralleled and the bus through the following formula (7)

[0121] ΔU = U bus，动 - U rack，静 ; (7)

[0122] Here, the pressure difference is the real-time pressure difference between the battery cluster to be paralleled and the bus.

[0123] In the step S104, when it is determined that voltage regulation and paralleling of the cabinet are allowed based on the pressure difference and the voltage regulation range of the paralleling cabinet, adjust the bus voltage and / or the voltage output value of the DC / DC module, and control the paralleling of the battery cluster to be paralleled when the pressure difference between the battery cluster to be paralleled and the bus meets the preset paralleling cabinet pressure difference condition.

[0124] Here, the preset paralleling cabinet pressure difference condition is the preset paralleling cabinet pressure difference threshold. For example, the preset paralleling cabinet pressure difference threshold is the relay closing pressure difference. Only as an example, the preset paralleling cabinet pressure difference threshold is 5V.

[0125] Determining that voltage regulation and paralleling of the cabinet are allowed based on the pressure difference and the voltage regulation range of the paralleling cabinet means that when the pressure difference is within the voltage regulation range of the paralleling cabinet and the pressure difference can be reduced to within 5V by adjusting the DC / DC module and / or the bus current, then the battery cluster to be paralleled is allowed to be paralleled, and the bus voltage and / or the voltage output value of the DC / DC module are adjusted to determine the specific timing of the parallel connection of the battery cluster to be paralleled.

[0126] That is to say, in some embodiments, before adjusting the bus voltage and / or the voltage output value of the DC / DC module when it is determined that voltage regulation and paralleling of the cabinet are allowed based on the pressure difference and the voltage regulation range of the paralleling cabinet, the parallel connection method further includes:

[0127] Judge whether the pressure difference meets the voltage regulation range of the paralleling cabinet;

[0128] If so, allow voltage regulation and paralleling of the cabinet;

[0129] If not, do not allow voltage regulation and paralleling of the cabinet.

[0130] In actual applications, in order to ensure the performance of the energy storage system, the paralleling cabinet duration needs to be reduced because adjusting the bus current during the paralleling process will cause changes in the system's soc, consistency, etc. Therefore, there are certain requirements for the paralleling cabinet duration.

[0131] Based on this, in some embodiments, in the grid connection method of the energy storage system, before determining the allowable voltage regulation and cabinet connection based on the pressure difference and the cabinet connection voltage regulation range, the grid connection method further includes:

[0132] Determine the cabinet connection duration threshold based on the circuit structure of the energy storage system; the cabinet connection duration threshold is used to limit the cabinet connection duration of the battery cluster to be connected;

[0133] Narrow the cabinet connection voltage regulation range based on the cabinet connection duration threshold to obtain an updated cabinet connection voltage regulation range, so that the battery cluster to be connected completes the cabinet connection within the cabinet connection duration threshold;

[0134] Judge whether to allow voltage regulation and cabinet connection based on the pressure difference and the updated cabinet connection voltage regulation range.

[0135] That is to say, in order to limit the cabinet connection duration of the battery cluster to be connected not to exceed the cabinet connection duration threshold, it is necessary to narrow the cabinet connection voltage regulation range.

[0136] Only as an example, the updated cabinet connection voltage regulation range is 70% of the original cabinet connection voltage regulation range.

[0137] Judging whether to allow voltage regulation and cabinet connection based on the pressure difference and the updated cabinet connection voltage regulation range includes:

[0138] If the pressure difference meets the updated cabinet connection voltage regulation range, it is determined that cabinet connection is allowed;

[0139] If the pressure difference does not meet the updated cabinet connection voltage regulation range, it is determined that cabinet connection is not allowed.

[0140] Exemplarily, if the real-time pressure difference between the battery cluster to be connected and the bus is less than or equal to 70% of the cabinet connection voltage regulation range, cabinet connection is allowed, otherwise, cabinet connection is not allowed.

[0141] After determining that cabinet connection is allowed, adjust the bus voltage and / or the voltage output value of the DC / DC module so that the real-time pressure difference between the battery cluster to be connected and the bus is reduced to within the relay closing pressure difference.

[0142] In the embodiments of the present application, to maintain the operation performance of the energy storage system, the voltage output value of the DC / DC module is preferentially adjusted. Specifically, it is preferentially considered that the DC / DC module outputs with the maximum voltage regulation ability to ensure that the system SOP (state of Power) is not too low as much as possible. After exceeding the adjustment range of the DC / DC module, the bus current is adjusted.

[0143] SOP also reflects the magnitude of the bus current. This solution preferentially considers the boost cabinet connection ability of DCDC. If the bus current reduction strategy is adopted, it will inevitably lead to low power and small current in the battery system in a short time.

[0144] Based on this, please refer to Figure 4, adjust the bus voltage and / or the voltage output value of the DC / DC module, including the following steps S401 - S402:

[0145] S401. When the pressure difference is within the boost range of the DC / DC module, adjust the voltage output value of the DC / DC module so that the pressure difference between the battery cluster to be paralleled and the bus voltage meets the preset paralleling cabinet pressure difference condition;

[0146] S402. When the pressure difference is outside the boost range of the DC / DC module, adjust the bus voltage and the DC / DC module so that the pressure difference between the battery cluster to be paralleled and the bus voltage meets the preset paralleling cabinet pressure difference condition.

[0147] Specifically, when it is necessary to adjust the bus voltage and the voltage output value of the DC / DC module simultaneously, the adjustment of the bus voltage and the voltage output value of the DC / DC module includes:

[0148] Determine the voltage output value of the DC / DC module; among them, in the discharging condition, the DC / DC module maintains the minimum voltage output, and in the charging condition, the DC / DC module maintains the maximum voltage output;

[0149] Adjust the bus voltage by adjusting the bus current; among them, in the discharging condition, the lower the bus current, the higher the bus voltage; in the charging condition, the lower the bus current, the lower the bus voltage.

[0150] When adjusting the bus voltage by adjusting the bus current, it is necessary to calculate the target current limiting value that makes the pressure difference between the bus and the battery cluster to be paralleled meet the preset paralleling cabinet pressure difference condition.

[0151] Therefore, in the embodiment of the present application, adjusting the bus voltage by adjusting the bus current includes:

[0152] Based on the pressure difference between the battery cluster to be paralleled and the bus, and the dynamic internal resistance during the operation of the energy storage system, calculate the target current limiting value of the bus; the pressure difference between the target current limiting voltage corresponding to the target current limiting value of the bus and the terminal voltage of the battery cluster to be paralleled meets the preset paralleling cabinet pressure difference condition;

[0153] Reduce the bus current to the target current limiting value to adjust the bus voltage to the target current limiting voltage.

[0154] Specifically, based on the pressure difference between the battery cluster to be paralleled and the bus, and the dynamic internal resistance during the operation of the energy storage system, calculating the target current limiting value and the target current limiting voltage of the bus includes:

[0155] According to the variation relationship between the bus current and the bus voltage under different working conditions, based on the pressure difference between the battery cluster to be paralleled and the bus, the maximum boost value of the boost range of the DC / DC module, and the dynamic internal resistance during the operation of the energy storage system, calculate the target change amount of the bus current under different working conditions;

[0156] Based on the bus current and the target change amount, determine the target current-limiting current of the bus under different working conditions.

[0157] Based on the pressure difference between the battery cluster to be paralleled and the bus, the maximum boost value of the boost range of the DC / DC module, and the dynamic internal resistance during the operation of the energy storage system, calculate the target change amount of the bus current; including:

[0158] Under the discharging condition, based on the sum value of the pressure difference and the maximum boost value, and the dynamic internal resistance, calculate the target change amount of the bus current;

[0159] Under the charging condition, based on the difference value of the pressure difference and the maximum boost value, and the dynamic internal resistance, calculate the target change amount of the bus current.

[0160] The following uses formulas to illustrate the specific applicable situations of the DC / DC module voltage regulation, the DC / DC module and the bus current-limiting voltage regulation under the charging and discharging conditions, and the specific calculation process of the target current-limiting current of the bus.

[0161] The discharging condition is as follows:

[0162] When 0 ≤ ΔU ≤ V DC / DCmax only DC / DC voltage regulation is required;

[0163] When -ΔV max ≤ ΔU < 0, the DC / DC maintains the minimum voltage output, and the target current-limiting current of the bus is calculated through the following formula (8):

[0164]

[0165] where, I0 is the dynamic current of the bus before adjustment, I1 is the target current-limiting current of the bus after adjustment, and ΔI is the target change amount of the bus current.

[0166] The charging condition is as follows:

[0167] When 0 ≤ ΔU ≤ V DC / DCmax only DC / DC voltage regulation is required;

[0168] When V DC / DCmax < ΔU ≤ ΔV max + V DC / DCmax the DC / DC module maintains the maximum voltage output, and the target current-limiting current of the bus is calculated through the following formula (9):

[0169]

[0170] Based on this, adjust the bus voltage, and control the battery cluster to be paralleled to be paralleled when the pressure difference between the battery cluster to be paralleled and the bus meets the preset paralleling cabinet pressure difference condition, including:

[0171] Maintain the busbar to operate at the target current limit within a preset current limit duration, and determine whether the pressure difference between the battery cluster to be paralleled and the busbar meets the preset paralleling cabinet pressure difference condition within the preset current limit duration;

[0172] If it meets the condition, control the battery cluster to be paralleled to be paralleled into the cabinet when the preset paralleling cabinet pressure difference condition is met;

[0173] If it does not meet the condition, control the busbar to resume the rated current.

[0174] That is to say, within the preset current limit duration, maintain this current value until the pressure difference meets the relay closing condition (that is, less than or equal to the relay closing pressure difference Vclose), and close the high-voltage relay to control the battery cluster to be paralleled to be paralleled into the cabinet.

[0175] It should be noted that after the high-voltage relay is closed, that is, after the battery cluster to be paralleled is paralleled into the cabinet, the system resumes discharging at the rated rate, and the busbar resumes the original rated current.

[0176] If within the preset current limit duration, the pressure difference between the battery cluster to be paralleled and the busbar does not drop below the relay closing pressure difference Vclose, the paralleling into the cabinet fails, and the busbar is controlled to resume the rated current.

[0177] In the embodiment of the present application, the current limit operation duration of the system is limited by the preset current limit duration, and the current limit operation duration of the system is prevented from being too long in advance by reducing the paralleling cabinet voltage regulation range. Thus, it is ensured that the system SOP is not too low, and the normal operation of the system is guaranteed.

[0178] The grid connection method described in the embodiment of the present application not only considers adjusting the terminal voltage of the battery cluster to be paralleled through the DC / DC module, but also performs current limit regulation on the DC bus voltage, achieving the purpose of bidirectional voltage regulation, broadening the grid connection pressure difference range between clusters, increasing the system availability and its discharge depth. At the same time, the voltage regulation requirement for the DC / DC is reduced. The reduction of the DC / DC output power requirement reduces the design cost, and the volume can also be further reduced.

[0179] The following shows the simulation experiment results of three pressure difference ranges: only considering the 5V pressure difference range on both sides of the main relay of the battery cluster, considering the boost range of the DC / DC module, and the current limit voltage regulation range determined by the DC / DC module and bus current regulation described in the embodiment of the present application, through simulation experiments.

[0180] Please refer to Figure 5 , Figure 5 shows a schematic diagram of the boost range of the DC / DC and the current limit voltage regulation range described in the embodiment of the present application; analyze Figure 5 In the upper half of the figure, the vertical coordinate is the soc value, and the broken line therein represents that the system is discharged from 100% soc to 0 and then charged to 100%. The remaining parallel lines are the soc of the static un-paralleled battery clusters at different socs.

[0181] Figure 5 In the lower part, the vertical coordinate is ΔV, with the unit of V, which is the difference between the bus voltage and the dynamic and static pressure difference of the stationary battery cluster. The horizontal coordinate is time. After putting the DC / DC voltage regulation range and the bus charge and discharge current limiting voltage regulation range into the figure, it can be seen that during the charge and discharge process of the system, the cabinet connection timing based on voltage consistency (≤5V) is greatly broadened.

[0182] Figures 6 - 8 In the upper area, the vertical coordinate represents Δsoc, and in the lower area, 0 / 1 is used to indicate whether the current meets the cabinet connection condition of voltage consistency (≤5V).

[0183] Please refer to Figure 6 , Figure 6 , which shows the simulation result diagram of the present application embodiment that only considers the 5V pressure difference range on both sides of the main relay of the battery cluster; Figure 6 , which shows the relationship between different static soc battery clusters (100%, 90%, 80%, 60%, 40%, 30%, 10%, 0%) within the 5V pressure difference range on both sides of the main relay of the battery cluster and Δsoc of the dynamic system; Analysis Figure 6 shows that for the vast majority of static battery clusters, Δsoc within the pressure difference range is greater than 20%.

[0184] Please refer to Figure 7 , Figure 7 , which shows the simulation result diagram of the present application embodiment that considers the boost range of the DC / DC module; When the DC / DC module is connected in series to the battery cluster, due to the voltage regulation function of the DC / DC module, the actual pressure difference range between the battery cluster and the bus is broadened to -5V to 35V. The relationship between different static soc battery clusters (100%, 90%, 80%, 60%, 40%, 30%, 10%, 0%) within this range and Δsoc of the dynamic system is as Figure 7 shown; Analysis Figure 7 shows that compared with the strategy of only considering the 5V pressure difference range, the Δsoc when power-on is allowed is smaller currently, and the system consistency is better.

[0185] Please refer to Figure 8 , Figure 8 , which shows the simulation result diagram of the present application embodiment that shows the current limiting voltage regulation range determined by the DC / DC module and the bus current regulation; On the basis of the series DC / DC forward voltage regulation, the bus current limiting voltage regulation strategy is added, and its cabinet connection voltage regulation range is broadened to -35V to 35V for discharge and -5V to 65V for charge. The relationship between different static soc battery clusters (100%, 90%, 80%, 60%, 40%, 30%, 10%, 0%) within this voltage range and Δsoc of the dynamic system is as Figure 8 shown, and basically all can meet the condition of |Δsoc|≤1%.

[0186] Compare and analyze the simulation results of Figures 6 - 8 . When the voltage regulation range is widened, the Δsoc when allowing parallel connection of cabinets (pressure difference ≤ 5V) will be significantly reduced or even become 0, that is, even if the soc is exactly the same, it can meet the parallel connection pressure difference of the cabinets, greatly improving the dynamic parallel connection consistency of the system during operation. Therefore, the grid connection method described in the embodiments of this application effectively improves the system consistency and the depth of discharge DOD (Depth of Discharge).

[0187] Based on the same inventive concept, an grid connection device for an energy storage system corresponding to the grid connection method of the energy storage system is also provided in the embodiments of this application. Since the principle of solving problems by the device in the embodiments of this application is similar to the above method in the embodiments of this application, the implementation of the device can refer to the implementation of the method, and the repeated parts will not be described again.

[0188] Please refer to Figure 9 , Figure 9 which shows a schematic diagram of the results of the grid connection device for the energy storage system described in the embodiments of this application. The grid connection device includes:

[0189] A first determination module 901, configured to determine the current-limiting voltage regulation range of the bus voltage in the energy storage system based on the operating parameters of the energy storage system; the current-limiting voltage regulation range is the maximum voltage regulation range adjusted by adjusting the bus current of the paralleled battery clusters;

[0190] A second determination module 902, configured to determine the parallel connection voltage regulation range for the battery cluster to be paralleled under different working conditions based on the current-limiting voltage regulation range and the boost range of the DC / DC module connected in series with the battery cluster to be paralleled; the working conditions include discharge and charge;

[0191] A third determination module 903, configured to determine the pressure difference between the battery cluster to be paralleled and the bus based on the terminal voltage of the battery cluster to be paralleled and the bus voltage of the paralleled battery clusters under the target working condition;

[0192] An adjustment module 904, configured to adjust the bus voltage and / or the voltage output value of the DC / DC module when it is determined that voltage regulation and parallel connection are allowed based on the pressure difference and the parallel connection voltage regulation range, and control the battery cluster to be paralleled when the pressure difference between the battery cluster to be paralleled and the bus meets the preset parallel connection pressure difference condition.

[0193] In some embodiments, the grid connection device for the energy storage system further includes:

[0194] A threshold reduction module, configured to determine the parallel connection duration threshold based on the circuit structure of the energy storage system before it is determined that voltage regulation and parallel connection are allowed based on the pressure difference and the parallel connection voltage regulation range; the parallel connection duration threshold is used to limit the parallel connection duration of the battery cluster to be paralleled;

[0195] ​​Narrow the parallel cabinet voltage regulation range based on the parallel cabinet duration threshold to obtain an updated parallel cabinet voltage regulation range, so that the battery clusters to be paralleled complete the parallel cabinet within the parallel cabinet duration threshold;

[0196] Judge whether voltage regulation and parallel cabinet are allowed based on the pressure difference and the updated parallel cabinet voltage regulation range.

[0197] In some embodiments, when the narrowing module in the grid connection device of the energy storage system judges whether voltage regulation and parallel cabinet are allowed based on the pressure difference and the updated parallel cabinet voltage regulation range, it specifically is used for:

[0198] If the pressure difference conforms to the updated parallel cabinet voltage regulation range, it is determined that parallel cabinet is allowed;

[0199] If the pressure difference does not conform to the updated parallel cabinet voltage regulation range, it is determined that parallel cabinet is not allowed.

[0200] In some embodiments, when the adjustment module in the grid connection device of the energy storage system adjusts the bus voltage and / or the voltage output value of the DC / DC module, it specifically is used for:

[0201] When the pressure difference is within the boost range of the DC / DC module, adjust the voltage output value of the DC / DC module so that the pressure difference between the battery clusters to be paralleled and the bus voltage conforms to the preset parallel cabinet pressure difference condition;

[0202] When the pressure difference is outside the boost range of the DC / DC module, adjust the bus voltage and the DC / DC module so that the pressure difference between the battery clusters to be paralleled and the bus voltage conforms to the preset parallel cabinet pressure difference condition.

[0203] In some embodiments, when the adjustment module in the grid connection device of the energy storage system adjusts the bus voltage and the voltage output value of the DC / DC module, it specifically is used for:

[0204] Determine the voltage output value of the DC / DC module; among them, in the discharging working condition, the DC / DC module maintains the minimum voltage output, and in the charging working condition, the DC / DC module maintains the maximum voltage output;

[0205] Adjust the bus voltage by adjusting the bus current; among them, in the discharging working condition, the lower the bus current, the higher the bus voltage; in the charging working condition, the lower the bus current, the lower the bus voltage.

[0206] In some embodiments, when the adjustment module in the grid connection device of the energy storage system adjusts the bus voltage by adjusting the bus current, it specifically is used for:

[0207] Based on the pressure difference between the battery clusters to be paralleled and the bus and the dynamic internal resistance during the operation of the energy storage system, calculate the target current limiting current of the bus; the pressure difference between the target current limiting voltage corresponding to the target current limiting current of the bus and the terminal voltage of the battery clusters to be paralleled conforms to the preset parallel cabinet pressure difference condition;

[0208] Reduce the bus current to the target current limit to adjust the bus voltage to the target current limit voltage.

[0209] In some embodiments, when the adjustment module in the grid connection device of the energy storage system adjusts the bus voltage and controls the parallel connection of the battery cluster to be connected when the pressure difference between the battery cluster to be connected and the bus meets the preset parallel cabinet pressure difference condition, it is specifically used for:

[0210] Maintain the bus operation at the target current limit within the preset current limit duration, and determine whether the pressure difference between the battery cluster to be connected and the bus meets the preset parallel cabinet pressure difference condition within the preset current limit duration;

[0211] If it meets the condition, control the parallel connection of the battery cluster to be connected when the preset parallel cabinet pressure difference condition is met;

[0212] If it does not meet the condition, control the bus to resume the rated current.

[0213] In some embodiments, when the first determination module in the grid connection device of the energy storage system determines the current limit voltage regulation range of the bus voltage based on the operation parameters of the energy storage system, it is specifically used for:

[0214] Calculate the maximum current limit value of the bus based on the minimum operation multiple, the current operation multiple, and the rated capacity of the energy storage system;

[0215] Calculate the current limit voltage regulation range of the bus voltage based on the maximum current limit value of the bus and the dynamic internal resistance during the operation of the energy storage system.

[0216] In some embodiments, when the first determination module in the grid connection device of the energy storage system determines the minimum operation multiple, the current operation multiple, and the rated capacity of the energy storage system and calculates the maximum current limit value of the bus, it is specifically used for:

[0217] Calculate the maximum current limit multiple based on the minimum operation multiple and the current operation multiple of the energy storage system;

[0218] Calculate the maximum current limit value of the bus based on the maximum current limit multiple and the rated capacity.

[0219] In some embodiments, when the second determination module in the grid connection device of the energy storage system determines the parallel cabinet voltage regulation range for the battery cluster to be connected under different working conditions based on the current limit voltage regulation range and the boost range of the DC / DC module connected in series with the battery cluster to be connected, it is specifically used for:

[0220] Determine the maximum current limit voltage regulation value in the current limit voltage regulation range and the maximum boost value in the boost range;

[0221] Based on the variation relationships between the bus current and the bus voltage under different working conditions, the maximum current-limiting voltage regulation value, and the maximum voltage boost value, determine the parallel cabinet voltage regulation range for the battery cluster to be paralleled under different working conditions.

[0222] In some embodiments, in the grid connection device of the energy storage system, under the discharging working condition, the parallel cabinet voltage regulation range is: greater than or equal to the negative maximum current-limiting voltage regulation value and less than or equal to the maximum voltage boost value;

[0223] Under the charging working condition, the parallel cabinet voltage regulation range is: greater than or equal to 0 and less than or equal to the sum value of the maximum voltage boost value and the maximum current-limiting voltage regulation value.

[0224] In some embodiments, in the adjustment module of the grid connection device of the energy storage system, when calculating the target current-limiting current and the target current-limiting voltage of the bus based on the pressure difference between the battery cluster to be paralleled and the bus and the dynamic internal resistance during the operation of the energy storage system, it is specifically used for:

[0225] According to the variation relationships between the bus current and the bus voltage under different working conditions, based on the pressure difference between the battery cluster to be paralleled and the bus, the maximum voltage boost value of the boost range of the DC / DC module, and the dynamic internal resistance during the operation of the energy storage system, calculate the target change amount of the bus current under different working conditions;

[0226] Based on the bus current and the target change amount, determine the target current-limiting current of the bus under different working conditions.

[0227] In some embodiments, in the adjustment module of the grid connection device of the energy storage system, when calculating the target change amount of the bus current under different working conditions based on the pressure difference between the battery cluster to be paralleled and the bus, the maximum voltage boost value of the boost range of the DC / DC module, and the dynamic internal resistance during the operation of the energy storage system, it is specifically used for:

[0228] Under the discharging working condition, calculate the target change amount of the bus current based on the sum value of the pressure difference and the maximum voltage boost value and the dynamic internal resistance;

[0229] Under the charging working condition, calculate the target change amount of the bus current based on the difference value between the pressure difference and the maximum voltage boost value and the dynamic internal resistance.

[0230] Based on the same inventive concept, embodiments of the present application also provide an electronic device corresponding to the grid connection method of the energy storage system. Since the principle of solving problems by the electronic device in the embodiments of the present application is similar to the above method in the embodiments of the present application, the implementation of the electronic device can refer to the implementation of the method, and the repeated parts will not be described again.

[0231] Please refer to Figure 10 , Figure 10 which shows the structural schematic diagram of the electronic device described in the embodiments of the present application, as Figure 10As shown, the electronic device 1000 includes: a processor 1002, a memory 1001, and a bus. The memory 1001 stores machine-readable instructions executable by the processor 1002. When the electronic device 1000 runs, the processor 1002 communicates with the memory 1001 through the bus. When the machine-readable instructions are executed by the processor 1002, the steps of the grid connection method of the energy storage system are executed.

[0232] Based on the same inventive concept, an embodiment of the present application also provides a computer-readable storage medium corresponding to the grid connection method of the energy storage system. Since the principle of solving problems by the computer-readable storage medium in the embodiment of the present application is similar to the above method in the embodiment of the present application, the implementation of the computer-readable storage medium can refer to the implementation of the method, and the repeated parts will not be described again.

[0233] A computer-readable storage medium stores a computer program thereon. When the computer program is run by a processor, the steps of the grid connection method of the energy storage system are executed.

[0234] Those skilled in the art can clearly understand that for the convenience and simplicity of description, the specific working processes of the above-described systems and devices can refer to the corresponding processes in the method embodiments, which will not be described in detail in this application. In the several embodiments provided in this application, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. The device embodiments described above are merely illustrative. For example, the division of the modules is only a logical function division, and there may be other division methods in actual implementation. For another example, multiple modules or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed mutual coupling or direct coupling or communication connection can be through some communication interfaces. The indirect coupling or communication connection of the devices or modules can be in an electrical, mechanical, or other form.

[0235] The modules described as separate components may or may not be physically separated. The components displayed as modules may or may not be physical units, that is, they may be located in one place, or they may be distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0236] In addition, in each embodiment of the present application, the functional units can be integrated into one processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit.

[0237] When the above-mentioned functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a non-volatile computer-readable storage medium executable by a processor. Based on such an understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a platform server, or a network device, etc.) to execute all or part of the steps of the methods described in various embodiments of this application. The foregoing storage medium includes: various media such as USB flash drives, mobile hard disks, ROM, RAM, magnetic disks, or optical discs that can store program codes.

[0238] The above is only the specific implementation manner of this application, but the protection scope of this application is not limited thereto. Any person skilled in the art within the technical scope disclosed by this application can easily think of changes or substitutions, which should all be covered by the protection scope of this application. Therefore, the protection scope of this application should be subject to the protection scope of the claims.

Claims

1. A grid connection method for an energy storage system, characterized in that, The grid connection method includes: Based on the operating parameters of the energy storage system, determine the current-limiting and voltage-regulating range of the bus voltage in the energy storage system; the current-limiting and voltage-regulating range is the maximum voltage-regulating range adjusted by adjusting the bus current of the paralleled battery cluster; Based on the current-limiting and voltage-regulating range and the boost range of the DC / DC module connected in series with the battery cluster to be paralleled, determine the paralleling voltage-regulating range for the battery cluster to be paralleled under different working conditions; the working conditions include discharging and charging; Based on the terminal voltage of the battery cluster to be paralleled and the bus voltage of the paralleled battery cluster under the target working condition, determine the voltage difference between the battery cluster to be paralleled and the bus; When it is determined that voltage-regulating paralleling is allowed based on the voltage difference and the paralleling voltage-regulating range, adjust the bus voltage and / or the voltage output value of the DC / DC module, and control the battery cluster to be paralleled to be paralleled when the voltage difference between the battery cluster to be paralleled and the bus meets the preset paralleling voltage difference condition; 2. The grid connection method of the energy storage system according to claim 1, characterized in that Before it is determined that voltage-regulating paralleling is allowed based on the voltage difference and the paralleling voltage-regulating range, the grid connection method further includes: Determine the paralleling duration threshold based on the circuit structure of the energy storage system; the paralleling duration threshold is used to limit the paralleling duration of the battery cluster to be paralleled; Narrow the paralleling voltage-regulating range based on the paralleling duration threshold to obtain an updated paralleling voltage-regulating range, so that the battery cluster to be paralleled can complete paralleling within the paralleling duration threshold; Judge whether voltage-regulating paralleling is allowed based on the voltage difference and the updated paralleling voltage-regulating range; 3. The grid connection method of the energy storage system according to claim 2, wherein Judging whether voltage-regulating paralleling is allowed based on the voltage difference and the updated paralleling voltage-regulating range includes: If the voltage difference meets the updated paralleling voltage-regulating range, determine that paralleling is allowed; If the voltage difference does not meet the updated paralleling voltage-regulating range, determine that paralleling is not allowed; 4. The grid connection method of the energy storage system according to claim 1, characterized in that, Adjusting the bus voltage and / or the voltage output value of the DC / DC module includes: When the voltage difference is within the boost range of the DC / DC module, adjust the voltage output value of the DC / DC module so that the voltage difference between the battery cluster to be paralleled and the bus voltage meets the preset paralleling voltage difference condition; When the voltage difference is outside the boost range of the DC / DC module, adjust the bus voltage and the DC / DC module so that the voltage difference between the battery cluster to be paralleled and the bus voltage meets the preset paralleling voltage difference condition; 5. The grid connection method of the energy storage system according to claim 1 or 4, characterized in that, The adjusting the bus voltage and the voltage output value of the DC / DC module includes: Determine the voltage output value of the DC / DC module; among them, the DC / DC module maintains the minimum voltage output in the discharging working condition, and the DC / DC module maintains the maximum voltage output in the charging working condition; Adjust the bus voltage by adjusting the bus current; among them, in the discharging working condition, the lower the bus current, the higher the bus voltage; in the charging working condition, the lower the bus current, the lower the bus voltage; 6. The grid connection method of the energy storage system according to claim 5, wherein Adjusting the bus voltage by adjusting the bus current includes: Based on the voltage difference between the battery cluster to be paralleled and the bus and the dynamic internal resistance during the operation of the energy storage system, calculate the target current-limiting current of the bus; the voltage difference between the target current-limiting voltage corresponding to the target current-limiting current of the bus and the terminal voltage of the battery cluster to be paralleled meets the preset paralleling voltage difference condition; Reduce the bus current to the target current-limiting current to adjust the bus voltage to the target current-limiting voltage; 7. The grid connection method of the energy storage system according to claim 6, characterized in that, Adjust the bus voltage, and control the battery cluster to be paralleled to be paralleled when the voltage difference between the battery cluster to be paralleled and the bus meets the preset paralleling voltage difference condition, including: Maintain the busbar to operate at the target current limiting value within a preset current limiting duration, and determine whether the pressure difference between the battery cluster to be paralleled and the busbar meets the preset paralleling cabinet pressure difference condition within the preset current limiting duration; If it meets the condition, control the battery cluster to be paralleled to be paralleled into the cabinet when the preset paralleling cabinet pressure difference condition is met; If it does not meet the condition, control the busbar to resume the rated current.

8. The grid connection method of the energy storage system according to claim 1, characterized in that, Based on the operating parameters of the energy storage system, determine the current limiting and voltage regulating range of the busbar voltage in the energy storage system, including: Based on the minimum operating multiple, the current operating multiple and the rated capacity of the energy storage system, calculate the maximum current limiting value of the busbar; Based on the maximum current limiting value of the busbar and the dynamic internal resistance during the operation of the energy storage system, calculate the current limiting and voltage regulating range of the busbar voltage.

9. The grid connection method of the energy storage system according to claim 8, characterized in that, Determine the minimum operating multiple, the current operating multiple and the rated capacity of the energy storage system, and calculate the maximum current limiting value of the busbar, including: Based on the minimum operating multiple and the current operating multiple of the energy storage system, calculate the maximum current limiting multiple; Based on the maximum current limiting multiple and the rated capacity, calculate the maximum current limiting value of the busbar.

10. The grid connection method of the energy storage system according to claim 1, characterized in that, Based on the current limiting and voltage regulating range and the boosting range of the DC / DC module connected in series with the battery cluster to be paralleled, determine the paralleling cabinet voltage regulating range for the battery cluster to be paralleled under different working conditions, including: Determine the maximum current limiting and voltage regulating value in the current limiting and voltage regulating range and the maximum boosting value in the boosting range; Based on the change relationship between the busbar current and the busbar voltage under different working conditions, the maximum current limiting and voltage regulating value, and the maximum boosting value, determine the paralleling cabinet voltage regulating range for the battery cluster to be paralleled under different working conditions.

11. The grid connection method of the energy storage system according to claim 10, wherein, Under the discharging working condition, the paralleling cabinet voltage regulating range is: greater than or equal to the negative maximum current limiting and voltage regulating value, and less than or equal to the maximum boosting value; Under the charging working condition, the paralleling cabinet voltage regulating range is: greater than or equal to 0, and less than or equal to the sum value of the maximum boosting value and the maximum current limiting and voltage regulating value.

12. The grid connection method of the energy storage system according to claim 6, wherein, Based on the pressure difference between the battery cluster to be paralleled and the busbar and the dynamic internal resistance during the operation of the energy storage system, calculate the target current limiting current and the target current limiting voltage of the busbar, including: According to the change relationship between the busbar current and the busbar voltage under different working conditions, based on the pressure difference between the battery cluster to be paralleled and the busbar, the maximum boosting value of the boosting range of the DC / DC module, and the dynamic internal resistance during the operation of the energy storage system, calculate the target change amount of the busbar current under different working conditions; Based on the busbar current and the target change amount, determine the target current limiting current of the busbar under different working conditions.

13. The grid connection method of the energy storage system according to claim 12, characterized in that, Based on the pressure difference between the battery cluster to be paralleled and the busbar, the maximum boosting value of the boosting range of the DC / DC module, and the dynamic internal resistance during the operation of the energy storage system, calculate the target change amount of the busbar current under different working conditions; including: Under the discharging working condition, based on the sum value of the pressure difference and the maximum boosting value and the dynamic internal resistance, calculate the target change amount of the busbar current; Under the charging working condition, based on the difference value of the pressure difference and the maximum boosting value and the dynamic internal resistance, calculate the target change amount of the busbar current.

14. A grid connection device for an energy storage system, characterized in that, The grid connection device includes: The first determination module is used to determine the current limiting and voltage regulating range of the busbar voltage in the energy storage system based on the operating parameters of the energy storage system; the current limiting and voltage regulating range is the maximum voltage regulating range adjusted by adjusting the busbar current of the paralleled battery cluster; A second determination module, configured to determine a cabinet connection voltage regulation range for the battery cluster to be paralleled under different working conditions based on the current limiting and voltage regulation range and the boost range of the DC / DC module connected in series with the battery cluster to be paralleled; the working conditions include discharging and charging; A third determination module, configured to determine the pressure difference between the battery cluster to be paralleled and the bus based on the terminal voltage of the battery cluster to be paralleled and the bus voltage of the paralleled cabinet battery cluster under the target working condition; An adjustment module, configured to adjust the bus voltage and / or the voltage output value of the DC / DC module when it is determined that voltage regulation and cabinet connection are allowed based on the pressure difference and the cabinet connection voltage regulation range, and control the battery cluster to be paralleled to be connected to the cabinet when the pressure difference between the battery cluster to be paralleled and the bus meets the preset cabinet connection pressure difference condition.

15. An electronic device, characterized in that, Comprising: A processor, a memory and a bus, wherein the memory stores machine-readable instructions executable by the processor. When the electronic device runs, the processor communicates with the memory through the bus. When the machine-readable instructions are executed by the processor, the steps of the grid connection method of the energy storage system according to any one of claims 1 to 13 are executed.

16. A computer-readable storage medium, characterized in that, A computer program is stored on the computer-readable storage medium. When the computer program is run by a processor, the steps of the grid connection method of the energy storage system according to any one of claims 1 to 13 are executed.

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