SOC balancing control method and device for energy storage system

Abstract

The present invention provides a SOC balancing control method and device for an energy storage system. The method includes: obtaining the actual bus voltage and output power values ​​of a DCDC converter, as well as the actual SOC value of the energy storage module corresponding to the DCDC converter; updating a droop control curve based on the actual SOC value and a pre-stored balanced SOC value, the droop control curve being used to characterize the relationship between the output power and bus voltage of the DCDC converter; determining a set bus voltage value for the DCDC converter based on the updated droop control curve and the actual output power value of the DCDC converter; and adjusting the duty cycle of each switch in the DCDC converter based on the set bus voltage value and the actual bus voltage value to balance the charge of each energy storage module in the energy storage system. The present invention can solve the problem of SOC imbalance among multiple energy storage modules and achieve charge balance among the energy storage modules in the energy storage system.

Description

Technical Field

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

[0002] Battery energy storage systems mainly use batteries to store electrical energy. Traditional battery energy storage systems are usually composed of multiple battery clusters connected in parallel. Each battery cluster usually requires multiple battery packs connected in series. The more battery packs that need to be connected in series, the greater the impact of each individual battery pack on the energy storage system.

[0003] Traditional energy storage system charge and discharge control methods, such as droop control, can usually only ensure the normal grid connection of multiple energy storage modules, but cannot guarantee the equal current control of each energy storage module, resulting in uneven power distribution among the energy storage modules and affecting the service life of the energy storage modules. Summary of the Invention

[0004] The present invention provides a SOC balancing control method and device for an energy storage system, which can solve the problem of SOC imbalance among multiple energy storage modules and achieve power balance among the energy storage modules in the energy storage system.

[0005] In a first aspect, the present invention provides a SOC balancing control method for an energy storage system, wherein the energy storage system includes multiple DC-DC converters and multiple energy storage modules, wherein a first end of each DCDC converter is connected to a DC bus and a second end is connected to the energy storage module. The method is applied to the DCDC converter and includes: obtaining an actual bus voltage value and an actual output power value of the DCDC converter, as well as an actual SOC value of the energy storage module corresponding to the DCDC converter; updating a droop control curve based on the actual SOC value and a pre-stored balanced SOC value, the droop control curve being used to characterize the relationship between the output power and the bus voltage of the DCDC converter; determining a bus voltage set value of the DCDC converter based on the updated droop control curve and the actual output power value of the DCDC converter; and adjusting the duty cycle of each switch in the DCDC converter based on the bus voltage set value and the actual bus voltage value to balance the power of each energy storage module in the energy storage system.

[0006] The present invention provides a SOC balancing control method for an energy storage system. On the one hand, the present invention can update a droop control curve in real time based on the actual SOC value of the energy storage module corresponding to the DCDC converter, determine a bus voltage setpoint based on the updated droop control curve, and adjust the duty cycle of each switch in the DCDC converter to achieve balanced charge in each energy storage module in the energy storage system. On the other hand, the present invention updates the droop control curve based on the actual SOC value of the energy storage module corresponding to the DCDC converter and a pre-stored balanced SOC value. This method achieves charge balancing in each energy storage module in the energy storage system without the need for communication with other DCDC converters, thus avoiding the data transmission process, simplifying the control logic for charge balancing in each energy storage module in the energy storage system, reducing the probability of errors in the charge balancing process, and improving the safety and reliability of the energy storage system.

[0007] In one possible implementation, updating the droop control curve based on the actual SOC value and the pre-stored balanced SOC value includes: determining a control origin of the droop control curve based on the actual SOC value and the pre-stored balanced SOC value, where the control origin is a critical state point where the DCDC converter is in a charging state or a discharging state; and redetermining the droop control curve based on the control origin.

[0008] In a possible implementation, determining the control origin of the droop control curve based on the actual SOC value and the pre-stored balanced SOC value includes: determining the control origin of the droop control curve based on the following formula;

[0009]

[0010] Among them, V P is the control origin of the droop control curve. When the output power of the DCDC converter is zero, the bus voltage of the DCDC converter is V P , V base is the basic output voltage of the DCDC converter, SOC is the actual SOC value of the energy storage module corresponding to the DCDC converter, is the balanced SOC value of the energy storage module corresponding to the DCDC converter, V outmax is the maximum output voltage of the DCDC converter.

[0011] In one possible implementation, determining a bus voltage set value of the DCDC converter based on the updated droop control curve and the actual output power value of the DCDC converter includes: determining the bus voltage set value of the DCDC converter based on the following formula;

[0012]

[0013] Among them, Vout is the bus voltage given value of the DCDC converter, V base is the basic output voltage of the DCDC converter, V droop P is the droop voltage of the DCDC converter, which indicates the output voltage of the DCDC converter when it works at rated power. out is the actual output power value of the DCDC converter, P rate is the rated power of the DCDC converter, SOC is the actual SOC value of the energy storage module corresponding to the DCDC converter, is the balanced SOC value of the energy storage module corresponding to the DCDC converter, V outmax is the maximum output voltage of the DCDC converter.

[0014] In one possible implementation, the duty cycle of each switch in the DCDC converter is adjusted based on the bus voltage set value and the bus voltage actual value, including: calculating the deviation between the bus voltage set value and the bus voltage actual value; performing PI calculation based on the deviation to obtain a current loop set value; and performing closed-loop control based on the current loop set value to generate a duty cycle signal for each switch to adjust each switch.

[0015] In one possible implementation, performing a PI calculation based on the deviation value to obtain a current loop set value includes: performing a PI calculation based on the deviation value to obtain a first control variable; comparing the magnitude relationship between the first control variable and a second control variable, and determining the larger control variable as the current loop set value; the second control variable is obtained by performing a PI calculation based on a deviation between a voltage set value and an actual voltage value of an energy storage device corresponding to the DCDC converter.

[0016] In one possible implementation, closed-loop control is performed based on a current loop set value to generate a duty cycle signal for each switch tube to adjust each switch tube, including: obtaining the actual current value of the DCDC converter; calculating the current deviation between the current loop set value and the actual current value; and performing PI calculation based on the current deviation to generate a duty cycle signal for each switch tube.

[0017] In one possible implementation, a PI calculation is performed based on the current deviation to generate a duty cycle signal for each switching tube, including: performing the PI calculation based on the current deviation to obtain a target control variable; modulating the target control variable to obtain a duty cycle signal for controlling the boost switching tube in the DCDC converter; and inverting the target control variable and modulating the inverted target control variable to obtain a duty cycle signal for controlling the buck switching tube in the DCDC converter.

[0018] In a second aspect, an embodiment of the present invention provides an SOC balancing control device for an energy storage system, wherein the energy storage system includes multiple DCDC converters and multiple energy storage modules, and the first end of each DCDC converter is connected to a DC bus and the second end is connected to the energy storage module; the device is applied to the DCDC converter and includes: a communication module for obtaining an actual bus voltage value and an actual output power value of the DCDC converter, as well as an actual SOC value of the energy storage module corresponding to the DCDC converter; a processing module for updating a droop control curve based on the actual SOC value and a pre-stored balanced SOC value, the droop control curve being used to characterize the relationship between the output power and the bus voltage of the DCDC converter; the processing module is further used to determine a bus voltage set value of the DCDC converter based on the updated droop control curve and the actual output power value of the DCDC converter; the processing module is further used to adjust the duty cycle of each switch tube in the DCDC converter based on the bus voltage set value and the bus voltage actual value to balance the power of each energy storage module in the energy storage system.

[0019] In one possible implementation, the processing module is specifically configured to determine a control origin of the droop control curve based on an actual SOC value and a pre-stored balanced SOC value, where the control origin is a critical state point where the DCDC converter is in a charging state or a discharging state; and redetermine the droop control curve based on the control origin.

[0020] In a possible implementation, the processing module is specifically configured to determine the control origin of the droop control curve based on the following formula:

[0021]

[0022] Among them, V P is the control origin of the droop control curve. When the output power of the DCDC converter is zero, the bus voltage of the DCDC converter is V P , V base is the basic output voltage of the DCDC converter, SOC is the actual SOC value of the energy storage module corresponding to the DCDC converter, is the balanced SOC value of the energy storage module corresponding to the DCDC converter, V outmax is the maximum output voltage of the DCDC converter.

[0023] In a possible implementation, the processing module is specifically configured to determine a bus voltage set value of the DCDC converter based on the following formula:

[0024]

[0025] Among them, V out is the bus voltage given value of the DCDC converter, Vbase is the basic output voltage of the DCDC converter, V droop P is the droop voltage of the DCDC converter, which indicates the output voltage of the DCDC converter when it works at rated power. out is the actual output power value of the DCDC converter, P rate is the rated power of the DCDC converter, SOC is the actual SOC value of the energy storage module corresponding to the DCDC converter, is the balanced SOC value of the energy storage module corresponding to the DCDC converter, V outmax is the maximum output voltage of the DCDC converter.

[0026] In one possible implementation, the processing module is specifically used to calculate the deviation between the bus voltage set value and the bus voltage actual value; based on the deviation value, PI calculation is performed to obtain the current loop set value; based on the current loop set value, closed-loop control is performed to generate a duty cycle signal for each switching tube to adjust each switching tube.

[0027] In one possible implementation, the processing module is specifically configured to perform a PI calculation based on the deviation value to obtain a first control variable; compare the magnitude relationship between the first control variable and the second control variable, and determine the larger control variable as the current loop set value; and the second control variable is obtained by performing a PI calculation based on a deviation between a voltage set value and an actual voltage value of an energy storage device corresponding to the DCDC converter.

[0028] In one possible implementation, the processing module is specifically used to obtain the actual current value of the DCDC converter; calculate the current deviation between the current loop set value and the actual current value; perform PI calculation based on the current deviation to generate a duty cycle signal of each switch tube.

[0029] In one possible implementation, the processing module is specifically configured to perform PI calculation based on the current deviation to obtain a target control variable; modulate the target control variable to obtain a duty cycle signal for controlling a boost switch tube in a DCDC converter; and invert the target control variable and modulate the inverted target control variable to obtain a duty cycle signal for controlling a buck switch tube in the DCDC converter.

[0030] In a third aspect, an embodiment of the present invention provides an electronic device, characterized in that the electronic device includes a memory and a processor, the memory stores a computer program, and the processor is used to call and run the computer program stored in the memory to perform the steps of the method described in the first aspect and any possible implementation method of the first aspect.

[0031] In a fourth aspect, an embodiment of the present invention provides a computer-readable storage medium, which stores a computer program, and is characterized in that when the computer program is executed by a processor, it implements the steps of the method described in the first aspect and any possible implementation method of the first aspect.

[0032] The technical effects brought about by any implementation method of the above-mentioned second to fourth aspects can refer to the technical effects brought about by the corresponding implementation method of the first aspect, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0034] Figure 1 is a structural diagram of an energy storage system provided by an embodiment of the present invention;

[0035] Figure 2 is a structural diagram of another energy storage system provided by an embodiment of the present invention;

[0036] Figure 3 1 is a flow chart of a SOC balancing control method for an energy storage system provided by an embodiment of the present invention;

[0037] Figure 4 1 is a schematic diagram of a circuit structure of a DCDC converter provided by an embodiment of the present invention;

[0038] Figure 5 is a schematic diagram of a droop control curve provided by an embodiment of the present invention;

[0039] Figure 6 This is a SOC balancing control block diagram of an energy storage system provided by an embodiment of the present invention;

[0040] Figure 7 1 is a schematic structural diagram of an SOC balancing control device for an energy storage system provided by an embodiment of the present invention;

[0041] Figure 8 It is a structural diagram of an electronic device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0042] In the following description, specific details such as particular system structures and techniques are provided for purposes of illustration, not limitation, to facilitate a thorough understanding of the embodiments of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail.

[0043] In the description of the present invention, unless otherwise specified, “ / ” means “or”. For example, A / B can mean A or B. “And / or” in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, “at least one” and “a plurality of” refer to two or more. Words such as “first” and “second” do not limit the quantity and execution order, and words such as “first” and “second” do not necessarily limit them to be different.

[0044] In the embodiments of this application, words such as "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of this application should not be construed as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner to facilitate understanding.

[0045] Furthermore, the terms "including," "having," and any variations thereof, as used in the description of this application are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or modules is not limited to the listed steps or modules, but may optionally include other steps or modules not listed, or may optionally include other steps or modules inherent to the process, method, product, or apparatus.

[0046] In order to make the purpose, technical solutions and advantages of the present invention more clear, the following will be described through specific embodiments in conjunction with the accompanying drawings of the present invention.

[0047] An embodiment of the present invention provides an energy storage system, which includes multiple DC-DC converters and multiple energy storage modules, wherein a first end of each DCDC converter is connected to a DC bus, and a second end is connected to an energy storage module.

[0048] As a possible implementation, Figure 1 FIG1 shows a schematic diagram of the structure of an energy storage system, in which multiple energy storage modules are connected to the grid in parallel using busbars. Figure 1As shown, the energy storage system includes a DC / AC energy storage converter, multiple DC-DC converters, and multiple energy storage modules (BAT). The first end of each DC-DC converter is connected to a DC bus (DC_BUS). The second end of each DC-DC converter is connected to its corresponding energy storage module (BAT). The DC bus (DC_BUS) is connected to the grid (GRID) through the DC / AC energy storage converter.

[0049] As another possible implementation, Figure 2 FIG1 shows a schematic diagram of the structure of another energy storage system, in which multiple energy storage modules are connected to the grid in parallel at both ends. Figure 2 As shown, the energy storage system includes a DC / AC energy storage converter, multiple DC-DC converters, and multiple energy storage modules (BAT). The first end of each DC-DC converter is connected to a DC bus (DC_BUS). The second end of each DCDC converter is connected in parallel to all the energy storage modules (BAT). The DC bus (DC_BUS) is connected to the grid (GRID) through the DC / AC energy storage converter.

[0050] The SOC balancing control method of an energy storage system provided by the embodiment of the present invention can be applied to Figure 1 or Figure 2 In any DCDC converter of any energy storage system shown. Figure 3 The flow chart of a method for SOC balancing control of an energy storage system provided by an embodiment of the present invention is shown. The execution subject is an SOC balancing control device of the energy storage system. The method includes steps S101-S104.

[0051] S101 : Acquire an actual bus voltage value and an actual output power value of a DCDC converter, as well as an actual SOC value of an energy storage module corresponding to the DCDC converter.

[0052] As a possible implementation, the balancing control device can periodically detect the operating parameters of the DCDC converter to obtain the actual bus voltage and output power values ​​of the DCDC converter, as well as the actual SOC value of the energy storage module corresponding to the DCDC converter. The detection period can be 1 second or 0.5 seconds, which is not limited in this application.

[0053] Exemplarily, the balancing control device may detect an actual value of the output voltage and an actual value of the output current of the DCDC converter, and then calculate an actual value of the output power of the DCDC converter based on the actual value of the output voltage and the actual value of the output current of the DCDC converter.

[0054] It should be noted that the actual SOC value of the energy storage module corresponding to the DCDC converter changes continuously as the DCDC converter operates. For example, when the DCDC converter is in the charging state, the actual SOC value gradually increases; when the DCDC converter is in the discharging state, the actual SOC value gradually decreases. As the energy storage system operates, the energy storage modules corresponding to different DCDC converters have different actual SOC values, resulting in an imbalance in the energy storage modules corresponding to each DCDC converter, which in serious cases affects the service life of the energy storage modules. Therefore, it is necessary to detect the actual SOC value of the energy storage module corresponding to the DCDC converter and balance the energy of the energy storage modules corresponding to the DCDC converter.

[0055] like Figure 4 As shown in FIG, an embodiment of the present invention provides a circuit structure diagram of a DCDC converter. Figure 4 The right side of the circuit is the first end of the DCDC converter. Figure 4 The left side of the circuit is the second end of the DCDC converter. The balancing control device can be based on Figure 4 The circuit shown in the figure obtains the actual value of the bus voltage V of the DCDC converter. bus_fdb And the actual SOC value of the energy storage module corresponding to the DCDC converter.

[0056] S102 : Update the droop control curve based on the actual SOC value and the pre-stored equilibrium SOC value.

[0057] In the embodiment of the present application, the droop control curve is used to characterize the linear relationship between the output power of the DCDC converter and the bus voltage.

[0058] like Figure 5 As shown in FIG, an embodiment of the present invention provides a schematic diagram of a droop control curve. Curve a1 is the droop control curve before updating. Curve a2 is the droop control curve after updating.

[0059] As a possible implementation manner, the balancing control device may determine a control origin of the droop control curve based on the actual SOC value and a pre-stored balanced SOC value, and redetermine the droop control curve based on the control origin.

[0060] The control origin is the critical state point of the DCDC converter in the charging state or the discharging state. Figure 5 The intersection of the droop control curve and the voltage V-axis.

[0061] Exemplarily, the balancing control device may determine the control origin of the droop control curve based on the following formula:

[0062]

[0063] Among them, V P is the control origin of the droop control curve. When the output power of the DCDC converter is zero, the bus voltage of the DCDC converter is V P , V base is the basic output voltage of the DCDC converter, SOC is the actual SOC value of the energy storage module corresponding to the DCDC converter, is the balanced SOC value of the energy storage module corresponding to the DCDC converter, V outmax is the maximum output voltage of the DCDC converter.

[0064] Exemplarily, the balancing control device may determine the updated droop control curve based on the following formula:

[0065]

[0066] Among them, V out is the bus voltage of the DCDC converter, V base is the basic output voltage of the DCDC converter, V droop P is the droop voltage of the DCDC converter, which indicates the output voltage of the DCDC converter when it works at rated power. out is the output power of the DCDC converter, P rate is the rated power of the DCDC converter, SOC is the actual SOC value of the energy storage module corresponding to the DCDC converter, is the balanced SOC value of the energy storage module corresponding to the DCDC converter, V outmax is the maximum output voltage of the DCDC converter.

[0067] It should be noted that the basic output voltage V base , the droop voltage of the DCDC converter V droop , the rated power P of the DCDC converter rate and the maximum output voltage of the DCDC converter V outmax The balancing control device may be determined based on the device parameters of the DCDC converter. The balancing control device may also directly receive a setting value input by a user.

[0068] It should be noted that the DCDC converter corresponds to the balanced SOC value of the energy storage module Indicates the target value of the energy storage module. Each DCDC converter in the energy storage system stores the same balanced SOC value. In this way, each DCDC converter is based on the same balanced SOC value Perform power balancing to achieve power balance among the energy storage modules in the energy storage system and improve the stability of the energy storage system.

[0069] For example, It can be 50%, or 40%, which is not limited in this application.

[0070] S103 : Determine a bus voltage set value of the DCDC converter based on the updated droop control curve and the actual output power value of the DCDC converter.

[0071] As a possible implementation manner, the balancing control device may determine the bus voltage set value of the DCDC converter based on the following formula.

[0072]

[0073] Among them, V out is the bus voltage given value of the DCDC converter, V base is the base output voltage of the DCDC converter, V droop is the droop voltage of the DCDC converter, indicating the output voltage of the DCDC converter when it operates at rated power, P out is the actual output power value of the DCDC converter, P rate is the rated power of the DCDC converter, SOC is the actual SOC value of the energy storage module corresponding to the DCDC converter, is the balanced SOC value of the energy storage module corresponding to the DCDC converter, V outmax is the maximum output voltage of the DCDC converter.

[0074] S104 : Based on the bus voltage set value and the bus voltage actual value, adjust the duty cycle of each switch tube in the DCDC converter to balance the power of each energy storage module in the energy storage system.

[0075] As a possible implementation manner, the balancing control device may generate a duty cycle signal of each switch tube through steps S1041 - S1043 to adjust each switch tube.

[0076] S1041. Calculate the deviation between the bus voltage set value and the bus voltage actual value.

[0077] For example, Figure 6 As shown in FIG. 1 , an embodiment of the present invention provides a SOC balancing control block diagram of an energy storage system. The balancing control device can be based on a bus voltage given value V bus_ref And the actual value of bus voltage V bus_fdb , calculate the deviation value.

[0078] S1042. Perform PI calculation based on the deviation value to obtain a current loop set value.

[0079] Exemplarily, the balancing control device may perform PI calculation based on the deviation value to obtain a first control variable; and directly determine the first control variable as a current loop given value.

[0080] In another exemplary embodiment, the balancing control device may perform PI calculation based on the deviation value to obtain a first control variable; compare the magnitude relationship between the first control variable and the second control variable, and determine the larger control variable as the current loop set value.

[0081] The second control variable is obtained by performing PI calculation based on a deviation between a voltage set value and an actual voltage value of the energy storage device corresponding to the DCDC converter.

[0082] For example, Figure 6 As shown, the balancing control device can obtain the voltage setting value V of the energy storage device bat_ref And the actual value of voltage V bat_fdb , calculate the voltage set value V of the energy storage device bat_ref And the actual value of voltage V bat_fdb The deviation between them is calculated based on the PI to obtain the second control amount.

[0083] It should be noted that the voltage set value of the energy storage device can be the equalization charging voltage. During the charging process, by comparing the first control quantity and the second control quantity, the larger value of the two is selected as the final current loop set value, thereby avoiding the overcharging problem caused by the current loop set value being too small and the duty cycle of the step-down switch being too large, thereby achieving the battery voltage stabilization effect during the charging process.

[0084] S1043. Perform closed-loop control based on the current loop given value to generate a duty cycle signal for each switch tube to adjust each switch tube.

[0085] As a possible implementation method, the balancing control device can obtain the actual current value of the DCDC converter; calculate the current deviation between the current loop set value and the actual current value; perform PI calculation based on the current deviation to generate a duty cycle signal for each switch tube.

[0086] Exemplarily, the balancing control device may perform PI calculation based on the current deviation to obtain a target control variable; and modulate the target control variable to obtain a duty cycle signal for controlling a boost switch tube in the DCDC converter.

[0087] For example, Figure 4 and Figure 6 As shown, the balancing control device can modulate the target control amount to obtain a duty cycle signal for controlling the boost switching tubes Q1 and Q2 in the DCDC converter.

[0088] In another exemplary embodiment, PI calculation is performed based on the current deviation to obtain a target control amount; the target control amount is inverted, and the inverted target control amount is modulated to obtain a duty cycle signal for controlling a buck switch in a DCDC converter.

[0089] For example, Figure 4 and Figure 6 As shown, the balancing control device can modulate the target control amount to obtain a duty cycle signal for controlling the boost switch tubes Q3 and Q4 in the DCDC converter.

[0090] like Figure 6 As shown, the embodiment of the present invention can also perform a limiting process on the current loop given value; and generate a duty cycle signal of each switch tube based on the limited current loop given value.

[0091] The present invention provides a SOC balancing control method for an energy storage system. On the one hand, the present invention can update a droop control curve in real time based on the actual SOC value of the energy storage module corresponding to the DCDC converter, determine a bus voltage setpoint based on the updated droop control curve, and adjust the duty cycle of each switch in the DCDC converter to achieve balanced charge in each energy storage module in the energy storage system. On the other hand, the present invention updates the droop control curve based on the actual SOC value of the energy storage module corresponding to the DCDC converter and a pre-stored balanced SOC value. This method achieves charge balancing in each energy storage module in the energy storage system without the need for communication with other DCDC converters, thus avoiding the data transmission process, simplifying the control logic for charge balancing in each energy storage module in the energy storage system, reducing the probability of errors in the charge balancing process, and improving the safety and reliability of the energy storage system.

[0092] It should be understood that the size of the serial numbers of the steps in the above embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0093] The following are device embodiments of the present invention. For details not fully described therein, reference may be made to the corresponding method embodiments described above.

[0094] Figure 7 A structural schematic diagram of an SOC balancing control device for an energy storage system provided by an embodiment of the present invention is shown. The energy storage system includes multiple DCDC converters and multiple energy storage modules, and the first end of each DCDC converter is connected to the DC bus and the second end is connected to the energy storage module.

[0095] The balancing control device 200 is applied to a DC-DC converter, and includes:

[0096] The communication module 201 is used to obtain the actual value of the bus voltage and the actual value of the output power of the DCDC converter, as well as the actual SOC value of the energy storage module corresponding to the DCDC converter.

[0097] Processing module 202 is used to update the droop control curve based on the actual SOC value and the pre-stored balanced SOC value. The droop control curve is used to characterize the linear relationship between the output power of the DCDC converter and the bus voltage.

[0098] The processing module 202 is also used to determine the bus voltage set value of the DCDC converter based on the updated droop control curve and the actual value of the output power of the DCDC converter.

[0099] The processing module 202 is further configured to adjust the duty cycle of each switch in the DCDC converter based on the bus voltage set value and the bus voltage actual value, so as to balance the power of each energy storage module in the energy storage system.

[0100] In one possible implementation, the processing module 202 is specifically configured to determine a control origin of the droop control curve based on the actual SOC value and a pre-stored balanced SOC value, where the control origin is a critical state point where the DCDC converter is in a charging state or a discharging state; and redetermine the droop control curve based on the control origin.

[0101] In a possible implementation, the processing module 202 is specifically configured to determine the control origin of the droop control curve based on the following formula.

[0102]

[0103] Among them, V P is the control origin of the droop control curve. When the output power of the DCDC converter is zero, the bus voltage of the DCDC converter is V P , V base is the basic output voltage of the DCDC converter, SOC is the actual SOC value of the energy storage module corresponding to the DCDC converter, is the balanced SOC value of the energy storage module corresponding to the DCDC converter, V outmax is the maximum output voltage of the DCDC converter.

[0104] In a possible implementation, the processing module 202 is specifically configured to determine a bus voltage set value of the DCDC converter based on the following formula:

[0105]

[0106] Among them, V out is the bus voltage given value of the DCDC converter, Vbase is the basic output voltage of the DCDC converter, V droop P is the droop voltage of the DCDC converter, which indicates the output voltage of the DCDC converter when it works at rated power. out is the actual output power value of the DCDC converter, P rate is the rated power of the DCDC converter, SOC is the actual SOC value of the energy storage module corresponding to the DCDC converter, is the balanced SOC value of the energy storage module corresponding to the DCDC converter, V outmax is the maximum output voltage of the DCDC converter.

[0107] In one possible implementation, the processing module 202 is specifically used to calculate the deviation value between the bus voltage set value and the bus voltage actual value; based on the deviation value, perform PI calculation to obtain the current loop set value; perform closed-loop control based on the current loop set value to generate a duty cycle signal for each switch tube to adjust each switch tube.

[0108] In one possible implementation, the processing module 202 is specifically configured to perform a PI calculation based on the deviation value to obtain a first control variable; compare the magnitude relationship between the first control variable and the second control variable, and determine the larger control variable as the current loop set value; and obtain the second control variable by performing a PI calculation based on a deviation between a voltage set value and an actual voltage value of an energy storage device corresponding to the DCDC converter.

[0109] In one possible implementation, the processing module 202 is specifically configured to obtain an actual current value of the DCDC converter; calculate a current deviation between a current loop set value and the actual current value; and perform PI calculation based on the current deviation to generate a duty cycle signal for each switch tube.

[0110] In one possible implementation, the processing module 202 is specifically configured to perform PI calculation based on the current deviation to obtain a target control variable; modulate the target control variable to obtain a duty cycle signal for controlling a boost switch tube in a DCDC converter; and invert the target control variable and modulate the inverted target control variable to obtain a duty cycle signal for controlling a buck switch tube in the DCDC converter.

[0111] Figure 8 Schematic diagram of the structure of an electronic device provided by an embodiment of the present invention. Figure 8 As shown, the electronic device 300 of this embodiment includes: a processor 301, a memory 302, and a computer program 303 stored in the memory 302 and executable on the processor 301. When the processor 301 executes the computer program 303, the steps in the above-mentioned method embodiments are implemented, for example Figure 3Alternatively, when the processor 301 executes the computer program 303, the functions of the modules / units in the above-mentioned device embodiments are realized, for example, Figure 7 The communication module 201 and the processing module 202 are shown.

[0112] Exemplarily, the computer program 303 may be divided into one or more modules / units, which are stored in the memory 302 and executed by the processor 301 to implement the present invention. The one or more modules / units may be a series of computer program instruction segments that can implement specific functions, and the instruction segments are used to describe the execution process of the computer program 303 in the electronic device 300. For example, the computer program 303 may be divided into Figure 7 The communication module 201 and the processing module 202 are shown.

[0113] The processor 301 may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor.

[0114] The memory 302 may be an internal storage unit of the electronic device 300, such as a hard disk or memory of the electronic device 300. The memory 302 may also be an external storage device of the electronic device 300, such as a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, etc. equipped on the electronic device 300. Furthermore, the memory 302 may include both an internal storage unit of the electronic device 300 and an external storage device. The memory 302 is used to store the computer program and other programs and data required by the terminal. The memory 302 may also be used to temporarily store data that has been output or is about to be output.

[0115] Those skilled in the art can clearly understand that, for the convenience and brevity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In actual applications, the above-mentioned functions can be distributed and completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiment 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. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of this application. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here.

[0116] In the above embodiments, the description of each embodiment has its own focus. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant description of other embodiments.

[0117] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present invention.

[0118] In the embodiments provided by the present invention, it should be understood that the disclosed devices / terminals and methods can be implemented in other ways. For example, the device / terminal embodiments described above are merely illustrative. For example, the division of the modules or units is merely a logical functional division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed can be through some interface, indirect coupling or communication connection of devices or units, and can be electrical, mechanical, or other forms.

[0119] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0120] In addition, the functional units in the various embodiments of the present invention may be integrated into a single processing unit, each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units.

[0121] If the integrated module / unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the present invention implements all or part of the process in the above-mentioned embodiment method, and can also be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium, and the computer program can implement the steps of the above-mentioned various method embodiments when executed by the processor. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable medium may include: any entity or device that can carry the computer program code, recording medium, U disk, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electric carrier signal, telecommunication signal and software distribution medium, etc.

[0122] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention, and should all be included in the scope of protection of the present invention.

Claims

1. A SOC balancing control method for an energy storage system, characterized in that: The energy storage system includes multiple DCDC converters and multiple energy storage modules, and the first end of each DCDC converter is connected to the DC bus, and the second end is connected to the energy storage module; The method is applied to the DCDC converter, comprising: Obtaining an actual bus voltage value and an actual output power value of the DCDC converter, as well as an actual SOC value of an energy storage module corresponding to the DCDC converter; Updating a droop control curve based on the actual SOC value and a pre-stored balanced SOC value, including: determining a control origin of the droop control curve based on the actual SOC value and the pre-stored balanced SOC value, the control origin being a critical state point at which the DCDC converter is in a charging state or a discharging state; and re-determining the droop control curve based on the control origin; the droop control curve being used to represent a relationship between the output power of the DCDC converter and the bus voltage; Determining a bus voltage set value of the DCDC converter based on the updated droop control curve and the actual output power value of the DCDC converter; Based on the bus voltage set value and the bus voltage actual value, the duty cycle of each switch tube in the DCDC converter is adjusted to balance the power of each energy storage module in the energy storage system.

2. The SOC balancing control method of the energy storage system according to claim 1, characterized in that: The determining the control origin of the droop control curve based on the actual SOC value and the pre-stored balanced SOC value includes: Based on the following formula, the control origin of the droop control curve is determined; Among them, V P is the control origin of the droop control curve. When the output power of the DCDC converter is zero, the bus voltage of the DCDC converter is V P , V base is the basic output voltage of the DCDC converter, SOC is the actual SOC value of the energy storage module corresponding to the DCDC converter, is the balanced SOC value of the energy storage module corresponding to the DCDC converter, V outmax is the maximum output voltage of the DCDC converter.

3. The SOC balancing control method of the energy storage system according to claim 1, characterized in that: The determining of a bus voltage set value of the DCDC converter based on the updated droop control curve and the actual output power value of the DCDC converter includes: Based on the following formula, the bus voltage set value of the DCDC converter is determined; Among them, V out is the bus voltage given value of the DCDC converter, V base is the base output voltage of the DCDC converter, V droop is the droop voltage of the DCDC converter, indicating the output voltage of the DCDC converter when it operates at rated power, P out is the actual output power value of the DCDC converter, P rate is the rated power of the DCDC converter, SOC is the actual SOC value of the energy storage module corresponding to the DCDC converter, is the balanced SOC value of the energy storage module corresponding to the DCDC converter, V outmax is the maximum output voltage of the DCDC converter.

4. The SOC balancing control method of the energy storage system according to claim 1, characterized in that: The step of adjusting the duty cycle of each switch in the DCDC converter based on the bus voltage set value and the bus voltage actual value includes: Calculating a deviation between the bus voltage set value and the bus voltage actual value; Based on the deviation value, PI calculation is performed to obtain a current loop set value; Closed-loop control is performed based on the current loop set value to generate duty cycle signals of the respective switching tubes to adjust the respective switching tubes.

5. The SOC balancing control method of the energy storage system according to claim 4, characterized in that: The step of performing PI calculation based on the deviation value to obtain a current loop given value includes: Performing PI calculation based on the deviation value to obtain a first control variable; The first control variable and the second control variable are compared in magnitude, and the larger control variable is determined as the current loop set value; the second control variable is obtained by PI calculation based on the deviation between the voltage set value and the actual voltage value of the energy storage device corresponding to the DCDC converter.

6. The SOC balancing control method of the energy storage system according to claim 4, characterized in that: The closed-loop control is performed based on the current loop given value to generate a duty cycle signal of each switch tube to adjust each switch tube, including: Obtaining an actual current value of the DCDC converter; Calculating a current deviation between the current loop set value and the current actual value; PI calculation is performed based on the current deviation to generate duty cycle signals of the switching tubes.

7. A SOC balancing control device for an energy storage system, characterized in that: The energy storage system includes multiple DCDC converters and multiple energy storage modules, and the first end of each DCDC converter is connected to the DC bus, and the second end is connected to the energy storage module; The device is applied to the DCDC converter, including: A communication module is used to obtain the actual value of the bus voltage and the actual value of the output power of the DCDC converter, as well as the actual SOC value of the energy storage module corresponding to the DCDC converter; a processing module, configured to update a droop control curve based on the actual SOC value and a pre-stored equilibrium SOC value, wherein the droop control curve is configured to represent a relationship between an output power of the DCDC converter and a bus voltage; The processing module is further configured to determine a bus voltage set value of the DCDC converter based on the updated droop control curve and the actual output power value of the DCDC converter; The processing module is further configured to adjust the duty cycle of each switch in the DCDC converter based on the bus voltage set value and the bus voltage actual value to balance the power of each energy storage module in the energy storage system; The processing module is specifically configured to determine a control origin of the droop control curve based on the actual SOC value and a pre-stored balanced SOC value, wherein the control origin is a critical state point at which the DCDC converter is in a charging state or a discharging state; and redetermine the droop control curve based on the control origin.

8. An electronic device, characterized in that: The electronic device includes a memory and a processor, wherein the memory stores a computer program, and the processor is configured to call and run the computer program stored in the memory to execute the method according to any one of claims 1 to 6.

9. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the method according to any one of claims 1 to 6 is implemented.

Images