Charge state balance control method and device and medium

Abstract

The invention discloses a state-of-charge balance control method and device and a medium, and the method comprises the steps: carrying out the calculation of the target three-phase adjustment power through the working voltage and working current of each phase in a direct-hanging type energy storage system, and the current charging and discharging power, carrying out the fundamental wave zero-sequence voltage conversion based on the target three-phase adjustment power, and carrying out the balance control of the state-of-charge. And the target zero-sequence voltage is injected into the three-phase modulation voltage after space vector modulation, so that real-time balance control over the three-phase charge state under the unbalanced working condition of the power grid is achieved, the control effect is improved, the zero-sequence voltage injection range is increased, and the control precision is improved. And the control speed for realizing the equilibrium state is improved.

Description

Technical Field

[0001] This invention relates to the field of power electronics technology, specifically to a method, device, and medium for state-of-charge equalization control. Background Technology

[0002] Direct-connected energy storage systems are an important component of the power grid. With the large-scale integration of renewable energy generation into the grid and the application of a high proportion of power electronic devices, the grid voltage may experience three-phase imbalance, which can lead to differences in the state of charge (SOC) of each energy storage unit in the energy storage system.

[0003] For the current state of charge (SOC) balancing control scheme under grid imbalance conditions, the existing scheme usually adopts the zero-sequence voltage injection method. The zero-sequence voltage injection method achieves three-phase SOC balancing by changing the three-phase charging and discharging power values. However, the existing scheme has unsatisfactory control effect and limited zero-sequence voltage injection, resulting in low speed of achieving SOC balancing.

[0004] Therefore, the existing scheme has the drawbacks of poor state-of-charge control and low speed in achieving state-of-charge balance. Summary of the Invention

[0005] The technical problem to be solved by the present invention is that the existing solutions have poor state-of-charge (SOC) control effect and low speed of achieving SOC. The purpose is to provide a SOC control method that solves the problems of poor SOC control effect and low speed of achieving SOC in the existing solutions.

[0006] This invention is achieved through the following technical solution:

[0007] In a first aspect, this application provides a state-of-charge (SOC) equalization control method, comprising:

[0008] The operating voltage and operating current of each phase in the direct-connected energy storage system are obtained, and the current charging and discharging power of the direct-connected energy storage system is calculated based on the operating voltage and operating current of each phase.

[0009] The target three-phase regulation power is calculated based on the operating voltage, operating current and current charging / discharging power of each phase, wherein the target three-phase regulation power includes the regulation power of each phase;

[0010] Based on the target three-phase regulated power, fundamental zero-sequence voltage conversion is performed to obtain the target zero-sequence voltage;

[0011] The target zero-sequence voltage is injected into the three-phase modulation voltage to achieve charge balance in the direct-connected energy storage system.

[0012] In one possible implementation, obtaining the operating voltage and operating current of each phase in the direct-connected energy storage system includes:

[0013] The output voltage of multiple power units in each phase is obtained, and the sum of the output voltages of each power unit is taken as the operating voltage of each phase;

[0014] Based on the operating voltage of each phase, the current of each power unit in each phase is calculated using Kirchhoff's laws and used as the operating current of each phase.

[0015] In one possible implementation, the calculation to obtain the target three-phase regulated power includes:

[0016] Obtain the average value of the current charging and discharging power as the target equalization value;

[0017] Perform Fourier transform on the operating voltage and operating current of each phase to obtain the corresponding voltage phase value and current phase value;

[0018] Based on the target equilibrium value, and the voltage phase value and current phase value of each phase, the initial three-phase regulation power is calculated using the three-phase regulation power formula.

[0019] The product of the initial three-phase regulating power and the preset proportional parameter is taken as the target three-phase regulating power.

[0020] In one possible implementation, the three-phase power regulation formula is:

[0021]

[0022] Wherein, ΔP A The regulating power of phase A, ΔP B The regulating power of phase B, ΔP C The power of phase C is the regulating power, P is the current charging / discharging power, and U is the current charging / discharging power. essA U is the operating voltage of phase A. essB U is the operating voltage of phase B. essC The operating voltage of phase C, I A The operating current of phase A is [current name]. The voltage phase value of phase A. The voltage phase value of phase B. The voltage phase value of phase C. The current phase value of phase A.

[0023] In one possible implementation, the fundamental zero-sequence voltage conversion based on the target three-phase regulated power to obtain the target zero-sequence voltage includes:

[0024] Based on the target three-phase regulating power, a target relationship is established regarding the fundamental zero-sequence voltage, wherein the target relationship is used to indicate that the regulating power of each phase in the target three-phase regulating power is equal to the power value of the fundamental zero-sequence voltage;

[0025] The target relation is rearranged and transformed to obtain the zero-sequence voltage amplitude and phase formula. The zero-sequence voltage amplitude and phase are calculated using the zero-sequence voltage amplitude and phase formula. The corresponding target zero-sequence voltage is then calculated based on the zero-sequence voltage amplitude and phase.

[0026] In one possible implementation, the zero-sequence voltage amplitude-phase formula is:

[0027]

[0028] Where U0 is the zero-sequence voltage amplitude, θ0 is the zero-sequence voltage phase, and I A The operating current of phase A is ΔP. A The regulating power of phase A, ΔP B The regulating power of phase B, ΔP C For the regulating power of phase C, This represents the current phase value of phase A.

[0029] In one possible implementation, injecting the target zero-sequence voltage into the three-phase modulation voltage to achieve charge balance in the direct-connected energy storage system includes:

[0030] The three-phase modulation voltage is obtained by space vector modulation.

[0031] The target zero-sequence voltage is superimposed on the three-phase modulation voltage to obtain a superimposed control voltage. A corresponding switching signal is generated based on the superimposed control voltage, wherein the switching signal is used to indicate the switching state of each power unit in the direct-connected energy storage system.

[0032] Secondly, this application provides a state-of-charge equalization control device, comprising:

[0033] The acquisition module is used to acquire the operating voltage and operating current of each phase in the direct-connected energy storage system, and to calculate and acquire the current charging and discharging power of the direct-connected energy storage system based on the operating voltage and operating current of each phase.

[0034] The processing module is used to calculate and obtain the target three-phase regulation power based on the operating voltage, the operating current and the current charging and discharging power of each phase, wherein the target three-phase regulation power includes the regulation power of each phase;

[0035] The control module is used to perform fundamental zero-sequence voltage conversion based on the target three-phase regulating power to obtain the target zero-sequence voltage, and inject the target zero-sequence voltage into the three-phase modulation voltage to make the charge balance of the direct-connected energy storage system.

[0036] Thirdly, this application provides an electronic device, including: a processor, and a memory communicatively connected to the processor;

[0037] The memory stores computer-executed instructions;

[0038] The processor executes computer execution instructions stored in the memory to implement the state-of-charge control method.

[0039] Fourthly, this application provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, are used to implement the state-of-charge equalization control method.

[0040] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0041] This application provides a state-of-charge (SOC) balancing control method, device, and medium. By calculating the target three-phase regulation power based on the operating voltage, operating current, and current charging / discharging power of each phase in a direct-connected energy storage system, and performing fundamental zero-sequence voltage conversion based on the target three-phase regulation power, a target zero-sequence voltage with proportional gain is obtained. This target zero-sequence voltage is then injected into the three-phase modulation voltage after space vector modulation, thereby achieving real-time SOC balancing control of the three phases under grid imbalance conditions. This improves the control effect, increases the zero-sequence voltage injection range, and increases the control speed for achieving SOC balancing. Attached Figure Description

[0042] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings:

[0043] Figure 1 A flowchart illustrating the state-of-charge (SOC) equalization control method provided in this application embodiment. Figure 1 ;

[0044] Figure 2 This is a schematic diagram of the topology of a direct-mounted energy storage system provided in an embodiment of this application;

[0045] Figure 3A flowchart illustrating the state-of-charge (SOC) equalization control method provided in this application embodiment. Figure 2 ;

[0046] Figure 4 This is a schematic diagram of the steady-state operation waveform of a direct-connected energy storage system.

[0047] Figure 5 This is a schematic diagram illustrating the SOC balancing effect of a direct-connected energy storage system under grid imbalance conditions.

[0048] Figure 6 A schematic diagram comparing the three-phase space vector modulation waveforms before and after zero-sequence voltage injection;

[0049] Figure 7 This is a schematic diagram of the structure of the state-of-charge equalization control device provided in the embodiments of this application;

[0050] Figure 8 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. Detailed Implementation

[0051] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application.

[0052] Energy storage technology can charge and discharge quickly and at high power, and has been a major focus of power system research since its inception. In recent years, direct-connected energy storage systems have gradually become a highly promising solution in the field of energy storage systems due to their high efficiency, transformer-free operation, and suitability for large-capacity energy storage systems.

[0053] With the integration of large-scale renewable energy generation into the grid and the application of a high proportion of power electronic devices, the grid voltage may experience three-phase imbalance. In this case, the three-phase charging and discharging power of the direct-connected energy storage system will have certain differences, which will lead to differences in the state of charge (SOC) values ​​of the three-phase sub-modules, affecting the operating efficiency of the energy storage system and even endangering its operational safety.

[0054] Therefore, it is particularly important to achieve real-time SOC balancing control of direct-connected energy storage systems under grid imbalance conditions. Traditional methods usually adopt zero-sequence voltage injection to change the three-phase charging and discharging power values ​​to achieve three-phase SOC balancing without changing the symmetrical relationship of the three-phase line voltages. However, its control structure principle is not perfect, the control effect is not ideal, and the zero-sequence voltage injection is limited, which further restricts the speed of SOC balancing.

[0055] During the charging and discharging process of an energy storage system, the power control strategy can ensure that the charging and discharging power of the energy storage system is constant and the three-phase power is evenly distributed. However, the grid voltage may become unbalanced when renewable energy is connected to the grid through power electronic devices. At this time, the three-phase charging and discharging power values ​​of the direct-connected energy storage system will be affected by the grid voltage, which will lead to differences in the three-phase SOC values. These differences will gradually increase and may even lead to overcharging or over-discharging over time, affecting the lifespan and overall stable operation of the energy storage system.

[0056] Therefore, this application provides a state-of-charge (SOC) equalization control method, device, and medium. By calculating the target three-phase regulation power based on the operating voltage, operating current, and current charging / discharging power of each phase in a direct-connected energy storage system, and performing fundamental zero-sequence voltage conversion based on the target three-phase regulation power, a target zero-sequence voltage with proportional gain is obtained. This target zero-sequence voltage is injected into the three-phase modulation voltage after space vector modulation, thereby achieving real-time equalization control of the three-phase SOC under grid imbalance conditions. This improves the control effect, increases the zero-sequence voltage injection range, and increases the control speed for achieving equalization. Consequently, under grid imbalance conditions, the charging / discharging power values ​​of the three phases are maintained at the same level through the SOC equalization control method provided in this application, and the three-phase SOC values ​​exhibit the same trend, thereby improving the overall lifespan and economic benefits of the energy storage system.

[0057] For a three-phase direct-connected energy storage system, its average SOC can be calculated using equation (1):

[0058]

[0059] Among them, SOC ki Let be the current SOC value of the i-th power unit in phase k. The average SOC value of phase k is the target of the equalization control. The three-phase average SOC value represents the equilibrium control objective to be achieved by the state-of-charge equilibrium control method provided in this application.

[0060] The technical solutions of this application and how they solve the aforementioned technical problems are described in detail below using specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.

[0061] Example 1

[0062] Figure 1 A flowchart illustrating the state-of-charge (SOC) equalization control method provided in this application embodiment. Figure 1 , Figure 2This is a schematic diagram of the topology of a direct-mounted energy storage system provided in the embodiments of this application, combined with... Figure 1 and Figure 2 As shown, the method includes:

[0063] S101. Obtain the operating voltage and operating current of each phase in the direct-connected energy storage system, and calculate the current charging and discharging power of the direct-connected energy storage system based on the operating voltage and operating current of each phase.

[0064] Specifically, such as Figure 2 As shown, the direct-connected energy storage system is a three-phase star connection, with each phase consisting of multiple power units connected in series. It is connected to the medium- and high-voltage power grid through a filter inductor, an AC fuse, and a pre-charging device. Each power unit consists of a low-voltage battery module, a switch module, a bidirectional DC / DC converter, a bus capacitor, a DC fuse, and a battery-side pre-charging device. Each switch module contains a bidirectional switch, which is used to mechanically bypass and disconnect the corresponding module in case of failure.

[0065] Furthermore, based on the voltages of multiple power units in each phase and the corresponding currents, the operating voltage and operating current of each phase are calculated and obtained.

[0066] S102. Calculate and obtain the target three-phase regulation power based on the operating voltage, operating current and current charging / discharging power of each phase, wherein the target three-phase regulation power includes the regulation power of each phase.

[0067] Specifically, after obtaining the operating voltage, operating current of each phase and the current charging and discharging power of the direct-connected energy storage system, the power value of each phase is calculated, and the three-phase regulation power is calculated based on the current power value of each phase and the average value of the current charging and discharging power.

[0068] Furthermore, after obtaining the three-phase regulating power, if it is directly substituted into the formula for calculating the zero-sequence voltage injection, the power difference at the moment of injection becomes zero, resulting in the calculated zero-sequence voltage injection value becoming zero. This repeatedly leads to a dead loop, making continuous control impossible and rendering the control ineffective. Therefore, by applying a proportional gain to the three-phase regulating power to obtain the target three-phase regulating power, that is, by adding a proportional element, a regulating process is provided for control, thereby achieving a reliable balanced control effect.

[0069] S103. Based on the target three-phase regulating power, perform fundamental zero-sequence voltage conversion to obtain the target zero-sequence voltage.

[0070] Specifically, after obtaining the target three-phase regulating power, a target relationship for the fundamental zero-sequence voltage is established based on the target three-phase regulating power. The target relationship indicates that the regulating power of each phase in the target three-phase regulating power is equal to the power value of the fundamental zero-sequence voltage. Through the established target relationship, the fundamental zero-sequence voltage conversion is realized, so as to calculate and obtain the corresponding target zero-sequence voltage.

[0071] S104. Inject the target zero-sequence voltage into the three-phase modulation voltage to achieve charge balance in the direct-connected energy storage system.

[0072] Specifically, the modulation method used in existing direct-connected energy storage systems is usually carrier phase-shift modulation. However, in order to ensure the normal operation of the direct-connected energy storage system, the zero-sequence voltage that can be injected is limited. When the grid voltage asymmetry is high, it may not be possible to inject an accurate zero-sequence voltage. Therefore, this application adopts a space vector modulation method to obtain a three-phase modulation voltage and superimposes the target zero-sequence voltage on the three-phase modulation voltage.

[0073] Space vector modulation (SVM) can reduce modulation intensity, avoid overmodulation, and has a larger injection range for zero-sequence voltage injection, thus achieving better SOC equalization.

[0074] This application provides a state-of-charge (SOC) balancing control method. By calculating the target three-phase regulation power based on the operating voltage, operating current, and current charging / discharging power of each phase in a direct-connected energy storage system, and by performing fundamental zero-sequence voltage conversion based on the target three-phase regulation power to obtain the target zero-sequence voltage after achieving proportional gain, the target zero-sequence voltage is injected into the three-phase modulation voltage after space vector modulation. This achieves real-time SOC balancing control under grid imbalance conditions, improves control effectiveness, increases the zero-sequence voltage injection range, and accelerates the control speed for achieving SOC balancing.

[0075] Example 2

[0076] Figure 3 A flowchart illustrating the state-of-charge (SOC) equalization control method provided in this application embodiment. Figure 2 ,like Figure 3 As shown, the method includes:

[0077] S201. Obtain the output voltage of multiple power units in each phase, and use the sum of the output voltages of each power unit as the operating voltage of each phase.

[0078] Specifically, the operating voltage of each phase is obtained by the following formula (2):

[0079]

[0080] Among them, Uk S is the operating voltage of phase k. ki Let U be the switching signal function of the i-th power unit in phase k. ki is the DC bus voltage of the i-th power unit in phase k, i.e., the output voltage of the DC / DC converter, and N is the number of cascaded power units per phase.

[0081] S202. Based on the operating voltage of each phase, the current of each power unit in each phase is calculated using Kirchhoff's laws and used as the operating current of each phase.

[0082] Specifically, after obtaining the operating voltage of each phase, the charging and discharging current of the corresponding battery module of the i-th power unit in phase k, which is also the operating current, is obtained by the following formula (3):

[0083]

[0084] Among them, i ki Let S be the current of the i-th power unit in phase k. ki Let i be the switching signal function of the i-th power unit in phase k. k U is the operating current of phase k. k This is the operating voltage for phase k.

[0085] S203. Calculate and obtain the current charging and discharging power of the direct-connected energy storage system based on the operating voltage and operating current of each phase.

[0086] Specifically, based on the operating voltage and current of each phase, the current charging and discharging power value of the direct-connected energy storage system is obtained through power calculation formula.

[0087] S204. Perform Fourier transform on the operating voltage and operating current of each phase to obtain the corresponding voltage phase value and current phase value.

[0088] S205. The initial three-phase regulating power is obtained by calculating the three-phase regulating power formula.

[0089] Specifically, the average value of the current charging and discharging power is obtained as the target equalization value. Based on the target equalization value, as well as the voltage phase value and current phase value of each phase, the initial three-phase regulating power is calculated using the three-phase regulating power formula. The three-phase regulating power formula is shown in the following formula (4):

[0090]

[0091] Wherein, ΔP A The regulating power of phase A, ΔP B The regulating power of phase B, ΔP CThe power of phase C is the regulating power, P is the current charging / discharging power, and U is the current charging / discharging power. essA U is the operating voltage of phase A. essB U is the operating voltage of phase B. essC The operating voltage of phase C, I A The operating current of phase A is [current name]. The voltage phase value of phase A. The voltage phase value of phase B. The voltage phase value of phase C. The current phase value of phase A.

[0092] Furthermore, since the control method includes a negative sequence current suppression circuit, the three-phase currents always remain symmetrical. Therefore, the current-related variables in equation (4) all use the current information of phase A to simplify the control.

[0093] S206. The product of the initial three-phase regulating power and the preset proportional parameter is taken as the target three-phase regulating power.

[0094] Specifically, after obtaining the initial three-phase regulating power, if it is directly substituted into the formula for calculating the zero-sequence voltage injection, the power difference at the moment of injection becomes zero, causing the calculated zero-sequence voltage injection value to become zero. This repeatedly leads to a dead loop, making continuous control impossible and thus rendering the control ineffective. Therefore, this embodiment adds a proportional element, that is, the product of the initial three-phase regulating power and a preset proportional parameter is obtained in the proportional element as the target three-phase regulating power. This proportional element provides an adjustment process for control, thereby achieving a reliable balanced control effect.

[0095] S207. Based on the target three-phase regulating power, establish the target relationship for the fundamental zero-sequence voltage.

[0096] Specifically, the expression for the pre-injected fundamental zero-sequence voltage is as follows: (5)

[0097] u0=U0cos(ωt+θ0)(5;

[0098] Where u0 is the preset fundamental zero-sequence voltage, U0 is the zero-sequence voltage amplitude, and θ0 is the zero-sequence voltage phase; for each phase, its regulating power value should be equal to the power value of its injected zero-sequence voltage, that is, the regulating power of each phase in the target three-phase regulating power is equal to the power value of the fundamental zero-sequence voltage, as indicated by the target relation. The target relation is as shown in the following equation (6):

[0099]

[0100] Wherein, ΔP AThe regulating power of phase A, ΔP B The regulating power of phase B, ΔP C For the regulating power of phase C, Let U0 be the phase value of the current in phase A, U0 be the amplitude of the zero-sequence voltage, θ0 be the phase of the zero-sequence voltage, and I be the phase value of the current in phase A. A I is the operating current of phase A. B I is the operating current of phase B. C This is the operating current of phase C.

[0101] S208. The target relation is rearranged and transformed to obtain the zero-sequence voltage amplitude and phase formula. The zero-sequence voltage amplitude and phase are calculated using the zero-sequence voltage amplitude and phase formula.

[0102] Specifically, the formula for the zero-sequence voltage amplitude and phase is as shown in equation (7):

[0103]

[0104] Where U0 is the zero-sequence voltage amplitude, θ0 is the zero-sequence voltage phase, and I A The operating current of phase A is ΔP. A The regulating power of phase A, ΔP B The regulating power of phase B, ΔP C For the regulating power of phase C, This represents the current phase value of phase A.

[0105] S209. Obtain the three-phase modulation voltage by means of space vector modulation.

[0106] Specifically, the modulation method used in direct-connected energy storage systems is usually carrier phase-shift modulation. To ensure the operation of direct-connected energy storage systems, the zero-sequence voltage injected in existing schemes is usually limited. When the grid voltage asymmetry is high, it may not be possible to inject an accurate zero-sequence voltage. Therefore, space vector modulation is used here. The advantage of space vector modulation is that it can reduce the modulation degree and avoid over-modulation. Moreover, for zero-sequence voltage injection, the injection range is larger, so the SOC equalization effect is better achieved.

[0107] S210. The target zero-sequence voltage is superimposed on the three-phase modulation voltage to obtain a superimposed control voltage, and a corresponding switching signal is generated based on the superimposed control voltage.

[0108] The switching signal is used to indicate the switching status of each power unit in the direct-connected energy storage system.

[0109] This application provides a state-of-charge (SOC) balancing control method. By calculating the target three-phase regulation power based on the operating voltage, operating current, and current charging / discharging power of each phase in a direct-connected energy storage system, and by performing fundamental zero-sequence voltage conversion based on the target three-phase regulation power to obtain the target zero-sequence voltage after achieving proportional gain, the target zero-sequence voltage is injected into the three-phase modulation voltage after space vector modulation. This achieves real-time SOC balancing control under grid imbalance conditions, improves control effectiveness, increases the zero-sequence voltage injection range, and accelerates the control speed for achieving SOC balancing.

[0110] To further verify the control effect of the proposed state-of-charge (SOC) equalization control method under grid imbalance conditions, a simulation model of a direct-connected energy storage system was established on a simulation platform according to specific simulation parameters. The specific simulation parameters are shown in Table 1 below:

[0111] Table 1

[0112]

[0113] Run a simulation model of the direct-connected energy storage system on a simulation platform and implement the state-of-charge control method described in the above embodiments.

[0114] Figure 4 This is a schematic diagram of the steady-state operating waveform of a direct-connected energy storage system, such as... Figure 4 The simulation results show that the direct-connected energy storage system operates stably under the designed control strategy, with good voltage and current waveforms and no obvious distortion; the phase-locked loop can accurately lock the phase, proving that the power control strategy is effective.

[0115] Figure 5 This is a schematic diagram illustrating the SOC balancing effect of a direct-connected energy storage system under grid imbalance conditions, such as... Figure 5As shown, initially, the three-phase voltages of the power grid are balanced, and the entire grid discharges externally. At this time, the three-phase power released by the direct-connected energy storage system is equal, so the average SOC value of the three phases remains consistent throughout the decrease. At 0.5s, the voltage of phase A of the power grid drops to 0.6 times its original value. At this time, the three-phase voltages are unbalanced. Since the control is not enabled, there is a significant difference in the power released by the three phases, and the corresponding average SOC values ​​also differ, with this difference gradually increasing. At 1s, the designed SOC balancing control is activated, and zero-sequence voltage begins to be injected. At this time, the power released by the three phases returns to equality, and the trend of change of the corresponding average SOC values ​​returns to the same, with the SOC difference no longer increasing. This proves that the designed control method has a good control effect. It should be noted that, in order to demonstrate the control effect, the grid imbalance condition is chosen to occur at 0.5s, and the control is activated at 1s, so the final three-phase SOC values ​​maintain the same difference. In actual control, the designed control will respond and start at 0.5s, so the trend of change of the three-phase SOC values ​​will always be the same, without any difference.

[0116] Figure 6 A schematic diagram comparing the three-phase space vector modulation waveforms before and after zero-sequence voltage injection, as shown below. Figure 6 As shown, (a) is the three-phase space vector modulation waveform before zero-sequence voltage injection, (b) is the three-phase space vector modulation waveform after zero-sequence voltage injection. It can be seen that the amplitude of the three-phase modulation wave is the same before injection, and the three-phase modulation wave changes after injection, and the corresponding three-phase charging and discharging power is also redistributed. (c) is the injected zero-sequence voltage waveform.

[0117] Figure 7 This is a schematic diagram of the structure of the state-of-charge equalization control device provided in the embodiments of this application, as shown below. Figure 7 As shown, the device 700 includes:

[0118] The acquisition module 701 is used to acquire the operating voltage and operating current of each phase in the direct-connected energy storage system, and to calculate and acquire the current charging and discharging power of the direct-connected energy storage system based on the operating voltage and operating current of each phase.

[0119] The processing module 702 is used to calculate and obtain the target three-phase regulation power based on the operating voltage, the operating current and the current charging and discharging power of each phase, wherein the target three-phase regulation power includes the regulation power of each phase;

[0120] Control module 703 is used to perform fundamental zero-sequence voltage conversion based on the target three-phase regulating power to obtain a target zero-sequence voltage, and inject the target zero-sequence voltage into the three-phase modulation voltage to achieve charge balance in the direct-connected energy storage system.

[0121] Furthermore, the acquisition module 701 is specifically used to acquire the output voltage of multiple power units in each phase, and to use the sum of the output voltages of each power unit as the operating voltage of each phase;

[0122] Based on the operating voltage of each phase, the current of each power unit in each phase is calculated using Kirchhoff's laws and used as the operating current of each phase.

[0123] Furthermore, the processing module 702 is specifically used to obtain the average value of the current charging and discharging power as the target equalization value;

[0124] Perform Fourier transform on the operating voltage and operating current of each phase to obtain the corresponding voltage phase value and current phase value;

[0125] Based on the target equilibrium value, and the voltage phase value and current phase value of each phase, the initial three-phase regulation power is calculated using the three-phase regulation power formula.

[0126] The product of the initial three-phase regulating power and the preset proportional parameter is taken as the target three-phase regulating power.

[0127] Furthermore, in processing module 702, the three-phase power regulation formula is:

[0128]

[0129] Wherein, ΔP A The regulating power of phase A, ΔP B The regulating power of phase B, ΔP C The power of phase C is the regulating power, P is the current charging / discharging power, and U is the current charging / discharging power. essA U is the operating voltage of phase A. essB U is the operating voltage of phase B. essC The operating voltage of phase C, I A The operating current of phase A is [current name]. The voltage phase value of phase A. The voltage phase value of phase B. The voltage phase value of phase C. The current phase value of phase A.

[0130] Furthermore, the control module 703 is specifically used to establish a target relationship with respect to the fundamental zero-sequence voltage based on the target three-phase regulating power, wherein the target relationship is used to indicate that the regulating power of each phase in the target three-phase regulating power is equal to the power value of the fundamental zero-sequence voltage;

[0131] The target relation is rearranged and transformed to obtain the zero-sequence voltage amplitude and phase formula. The zero-sequence voltage amplitude and phase are calculated using the zero-sequence voltage amplitude and phase formula. The corresponding target zero-sequence voltage is then calculated based on the zero-sequence voltage amplitude and phase.

[0132] Furthermore, in control module 703, the formula for the zero-sequence voltage amplitude and phase is:

[0133]

[0134] Where U0 is the zero-sequence voltage amplitude, θ0 is the zero-sequence voltage phase, and I A The operating current of phase A is ΔP. A The regulating power of phase A, ΔP B The regulating power of phase B, ΔP C For the regulating power of phase C, This represents the current phase value of phase A.

[0135] Furthermore, the control module 703 is specifically used to acquire the three-phase modulation voltage through space vector modulation.

[0136] The target zero-sequence voltage is superimposed on the three-phase modulation voltage to obtain a superimposed control voltage. A corresponding switching signal is generated based on the superimposed control voltage, wherein the switching signal is used to indicate the switching state of each power unit in the direct-connected energy storage system.

[0137] Figure 8 This is a schematic diagram of the structure of the electronic device provided in the embodiments of this application, such as... Figure 8 As shown, the device 800 includes at least one processor 801 and a memory 802. The electronic device 800 also includes a communication component 803. The processor 801, memory 802, and communication component 803 are connected via a bus 804.

[0138] In the specific implementation process, at least one processor 801 executes the computer execution instructions stored in the memory 802, causing at least one processor 801 to execute the state-of-charge equalization control method executed on the electronic device side as described above.

[0139] The specific implementation process of processor 801 can be found in the above method embodiments, and its implementation principle and technical effect are similar. It will not be repeated here.

[0140] This application also provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, implement the state-of-charge equalization control method as described above.

[0141] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for state-of-charge (SOC) equalization control, characterized in that, The method includes: The operating voltage and operating current of each phase in the direct-connected energy storage system are obtained, and the current charging and discharging power of the direct-connected energy storage system is calculated based on the operating voltage and operating current of each phase. The target three-phase regulation power is calculated based on the operating voltage, operating current and current charging / discharging power of each phase, wherein the target three-phase regulation power includes the regulation power of each phase; Based on the target three-phase regulated power, fundamental zero-sequence voltage conversion is performed to obtain the target zero-sequence voltage; The target zero-sequence voltage is injected into the three-phase modulation voltage to balance the charge of the direct-connected energy storage system.

2. The state-of-charge equalization control method according to claim 1, characterized in that, The acquisition of the operating voltage and operating current of each phase in the direct-connected energy storage system includes: The output voltage of multiple power units in each phase is obtained, and the sum of the output voltages of each power unit is taken as the operating voltage of each phase; Based on the operating voltage of each phase, the current of each power unit in each phase is calculated using Kirchhoff's laws and used as the operating current of each phase.

3. The state-of-charge equalization control method according to claim 1, characterized in that, The calculation to obtain the target three-phase regulation power includes: Obtain the average value of the current charging and discharging power as the target equalization value; Perform Fourier transform on the operating voltage and operating current of each phase to obtain the corresponding voltage phase value and current phase value; Based on the target equilibrium value, and the voltage phase value and current phase value of each phase, the initial three-phase regulation power is calculated using the three-phase regulation power formula. The product of the initial three-phase regulating power and the preset proportional parameter is taken as the target three-phase regulating power.

4. The state-of-charge equalization control method according to claim 3, characterized in that, The three-phase power regulation formula is as follows: Where, ΔP A The regulating power of phase A, ΔP B The regulating power of phase B, ΔP C The power of phase C is the regulating power, P is the current charging / discharging power, and U is the current charging / discharging power. essA U is the operating voltage of phase A. essB U is the operating voltage of phase B. essC The operating voltage of phase C, I A The operating current of phase A is [current name]. The voltage phase value of phase A. The voltage phase value of phase B. The voltage phase value of phase C. The current phase value of phase A.

5. The state-of-charge equalization control method according to claim 1, characterized in that, The step of performing fundamental zero-sequence voltage conversion based on the target three-phase regulated power to obtain the target zero-sequence voltage includes: Based on the target three-phase regulating power, a target relationship is established regarding the fundamental zero-sequence voltage, wherein the target relationship is used to indicate that the regulating power of each phase in the target three-phase regulating power is equal to the power value of the fundamental zero-sequence voltage; The target relation is rearranged and transformed to obtain the zero-sequence voltage amplitude and phase formula. The zero-sequence voltage amplitude and phase are calculated using the zero-sequence voltage amplitude and phase formula. The corresponding target zero-sequence voltage is then calculated based on the zero-sequence voltage amplitude and phase.

6. The state-of-charge equalization control method according to claim 5, characterized in that, The formula for the zero-sequence voltage amplitude and phase is: Where U0 is the zero-sequence voltage amplitude, θ0 is the zero-sequence voltage phase, and I A The operating current of phase A is ΔP. A The regulating power of phase A, ΔP B The regulating power of phase B, ΔP C For the regulating power of phase C, This represents the current phase value of phase A.

7. The state-of-charge equalization control method according to claim 1, characterized in that, Injecting the target zero-sequence voltage into the three-phase modulation voltage to achieve charge balance in the direct-connected energy storage system includes: The three-phase modulation voltage is obtained by space vector modulation. The target zero-sequence voltage is superimposed on the three-phase modulation voltage to obtain a superimposed control voltage. A corresponding switching signal is generated based on the superimposed control voltage, wherein the switching signal is used to indicate the switching state of each power unit in the direct-connected energy storage system.

8. A state-of-charge equalization control device, characterized in that, include: The acquisition module is used to acquire the operating voltage and operating current of each phase in the direct-connected energy storage system, and to calculate and acquire the current charging and discharging power of the direct-connected energy storage system based on the operating voltage and operating current of each phase. The processing module is used to calculate and obtain the target three-phase regulation power based on the operating voltage, the operating current and the current charging and discharging power of each phase, wherein the target three-phase regulation power includes the regulation power of each phase; The control module is used to perform fundamental zero-sequence voltage conversion based on the target three-phase regulating power to obtain the target zero-sequence voltage, and inject the target zero-sequence voltage into the three-phase modulation voltage to make the charge balance of the direct-connected energy storage system.

9. An electronic device, characterized in that, include: At least one processor and memory; The memory stores computer-executed instructions; The at least one processor executes computer execution instructions stored in the memory, causing the at least one processor to perform the state-of-charge equalization control method as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable instructions, which, when executed by a processor, are used to implement the state-of-charge equalization control method as described in any one of claims 1 to 7.

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