Energy storage battery charging control method and device and energy storage system

Abstract

The invention provides an energy storage battery charging control method and device and an energy storage system, and relates to the technical field of energy storage charging. The method comprises the following steps: acquiring an AC voltage peak value of an AC power grid of the energy storage system and a battery voltage of an energy storage battery of the energy storage system; generating a charging control signal according to the magnitude relationship between the alternating current voltage peak value and the battery voltage; and controlling a charging control circuit of the energy storage system according to the charging control signal so as to charge the energy storage battery through the alternating current power grid. According to the invention, automatic charging control can be carried out based on the existing energy storage system.

Description

Technical Field

[0001] This application relates to the field of energy storage replenishment technology, and more specifically, to an energy storage battery replenishment control method, device, and energy storage system. Background Technology

[0002] Due to their energy storage characteristics, energy storage batteries can achieve controllable energy transfer during events. This characteristic plays an important role in dealing with overloaded distribution substations and managing substation voltage.

[0003] However, the overload and voltage problems of distribution substations have obvious seasonal characteristics. For example, overload in the substations basically only occurs in July and August, and there are almost no overload situations at other times. Under such circumstances, the energy storage batteries will experience power loss due to long-term idleness or failure.

[0004] Existing methods for replenishing energy storage batteries often require additional hardware design, resulting in higher costs. Summary of the Invention

[0005] The purpose of this application is to address the shortcomings of the prior art by providing a method, apparatus, and energy storage system for automatic power replenishment control of an energy storage battery, so as to enable automatic power replenishment control based on existing energy storage systems.

[0006] To achieve the above objectives, the technical solutions adopted in the embodiments of this application are as follows: In a first aspect, embodiments of this application provide a method for controlling the replenishment of an energy storage battery, applied to a controller of an energy storage system, the method comprising: Obtain the peak AC voltage of the AC grid of the energy storage system and the battery voltage of the energy storage battery of the energy storage system; Based on the relationship between the peak AC voltage and the battery voltage, a power replenishment control signal is generated; The energy storage system's energy replenishment control circuit is controlled according to the replenishment control signal to replenish the energy storage battery through the AC power grid.

[0007] Optionally, generating a charging control signal based on the relationship between the peak AC voltage and the battery voltage includes: If the battery voltage is less than the peak value of the AC voltage, a soft-start enable signal and a soft-start power replenishment control signal are generated. The step of controlling the power supply control circuit of the energy storage system according to the power supply control signal includes: The AC and DC sides of the power supply control circuit are controlled to perform AC soft start and DC soft start according to the soft start activation signal; According to the soft-start power replenishment control signal, the power replenishment control circuit is controlled to convert the AC signal power of the AC grid into a DC signal to perform soft-start power replenishment for the energy storage battery.

[0008] Optionally, generating a charging control signal based on the relationship between the peak AC voltage and the battery voltage includes: If the battery voltage is greater than or equal to the peak value of the AC voltage, and the battery voltage is less than the minimum value of the battery voltage, an interval chopping compensation control signal is generated. The step of controlling the power supply control circuit of the energy storage system according to the power supply control signal includes: According to the interval chopping power supply control signal, the power supply control circuit is controlled to convert the AC signal interval power of the AC power grid into a DC signal to provide interval power supply for the energy storage battery.

[0009] Optionally, the generation of the interval chopping compensation control signal includes: A drive identification signal is generated based on the real-time AC voltage of the AC power grid, the peak value of the AC voltage, and the battery voltage. The drive identification signal is either a high-level signal or a low-level signal. The interval chopping power supply control signal is generated based on the preset drive control signal and the drive identification signal.

[0010] Optionally, generating the drive identification signal based on the real-time AC voltage of the AC power grid, the peak value of the AC voltage, and the battery voltage includes: A chopper comparison voltage is generated based on the real-time AC voltage, the peak value of the AC voltage, and the minimum value of the battery voltage. If the battery voltage is greater than the chopper comparison voltage, the drive identification signal is determined to be a high-level signal; If the battery voltage is less than or equal to the chopper comparison voltage, the drive identification signal is determined to be a low-level signal.

[0011] Optionally, before generating the interval chopping compensation control signal based on the preset drive control signal and the drive identification signal, the method further includes: Adjust the supplementary power parameters according to the power quality parameters of the AC power grid; The preset drive control signal is generated based on the power replenishment parameters.

[0012] Optionally, adjusting the supplementary power parameters based on the grid quality parameters of the AC power grid includes: Based on the historical power quality data of the AC power grid, the predicted power grid state of the AC power grid is determined; The supplementary power parameters are adjusted based on the predicted grid condition of the AC power grid.

[0013] Secondly, embodiments of this application also provide an energy storage battery charging control device, applied to a controller of an energy storage system, the device comprising: The voltage acquisition module is used to acquire the peak AC voltage of the AC grid of the energy storage system and the battery voltage of the energy storage battery of the energy storage system. A control signal generation module is used to generate a power replenishment control signal based on the relationship between the peak AC voltage and the battery voltage. The power replenishment control module is used to control the power replenishment control circuit of the energy storage system according to the power replenishment control signal, so as to replenish the energy storage battery through the AC power grid.

[0014] Optionally, the control signal generation module is specifically used to generate a soft-start enable signal and a soft-start power replenishment control signal if the battery voltage is less than the peak value of the AC voltage. The power replenishment control module is specifically used to control the AC side and DC side of the power replenishment control circuit to perform AC soft start and DC soft start according to the soft start activation signal; and to control the power replenishment control circuit to convert the AC signal power of the AC grid into a DC signal according to the soft start power replenishment signal, so as to perform soft start power replenishment for the energy storage battery.

[0015] Optionally, the control signal generation module is specifically used to generate an interval chopping compensation control signal if the battery voltage is greater than or equal to the peak value of the AC voltage and the battery voltage is less than the minimum value of the battery voltage. The power replenishment control module is specifically used to control the power replenishment control circuit to convert the AC signal interval power of the AC power grid into a DC signal according to the interval chopping power replenishment control signal, so as to provide interval power replenishment for the energy storage battery.

[0016] Optionally, the control signal generation module is specifically used to generate a drive identification signal based on the real-time AC voltage of the AC power grid, the peak value of the AC voltage, and the battery voltage, wherein the drive identification signal is a high-level signal or a low-level signal; and to generate the interval chopping power supplementation control signal based on a preset drive control signal and the drive identification signal.

[0017] Optionally, the control signal generation module is specifically used to generate a chopper comparison voltage based on the real-time AC voltage, the peak value of the AC voltage, and the minimum value of the battery voltage; if the battery voltage is greater than the chopper comparison voltage, the drive identification signal is determined to be a high-level signal; if the battery voltage is less than or equal to the chopper comparison voltage, the drive identification signal is determined to be a low-level signal.

[0018] Optionally, the control signal generation module is further configured to adjust the supplementary power parameters according to the power quality parameters of the AC power grid; and generate the preset drive control signal according to the supplementary power parameters.

[0019] Optionally, the control signal generation module is further configured to determine the predicted grid state of the AC power grid based on the historical grid quality data of the AC power grid; and adjust the supplementary power parameters based on the predicted grid state of the AC power grid.

[0020] Thirdly, embodiments of this application also provide an energy storage system, the energy storage system including: an AC power grid, a power conversion device and an energy storage battery, the power conversion device including: a controller and a power replenishment control circuit, the power replenishment control circuit being connected to the AC power grid and the energy storage battery, the input terminal of the controller being connected to the sampling terminal of the AC power grid and the sampling terminal of the energy storage battery respectively, and the output terminal of the controller being connected to the control terminal of the power replenishment control circuit; The controller employs the energy storage battery replenishment control method as described in any of the first aspects to replenish the energy storage battery via the AC power grid.

[0021] Optionally, the power supply control circuit includes: an AC soft-start module, a power conversion module, and a DC soft-start module. The AC power grid is connected to the input terminal of the AC soft-start module, the output terminal of the AC soft-start module is connected to the input terminal of the power conversion module, the output terminal of the power conversion module is connected to the input terminal of the DC soft-start module, and the output terminal of the DC soft-start module is connected to the energy storage battery.

[0022] The beneficial effects of this application are: The energy storage battery replenishment control method, device, and energy storage system provided in this application replenish the energy storage battery via the AC power grid based on existing energy storage systems. This allows for automatic replenishment to adapt to different battery voltage states without additional hardware, reducing the cost of replenishing the energy storage battery. Based on the relationship between the peak AC voltage of the AC power grid and the battery voltage of the energy storage battery, a replenishment control signal matching this relationship is generated. This signal controls the replenishment control circuit, enabling replenishment of the energy storage battery via the AC power grid. This ensures that the replenishment state of the energy storage battery is consistent with its battery voltage, guaranteeing the safety of the replenishment process and achieving a safe and efficient replenishment procedure. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded 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.

[0024] Figure 1 A system architecture diagram of the energy storage system provided in the embodiments of this application; Figure 2 This is a schematic diagram of the power conversion device provided in the embodiments of this application; Figure 3 A flowchart illustrating the energy storage battery charging control method provided in the embodiments of this application. Figure 1 ; Figure 4 A flowchart illustrating the energy storage battery charging control method provided in the embodiments of this application. Figure 2 ; Figure 5 A flowchart illustrating the energy storage battery charging control method provided in the embodiments of this application. Figure 3 ; Figure 6 A flowchart illustrating the energy storage battery charging control method provided in the embodiments of this application. Figure 4 ; Figure 7 A waveform diagram of the interval chopper compensation current provided in the embodiments of this application; Figure 8 The waveform diagram of the working energy storage battery provided in the embodiment of this application; Figure 9 A flowchart illustrating the energy storage battery charging control method provided in the embodiments of this application; Figure 10 This is a schematic diagram of the structure of the energy storage battery charging control device provided in the embodiments of this application. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of this application, but not all embodiments.

[0026] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0027] Furthermore, the terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Additionally, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0028] It should be noted that, where there is no conflict, the features in the embodiments of this application can be combined with each other.

[0029] To better understand the energy storage battery charging control method provided in this application, the specific implementation of the energy storage system used in this application will be explained first.

[0030] Figure 1 The system architecture diagram of the energy storage system provided in the embodiments of this application is as follows: Figure 1 As shown, the energy storage system may include: an AC power grid 10, a power conversion device 20, and an energy storage battery 30.

[0031] In this embodiment, the AC power grid 10 converts energy with the energy storage battery 30 through the power conversion system (PCS) 20. On the one hand, the energy storage battery 30 can assist the AC power grid 10 in providing power, and on the other hand, the AC power grid 10 can charge the energy storage battery 30.

[0032] The power conversion device 20 collects the peak AC voltage of the AC power grid 10 and the battery voltage of the energy storage battery 30, and controls the AC power grid 10 to replenish the energy storage battery 30 based on the peak AC voltage and the battery voltage.

[0033] In some embodiments, such as Figure 1 As shown, the energy storage system may also include an Energy Management System (EMS) 40, a Battery Management System (BMS) 50, a Thermal Management System 60, and a Fire Protection System 70. The Energy Management System 40 interacts with and controls the Power Conversion Device 20, the Battery Management System 50, the Thermal Management System 60, and the Fire Protection System 70. The specific application scenarios of the interaction between the various parts are not described in this embodiment.

[0034] In some embodiments, Figure 2 This is a schematic diagram of the power conversion device provided in the embodiments of this application, such as... Figure 2 As shown, the power conversion device 20 may include: a controller 21 and a power supply control circuit 22. The power supply control circuit 22 is connected to the AC power grid 10 and the energy storage battery 30. The input terminal of the controller 21 is connected to the sampling terminal of the AC power grid 10 and the sampling terminal of the energy storage battery 30, respectively. The output terminal of the controller 21 is connected to the control terminal of the power supply control circuit 22.

[0035] Specifically, the controller 21 collects the peak AC voltage of the AC power grid 10 and the battery voltage of the energy storage battery 30, and generates a power replenishment control signal based on the peak AC voltage and the battery voltage. Based on the power replenishment control signal, the controller controls the power replenishment control circuit 22 to replenish the energy storage battery 30 through the AC power grid 10.

[0036] Furthermore, such as Figure 2 As shown, the power supply control circuit 22 may include: an AC soft start module 221, a power conversion module 222, and a DC soft start module 223. The AC power grid 10 is connected to the input terminal of the AC soft start module 221, the output terminal of the AC soft start module 221 is connected to the input terminal of the power conversion module 222, the output terminal of the power conversion module 222 is connected to the input terminal of the DC soft start module 223, and the output terminal of the DC soft start module 223 is connected to the energy storage battery 30.

[0037] In this embodiment, by controlling the AC soft start module 221 and the DC soft start module 223 to perform a soft start, the power conversion module 222 can be controlled to slowly replenish the energy storage battery 30. When the energy storage battery 30 meets the soft start termination condition, the AC soft start module 221 and the DC soft start module 223 can be controlled to close the soft start circuit and close the main circuit, so as to control the power conversion module 222 to replenish the energy storage battery 30 normally.

[0038] In some embodiments, the power supply control circuit 22 may further include an AC electromagnetic compatibility (EMC) module 224 and a DC electromagnetic compatibility module 225. The AC EMC module 224 is disposed between the AC power grid 10 and the AC soft start module 221, and the DC EMC module 225 is disposed between the DC soft start module 223 and the energy storage battery 30.

[0039] In some embodiments, the power conversion device 20 may further include an auxiliary power supply 226, which can supply power to the controller 21. The auxiliary power supply 226 may also convert the supply voltage of the auxiliary power supply 226 through a low dropout regulator (LDO) to meet the power supply requirements of the controller 21. For example, 12V can be converted to 5V and 5V can be converted to 3.3V.

[0040] In some embodiments, the power conversion device 20 may further include a fan, and the auxiliary power supply 226 may power the fan, which may cool the power conversion device 20.

[0041] In some embodiments, the power conversion device 20 may further include a communication module, an auxiliary power supply 226 may power the communication module, and a controller 21 may be connected to the communication module to communicate with external modules through the communication module.

[0042] Furthermore, such as Figure 2 As shown, the AC soft-start module 221 may include: a first main circuit switch S1, a first soft-start resistor R1, and a first controllable switch S2, wherein the first soft-start resistor R1 and the first controllable switch S2 are connected in series, and the first main circuit switch S1 is connected in parallel with the first soft-start resistor R1 and the first controllable switch S2. The DC soft-start module 223 may include: a second main circuit switch S3, a second soft-start resistor R2, and a second controllable switch S4, wherein the second soft-start resistor R2 and the second controllable switch S4 are connected in series, and the second main circuit switch S3 is connected in parallel with the second soft-start resistor R2 and the second controllable switch S4. The power conversion module 222 may include: an inductor Lm, a full-bridge circuit Sm composed of power switching devices, and a bus capacitor C.

[0043] Among them, the AC soft start module 221 and the power conversion module 222 can be set with three channels respectively in the three phases A, B and C, and the DC soft start module 223 can be set with two channels respectively in the positive and negative terminals of the DC bus.

[0044] When the first main circuit switch S1 is opened and the first controllable switch S2 is closed, the AC signal performs AC soft start through the first soft start resistor R1 to charge the bus capacitor C. After the bus voltage stabilizes, the AC soft start is completed, the first main circuit switch S1 is closed and the first controllable switch S2 is opened.

[0045] Then, the second main circuit switch S3 is opened and the second controllable switch S4 is closed. After the AC signal is converted into a DC signal by the power conversion module 222, the DC signal slowly replenishes the energy storage battery 30 through the second soft-start resistor R2. When the battery voltage of the energy storage battery 30 is pre-charged to close to the bus voltage, the second main circuit switch S3 is closed and the second controllable switch S4 is opened to start full power replenishment.

[0046] The following describes the specific implementation of the energy storage battery charging control method applied to the controller, with reference to the embodiments.

[0047] Figure 3 A flowchart illustrating the energy storage battery charging control method provided in the embodiments of this application. Figure 1 ,like Figure 3 As shown, the method may include: S301. Obtain the peak AC voltage of the AC grid of the energy storage system and the battery voltage of the energy storage battery of the energy storage system.

[0048] In this embodiment, the controller is connected to the AC sampling terminal and the DC sampling terminal of the power supply control circuit to sample the AC voltage peak value Uac_peak of the AC grid and the battery voltage Udc_batter of the energy storage battery, respectively.

[0049] Specifically, such as Figure 2 As shown, the controller can be connected to the input terminals of the AC soft-start module and the DC soft-start module respectively to sample the AC voltage peak value Uac_peak and the battery voltage Udc_batter.

[0050] For example, for a three-phase four-wire system, the peak AC voltage Uac_peak is the effective value of the single-phase AC voltage × 2.828. For a three-phase three-wire system, considering the use of space vector control, the peak AC voltage Uac_peak is the effective value of the single-phase AC voltage × 2.449, which is the line voltage × 1.414. Line voltage = phase voltage × 1.732.

[0051] S302. Generate a power replenishment control signal based on the relationship between the peak AC voltage and the battery voltage.

[0052] In this embodiment, the peak AC voltage Uac_peak and the battery voltage Udc_batter are compared. Based on the magnitude relationship between the peak AC voltage Uac_peak and the battery voltage Udc_batter, a power supplement control signal matching the magnitude relationship is generated. The power supplement control signal matching the magnitude relationship can adjust the output power or output current of the power supplement control circuit.

[0053] Specifically, if the battery voltage Udc_batter is less than the AC voltage peak Uac_peak, a soft-start power replenishment control signal is generated; if the battery voltage Udc_batter is greater than or equal to the AC voltage peak Uac_peak, a full-power power replenishment control signal is generated.

[0054] S303. Control the energy storage system's energy replenishment control circuit according to the energy replenishment control signal to replenish the energy storage battery through the AC power grid.

[0055] In this embodiment, if the battery voltage Udc_batter is less than the AC voltage peak Uac_peak, the power supply control circuit is controlled to perform a soft start according to the soft start power supply control signal, so as to slowly supply power to the energy storage battery through the AC grid. If the battery voltage Udc_batter is greater than or equal to the AC voltage peak Uac_peak, the power supply control circuit is controlled to end the soft start according to the full power power supply control signal, so as to supply full power power to the energy storage battery through the AC grid.

[0056] The energy storage battery replenishment control method provided in the above embodiments replenishes the energy storage battery through the AC power grid based on the existing energy storage system. It can automatically adapt to different battery voltage states for replenishment without adding additional hardware, reducing the cost of replenishing the energy storage battery. According to the relationship between the peak AC voltage of the AC power grid and the battery voltage of the energy storage battery, a replenishment control signal matching the relationship is generated. The replenishment control circuit is controlled according to the replenishment control signal to realize the replenishment of the energy storage battery through the AC power grid. This ensures that the replenishment state of the energy storage battery is consistent with the battery voltage, ensuring the safety of energy storage battery replenishment and realizing a safe and efficient replenishment process.

[0057] In one possible implementation, Figure 4 A flowchart illustrating the energy storage battery charging control method provided in the embodiments of this application. Figure 2 ,like Figure 4 As shown, the process of generating a power replenishment control signal based on the relationship between the peak AC voltage and the battery voltage in the above-mentioned S302 may include: S401. If the battery voltage is less than the peak AC voltage, generate a soft start enable signal and a soft start power replenishment control signal.

[0058] The process of controlling the energy storage system's power supply control circuit according to the power supply control signal in the above-mentioned S303 may include: S402. Based on the soft start start signal, control the AC and DC sides of the power supply control circuit to perform AC soft start and DC soft start.

[0059] S403. Based on the soft-start power replenishment control signal, control the power replenishment control circuit to convert the AC signal power of the AC grid into a DC signal to perform soft-start power replenishment for the energy storage battery.

[0060] In this embodiment, when the battery voltage Udc_batter is less than the AC voltage peak Uac_peak, in order to avoid the impact of the large current of the AC grid on the energy storage battery, it is necessary to slowly charge the energy storage battery. Specifically, slow charging can be achieved through soft start.

[0061] Specifically, when the battery voltage Udc_batter is less than the AC voltage peak Uac_peak, a soft-start enable signal and a soft-start charging control signal are generated. First, according to the soft-start enable signal, the first main circuit switch S1 is opened and the first controllable switch S2 is closed. The AC power supply charges the bus capacitor C through the first soft-start resistor R1, inductor Lm, and full-bridge circuit Sm. After the bus voltage stabilizes, according to the soft-start enable signal, the second main circuit switch S3 is opened and the second controllable switch S4 is closed. The energy storage battery is slowly charged through the second soft-start resistor R2.

[0062] During the slow recharging of the energy storage battery, the full-bridge circuit Sm is controlled by the soft-start recharging control signal to perform power conversion, so as to convert the AC signal into a DC signal.

[0063] Furthermore, when the battery voltage of the energy storage battery 30 is precharged to near the bus voltage, the first main circuit switch S1 and the second main circuit switch S3 are closed, and the first controllable switch S2 and the second controllable switch S4 are opened to start full-power charging.

[0064] The energy storage battery charging control method provided in the above embodiments controls the AC grid to slowly charge the energy storage battery according to the soft start start signal and the soft start charging control signal when the battery voltage is less than the peak AC voltage, ensuring that the energy storage battery will not be damaged by the large current impact and ensuring the safety of the energy storage battery.

[0065] In another possible implementation Figure 5 A flowchart illustrating the energy storage battery charging control method provided in the embodiments of this application. Figure 3 ,like Figure 5 As shown, the process of generating a power replenishment control signal based on the relationship between the peak AC voltage and the battery voltage in the above-mentioned S302 may include: S404. If the battery voltage is greater than or equal to the peak AC voltage and the battery voltage is less than the minimum battery voltage, generate an interval chopping compensation control signal.

[0066] The process of controlling the energy storage system's power supply control circuit according to the power supply control signal in the above-mentioned S303 may include: S405. Based on the interval chopping power supply control signal, control the power supply control circuit to convert the AC signal interval power of the AC grid into a DC signal to provide interval power supply for the energy storage battery.

[0067] In this embodiment, when the battery voltage Udc_batter is greater than or equal to the AC voltage peak Uac_peak and less than the battery voltage minimum Udc_min, the energy storage battery can be fully charged. However, in order to avoid large grid voltage fluctuations or harmonic interference that lead to low charging efficiency or even trigger the protection mechanism of the battery or converter, causing the charging process to be interrupted, this solution adopts an interval chopping charging method to ensure the stability and efficiency of the charging process.

[0068] Specifically, when the battery voltage Udc_batter is greater than or equal to the peak AC voltage Uac_peak and less than the minimum battery voltage Udc_min, an intermittent chopping power supply control signal is generated. The intermittent chopping power supply control signal is an intermittent pulse width modulation (PWM) signal that can control the power conversion module to work intermittently. That is, the power conversion module can be controlled to work normally according to the PWM signal for a period of time and not work for a period of time, so that the power conversion module can perform intermittent power conversion, so that the AC grid can provide intermittent power supply to the energy storage battery.

[0069] The energy storage battery replenishment control method provided in the above embodiments controls the AC grid to replenish the energy storage battery intermittently according to the interval chopping replenishment control signal when the battery voltage is greater than or equal to the peak value of the AC voltage, thereby ensuring the stability and efficiency of the replenishment process.

[0070] In one possible implementation, Figure 6 A flowchart illustrating the energy storage battery charging control method provided in the embodiments of this application. Figure 4 ,like Figure 6 As shown, the process of generating the interval chopping compensation control signal by S404 can include: S501. Based on the real-time AC voltage, peak AC voltage, and battery voltage of the AC power grid, generate a drive identification signal. The drive identification signal can be a high-level signal or a low-level signal.

[0071] S502. Generate interval chopping power supply control signals based on preset drive control signals and drive identification signals.

[0072] In this embodiment, when the battery voltage Udc_batter is greater than or equal to the AC voltage peak Uac_peak, the target voltage value is calculated based on the real-time AC voltage Uac_run, the AC voltage peak Uac_peak, and the battery voltage Udc_batter. If the target voltage value is within the preset voltage range, a high-level drive flag signal is generated, i.e., Flag_drive=1. If the target voltage value is not within the preset voltage range, a low-level drive flag signal is generated, i.e., Flag_drive=0.

[0073] For example, a target voltage value can be generated by subtracting the absolute value of the real-time AC voltage Uac_run from the sum of the absolute values ​​of the battery voltage Udc_batter and the peak AC voltage Uac_peak. When the real-time AC voltage Uac_run is small, the target voltage value is within the preset voltage range, and Flag_drive=1. When the real-time AC voltage Uac_run increases, the target voltage value is no longer within the preset voltage range, and Flag_drive=0.

[0074] The preset drive control signal is a PWM signal generated based on the preset power-up parameters. Since the real-time AC voltage is constantly changing, the drive flag signal Flag_drive also switches between high level 0 and low level 1 as the real-time AC voltage changes periodically. The preset drive control signal and the drive flag signal Flag_drive are multiplied or ANDed to generate the interval chopping power-up control signal.

[0075] In some embodiments, the process of generating a drive identification signal based on the real-time AC voltage of the AC power grid, the peak AC voltage, and the battery voltage in step S501 may include: Based on the real-time AC voltage, the peak AC voltage, and the minimum battery voltage, a chopper comparison voltage is generated. If the battery voltage is greater than the chopper comparison voltage, the drive identification signal is determined to be a high-level signal; if the battery voltage is less than or equal to the chopper comparison voltage, the drive identification signal is determined to be a low-level signal.

[0076] In this embodiment, a chopper comparison voltage is generated by subtracting the absolute value of the AC voltage peak Uac_peak from the sum of the absolute value of the real-time AC voltage Uac_run and the minimum battery voltage Udc_min. The relationship between the battery voltage Udc_batter and the chopper comparison voltage is then determined, and a drive identification signal is generated.

[0077] When the battery voltage Udc_batter is greater than the chopper comparison voltage, the drive flag signal is determined to be a high-level signal, i.e., Flag_drive=1. When the battery voltage Udc_batter is less than or equal to the chopper comparison voltage, the drive flag signal is determined to be a low-level signal, i.e., Flag_drive=0.

[0078] Example, Figure 7 The waveform diagram of the interval chopper compensation current provided in the embodiments of this application is as follows: Figure 7As shown, the desired waveform of the given current is a sine wave. Using an interval chopper operating mode, when Udc_batter ≤ (abs(Uac_run) + Udc_min - abs(Uac_peak)), Flag_drive = 0. The preset drive control signal and the drive flag signal Flag_drive = 0 are multiplied or ANDed to make the power conversion device's supplementary current 0. When Udc_batter > (abs(Uac_run) + Udc_min - abs(Uac_peak)), Flag_drive = 1. The preset drive control signal and the drive flag signal Flag_drive = 1 are multiplied or ANDed to make the power conversion device's supplementary current the preset supplementary current.

[0079] The energy storage battery replenishment control method provided in the above embodiments generates a high-level or low-level drive identification signal based on the real-time AC voltage, peak AC voltage, and battery voltage of the AC power grid. Based on the preset drive control signal and drive identification signal, an interval chopping replenishment control signal is generated so as to control whether the power conversion device performs power conversion as the real-time AC voltage changes, thereby realizing the AC power grid to provide interval replenishment to the energy storage battery and ensuring the stability and efficiency of the replenishment process.

[0080] Furthermore, when the battery voltage Udc_batter is greater than or equal to the minimum battery voltage Udc_min, the interval chopper working mode is exited and the energy storage battery operates normally. Normal operation includes the energy storage battery operating in discharge mode when the AC grid is overloaded, assisting the AC grid in supplying power to the load, and the energy storage battery operating in charging mode when the AC grid has sufficient energy, allowing the AC grid to charge the energy storage battery.

[0081] Example, Figure 8 The working waveform diagram of the energy storage battery provided in the embodiments of this application is as follows: Figure 8 As shown, when the battery voltage Udc_batter is between the minimum battery voltage Udc_min and the maximum battery voltage Udc_max, the energy storage battery is operating normally. When the battery voltage Udc_batter is between the peak AC voltage Uac_peak and the minimum battery voltage Udc_min, the energy storage battery is operating in the interval chopper mode. When the battery voltage Udc_batter is less than the peak AC voltage Uac_peak, the energy storage battery is operating in the pre-charge mode.

[0082] Assuming a three-phase four-wire energy storage system, its AC voltage is 220V (RMS value), and the peak AC voltage Uac_peak = 220V × 2.828 ≈ 622V.

[0083] When the detected battery voltage Udc_batter < 622V, the system enters the pre-charge mode. At this time, the system slowly charges the energy storage battery through the AC soft start module and the DC soft start module. When the battery voltage reaches the condition for the main contactor to close, the system automatically switches the main circuit switches of the AC soft start module and the DC soft start module, and sets the charge current given parameter to 0.

[0084] Assume that the minimum operating voltage of the system Udc_min = 700V. When 622V < Udc_batter < 700V, the system enters the interval chopping working mode. In this stage, the system dynamically adjusts the charge current according to the relationship between the real-time AC voltage Uac_run and the battery voltage Udc_batter.

[0085] Specifically, when Udc_batter ≥ (|Uac_run| + Udc_min - |Uac_peak|), Flag_drive = 1, and the charge current given parameter is set to a preset value (e.g., 10A); when Udc_batter < (|Uac_run| + Udc_min - Uac_peak), Flag_drive = 0, and the charge current given parameter is set to 0.

[0086] For example, in the case of 622V < Udc_batter < 700V, assume Udc_batter = 650V. When Uac_run = 300V, since Udc_batter > (|300| + 700 - |622|) = 378V, the system outputs a charge current of 10A. When Uac_run = 600V, since Udc_batter < (|600| + 700 - |622|) = 678V, the system pauses charging.

[0087] The above dynamic adjustment is continuously carried out within each power frequency cycle to ensure that while the battery voltage gradually rises, the system is prevented from being unstable.

[0088] When Udc_batter > 700V, the system enters the normal working mode and continuously charges until the battery SOC or the single cell voltage reaches the preset stop value.

[0089] In a possible implementation, before the above S502 generates the interval chopping charge control signal according to the preset drive control signal and the drive identification signal, the method may further include: Adjust the charge parameters according to the grid quality parameters of the AC power grid; generate a preset drive control signal according to the charge parameters.

[0090] In this embodiment, to solve the problem of charge efficiency cancellation in a complex grid environment, the charge strategy can be adjusted by evaluating the grid state.

[0091] Specifically, the grid quality parameters of the AC power grid are obtained. These parameters can include the effective value of the grid voltage, frequency deviation, total harmonic distortion rate, etc. The system automatically switches between various power supply modes based on these parameters. If the grid quality parameters indicate that the grid is in good condition, the normal mode can be used. In this mode, the system uses the interval chopping working mode described above to supply power according to the preset power supply parameters, and generates a preset drive control signal based on the preset power supply current.

[0092] If the power grid quality parameters indicate significant fluctuations, a stable mode can be adopted. In stable mode, the supplementary power output needs to be reduced and the supplementary power duration extended to ensure system stability. In stable mode, the rate of change of the preset supplementary current can be reduced to minimize the impact on the power grid. The rate of change of the supplementary current can be adjusted using a slope limiter that displays the speed of change of the preset supplementary current.

[0093] If the power grid quality parameters indicate a high harmonic content in the grid voltage, a harmonic suppression mode can be adopted. By enabling the active harmonic suppression function, a current compensation command with the same magnitude but opposite phase as the harmonic is generated. Combined with the preset compensation current command, the current loop controller generates the reverse voltage component required to cancel the harmonic. Based on this reverse voltage component, a PWM signal to suppress the harmonic is generated to ensure the quality of the compensation current.

[0094] If the power grid quality parameters indicate a change in the power grid frequency, a power adjustment mode can be adopted to dynamically adjust the supplementary power according to a preset power adjustment algorithm, generate a supplementary current based on the adjusted supplementary power, and generate a PWM signal based on the supplementary current.

[0095] In some embodiments, the grid voltage waveform, frequency, and harmonic content can be sampled at high speed and analyzed using Fast Fourier Transform (FFT) to determine grid quality parameters.

[0096] The energy storage battery replenishment control method provided in the above embodiments adjusts the replenishment parameters according to the power grid quality parameters, so that the replenishment parameters can conform to the power grid status and improve system stability.

[0097] In one possible implementation, the process of adjusting the supplementary power parameters based on the grid quality parameters of the AC power grid may include: Based on historical power grid quality data of the AC power grid, the predicted power grid state of the AC power grid is determined; based on the predicted power grid state of the AC power grid, the supplementary power parameters are adjusted.

[0098] In this embodiment, the changing trend of the power grid state is analyzed and predicted based on the historical power grid quality data of the AC power grid, the predicted power grid state of the AC power grid is determined, and the power replenishment parameters are adjusted in advance according to the power replenishment strategy corresponding to the predicted power grid state.

[0099] For example, when a significant fluctuation in grid voltage is predicted, the system can reduce the power supply or temporarily interrupt the power supply in advance to avoid potential instability.

[0100] The energy storage battery replenishment control method provided in the above embodiments can predict the grid status and adjust the replenishment parameters in advance to avoid potential risks and improve system stability and safety.

[0101] Example, Figure 9 A flowchart illustrating the energy storage battery charging control method provided in this application embodiment is shown below. Figure 9 As shown, the energy storage battery recharging control process includes: S601. Determine whether the real-time AC voltage of the AC power grid and the battery voltage meet the preset start-up conditions.

[0102] S602. If the preset start-up conditions are not met, determine whether the energy storage system should start the power replenishment mode.

[0103] S603. When the energy storage system is in charge mode, determine the relationship between the peak AC voltage and the battery voltage.

[0104] S604. If the battery voltage is lower than the peak AC voltage, proceed with the AC soft start procedure.

[0105] S605, Enter DC soft start process.

[0106] S606, Generate soft-start power-up control signal.

[0107] S607. If the battery voltage is greater than or equal to the peak AC voltage, generate the drive identification signal Flag_drive.

[0108] S608. Based on the preset drive control signal and drive identifier signal Flag_drive, perform interval chopping power compensation control signal.

[0109] S609. If the preset start-up conditions are not met and the energy storage system is not in power replenishment mode, control the energy storage system to shut down and send a fault signal.

[0110] Based on the above method embodiments, this application also provides an energy storage battery charging control device, which is applied to the controller of an energy storage system. Figure 10 This is a schematic diagram of the structure of the energy storage battery charging control device provided in the embodiments of this application, as shown below. Figure 10 As shown, the device may include: The voltage acquisition module 701 is used to acquire the peak AC voltage of the AC grid of the energy storage system and the battery voltage of the energy storage battery of the energy storage system. The control signal generation module 702 is used to generate a power replenishment control signal based on the relationship between the peak value of the AC voltage and the battery voltage. The power replenishment control module 703 is used to control the power replenishment control circuit of the energy storage system according to the power replenishment control signal, so as to replenish the energy storage battery through the AC power grid.

[0111] Optionally, the control signal generation module 702 is specifically used to generate a soft-start enable signal and a soft-start power replenishment control signal if the battery voltage is less than the peak value of the AC voltage; The power replenishment control module 703 is specifically used to control the AC side and DC side of the power replenishment control circuit to perform AC soft start and DC soft start according to the soft start activation signal; and to control the power replenishment control circuit to convert the AC signal power of the AC grid into a DC signal according to the soft start power replenishment signal, so as to perform soft start power replenishment for the energy storage battery.

[0112] Optionally, the control signal generation module 702 is specifically used to generate an interval chopping compensation control signal if the battery voltage is greater than or equal to the peak value of the AC voltage and the battery voltage is less than the minimum value of the battery voltage. The power replenishment control module 703 is specifically used to control the power replenishment control circuit to convert the AC signal interval power of the AC power grid into a DC signal according to the interval chopping power replenishment control signal, so as to provide interval power replenishment for the energy storage battery.

[0113] Optionally, the control signal generation module 702 is specifically used to generate a drive identification signal based on the real-time AC voltage of the AC power grid, the peak value of the AC voltage, and the battery voltage, wherein the drive identification signal is a high-level signal or a low-level signal; and to generate the interval chopping power supplementation control signal based on a preset drive control signal and the drive identification signal.

[0114] Optionally, the control signal generation module 702 is specifically used to generate a chopper comparison voltage based on the real-time AC voltage, the peak value of the AC voltage, and the minimum value of the battery voltage; if the battery voltage is greater than the chopper comparison voltage, the drive identification signal is determined to be a high-level signal; if the battery voltage is less than or equal to the chopper comparison voltage, the drive identification signal is determined to be a low-level signal.

[0115] Optionally, the control signal generation module 702 is further configured to adjust the supplementary power parameters according to the power grid quality parameters of the AC power grid; and generate the preset drive control signal according to the supplementary power parameters.

[0116] Optionally, the control signal generation module 702 is further configured to determine the predicted grid state of the AC power grid based on the historical grid quality data of the AC power grid; and adjust the supplementary power parameters based on the predicted grid state of the AC power grid.

[0117] The above-described device is used to execute the method provided in the foregoing embodiments, and its implementation principle and technical effect are similar, so they will not be described again here.

[0118] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for controlling the replenishment of an energy storage battery, characterized in that, The method, applied to a controller for an energy storage system, includes: Obtain the peak AC voltage of the AC grid of the energy storage system and the battery voltage of the energy storage battery of the energy storage system; Based on the relationship between the peak AC voltage and the battery voltage, a power replenishment control signal is generated; The energy storage system's energy replenishment control circuit is controlled according to the replenishment control signal to replenish the energy storage battery through the AC power grid.

2. The method as described in claim 1, characterized in that, The step of generating a power replenishment control signal based on the relationship between the peak AC voltage and the battery voltage includes: If the battery voltage is less than the peak value of the AC voltage, a soft-start enable signal and a soft-start power replenishment control signal are generated. The step of controlling the power supply control circuit of the energy storage system according to the power supply control signal includes: The AC and DC sides of the power supply control circuit are controlled to perform AC soft start and DC soft start according to the soft start activation signal. According to the soft-start power replenishment control signal, the power replenishment control circuit is controlled to convert the AC signal power of the AC grid into a DC signal to perform soft-start power replenishment for the energy storage battery.

3. The method as described in claim 1, characterized in that, The step of generating a power replenishment control signal based on the relationship between the peak AC voltage and the battery voltage includes: If the battery voltage is greater than or equal to the peak value of the AC voltage, and the battery voltage is less than the minimum value of the battery voltage, an interval chopping compensation control signal is generated. The step of controlling the power supply control circuit of the energy storage system according to the power supply control signal includes: According to the interval chopping power supply control signal, the power supply control circuit is controlled to convert the AC signal interval power of the AC power grid into a DC signal to provide interval power supply for the energy storage battery.

4. The method as described in claim 3, characterized in that, The generation of the interval chopping compensation control signal includes: A drive identification signal is generated based on the real-time AC voltage of the AC power grid, the peak value of the AC voltage, and the battery voltage. The drive identification signal is either a high-level signal or a low-level signal. The interval chopping power supply control signal is generated based on the preset drive control signal and the drive identification signal.

5. The method as described in claim 4, characterized in that, The step of generating a drive identification signal based on the real-time AC voltage of the AC power grid, the peak value of the AC voltage, and the battery voltage includes: A chopper comparison voltage is generated based on the real-time AC voltage, the peak value of the AC voltage, and the minimum value of the battery voltage. If the battery voltage is greater than the chopper comparison voltage, the drive identification signal is determined to be a high-level signal; If the battery voltage is less than or equal to the chopper comparison voltage, the drive identification signal is determined to be a low-level signal.

6. The method as described in claim 4, characterized in that, Before generating the interval chopping compensation control signal based on the preset drive control signal and the drive identification signal, the method further includes: Adjust the supplementary power parameters according to the power quality parameters of the AC power grid; The preset drive control signal is generated based on the power replenishment parameters.

7. The method as described in claim 6, characterized in that, The step of adjusting the supplementary power parameters according to the grid quality parameters of the AC power grid includes: Based on the historical power quality data of the AC power grid, the predicted power grid state of the AC power grid is determined; The supplementary power parameters are adjusted based on the predicted grid condition of the AC power grid.

8. A battery charging control device, characterized in that, A controller for an energy storage system, the device comprising: The voltage acquisition module is used to acquire the peak AC voltage of the AC grid of the energy storage system and the battery voltage of the energy storage battery of the energy storage system. A control signal generation module is used to generate a power replenishment control signal based on the relationship between the peak AC voltage and the battery voltage. The power replenishment control module is used to control the power replenishment control circuit of the energy storage system according to the power replenishment control signal, so as to replenish the energy storage battery through the AC power grid.

9. An energy storage system, characterized in that, The energy storage system includes: an AC power grid, a power conversion device, and an energy storage battery. The power conversion device includes: a controller and a power replenishment control circuit. The power replenishment control circuit is connected to the AC power grid and the energy storage battery. The input terminal of the controller is connected to the sampling terminal of the AC power grid and the sampling terminal of the energy storage battery, respectively. The output terminal of the controller is connected to the control terminal of the power replenishment control circuit. The controller employs the energy storage battery replenishment control method as described in any one of claims 1 to 7 to replenish the energy storage battery through the AC power grid.

10. The energy storage system as described in claim 9, characterized in that, The power replenishment control circuit includes an AC soft-start module, a power conversion module, and a DC soft-start module. The AC power grid is connected to the input terminal of the AC soft-start module, the output terminal of the AC soft-start module is connected to the input terminal of the power conversion module, the output terminal of the power conversion module is connected to the input terminal of the DC soft-start module, and the output terminal of the DC soft-start module is connected to the energy storage battery.

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