Energy storage converter, control method of energy storage converter and energy storage system

Abstract

The invention discloses an energy storage converter, a control method of the energy storage converter and an energy storage system, and relates to the technical field of electric power. The energy storage converter can comprise a power conversion circuit, a direct current side switch module connected with the direct current side of the power conversion circuit, and a capacitor array connected between the positive electrode and the negative electrode of the direct current side of the power conversion circuit. Moreover, the side, away from the power conversion circuit, of the DC side switch module serves as the DC side of the energy storage converter and is used for connecting an energy storage battery, and the AC side of the energy storage converter is used for connecting an AC power grid. On the basis, when the operation mode of the energy storage converter is determined to be the reactive mode, the energy storage converter can be controlled to carry out reactive adjustment, and the direct current side switch module is controlled to be disconnected, so that the connection between the energy storage battery and the energy storage converter is disconnected, and the energy storage battery can be prevented from working for a long time in the reactive mode; therefore, the service life of the energy storage battery is prolonged to a certain extent.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electric power, in particular to a power conversion system, a control method of the power conversion system and a power storage system. BACKGROUND

[0002] The power conversion system (PCS) is widely used in the power system. In the grid-connected state, the power conversion system can control the power conversion circuit to charge or discharge the connected power storage battery according to the demand, such as the received mode instruction, to realize active scheduling or reactive scheduling of the connected alternating current power grid, so as to support the power grid.

[0003] Since the power storage battery charges the capacitor array in the power conversion system in the reactive mode, the power storage battery is in a working state for a long time, which affects the service life of the battery. SUMMARY

[0004] In view of the above problems, the present application provides a power conversion system, a control method of the power conversion system and a power storage system to prolong the service life of the power storage battery.

[0005] The specific scheme is as follows:

[0006] The first aspect of the present application provides a power conversion system, comprising: a direct current side switch module, a capacitor array, a power conversion circuit and a controller; wherein,

[0007] The direct current side switch module is connected to the direct current side of the power conversion circuit; the side of the direct current side switch module away from the power conversion circuit is used as the direct current side of the power conversion system and is used for connecting the power storage battery;

[0008] The capacitor array is connected between the positive and negative poles of the direct current side of the power conversion circuit;

[0009] The alternating current side of the power conversion circuit is used as the alternating current side of the power conversion system and is used for connecting the alternating current power grid;

[0010] The controller is used for controlling the operation of the power conversion circuit and the on-off of the direct current side switch module; and when it is determined that the operation mode of the power conversion system is the reactive mode, the controller controls the direct current side switch module to be disconnected.

[0011] The second aspect of the present application provides a control method of a power conversion system, the power conversion system comprising: a power conversion circuit, a direct current side switch module connected to the direct current side of the power conversion circuit and the direct current side of the power storage battery, and a capacitor array connected between the positive and negative poles of the direct current side of the power conversion circuit; and the alternating current side of the power conversion circuit is connected to the alternating current power grid; the method comprises:

[0012] determine an operation mode of the energy storage converter according to the received mode instruction;

[0013] when the operation mode is determined as the reactive mode, perform reactive dispatching and control the DC side switch module to be disconnected.

[0014] The third aspect of the present application provides an energy storage system, comprising: an energy storage converter, and an energy storage battery connected to the energy storage converter.

[0015] The energy storage converter comprises:

[0016] a power conversion circuit, an AC side of the power conversion circuit being used for connecting an AC power grid;

[0017] a DC side switch module connected between a DC side of the power conversion circuit and a DC side of the energy storage battery;

[0018] a capacitor array connected between positive and negative poles of the DC side of the power conversion circuit;

[0019] and a controller used for implementing the control method of the energy storage converter.

[0020] According to the technical solution described above, the energy storage converter can comprise: a power conversion circuit, a DC side switch module connected to a DC side of the power conversion circuit, and a capacitor array connected between positive and negative poles of the DC side of the power conversion circuit; and a side of the DC side switch module away from the power conversion circuit is used as a DC side of the energy storage converter and is used for connecting an energy storage battery, and an AC side of the energy storage converter is used for connecting an AC power grid. On this basis, when the operation mode of the energy storage converter is determined as the reactive mode, the energy storage converter can be controlled to perform reactive dispatching and the DC side switch module can be controlled to be disconnected, thereby disconnecting the energy storage battery from the energy storage converter and avoiding long-term operation of the energy storage battery in the reactive mode, so as to prolong the service life of the energy storage battery to a certain extent. BRIEF DESCRIPTION OF DRAWINGS

[0021] Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The detailed description is made with reference to the accompanying drawings.

[0022] Figure 1 is a structural schematic diagram of an energy storage converter according to an embodiment of the present application;

[0023] Figure 2 illustrates a circuit structural schematic diagram of a power system;

[0024] Figure 3 is a flowchart of a control method of a storage converter according to an embodiment of the present application;

[0025] Figure 4 An example of a control process diagram when the active and reactive power of the storage converter is switched is shown.

[0026] Figure 5 A hardware structure block diagram of a control device is shown.

[0027] Reference signs:

[0028] 11 - DC side switch module; 12 - capacitor array; 13 - power conversion circuit; 14 - controller; K1 - battery positive electrode switch element; K2 - battery negative electrode switch element; K3 - slow start switch element; R - slow start resistor; 15 - filter protection module; 16 - AC side switch module; 1 - storage converter; 2 - storage battery; 3 - AC power grid; 51 - processor; 52 - communication interface; 53 - memory; 54 - communication bus. DETAILED DESCRIPTION

[0029] The embodiments of the present application are described below with reference to the accompanying drawings. The terms used in the embodiment part of the present application are only used to explain the specific embodiments of the present application, and are not intended to limit the present application. Those skilled in the art can know that as technology develops and new scenarios appear, the technical solutions provided by the embodiments of the present application are also applicable to similar technical problems.

[0030] The present application provides a storage converter, a control method of storage conversion and a storage system, which can be applied to solve the problem of long-term invalid work of the storage battery in the reactive mode, so as to prolong the service life of the storage battery.

[0031] Figure 1 is a structural diagram of a storage converter according to an embodiment of the present application. As shown in Figure 1 , the storage converter can include a DC side switch module 11, a capacitor array 12, a power conversion circuit 13 and a controller 14.

[0032] Specifically, the power conversion circuit 13 can be used to realize rectification conversion and inversion conversion.

[0033] The DC side switch module 11 is connected to the DC side of the power conversion circuit 13; and the side of the DC side switch module 11 away from the power conversion circuit 13 is used as the DC side of the storage converter for connecting the storage battery. In addition, the DC side switch module 11 is connected to the controller 14 through a signal line and is turned on or turned off under the control of the controller 14.

[0034] The capacitor array 12 is connected between the positive and negative terminals of the DC side of the power conversion circuit 13. It should be noted that the capacitor array 12 can be obtained by combining multiple capacitors; furthermore, in some scenarios, the capacitor array can be replaced by a single capacitor.

[0035] The AC side of the power conversion circuit 13 serves as the AC side of the energy storage converter and is used to connect to the AC power grid.

[0036] The controller 14 is connected via signal lines (such as...) Figure 1 (As shown by the dashed line in the diagram) connects the DC-side switching module 11 and the power conversion circuit 13. The controller 14 can be used to: control the operation of the power conversion circuit 13 and the switching on / off of the DC-side switching module 11; and, when it is determined that the operating mode of the energy storage converter is reactive mode, control the DC-side switching module 11 to disconnect. The reactive mode can refer to a pure reactive mode.

[0037] In addition, the energy storage converter may also include an AC side switching module.

[0038] The AC-side switch module is connected to the AC side of the power conversion circuit 13; and the side of the AC-side switch module furthest from the AC side of the power conversion circuit 13 serves as the AC side of the energy storage converter, used for connecting to the AC power grid. The AC-side switch module can also be connected to the controller 14 via a signal line, and can be turned on or off under the control of the controller 14.

[0039] Based on the above, optionally, the energy storage converter may also include a filter protection module located on the connection line between the AC side and the AC side switching module of the power conversion circuit 13, for filtering and circuit protection.

[0040] In the grid-connected state of the aforementioned energy storage converter, the DC side of the converter is connected to the energy storage battery, and the AC side is connected to the AC power grid. The controller of the energy storage converter can determine the operating mode of the converter based on the received mode commands. If there is a reactive power dispatch requirement, i.e., the operating mode is reactive power mode, the controller of the energy storage converter will control the DC side switching module to disconnect, so that the energy storage converter can perform reactive power dispatch while disconnected from the energy storage battery. For example, the DC power obtained by the power conversion circuit 13 can be used to charge the capacitor array 12, thereby providing reactive power to the AC power grid connected to the AC side of the energy storage converter. Since the DC side switching module is disconnected, the energy storage battery is in a static state, which to a certain extent avoids the low-power charging and discharging of the energy storage battery in reactive power mode, thus extending the service life of the energy storage battery.

[0041] The energy storage converter provided by the embodiments of the present application can be applied to a power system, which can include an energy storage converter, an energy storage battery connected to the DC side of the energy storage converter, and an AC power grid connected to the AC side of the energy storage converter.

[0042] Next, the energy storage converter provided by the embodiments of the present application is exemplarily described in combination with the above power system.

[0043] In one or more embodiments provided by the present application, the controller 14 can also be configured to:

[0044] Before controlling the DC side switch module 11 to be disconnected, the remaining capacity of the energy storage battery is determined, and the energy storage battery is charged when the remaining capacity of the energy storage battery is lower than a preset health threshold.

[0045] The remaining capacity (State Of Charge, SOC) of the energy storage battery can be detected by the energy storage converter, that is, the energy storage converter can further include a detection device for detecting the remaining capacity of the connected energy storage battery, which can be connected to the controller 14 through a signal line to provide the detected remaining capacity of the energy storage battery. The remaining capacity of the energy storage battery can also be directly obtained, such as obtained through a battery management system (Battery Management System, BMS) of the energy storage battery, which is not limited in the present application.

[0046] The health threshold can be a remaining capacity threshold set to avoid over-discharge of the energy storage battery due to long-term static placement. For example, the health threshold can be set to 40%.

[0047] Optionally, the charging of the energy storage battery can be stopped when the remaining capacity of the energy storage battery is equal to the health threshold; or the charging of the energy storage battery can be stopped when the remaining capacity of the energy storage battery is higher than the health threshold, such as higher than the health threshold by a preset value; thereby reducing the possibility of battery depletion caused by long-term static placement.

[0048] The above scheme improves the remaining capacity of the energy storage battery by determining the remaining capacity of the energy storage battery before controlling the DC side switch module to be disconnected, and charging the energy storage battery when the remaining capacity of the energy storage battery is low. By continuously charging the energy storage battery when the remaining capacity of the energy storage battery is lower than the health threshold, it can be ensured that the remaining capacity of the energy storage battery is not lower than the health threshold when the DC side switch module is disconnected, thereby reducing the possibility of the energy storage battery being placed at a low capacity, reducing the risk of the energy storage battery being damaged by depletion, and prolonging the service life of the energy storage battery.

[0049] In one or more embodiments provided by the present application, the controller 14 can also be configured to:

[0050] After the DC side switch module 11 is controlled to be turned off, in response to a received remaining capacity alarm signal for characterizing that the remaining capacity of the energy storage battery is not higher than a preset alarm threshold, the DC side switch module 11 is controlled to be turned on, the energy storage battery is charged until the remaining capacity of the energy storage battery reaches a preset health threshold, and then the DC side switch module 11 is controlled to be turned off.

[0051] The remaining capacity alarm signal can be a signal sent by a battery management system BMS of the energy storage battery when detecting that the remaining capacity of the battery is not higher than the alarm threshold, or a signal sent by other devices, such as an alarm signal sent by a detection device inside the energy storage converter, or an alarm signal generated and sent by the controller 14 based on a detection result of the detection device on the remaining capacity. The application does not limit the source of the remaining capacity alarm signal. The health threshold is greater than the alarm threshold. The alarm threshold can be a remaining capacity threshold set to avoid damage caused by power loss of the energy storage battery. For example, the alarm threshold can be 0%.

[0052] By the above scheme, the low remaining capacity of the energy storage battery can be sensed in time during the reactive power scheduling of the energy storage converter, and corresponding processing can be performed. Specifically, after receiving the remaining capacity alarm signal, the DC side switch module is controlled to be turned on, the connection with the energy storage battery is established, the energy storage battery is charged, the remaining capacity of the energy storage battery is increased to the health threshold, the risk of low battery capacity is reduced, the occurrence of battery damage caused by long-term static is avoided, the DC side switch module is controlled to be turned off, the connection with the energy storage battery is cut off, the invalid work of the energy storage battery connected to the energy storage converter in the reactive power mode is avoided, the battery is protected, the service life of the battery is prolonged, and the frequent control of the DC side switch module can be avoided to a certain extent.

[0053] On the basis of the above scheme, the remaining capacity of the energy storage battery can be judged before the DC side switch module is turned off. If the remaining capacity is lower than the health threshold, the energy storage battery is charged, and the step of controlling the DC side switch module to be turned off is performed when the remaining capacity is not lower than the health threshold. Then, in the process of reactive power scheduling, the energy storage battery with power loss caused by static is charged according to the above scheme.

[0054] In one or more embodiments provided in the application, the controller 14 can also be used to:

[0055] Before the DC side switch module 11 is controlled to be turned off, the active power on the DC side of the power conversion circuit 13 is reduced to a preset low power threshold.

[0056] It should be noted that if the active power on the DC side is high, there may be a large current in the circuit, and the voltage across the energy storage battery may be high. At this time, if the DC side switch module is opened, an arc will be generated, which may damage the DC side switch module. Based on this, in the case of needing to open the DC side switch module, the active power on the DC side can be reduced first to reduce the DC side current, and then the DC side switch module is controlled to be opened, so as to ensure the safety of the system and prolong the service life of the DC side switch module.

[0057] In particular, before the DC side switch module is controlled to be opened, there may be a variety of situations. For example:

[0058] First, the energy storage converter is charging the energy storage battery in the process of reactive power dispatching. In this case, the energy storage battery can be charged with active power that does not affect reactive power dispatching, and the above-mentioned active power that does not affect reactive power dispatching is not higher than the low power threshold.

[0059] Second, after the energy storage converter is successfully connected to the grid with zero power, it is determined that the operating mode is a reactive mode. In this case, the active power on the DC side is zero, and the DC side switch module can be directly controlled to be opened.

[0060] Third, the energy storage converter is switched from an active mode to a reactive mode. In this case, the remaining capacity of the energy storage battery may be high, and the voltage across the energy storage battery is also high. Therefore, the active power on the DC side is first reduced to the low power threshold, and then the DC side switch module 11 is opened. On this basis, if the remaining capacity of the energy storage battery is higher than the health threshold, the energy storage battery can be used to charge the capacitor array to reduce the active power on the DC side. When the remaining capacity tends to or equals the health threshold, the charging of the capacitor array by the energy storage battery is stopped. In particular, if the remaining capacity of the energy storage battery is not higher than the alarm threshold, the energy storage battery can be charged to the health threshold with active power that does not affect reactive power dispatching.

[0061] In one or more embodiments provided in the present application, the controller 14 can also be used to:

[0062] When the operating mode of the energy storage converter is switched from a reactive mode to an active mode, the DC side switch module 11 is controlled to be closed.

[0063] It should be noted that when the energy storage converter operates in a reactive mode, the DC side switch module is opened. In order to realize active power dispatching, it is necessary to close the DC side switch module again. By controlling the DC side switch module to be closed by the above-mentioned scheme, the reconnection of the energy storage battery is realized, and the energy storage battery is converted from a static state to a working state, so that the energy storage converter can perform active power dispatching and provide energy for the AC power grid.

[0064] In one or more embodiments provided in the present application, the controller 14 can also be used to:

[0065] Before controlling the closing of the DC side switch module 11, the voltage deviation between the energy storage battery and the capacitor array 12 is determined, and if the voltage deviation does not meet the preset deviation range, the voltage deviation between the energy storage battery and the capacitor array 12 is reduced.

[0066] It should be noted that before controlling the closing of the DC side switch module, there can be various situations, such as the need to charge the energy storage battery during reactive power scheduling, or the need to accept active power scheduling. The voltage deviation not meeting the preset deviation range can include: the voltage of the energy storage battery is higher than the voltage of the capacitor array by a preset voltage value, or the voltage of the capacitor array is higher than the voltage of the energy storage battery by a preset voltage value. The preset voltage value can be the maximum closing allowable voltage value of the DC side switch module.

[0067] The above scheme can reduce the voltage deviation between the energy storage battery and the capacitor array when the DC side switch module is closed to a certain extent, thereby reducing the possibility of excessive closing impact current, and providing a basis for ensuring the safe and stable operation of the system.

[0068] In one or more embodiments provided in the present application, the energy storage converter can further include a slow-start circuit connected in parallel with the DC side switch module 11.

[0069] It should be noted that the DC side of the power conversion circuit can be connected to the energy storage battery through the closed DC side switch module, or can be connected to the energy storage battery through the conductive slow-start circuit, that is, the slow-start circuit is connected to the DC side of the power conversion circuit, and the side of the slow-start circuit away from the power conversion circuit can be used to connect the energy storage battery.

[0070] In addition, the slow-start circuit can be connected to the controller 14 through a signal line, and the controller 14 can also be used to:

[0071] Control the slow-start circuit to be conductive or disconnected.

[0072] Optionally, the slow-start circuit can include a slow-start switch module and a slow-start resistor. It should be noted that the energy storage battery can be connected to the power conversion circuit through the slow-start resistor and the closed slow-start switch module.

[0073] In a possible implementation, the process of reducing the voltage deviation between the energy storage battery and the capacitor array 12 by the controller 14 can include:

[0074] In a case that the voltage of the energy storage battery is greater than the voltage of the capacitor array, the control device controls the slow closing circuit to be turned on, and controls the slow closing circuit to be turned off after the voltage deviation between the energy storage battery and the capacitor array meets the preset deviation range.

[0075] In a case that the voltage of the energy storage battery is less than the voltage of the capacitor array, the control device controls the power conversion circuit to be inverter, until the voltage deviation between the energy storage battery and the capacitor array meets the preset deviation range.

[0076] It should be noted that the control of the slow closing circuit to be turned on can include the control of the slow closing switch module to be closed, and the control of the slow closing circuit to be turned off can include the control of the slow closing switch module to be opened. Based on this, when the slow closing circuit is turned on, the DC side of the power conversion circuit can be connected to the energy storage battery through the slow closing resistor and the closed slow closing switch module, so as to reduce the closing impact current by the slow closing resistor.

[0077] The above scheme realizes the connection with the energy storage battery by controlling the slow closing circuit to be turned on when the voltage of the energy storage battery is high, so as to charge the capacitor array by the energy storage battery and reduce the voltage of the energy storage battery. In addition, the voltage of the capacitor array is reduced by controlling the power conversion circuit to be inverter and discharging the AC side when the voltage of the capacitor array is high, and the opening and closing actions of the switch module in the slow closing circuit are reduced, which helps to prolong the service life of the slow closing switch module. Finally, the purpose of reducing the voltage deviation between the energy storage battery and the capacitor array is achieved.

[0078] In another possible implementation, the process of reducing the voltage deviation between the energy storage battery and the capacitor array by the controller 14 can include:

[0079] controlling the slow closing circuit to be turned on;

[0080] controlling the slow closing circuit to be turned off after the voltage deviation between the energy storage battery and the capacitor array meets the preset deviation range.

[0081] By the above scheme, the connection with the energy storage battery is realized by turning on the slow closing circuit. On this basis, the energy storage battery can be used to charge the capacitor array when the voltage of the energy storage battery is high, and the capacitor array can be used to charge the energy storage battery when the voltage of the capacitor array is high, so as to reduce the voltage deviation between the energy storage battery and the capacitor array. In addition, the same control scheme is adopted for different situations in the above scheme, which reduces the complexity of the control logic and helps to reduce the error rate. In addition, the description of the slow closing circuit can be referred to the foregoing description.

[0082] Further, the controller 14 can stop reducing the voltage deviation between the energy storage battery and the capacitor array when the voltage deviation between the energy storage battery and the capacitor array meets the preset deviation range during the reduction of the voltage deviation, such as controlling the slow start circuit to be disconnected or controlling the power conversion circuit to stop inverting, so as to quickly respond to the requirement of closing the DC side switch module; in order to further avoid the closing impact and ensure the safety of the system operation, the voltage deviation between the capacitor array of the energy storage battery can be stopped when the voltage deviation between the capacitor array of the energy storage battery tends to or equals to the preset value, wherein the preset value is less than the maximum closing allowable voltage value of the DC side switch module.

[0083] Based on the above, Figure 2 The circuit structure schematic diagram of the power system is illustrated, and the power system can include: Figure 2 As shown, the power system can include: an energy storage converter 1, an energy storage battery 2 connected to the DC side of the energy storage converter 1, and an AC power grid 3 connected to the AC side of the energy storage converter 1. Figure 2 Another circuit structure schematic diagram of the energy storage converter is also illustrated, and the energy storage converter 1 can include:

[0084] a power conversion circuit 13;

[0085] a capacitor array 12 connected between the positive and negative electrodes of the DC side of the power conversion circuit 13;

[0086] a battery positive electrode switch element K1 and a battery negative electrode switch element K2 connected to the DC side of the power conversion circuit 13, wherein the side of the battery positive electrode switch element K1 away from the power conversion circuit 13 is used to connect the positive electrode of the energy storage battery 2, and the side of the battery negative electrode switch element K2 away from the power conversion circuit 13 is used to connect the negative electrode of the energy storage battery 2; a slow start switch element K3 and a slow start resistor R connected in series in parallel with the battery positive electrode switch element K1;

[0087] a filter protection module 15 connected to the AC side of the power conversion circuit 13;

[0088] and an AC side switch module 16 connected to the side of the filter protection module 15 away from the power conversion circuit 13, and the side of the AC side switch module 16 away from the power conversion circuit 13 is used to connect the AC power grid 3.

[0089] Further, the energy storage converter 1 further includes a controller 14 connected to the power conversion circuit 13, the battery positive electrode switch element K1, the battery negative electrode switch element K2, the slow start switch element K3, and the AC side switch module 16 through a signal line.

[0090] It should be noted that the battery positive switch element K1 and the battery negative switch element K2 can constitute a direct current side switch module. The slow start switch element K3 and the battery negative switch element K2 can constitute a slow start switch module, that is, the slow start switch module can share the switch element connected to the negative pole of the battery with the direct current side switch module, so as to reduce the circuit complexity and save elements; alternatively, a switch element connected in parallel with the battery negative switch element can be provided, and the slow start switch module is constituted by the element and the slow start switch element. In addition, the slow start switch module and the slow start resistor R can constitute a slow start circuit.

[0091] On the basis of the above, the process of controlling the direct current side switch module to be closed (or opened) can include: controlling the battery positive switch element K1 and the battery negative switch element K2 to be closed (or opened); the process of controlling the slow start circuit to be turned on (or turned off) can include: controlling the slow start switch element K3 and the battery negative switch element K2 to be closed (or opened).

[0092] Alternatively, the description of each module constituting the energy storage converter 1 can refer to the description above, and will not be repeated here. In addition, the battery positive switch element K1, the battery negative switch element K2 and the slow start switch element K3 can be contactors or other switch elements; the alternating current side switch module 16 can be a relay or other switch element.

[0093] Next, the control method of the energy storage converter provided by the embodiment of the present application will be described. The control method of the energy storage converter described below can be mutually corresponding to the energy storage converter described above. The control method can be used to control the energy storage converter to realize the active and reactive switching of the energy storage converter. The energy storage converter can include: a power conversion circuit, a direct current side switch module connected between the direct current side of the power conversion circuit and the direct current side of the energy storage battery, and a capacitor array connected between the positive and negative poles of the direct current side of the power conversion circuit. In addition, the alternating current side of the power conversion circuit is connected to an alternating current power grid. Alternatively, the method can be implemented by a controller in the energy storage converter, or can be implemented by other control devices, which is not limited by the present application.

[0094] Figure 3 is a flow diagram of a control method of an energy storage converter according to an embodiment of the present application. As shown in Figure 3 The method can include the following steps:

[0095] Step S101, according to the received mode instruction, determine the operation mode of the energy storage converter.

[0096] The mode instruction can be an active and reactive instruction value, and the active and reactive instruction value can be used to determine the current operation mode, which can include a pure active mode, an active and reactive mode, and a pure reactive mode. For example, when the active instruction value is zero, the operation mode of the energy storage converter is the pure reactive mode, i.e., the reactive mode described in the present application. It should be noted that when the reactive dispatch task is implemented, there are various control methods. For example, the reactive power can be automatically adjusted according to the voltage, i.e., the reactive mode can be a Q(U) mode.

[0097] In step S102, when it is determined that the operation mode is the reactive mode, the reactive dispatch is performed, and the DC side switch module is controlled to be disconnected.

[0098] The above-mentioned reactive dispatch can include charging the capacitor array with the DC power obtained by rectifying the power conversion circuit to provide reactive compensation for the AC power grid. That is, the above-mentioned scheme realizes the reactive dispatch task without adding additional hardware circuits (such as rectification circuits), and the hardware cost and circuit maintenance cost for realizing the reactive regulation are also low.

[0099] It should be noted that if the DC side switch module is in the closed state in the reactive mode, there will inevitably be a small power charging and discharging of the energy storage battery. The reasons can be that there is a voltage deviation between the energy storage battery and the capacitor array, there is a voltage deviation between the batteries connected in parallel inside the energy storage battery, there is a line impedance, and there is an influence of the software control strategy, etc. That is, the energy storage battery will be in a working state for a long time, and the possibility of invalid work is high.

[0100] Based on this, the above-mentioned method disconnects the connection between the energy storage converter and the energy storage battery by disconnecting the DC side switch module during the reactive regulation, so that the energy storage battery can be in a resting state and does not need to work for a long time, avoiding the occurrence of small power charging and discharging of the energy storage battery in the reactive mode, and prolonging the service life of the energy storage battery.

[0101] In one or more embodiments provided in the present application, the determination of the operation mode as the reactive mode can include:

[0102] After the energy storage converter is connected to the grid with zero power, and the grid connection is successful, the operation mode is determined as the reactive mode according to the received mode instruction.

[0103] It should be noted that when the energy storage converter is started, the control mode of first starting and then judging the operation mode can be adopted, and the energy storage converter can be controlled to connect to the grid with zero power at the time of starting, at which time the DC side switch module is closed, and the energy storage battery can charge the capacitor array through the closed DC side switch module; after successful connection to the grid, the operation mode is judged, and it is determined whether the operation mode is the PQ mode or the Q(U) mode, wherein the PQ mode can refer to the active and reactive power mode; if it is determined according to the received mode instruction that the operation mode is the reactive power mode, reactive power dispatching is performed and the DC side switch module is controlled to be opened, it should be noted that before the DC side switch module is controlled to be opened, the active power on the DC side of the active power converter circuit is zero, and then the energy storage converter performs reactive power dispatching in the state that the DC side switch module is opened; if it is determined according to the received mode instruction that the operation mode is the active power mode, active power dispatching is performed.

[0104] In another possible implementation, when the energy storage converter is started, the operation mode can also be judged before starting, based on which, when it is determined that the operation mode is the reactive power mode, the control mode of AC side starting and grid connection is adopted, and when it is determined that the operation mode is the active power mode, the control mode of DC side starting and grid connection is adopted.

[0105] In one or more embodiments provided in the present application, the above-mentioned determination of the operation mode as the reactive power mode can include:

[0106] The operation mode is determined to be switched from the active power mode to the reactive power mode.

[0107] That is, the energy storage converter runs in the active power mode, the DC side switch module is closed, and the connection line between the energy storage battery and the capacitor array is conductive, so when it is determined according to the received mode instruction that the operation mode is the reactive power mode and the energy storage converter needs to be switched to the reactive power mode to receive reactive power dispatching, the DC side switch module needs to be controlled to be opened to avoid long-term invalid work of the energy storage battery.

[0108] In one or more embodiments provided in the present application, before the DC side switch module is controlled to be opened, steps A-B below can also be included:

[0109] Step A, judging the remaining capacity of the energy storage battery.

[0110] The description of the remaining capacity and its acquisition method can be referred to the foregoing description, which will not be repeated here. Step A specifically compares the remaining capacity of the energy storage battery with a preset health threshold, and the description of the health threshold can be referred to the foregoing; if the remaining capacity of the energy storage battery is not lower than the health threshold, it indicates that the remaining capacity requirement is met, and the step of controlling the DC side switch module to be opened is performed; if the remaining capacity of the energy storage battery is lower than the health threshold, it indicates that the remaining capacity requirement is not met, and step B is performed.

[0111] Step B, charging the energy storage battery.

[0112] It should be noted that when the energy storage battery is in a low power range, such as below the health threshold, the risk of over-discharge of the energy storage battery decreases as the remaining power increases. Based on this, compared to not charging, the above method can increase the remaining power of the energy storage battery that is about to be in a stationary state by charging the energy storage battery, thereby reducing the risk of over-discharge of the energy storage battery to some extent.

[0113] On this basis, to meet the remaining power requirement, the charging of the energy storage battery in step B can be charging the energy storage battery when the remaining power of the energy storage battery is below the health threshold.

[0114] In one possible implementation, after performing the above step B, it can return to step A, thereby achieving the purpose of increasing the remaining power of the energy storage battery to at least the health threshold before the DC side switch module is controlled to be disconnected, to meet the remaining power requirement of the energy storage battery, ensure the health status of the energy storage battery, and provide a basis for prolonging the service life of the battery.

[0115] In combination with the above, Figure 4 An example of a control process diagram of an energy storage converter when active and reactive power switching is shown, in combination with Figure 4 The process can include:

[0116] After the operating mode is switched to the reactive mode, the first step is performed;

[0117] The first step is to determine the remaining power of the energy storage battery; if the remaining power of the energy storage battery does not meet the remaining power requirement, the second step is performed; if it meets the remaining power requirement, the third step is performed;

[0118] The second step is to charge the energy storage battery, and return to perform the first step;

[0119] The third step is to control the DC side switch module to be disconnected;

[0120] The fourth step is to operate in the reactive mode under the condition that the DC side switch module is disconnected.

[0121] It should be noted that after the operating mode is switched to the reactive mode, the energy storage converter starts to receive reactive dispatching control to perform reactive power adjustment, at which time the energy storage battery or the AC side can be used to charge the capacitor array; when the remaining power of the energy storage battery does not meet the requirement, the energy storage battery needs to be charged while performing reactive power adjustment; to avoid affecting the reactive power adjustment, the energy storage battery can be charged under the condition that the reactive power requirement is met; after the DC side switch module is disconnected, the energy storage converter will be used as a reactive power compensation device to receive grid dispatching and charge the capacitor array using the AC side.

[0122] In one or more embodiments provided in the present application, after the step of controlling the DC side switch module to be opened, the following steps C-E can be further included:

[0123] Step C, in response to the received remaining power alarm signal, controlling the DC side switch module to be closed.

[0124] The remaining power alarm signal can be used to represent that the remaining power of the energy storage battery is not higher than a preset alarm threshold. Optionally, the signal can be a signal sent by the energy storage battery BMS when detecting that the remaining power of the energy storage battery is not higher than the alarm threshold, i.e., the alarm threshold can be set by the energy storage battery BMS. Receiving the remaining power alarm signal can represent that the risk of over-discharge of the energy storage battery is high, and the DC side switch module needs to be closed to access the energy storage battery and charge the energy storage battery.

[0125] In another possible implementation, the detection result of the remaining power of the energy storage battery can also be obtained in the reactive operation, and the DC side switch module can be controlled to be closed when the detection result is not higher than the alarm threshold. Optionally, the above-mentioned detection result can be detected by a detection device inside the energy storage converter, or can be detected by the energy storage battery BMS.

[0126] Step D, charging the energy storage battery until the remaining power of the energy storage battery reaches a preset health threshold.

[0127] The health threshold is greater than the alarm threshold. For example, during the process of reactive adjustment of the energy storage converter, if the DC side switch module is opened, the energy storage converter can operate in Q(U) mode, and if the DC side switch module is closed, the energy storage converter can be switched from Q(U) mode to PQ mode to charge the energy storage battery.

[0128] By raising the remaining power of the energy storage battery to the health threshold, it can be ensured that the energy storage battery is in a healthy state. In addition, the descriptions of the alarm threshold and the health threshold can be referred to the above, which will not be repeated here.

[0129] Step E, controlling the DC side switch module to be opened.

[0130] By the above scheme, after the DC side switch module is disconnected, the situation that the remaining power of the energy storage battery is not higher than the preset alarm threshold can be learned in time through the remaining power alarm signal, and the energy storage battery is reconnected by controlling the DC side switch module to be closed, and then the energy storage battery is charged, the remaining power of the energy storage battery is improved, the risk of over-discharge of the energy storage battery is reduced, and thus the battery power loss protection task can be achieved, the battery life can be prolonged, and then the DC side switch module is controlled to be disconnected after the remaining power is improved to at least the health threshold, so as to cut off the connection with the energy storage battery, thereby avoiding long-term small power charging and discharging of the energy storage battery in the reactive mode, and further prolonging the battery life.

[0131] In one or more embodiments provided in the present application, the above charging of the energy storage battery can include:

[0132] Charging the energy storage battery with active power that does not affect the performed reactive dispatch.

[0133] In the case where it is determined according to the mode instruction that the operation mode of the energy storage converter is the reactive mode, if the remaining power of the energy storage battery is low and needs to be charged, the DC side switch module is controlled to be closed if it is disconnected, and then the energy storage converter is controlled to perform active dispatch to charge the energy storage battery. Since the energy storage converter is also subjected to the reactive dispatch of the system when charging the energy storage battery, based on this, the charging of the energy storage battery with active power that does not affect the performed reactive dispatch can avoid affecting the reactive regulation process of the energy storage converter, thereby meeting the reactive dispatch requirement of the system and achieving the battery charging task under the premise of meeting the reactive power.

[0134] In one or more embodiments provided in the present application, before the DC side switch module is controlled to be disconnected, the following steps can also be included:

[0135] Step F, judging the DC side active power of the power conversion circuit.

[0136] The judgment in step F is specifically whether the DC side active power of the power conversion circuit is higher than a preset low power threshold; if not, it can be represented that the current in the line is small, and then the step of controlling the DC side switch module to be disconnected is performed; if it is higher than the low power threshold, it can be represented that the condition for directly disconnecting the DC side switch module is not met, and then step G is performed. The low power threshold can be a preset active power threshold for ensuring system safety, and its specific value can be set according to factors such as the insulation quality, arc extinguishing capacity of the DC side switch module, current and voltage level in the system, and the like. For example, the low power threshold can tend to or equal to zero.

[0137] Step G, reducing the active power on the DC side of the power conversion circuit.

[0138] Then the step of controlling the DC side switch module to be open is performed. For example, the step of controlling the DC side switch module to be open is performed after the active power on the DC side of the power conversion circuit is reduced to be not higher than the low power threshold.

[0139] The above scheme can make the active power on the DC side be low when the DC side switch module is open, thereby reducing the risk of arc generation, increasing the operation safety of the system to a certain extent, and helping to prolong the service life of the DC side switch module.

[0140] In combination with the above, it should be noted that step F can be performed after it is determined that the remaining capacity of the energy storage battery is not lower than the health threshold, to judge the active power on the DC side, so as to avoid arc generation when the DC side switch module is open, thereby ensuring system safety. In particular, if the active power on the DC side is higher than the low power threshold and the remaining capacity of the energy storage battery is high, such as higher than the health threshold, the energy storage battery can also be used to charge the capacitor array to reduce the active power on the DC side. In addition, in the case where it is determined that the remaining capacity of the energy storage battery is not higher than the alarm threshold, in addition to performing step F, the active power for charging the energy storage battery can also be controlled to avoid arc hazards, such as charging the energy storage battery with active power that does not affect reactive power dispatching, wherein the active power that does not affect reactive power dispatching can be not higher than the low power threshold. Based on this, after completing the charging of the energy storage battery, the step of controlling the DC side switch module to be open can be directly performed.

[0141] In one or more embodiments provided in the present application, the control method of the energy storage converter can further include:

[0142] When the operating mode of the energy storage converter is switched from the reactive mode to the active mode, the DC side switch module is controlled to be closed.

[0143] The above step of controlling the DC side switch module to be closed realizes the reconnection of the energy storage battery, and the energy storage battery is converted from a static state to a working state, so that the energy storage converter performs active dispatching to provide energy for the AC power grid.

[0144] In one or more embodiments provided in the present application, before the DC side switch module is controlled to be closed, the following step can be further included:

[0145] Step H, judging the voltage deviation between the energy storage battery and the capacitor array.

[0146] Specifically, it is judged whether the voltage deviation between the energy storage battery and the capacitor array satisfies a preset deviation range. If the voltage deviation does not satisfy the preset deviation range, that is, the voltage of the energy storage battery is higher than the voltage of the capacitor array by a preset voltage value, or the voltage of the capacitor array is higher than the voltage of the energy storage battery by a preset voltage value, step I is performed; otherwise, it is indicated that the DC side closing condition is satisfied, and the step of controlling the DC side switch module to be closed can be directly performed.

[0147] Step I, reducing the voltage deviation between the energy storage battery and the capacitor array.

[0148] By the above steps, the voltage deviation between the energy storage battery and the capacitor array can be reduced, the closing impact current is reduced, the system operation safety is ensured to a certain extent, and the possibility of damaging the DC side switch module is reduced.

[0149] In one or more embodiments provided in the application, the energy storage converter can further include a slow start circuit connected to the energy storage battery and the DC side of the power conversion circuit, that is, the slow start circuit is connected to the energy storage battery away from the power conversion circuit.

[0150] Optionally, the slow start circuit and the DC side switch module can be refined as described above.

[0151] In a possible implementation, the step I of reducing the voltage deviation between the energy storage battery and the capacitor array can include steps J-K as follows:

[0152] Step J, controlling the slow start circuit to be turned on.

[0153] It should be noted that the slow start circuit includes a slow start resistor, and the voltage division effect of the resistor can reduce the impact current during closing. On this basis, the slow start circuit is connected to the energy storage battery by being turned on, so as to balance the voltage of the energy storage battery and the voltage of the capacitor array through the charging operation.

[0154] Step K, after the voltage deviation between the energy storage battery and the capacitor array satisfies the preset deviation range, controlling the slow start circuit to be turned off.

[0155] The above steps achieve the connection with the energy storage battery by turning on the slow start circuit, and relieve the closing impact. Then, the charging operation or the discharging operation of the energy storage battery is achieved by turning on the slow start circuit, and the voltage deviation between the energy storage battery and the capacitor array is reduced. In addition, the slow start circuit is controlled to be turned off when the voltage deviation satisfies the preset deviation range, which provides a basis for responding to active scheduling as soon as possible.

[0156] Optionally, if the DC side switch module is controlled to be closed in order to increase the remaining power of the energy storage battery, the energy storage battery can also be supplied with power by the conduction of the slow start circuit.

[0157] In another possible implementation, the step I of reducing the voltage deviation between the energy storage battery and the capacitor array can include steps L-N as follows:

[0158] Step L, judging the voltage of the energy storage battery and the capacitor array; if the voltage of the energy storage battery is greater than the voltage of the capacitor array, performing step M; if the voltage of the energy storage battery is less than the voltage of the capacitor array, performing step N.

[0159] Step M, controlling the slow start circuit to be conducted and closed, and after the voltage deviation between the energy storage battery and the capacitor array meets the preset deviation range, controlling the slow start circuit to be disconnected.

[0160] Step N, controlling the power conversion circuit to be inverter, until the voltage deviation between the energy storage battery and the capacitor array meets the preset deviation range.

[0161] The above scheme reduces the voltage of the energy storage battery and the voltage deviation by conducting the slow start circuit to charge the capacitor array when the voltage of the energy storage battery is high, and reduces the voltage of the capacitor array by controlling the power conversion circuit to be inverter to discharge the AC side when the voltage of the capacitor array is high, thereby achieving the purpose of reducing the voltage deviation between the energy storage battery and the capacitor array.

[0162] The control method of the energy storage converter provided in the embodiments of the present application can be implemented by a control device with data processing capability. Optionally, Figure 5 A hardware structure block diagram of a control device is shown, referring to Figure 5 The hardware structure of the control device can include at least one processor 51, at least one communication interface 52, at least one memory 53 and at least one communication bus 54.

[0163] In the embodiments of the present application, the number of the processor 51, the communication interface 52, the memory 53 and the communication bus 54 is at least one, and the processor 51, the communication interface 52 and the memory 53 complete communication with each other through the communication bus 54.

[0164] The processor 51 can be a central processing unit CPU, or a specific integrated circuit ASIC (Application Specific Integrated Circuit), or one or more integrated circuits configured to implement the embodiments of the present application, etc.

[0165] The memory 53 can include a high-speed RAM memory and can also include a non-volatile memory such as at least one disk memory;

[0166] The memory is configured to store a computer program, and the processor is configured to execute the computer program, so that the control device is capable of implementing any of the control methods of the energy storage converter.

[0167] Optionally, the control device can be a controller in the energy storage converter.

[0168] The embodiments of the present application further provide an energy storage system, which can include an energy storage converter, and an energy storage battery connected to the energy storage converter.

[0169] Specifically, the energy storage converter can include a power conversion circuit, a direct current side switch module connected to the direct current side of the power conversion circuit and the direct current side of the energy storage battery, a capacitor array connected between the positive and negative poles of the direct current side of the power conversion circuit, and a controller.

[0170] The alternating current side of the power conversion circuit can be configured to be connected to an alternating current power grid, and the controller can be configured to implement any of the control methods of the energy storage converter.

[0171] Optionally, the refinements and additional descriptions of the energy storage converter and the controller can refer to the above.

[0172] The embodiments of the present application further provide a storage medium carrying one or more computer programs, which can enable an electronic device to implement any of the control methods of the energy storage converter provided by the embodiments of the present application when the one or more computer programs are executed by the electronic device.

[0173] The embodiments of the present application further provide a computer program product including computer readable instructions, which can enable an electronic device to implement any of the control methods of the energy storage converter provided by the embodiments of the present application when the computer readable instructions are run on the electronic device.

[0174] Finally, it should be noted that, in the description above, relational terms such as first and second, and the like can be used solely to distinguish one from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by "comprises... a" does not, without more constraints, exclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element.

[0175] In the description above, each of the embodiments is focused on the difference from other embodiments, and each of the embodiments can be combined as needed, and the same or similar parts are referred to each other.

[0176] The above description of disclosed embodiments enables a person skilled in the art to implement or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An energy storage converter, characterized in that, include: DC-side switching module, capacitor array, power conversion circuit, and controller; among which, The DC-side switching module is connected to the DC side of the power conversion circuit; the side of the DC-side switching module away from the power conversion circuit serves as the DC side of the energy storage converter, used to connect the energy storage battery. The capacitor array is connected between the positive and negative terminals of the DC side of the power conversion circuit; The AC side of the power conversion circuit serves as the AC side of the energy storage converter, and is used to connect to the AC power grid. The controller is used to: control the operation of the power conversion circuit and the switching on and off of the DC-side switching module; and, when it is determined that the operating mode of the energy storage converter is reactive mode, control the DC-side switching module to disconnect.

2. The energy storage converter according to claim 1, characterized in that, The controller is also used for: Before the DC-side switch module is disconnected, the remaining power of the energy storage battery is determined, and the energy storage battery is charged if the remaining power of the energy storage battery is lower than a preset health threshold.

3. The energy storage converter according to claim 1, characterized in that, The controller is also used for: After the DC-side switch module is opened, in response to the received residual power alarm signal indicating that the residual power of the energy storage battery is not higher than a preset alarm threshold, the DC-side switch module is closed to charge the energy storage battery until the residual power of the energy storage battery reaches a preset health threshold, and then the DC-side switch module is opened; the health threshold is greater than the alarm threshold.

4. The energy storage converter according to any one of claims 1-3, characterized in that, The controller is also used for: Before the DC-side switching module is disconnected, the active power on the DC side of the power conversion circuit is reduced to a preset low power threshold.

5. The energy storage converter according to claim 1, characterized in that, The controller is also used to: control the DC side switch module to close when the operating mode of the energy storage converter switches from reactive mode to active mode.

6. The energy storage converter according to claim 3 or 5, characterized in that, The controller is also used for: Before controlling the DC-side switch module to close, the voltage deviation between the energy storage battery and the capacitor array is determined, and if the voltage deviation does not meet the preset deviation range, the voltage deviation between the energy storage battery and the capacitor array is reduced.

7. The energy storage converter according to claim 6, characterized in that, The energy storage converter also includes a soft-start circuit connected in parallel with the DC-side switching module; The controller is also used to control the soft-start circuit to be turned on or off.

8. The energy storage converter according to claim 7, characterized in that, The process by which the controller reduces the voltage deviation between the energy storage battery and the capacitor array includes: Control the activation of the soft-start circuit; Once the voltage deviation between the energy storage battery and the capacitor array meets the preset deviation range, the soft-start circuit is controlled to disconnect.

9. The energy storage converter according to claim 7, characterized in that, The process by which the controller reduces the voltage deviation between the energy storage battery and the capacitor array includes: When the voltage of the energy storage battery is greater than the voltage of the capacitor array, the soft-start circuit is turned on; after the voltage deviation between the energy storage battery and the capacitor array meets the preset deviation range, the soft-start circuit is turned off. When the voltage of the energy storage battery is less than the voltage of the capacitor array, the power conversion circuit is controlled to invert until the voltage deviation between the energy storage battery and the capacitor array meets the preset deviation range.

10. A control method for an energy storage converter, characterized in that, The energy storage converter includes: a power conversion circuit, a DC-side switching module connecting the DC side of the power conversion circuit and the energy storage battery, and a capacitor array connected between the positive and negative terminals of the DC side of the power conversion circuit; and the AC side of the power conversion circuit is connected to the AC power grid; the method includes: The operating mode of the energy storage converter is determined based on the received mode command; When the operating mode is determined to be reactive mode, reactive power scheduling is performed, and the DC-side switching module is controlled to disconnect.

11. The control method for the energy storage converter according to claim 10, characterized in that, Before the DC-side switching module is disconnected, the following is also included: Determine the remaining power of the energy storage battery; If the remaining power of the energy storage battery is lower than a preset health threshold, the energy storage battery will be charged.

12. The control method for the energy storage converter according to claim 10, characterized in that, After the DC-side switch module is disconnected, the following steps are also included: In response to the received remaining power alarm signal, the DC side switch module is controlled to close; wherein, the remaining power alarm signal is used to indicate that the remaining power of the energy storage battery is not higher than a preset alarm threshold; The energy storage battery is charged until the remaining power of the energy storage battery reaches a preset health threshold; wherein the health threshold is greater than the alarm threshold. The DC-side switch module is disconnected.

13. The control method for the energy storage converter according to claim 11 or 12, characterized in that, Charging the energy storage battery includes: The energy storage battery is charged with active power that does not affect the reactive power dispatch being performed.

14. The control method for the energy storage converter according to any one of claims 10-12, characterized in that, Before the DC-side switching module is disconnected, the following is also included: Determine the active power on the DC side of the power conversion circuit; If the active power on the DC side is higher than the preset low power threshold, the active power on the DC side is reduced.

15. The control method for the energy storage converter according to any one of claims 10-12, characterized in that, Determining the operating mode as reactive power mode includes: After the energy storage converter is started and connected to the grid at zero power and the grid connection is successful, the operating mode is determined to be reactive power mode based on the received mode command; or, The operating mode is determined to switch from active mode to reactive mode.

16. The control method for the energy storage converter according to claim 10, characterized in that, The method also includes: When the operating mode of the energy storage converter switches from reactive mode to active mode, the DC side switch module is controlled to close.

17. The control method for the energy storage converter according to claim 12 or 16, characterized in that, Before controlling the DC-side switch module to close, the following is also included: Determine the voltage deviation between the energy storage battery and the capacitor array; If the voltage deviation does not meet the preset deviation range, the voltage deviation between the energy storage battery and the capacitor array is reduced.

18. The control method for the energy storage converter according to claim 17, characterized in that, The energy storage converter also includes a soft-start circuit on the DC side connecting the energy storage battery and the power conversion circuit.

19. The control method for the energy storage converter according to claim 18, characterized in that, Reducing the voltage deviation between the energy storage battery and the capacitor array includes: Control the opening and closing of the soft-start circuit; Once the voltage deviation between the energy storage battery and the capacitor array meets the preset deviation range, the soft-start circuit is controlled to disconnect.

20. The control method for the energy storage converter according to claim 18, characterized in that, Reducing the voltage deviation between the energy storage battery and the capacitor array includes: Determine the voltage levels of the energy storage battery and the capacitor array; If the voltage of the energy storage battery is greater than the voltage of the capacitor array, the soft-start circuit is controlled to close. After the voltage deviation between the energy storage battery and the capacitor array meets the preset deviation range, the soft-start circuit is controlled to open. If the voltage of the energy storage battery is less than the voltage of the capacitor array, the power conversion circuit is controlled to invert until the voltage deviation between the energy storage battery and the capacitor array meets the preset deviation range.

21. An energy storage system, characterized in that, include: An energy storage converter, and an energy storage battery connected to the energy storage converter; The energy storage converter includes: A power conversion circuit, wherein the AC side of the power conversion circuit is used to connect to an AC power grid; A switching module that connects the DC side of the power conversion circuit and the DC side of the energy storage battery; A capacitor array connected between the positive and negative terminals of the DC side of the power conversion circuit; And a controller, the controller being used to implement the control method for the energy storage converter as described in any one of claims 10-20.

Images