Energy storage system and control method
By designing power-taking units and auxiliary power supplies in the energy storage system, we ensure that there is no branch circuit between the battery cluster and the PCS, and solve the problem of inaccurate SOC calculation caused by the power-taking branch circuit between the sampling sensor and the battery cluster, and realize the accuracy of the SOC calculation of the battery cluster and the timely recharge of the battery, avoiding the risks of overcharge and overdischarge and battery damage.
Patent Information
- Application Number
- CN202411693139.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-25
- Publication Date
- 2025-02-28
AI Technical Summary
In the PCS design with integrated high-voltage box function, there is a power-taking branch circuit between the sampling sensor and the battery cluster, which causes the battery current generated by the partial current of the PCS to be inconsistent with the actual battery current, resulting in inaccurate calculation of the SOC of the battery cluster, which in turn causes the risk of overcharge and overdischarge.
Design an energy storage system to collect power from the power grid through the power supply unit for AC isolation conversion and rectification, output DC current to charge the auxiliary power supply, ensure that there is no branch circuit between the battery cluster and the PCS, and ensure that the battery current collected by the sampling sensor is consistent with the actual battery current.
Ensure the accuracy of the SOC calculation of the battery cluster, avoid the risk of overcharge and overdischarge caused by inaccurate SOC calculation, and realize timely recharge of the battery cluster through the recharge control unit to avoid battery damage.
Smart Images
Figure CN119543254A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of electrical equipment, and in particular to an energy storage system and a control method. Background Art
[0002] The energy storage system includes battery packs, power conversion system (PCS), energy storage high-voltage box and other parts. The energy storage high-voltage box is a high-voltage circuit management module connecting the battery cluster and PCS. It has a battery control unit (BCU), shunt, contactor, etc., which can perform corresponding battery protection and disconnect battery power supply according to needs. Common solutions include Figure 1 As shown in the figure, some functions of the high-voltage box overlap with those of the PCS, which will bring additional costs and volume.
[0003] In recent years, some manufacturers have proposed a solution for PCS integrated high-voltage box. Figure 2 As shown in the figure, the battery control unit, shunt, contactor and other functions are integrated into the PCS. The PCS with integrated high-voltage box function saves the cables, communication lines, redundant contactors, etc. in the connection part, which not only saves cost and volume, but also improves communication quality and shortens response time. The PCS with integrated high-voltage box function is widely used.
[0004] However, when designing an energy storage system using a PCS with integrated high-voltage box function, sampling sensors such as shunts are already integrated into the PCS. If the auxiliary power supply of the energy storage system equipment is drawn from the battery, it is inevitable that power will be drawn from the sampling sensors inside the PCS and between the battery clusters, such as Figure 2 As shown, there is a power-taking branch circuit between the sampling sensor and the battery, which is not a completely series relationship. Therefore, the battery current sampled by the shunt inside the PCS is inconsistent with the actual battery current, and there is a phenomenon of "power stealing" in the branch circuit. The calculation of the remaining capacity (State Of Charge, SOC) of the battery cluster is highly dependent on the accuracy of battery current sampling. If this situation continues for a long time, the calculation deviation of the battery cluster SOC will become larger and larger, and the battery cluster SOC will be inaccurately calculated, which will lead to the danger of overcharging and over-discharging. Summary of the invention
[0005] In view of this, the present invention provides an energy storage system and a control method to solve the technical problem that the battery current sampled by the shunt in a PCS with integrated high-voltage box function is different from the actual battery current, and the SOC calculation of the battery cluster is inaccurate, resulting in the danger of overcharging and over-discharging.
[0006] The technical solution proposed by the present invention is as follows:
[0007] A first aspect of the present invention provides an energy storage system, comprising a battery cluster and an energy storage inverter, wherein the energy storage inverter integrates a high-voltage box function, and the energy storage system also comprises a power extraction unit and an auxiliary power supply; the input end of the power extraction unit is connected to an AC power grid, and the output end of the power extraction unit is connected to the input end of the auxiliary power supply, for performing AC isolation conversion and rectification on the AC current of the AC power grid to output a DC current; the output end of the auxiliary power supply is connected to a device in the energy storage system, for converting the DC current output by the power extraction unit into a DC voltage required for the operation of the device in the energy storage system, and for powering the device in the energy storage system.
[0008] Optionally, the energy storage system also includes a power replenishment control unit, one end of which is connected to the output end of the power taking unit, and the other end of which is connected to the battery cluster, for charging the battery cluster through the direct current output by the power taking unit when the remaining power of the battery cluster is lower than a set value.
[0009] Optionally, the power supply unit includes an isolation transformer circuit and a rectifier circuit, the input end of the isolation transformer circuit is connected to the AC power grid, the output end of the isolation transformer circuit is connected to the input end of the rectifier circuit, and the output end of the rectifier circuit is respectively connected to the input end of the auxiliary power supply and one end of the power compensation control unit.
[0010] Optionally, the isolation transformer circuit includes an isolation transformer, a primary side of the isolation transformer is connected to an AC power grid, and a secondary side of the isolation transformer is connected to an input end of the rectifier circuit.
[0011] Optionally, the rectifier circuit includes a rectifier element and a voltage stabilizing filter capacitor, the positive electrode of the rectifier element is connected to an output end of the isolation transformer circuit, the negative electrode of the rectifier element is connected to one end of the voltage stabilizing filter capacitor, and the other end of the voltage stabilizing filter capacitor is connected to another output end of the isolation transformer circuit.
[0012] Optionally, the rectifying element is a rectifying bridge or a diode.
[0013] Optionally, the power replenishment control unit includes a switch device and a current limiting resistor, one end of the switch device is connected to the battery cluster, the other end of the switch device is connected to the current limiting resistor, and the other end of the current limiting resistor is connected to the output end of the power taking unit.
[0014] Optionally, the isolation transformer adopts a single-winding isolation transformer; or the isolation transformer adopts a multi-winding isolation transformer, the number of secondary windings of the multi-winding isolation transformer, the number of the rectifier circuits, the number of the power compensation control units and the number of battery packs in the battery cluster are the same, and each secondary winding of the multi-winding isolation transformer is connected to the corresponding rectifier circuit, the power compensation control unit and the battery pack in sequence.
[0015] Optionally, one end of the energy storage inverter is connected to the battery cluster, and the other end is connected to the AC power grid, and is used to convert the DC input of the battery cluster into AC output and then connect the AC output to the AC power grid, and collect the battery current of the battery cluster through a sampling sensor, and manage the charging and discharging of the battery cluster according to the battery current.
[0016] Optionally, the energy storage inverter includes a PCS control board with an integrated battery control unit, and a DCEMI filter, a sampling sensor, a DC contactor, a pre-charging circuit, a bidirectional DCAC converter, an AC filter, an AC relay and an ACEMI filter connected in sequence between the battery cluster and the AC power grid. The PCS control board controls the opening and closing of the DC contactor according to the battery current of the battery cluster collected by the sampling sensor, and manages the charging and discharging of the battery cluster.
[0017] The second aspect of the present invention provides a control method for an energy storage system, which is applied to the energy storage system as described in the first aspect, including: converting the DC current output by the power taking unit into the DC voltage required for the operation of the equipment in the energy storage system through an auxiliary power supply, and supplying power to the equipment in the energy storage system; judging whether the remaining power of the battery cluster is lower than a set value, when the remaining power of the battery cluster is lower than the set value, controlling the DC current output by the power taking unit to charge the battery cluster through a power supplement control unit; when the remaining power of the battery cluster is higher than or equal to the set value, charging the battery cluster through an energy storage inverter.
[0018] It can be seen from the above technical solutions that the present invention has the following advantages:
[0019] The present invention provides an energy storage system and control method, which draws power from a power grid through a power taking unit, performs AC isolation conversion and rectification, and then outputs a DC current to charge an auxiliary power supply. The auxiliary power supply converts the DC current output by the power taking unit into a DC voltage required for the operation of equipment in the energy storage system, and supplies power to the equipment in the energy storage system. Even if the sampling sensor is integrated inside the OCS, since there is no branch circuit between the battery cluster and the PCS for power drawing, the battery current collected by the sampling sensor inside the PCS is consistent with the actual battery current, thereby ensuring the accuracy of the battery cluster SOC calculation and avoiding the risk of overcharging and over-discharging caused by inaccurate SOC calculation of the battery cluster.
[0020] At the same time, the charging control unit controls whether to recharge the battery cluster, which facilitates timely charging of the battery during operation and maintenance to avoid battery damage. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] In order to more clearly express the technical solutions of the embodiments of the present invention, the drawings required for describing the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.
[0022] Figure 1 It is a structural schematic diagram of an energy storage system in the related technology of the present invention;
[0023] Figure 2 It is a structural schematic diagram of another energy storage system in the related technology of the present invention;
[0024] Figure 3 This is a schematic diagram of the structure of an energy storage system in an embodiment of the present invention;
[0025] Figure 4 Schematic diagram of the structure of another energy storage system in an embodiment of the present invention. DETAILED DESCRIPTION
[0026] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0027] In the description of the present invention, it should be noted that the terms "inside", "outside", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.
[0028] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, it can also be the internal connection of two elements, it can be a wireless connection, or it can be a wired connection. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.
[0029] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.
[0030] At present, there are two problems when designing energy storage systems using PCS with integrated high-voltage box functions:
[0031] 1. The sampling sensor has been integrated into the PCS. If the auxiliary power supply of the energy storage system equipment is powered by the battery, it is inevitable that power will be drawn from the sampling sensor inside the PCS and the battery cluster, such as Figure 2 As shown in the figure, there is a power-taking branch circuit between the sampling sensor and the battery, which is not a completely series relationship. Therefore, the battery current sampled by the sampling sensor inside the PCS is inconsistent with the actual battery current, and there is a phenomenon of "power stealing" in the branch circuit. However, the SOC calculation of the battery cluster is highly dependent on the accuracy of battery current sampling. If this situation continues to occur for a long time, the calculation deviation of the battery cluster SOC will become larger and larger, and the battery cluster SOC will be inaccurately calculated, which will lead to the danger of overcharging and over-discharging.
[0032] 2. When the PCS fails or other external abnormalities (such as power outages) occur, the battery cluster may not be able to charge for a long time or may not be able to charge. The battery will be over-consumed, the SOC will be lower than the power-loss threshold, and the battery will be depleted; if the battery cannot be recharged in time, in severe cases, the battery will be irreversibly damaged, and face high maintenance costs such as battery replacement. However, most energy storage systems are usually not designed with battery recharge devices or circuits, facing problems such as difficulty in recharging, inconvenience in later maintenance, and battery damage.
[0033] The PCS with integrated high-voltage box function brings many advantages in terms of cost, volume, etc. For the PCS with integrated high-voltage box function, the present invention provides an energy storage system, in which the high-voltage box function is integrated in the PCS. The energy storage system can solve the problem of "power stealing" of the auxiliary power supply that supplies power to the energy storage system equipment, ensure that the battery current sampled by the shunt in the PCS is the same as the actual battery current, and ensure the accuracy of the battery cluster SOC calculation.
[0034] An embodiment of the present invention provides an energy storage system, such as Figure 3 As shown, the energy storage system includes a battery cluster and an energy storage inverter, and the energy storage inverter integrates the function of a high-voltage box.
[0035] The energy storage system also includes a power taking unit and an auxiliary power supply. The input end of the power taking unit is connected to the AC power grid, and the output end of the power taking unit is connected to the input end of the auxiliary power supply, and is used to isolate and convert the AC current of the AC power grid into a DC current after rectification; the output end of the auxiliary power supply is connected to the equipment in the energy storage system, and is used to convert the DC current output by the power taking unit into the DC voltage required for the equipment in the energy storage system to work, and to power the equipment in the energy storage system.
[0036] Specifically, a battery cluster, which includes multiple battery packs, provides DC power supply and energy storage.
[0037] One end of the energy storage inverter with integrated high-voltage box function is connected to the battery cluster, and the other end is connected to the AC grid. It is used to convert the DC input of the battery cluster into AC output and then connect the AC output to the AC grid, collect the battery current of the battery cluster through the sampling sensor, and manage the charging and discharging of the battery cluster according to the battery current. It has the power conversion unit and sampling and control unit of the original PCS, which mainly realizes the charging and discharging function, and can convert the DC input of the battery cluster into AC output and then connect it to the grid. It also includes the core components in the original high-voltage box such as the battery control unit BCU, contactor, pre-charging circuit, sampling sensor and voltage sampling circuit, to realize battery monitoring, SOC calculation and related protection functions.
[0038] In one example, the energy storage inverter includes a PCS control board with an integrated battery control unit, and a DCEMI filter, a sampling sensor, a DC contactor, a pre-charging circuit, a bidirectional DCAC converter, an AC filter, an AC relay and an ACEMI filter connected in sequence between the battery cluster and the AC power grid. The PCS control board controls the opening and closing of the DC contactor according to the battery current of the battery cluster collected by the sampling sensor, and manages the charging and discharging of the battery cluster.
[0039] Specifically, the sampling sensor adopts a shunt.
[0040] The pre-charging circuit includes a pre-charging resistor and a pre-charging diode, and the pre-charging resistor and the pre-charging diode are connected in series between the DCEMI filter and the bidirectional DCAC converter.
[0041] Furthermore, a DC SPD and an AC SPD are also provided in the energy storage inverter to protect the energy storage system.
[0042] The power taking unit takes power from the power grid, performs AC isolation conversion and rectification on the AC current of the AC power grid, and then outputs DC current.
[0043] The auxiliary power supply is usually an isolated power supply such as a flyback DC / DC power supply, which converts high-voltage DC into low-voltage DC to provide low-voltage power supply to the equipment in the energy storage system (such as energy storage system fans, dehumidifiers, fire protection equipment, etc.).
[0044] The auxiliary power supply obtains DC current from the power taking unit and does not need to take power from the battery cluster. Therefore, there is no branch circuit in the energy storage inverter with integrated high-voltage box function, ensuring that the battery current sampled by the sampling sensor inside the PCS is the same as the actual battery current.
[0045] An energy storage system according to an embodiment of the present invention draws power from a power grid through a power taking unit, performs AC isolation conversion and rectification, and then outputs a DC current to charge an auxiliary power supply. The auxiliary power supply converts the DC current output by the power taking unit into a DC voltage required for the operation of equipment in the energy storage system, and supplies power to the equipment in the energy storage system. Even if the sampling sensor is integrated inside the PCS, since there is no branch circuit between the battery cluster and the PCS for power drawing, the battery current collected by the sampling sensor inside the PCS is consistent with the actual battery current, thereby ensuring the accuracy of the battery cluster SOC calculation and avoiding the risk of overcharging and over-discharging caused by inaccurate SOC calculation of the battery cluster.
[0046] In some embodiments, the energy storage system further includes a power replenishment control unit, one end of which is connected to the output end of the power taking unit, and the other end of which is connected to the battery cluster, for charging the battery cluster through the DC current output by the power taking unit when the remaining power of the battery cluster is lower than a set value.
[0047] Specifically, the power replenishment control unit includes a switching device QF and a current limiting resistor R, one end of the switching device QF is connected to the battery cluster, the other end of the switching device QF is connected to the current limiting resistor R, and the other end of the current limiting resistor R is connected to the output end of the power taking unit.
[0048] The switch device QF is in the disconnected state during normal operation to ensure electrical isolation. When power replenishment is required, maintenance personnel can close it and connect it to the battery cluster to provide a power replenishment path.
[0049] The current limiting resistor R is connected in series with the switch, and its main purpose is to limit the charging current and prevent overcurrent damage in the charging circuit.
[0050] When the energy storage system is operating normally, the switch device QF in the power replenishment control unit is in the disconnected state, ensuring that the battery cluster is electrically isolated from the DC current rectified and output by the power extraction unit. When the battery cluster cannot be charged for a long time and the battery cluster power is over-consumed, if the SOC is too low to allow discharge, resulting in the PCS failing to start normally and failing to charge and replenish the battery cluster normally through the power conversion unit, the maintenance personnel can close the switch device QF. Since the rectified DC voltage is within the normal operating voltage range, the DC voltage can replenish the battery cluster after closing. The maximum replenishment voltage is the uncontrolled rectifier voltage, which will not cause overcharging of the battery cluster.
[0051] If the current SOC of the battery cluster is sufficient to allow the PCS to start up, the switch device QF can be disconnected to stop the power replenishment, and the PCS can be started to charge the battery cluster normally through the power conversion unit of the PCS.
[0052] The energy storage system of the embodiment of the present invention controls whether to recharge the battery cluster through the recharge control unit, which facilitates timely recharging of the battery during the operation and maintenance process to avoid battery damage. The energy storage system has a simple structure and high reliability.
[0053] In some embodiments, the power supply unit includes an isolation transformer circuit and a rectifier circuit. The input end of the isolation transformer circuit is connected to the AC power grid, the output end of the isolation transformer circuit is connected to the input end of the rectifier circuit, and the output end of the rectifier circuit is respectively connected to the input end of the auxiliary power supply and one end of the power replenishment control unit.
[0054] Specifically, the isolation transformer adopts an industrial frequency isolation transformer, the primary side of the isolation transformer is connected to the AC power grid, and the secondary side of the isolation transformer is connected to the rectifier circuit. Its main functions are to isolate the windings and convert the voltage.
[0055] The isolation transformer needs to have a suitable transformation ratio to ensure that it is within the normal voltage range of the battery cluster after passing through the rectification circuit. That is, the lowest rectification voltage needs to be greater than the lower limit of the battery cluster to prevent failure to recharge, and the highest rectification voltage needs to be less than or equal to the upper limit of the battery system to prevent overcharging.
[0056] Furthermore, the rectifier circuit includes a rectifier element D and a voltage stabilizing filter capacitor C, the positive electrode of the rectifier element D is connected to an output end of the isolation transformer circuit, the negative electrode of the rectifier element D is connected to one end of the voltage stabilizing filter capacitor C, and the other end of the voltage stabilizing filter capacitor C is connected to another output end of the isolation transformer circuit.
[0057] Specifically, the rectifying element D is a device such as a rectifying bridge or a diode. In one example, the rectifying element D is a rectifying diode.
[0058] The AC power output from the secondary side of the isolation transformer is rectified, stabilized and filtered by the rectifier element D and the voltage stabilizing filter capacitor C of the rectifier circuit to become a stable DC power supply, which can be used to power system equipment through an auxiliary power supply and can also be used to supplement the battery cluster.
[0059] In some embodiments, the isolation transformer adopts a single-winding isolation transformer; or the isolation transformer adopts a multi-winding isolation transformer. When the isolation transformer adopts a multi-winding isolation transformer, the number of secondary windings, the number of rectifier circuits, the number of power replenishment control units of the multi-winding isolation transformer and the number of battery packs of the battery cluster are the same, and the secondary winding of each multi-winding isolation transformer is sequentially connected to the corresponding rectifier circuit, power replenishment control unit and battery pack.
[0060] like Figure 4 In the illustrated embodiment, the number of secondary windings of the multi-winding isolation transformer, the number of rectifier circuits, the number of power-compensation control units, and the number of battery packs of the battery cluster are all three groups. The switch devices in the three groups of power-compensation control units include a first switch device QF1, a second switch device QF2, and a third switch device QF3. The secondary winding of the isolation transformer has three secondary windings Ns1, Ns2, and Ns3.
[0061] When the energy storage system operates normally, the first switch device QF1, the second switch device QF2 and the third switch device QF3 in the power replenishment control unit remain in the disconnected state to ensure that each battery pack is electrically isolated from the rectified DC power. When the battery pack is low on power, the corresponding switch can be closed to replenish power for each pack individually.
[0062] After the energy storage system has been running for a period of time, it is inevitable that the capacities of the battery packs will be inconsistent. The different capacities of the battery packs are likely to produce a "barrel effect", which greatly affects the utilization rate of the battery system. At this time, it is also necessary to recharge the individual battery packs. The corresponding battery packs can be recharged by closing the corresponding recharge switch; for example, by closing the first switch device QF1, PACK1 can be recharged separately.
[0063] The embodiment of the present invention can simultaneously supplement power for a single battery pack and has the function of balancing the SOC of the battery pack, which can effectively improve the overall capacity utilization of the energy storage system and bring considerable economic benefits.
[0064] An embodiment of the present invention also provides a control method for an energy storage system, which is applied to an energy storage system such as the above embodiment, including: converting the DC current output by the power taking unit into the DC voltage required for the operation of the equipment in the energy storage system through an auxiliary power supply, and supplying power to the equipment in the energy storage system; judging whether the remaining power of the battery cluster is lower than a set value, when the remaining power of the battery cluster is lower than the set value, controlling the DC current output by the power taking unit to charge the battery cluster through a power supplement control unit; when the remaining power of the battery cluster is higher than or equal to the set value, charging the battery cluster through an energy storage inverter.
[0065] Specifically, when the energy storage system is running, the AC grid GRID supplies power to the primary winding Np of the isolation transformer, and generates a suitable AC voltage in the secondary winding Ns; this voltage is rectified by the rectifier element D and the voltage stabilizing filter capacitor CC, and then becomes a smooth high-voltage DC. The auxiliary power supply takes power from the rectified high-voltage DC, and after the flyback DC / DC conversion circuit, the high-voltage DC is converted into an isolated low-voltage DC to power the energy storage system equipment.
[0066] During the entire power-drawing process, the auxiliary power supply actually only draws power from the AC power grid GRID. Even if the shunt is placed inside the PCS, power is drawn from a non-branch circuit between the battery and the PCS, ensuring that the battery current collected by the shunt inside the PCS is consistent with the actual battery current, thereby ensuring the accuracy of the battery cluster SOC calculation.
[0067] When the energy storage system is operating normally, the switch device QF in the power replenishment control unit is in the disconnected state, ensuring that the battery cluster is electrically isolated from the DC current rectified and output by the power extraction unit. When the battery cluster cannot be charged for a long time and the battery cluster power is over-consumed, if the SOC is too low to allow discharge, resulting in the PCS failing to start normally and failing to charge and replenish the battery cluster normally through the power conversion unit, the maintenance personnel can close the switch device QF. Since the rectified DC voltage is within the normal operating voltage range, the DC voltage can replenish the battery cluster after closing. The maximum replenishment voltage is the uncontrolled rectifier voltage, which will not cause overcharging of the battery cluster.
[0068] The control method of the energy storage system of the embodiment of the present invention ensures that the battery current collected by the shunt in the PCS is consistent with the actual battery current, ensuring the accuracy of the battery cluster SOC calculation; and has a battery cluster power replenishment function, which facilitates operation and maintenance and avoids battery damage.
[0069] Although example embodiments and their advantages have been described in detail, those skilled in the art may make various changes, substitutions and modifications to these embodiments without departing from the spirit of the invention and the scope of protection defined by the appended claims. Such modifications and variations are all within the scope defined by the appended claims.
Claims
1. An energy storage system, comprising a battery cluster and an energy storage inverter, wherein the energy storage inverter integrates a high-voltage box function, characterized in that: The energy storage system also includes a power taking unit and an auxiliary power supply; The input end of the power taking unit is connected to the AC power grid, and the output end of the power taking unit is connected to the input end of the auxiliary power supply, and is used to perform AC isolation conversion and rectification on the AC current of the AC power grid to output DC current; The output end of the auxiliary power supply is connected to the equipment in the energy storage system, and is used to convert the DC current output by the power taking unit into the DC voltage required for the equipment in the energy storage system to work, and to supply power to the equipment in the energy storage system.
2. The energy storage system according to claim 1, characterized in that: It also includes a power replenishment control unit, one end of which is connected to the output end of the power taking unit, and the other end of which is connected to the battery cluster, for charging the battery cluster through the direct current output by the power taking unit when the remaining power of the battery cluster is lower than a set value.
3. The energy storage system according to claim 2, characterized in that: The power supply unit includes an isolation transformer circuit and a rectifier circuit. The input end of the isolation transformer circuit is connected to the AC power grid, the output end of the isolation transformer circuit is connected to the input end of the rectifier circuit, and the output end of the rectifier circuit is respectively connected to the input end of the auxiliary power supply and one end of the power compensation control unit.
4. The energy storage system according to claim 3, characterized in that: The isolation transformer circuit comprises an isolation transformer, the primary side of the isolation transformer is connected to the AC power grid, and the secondary side of the isolation transformer is connected to the input end of the rectifier circuit.
5. The energy storage system according to claim 3, characterized in that: The rectifier circuit includes a rectifier element and a voltage stabilizing filter capacitor, the positive electrode of the rectifier element is connected to an output end of the isolation transformer circuit, the negative electrode of the rectifier element is connected to one end of the voltage stabilizing filter capacitor, and the other end of the voltage stabilizing filter capacitor is connected to another output end of the isolation transformer circuit.
6. The energy storage system according to claim 2, characterized in that: The power replenishment control unit includes a switch device and a current limiting resistor, one end of the switch device is connected to the battery cluster, the other end of the switch device is connected to the current limiting resistor, and the other end of the current limiting resistor is connected to the output end of the power taking unit.
7. The energy storage system according to claim 4, characterized in that: The isolation transformer adopts a single-winding isolation transformer; Or the isolation transformer adopts a multi-winding isolation transformer, the number of secondary windings of the multi-winding isolation transformer, the number of the rectifier circuits, the number of the power compensation control units and the number of battery packs in the battery cluster are the same, and each secondary winding of the multi-winding isolation transformer is connected to the corresponding rectifier circuit, the power compensation control unit and the battery pack in sequence.
8. The energy storage system according to claim 1, characterized in that: One end of the energy storage inverter is connected to the battery cluster, and the other end is connected to the AC power grid, and is used to convert the DC input of the battery cluster into AC output and then connect the AC output to the AC power grid, and collect the battery current of the battery cluster through a sampling sensor, and manage the charging and discharging of the battery cluster according to the battery current.
9. The energy storage system according to claim 8, characterized in that: The energy storage inverter includes a PCS control board with an integrated battery control unit, and a DCEMI filter, a sampling sensor, a DC contactor, a pre-charging circuit, a bidirectional DCAC converter, an AC filter, an AC relay and an ACEMI filter connected in sequence between the battery cluster and the AC power grid. The PCS control board controls the opening and closing of the DC contactor according to the battery current of the battery cluster collected by the sampling sensor, and manages the charging and discharging of the battery cluster.
10. A control method for an energy storage system, applied to the energy storage system according to any one of claims 1 to 9, characterized in that: include: The auxiliary power supply is used to convert the DC current output by the power taking unit into the DC voltage required for the operation of the equipment in the energy storage system, and to supply power to the equipment in the energy storage system; Determine whether the remaining power of the battery cluster is lower than a set value, and when the remaining power of the battery cluster is lower than the set value, control the DC current output by the power taking unit to charge the battery cluster through the power supplement control unit; When the remaining power of the battery cluster is higher than or equal to a set value, the battery cluster is charged by an energy storage inverter.