Control System and Control Method for Energy Storage System

Abstract

The present invention provides a control system and a control method for an energy storage system. The control system includes: a first energy storage system, which includes BMS1, a PCS1 electrically connected to the first energy storage system, and a first switch for controlling the connection or disconnection of the PCS1. The PCS1 is communicatively connected to the BMS1; a second energy storage system, which includes BMS2, a PCS2 electrically connected to the second energy storage system, and a second switch for controlling the connection or disconnection of the PCS2. The PCS2 is communicatively connected to the BMS2. Among them, both the first switch and the second switch are communicatively connected to both BMS1 and BMS2 at the same time. In the above control system, during the test process of mutual charge and discharge between the first energy storage system and the second energy storage system, the first switch and the second switch are simultaneously controlled by BMS1 or BMS2 to control the simultaneous shutdown of PCS1 and PCS2, ensuring the operation safety during the test process of the first energy storage system and the second energy storage system.

Description

Technical Field

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

[0002] At present, the capacity and power of distributed power energy storage systems are both continuously increasing. When a set of energy storage system is tested during factory testing, MW-level charge and discharge power are required. If the energy storage system uses the electric energy of the power grid for charge and discharge experiments, it will cause waste of electric energy and increase the production cost of the energy storage system. The current solution is to test two sets of energy storage systems simultaneously. When one energy storage system is tested for discharge, the other energy storage system is tested for charge. If the charging powers of the two energy storage systems are different, the two energy storage systems cannot be fully charged and discharged. For example, if the charging power of one is 1.3 MW and the discharging power of the other is 1.4 MW, the charge-discharge difference of 0.1 MW between the two systems is the power that the power grid needs to absorb or use by the load. In the test scheme connecting the load, the two energy storage systems need to be turned on and off simultaneously, and the interval time should be controlled within at least 20 ms. Currently, the conventional method is to separately configure a set of EMS control system, that is, to achieve the synchronous switching on and off of the two energy storage systems through this EMS system, but the cost of this device is relatively high.

[0003] In view of this, it is necessary to improve the existing control system for energy storage systems to solve the above technical problems. Summary of the Invention

[0004] The present invention provides a control system and a control method for an energy storage system to solve one of the above problems.

[0005] To achieve the above object, the technical solution provided by the present invention is as follows:

[0006] A control system for an energy storage system, the control system includes: a first energy storage system, the first energy storage system includes BMS1, PCS1 electrically connected to the first energy storage system, a first switch for controlling the connection or disconnection of the PCS1, and the PCS1 is communicatively connected to the BMS1;

[0007] A second energy storage system, the second energy storage system includes BMS2, PCS2 electrically connected to the second energy storage system, a second switch for controlling the connection or disconnection of the PCS2, and the PCS2 is communicatively connected to the BMS2;

[0008] Wherein, the first switch and the second switch are both communicatively connected to BMS1 and BMS2 simultaneously.

[0009] Further, the output ends of the PCS1 and PCS2 are connected in parallel to form a system output end, and the system output end is electrically connected to the power grid and an external load respectively.

[0010] Further, the control system further includes a main line electrically connected to the system output end, a power grid branch line connecting the main line and the power grid, a load branch line connecting the main line and the load, and a protection device provided on the power grid branch line for controlling the connection or disconnection between the system output end and the power grid. Both the protection device and the protection device are communicatively connected to the BMS1 or both are communicatively connected to the BMS2.

[0011] Further, the control system further includes a current sensor provided on the power grid branch line and used for detecting whether there is current flowing from the PCS1 or PCS2 to the power grid. The current sensor is located on the side of the protection device away from the power grid, and the current sensor is communicatively connected to the BMS1 or BMS2.

[0012] Further, the control system includes an inverter provided on the main line.

[0013] Further, both the first switch and the second switch are dry contacts.

[0014] The present invention also relates to a control method for the control system of the above-mentioned energy storage system. The control method includes: the BMS1 controls the PCS1 to charge the second energy storage system with the first energy storage system; or, the BMS2 controls the PCS2 to charge the first energy storage system with the second energy storage system.

[0015] If at least one of the BMS1 and BMS2 detects a shutdown signal, the BMS1 and / or BMS2 controls the first switch and the second switch to be disconnected simultaneously, so that the PCS1 and the PCS2 are shut down simultaneously.

[0016] Further, the shutdown signal includes one or more of the first energy storage system being fully charged, the first energy storage system being fully discharged, the second energy storage system being fully charged, the second energy storage system being fully discharged, the PCS1 malfunctioning, and the PCS2 malfunctioning.

[0017] Further, the output ends of the PCS1 and PCS2 are connected in parallel to form a system output end, and the system output end is electrically connected to the power grid and an external load respectively. After the PCS1 and the PCS2 are shut down simultaneously,

[0018] If the first energy storage system or the second energy storage system is fully discharged, and the second energy storage system or the first energy storage system is not fully charged, then the power grid is used to control the PCS2 to continue charging the second energy storage system or control the PCS1 to continue charging the first energy storage system until it is fully charged.

[0019] Or,

[0020] If the second energy storage system or the first energy storage system is fully charged, and the first energy storage system or the second energy storage system is not fully discharged, then control PCS1 to supply power to the external load from the first energy storage system or control PCS2 to supply power to the external load from the second energy storage system until it is fully discharged.

[0021] Furthermore, the control system further includes a current sensor for detecting whether there is current flowing into the power grid and a protection device disposed between the current sensor and the power grid. Both the current sensor and the protection device are communicatively connected to BMS1 or both are communicatively connected to BMS2. If the current sensor detects that current is passing through, then BMS1 or BMS2 controls the protection device to disconnect.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows: In the control system for an energy storage system of the present invention, during the test process of mutual charging and discharging between the first energy storage system and the second energy storage system, BMS1 or BMS2 simultaneously controls the first switch and the second switch to control PCS1 and PCS2 to shut down simultaneously, ensuring the operating safety of the first energy storage system and the second energy storage system during the test process. Description of the Drawings

[0023] Figure 1 is a topology diagram of the control system for an energy storage system of the present invention.

[0024] Figure 2 is a flowchart of the working process of an embodiment of the control method of the control system for an energy storage system of the present invention.

[0025] Figure 3 is a flowchart of the working process of another embodiment of the control method of the control system for an energy storage system of the present invention.

[0026] Wherein, 1 - the first energy storage system, 2 - the second energy storage system, 3 - the first switch, 4 - the second switch, 5 - the protection device, 6 - the current sensor, 7 - the inverter, 8 - the power grid, 9 - the external load, 10 - the main line, 11 - the power grid branch line, 12 - the load branch line. Detailed Embodiments

[0027] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0028] It should be noted that the orientation or positional relationship indicated in the present invention is based on the orientation or positional relationship shown in the auxiliary drawings, which is only for facilitating the simplified description of the present invention, rather than indicating or implying that the device referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation on the protection scope of the present invention.

[0029] In the various drawings of the present invention, for the convenience of illustration, the dimensions of some structures or parts are exaggerated relative to other structural parts. Therefore, it is only used to illustrate the basic structure of the subject matter of the present invention.

[0030] The present invention provides a control system for an energy storage system, which is used to control the charging and discharging processes of two energy storage systems in the mutual charging and discharging test of the two energy storage systems. As Figure 1 shown, the control system includes: a first energy storage system 1, a PCS1 electrically connected to the first energy storage system 1, a first switch 3 for controlling the connection or disconnection of the PCS1. The first energy storage system 1 includes a BMS1, and the PCS1 is communicatively connected to the BMS1; a second energy storage system 2, a PCS2 electrically connected to the second energy storage system 2, a second switch 4 for controlling the connection or disconnection of the PCS2. The second energy storage system 2 includes a BMS2, and the PCS2 is communicatively connected to the BMS2; wherein, both the first switch 3 and the second switch 4 are communicatively connected to the BMS1 and the BMS2 at the same time.

[0031] The control system of the present invention simultaneously controls the first switch 3 and the second switch 4 through the BMS1 or the BMS2 to control the PCS1 and the PCS2 to stop operating simultaneously, ensuring the operation safety of the first energy storage system 1 and the second energy storage system 2 during the test process.

[0032] Among them, both the first energy storage system 1 and the second energy storage system 2 further include a battery system (not shown). The BMS1 and the BMS2 (Battery Management System) are both battery management systems, and their main functions are to intelligently manage and maintain the battery system, monitor the state of the battery system, prevent the battery system from overcharging and over-discharging, so as to extend the service life of the battery; the PCS1 and the PCS2 (Power Conversion System) are both bidirectional energy storage inverters, which are connected between the battery system in the energy storage system and the power grid and / or external load, and can control the charging and discharging processes of the energy storage system, and can directly supply power to the AC external load in the absence of the power grid.

[0033] In the control system of the present invention, the BMS1 controls the PCS1 to perform the charging and discharging operations on the battery system in the first energy storage system 1, and the BMS2 controls the PCS2 to perform the charging and discharging operations on the battery system in the second energy storage system 2.

[0034] In this embodiment, both the first switch 3 and the second switch 4 are dry contacts. Since there is no polarity between the two contacts of a dry contact, as an electrical switch, it is applicable to industrial control. During the process of mutual charge and discharge between the first energy storage system 3 and the second energy storage system 4, dry contacts are used to achieve the timeliness of controlling the PCS1 and PCS2.

[0035] Further, the output ends of the PCS1 and PCS2 are connected in parallel to form a system output end, and the system output end is electrically connected to the power grid 8 and the external load 9 respectively. The power grid 8 is used to supply power to the first energy storage system 1 and the second energy storage system 2 through the PCS1 or PCS2 respectively, or the first energy storage system 1 and the second energy storage system 2 supply power to the external load 9 through the PCS1 and PCS2 respectively. Especially during the process of mutual charge and discharge between two energy storage systems with different powers, when one of the first energy storage system 1 and the second energy storage system 2 is not fully charged, the power grid 8 is used to continue charging the first energy storage system 1 or the second energy storage system 2 until it is fully charged. When one of the first energy storage system 1 and the second energy storage system 2 is not fully discharged, the first energy storage system 1 or the second energy storage system 2 supplies power to the external load 9 through the corresponding PCS1 or PCS2, so that the first energy storage system 1 or the second energy storage system 2 reaches the state of being fully charged or fully discharged.

[0036] Generally, when one of the first energy storage system 1 and the second energy storage system 2 is fully charged or fully discharged, the BMS1 or BMS2 controls the first switch 3 and the second switch 4 to disconnect simultaneously, so that the PCS1 and PCS2 no longer perform charge and discharge operations on the first energy storage system 1 and the second energy storage system 2. However, in order to avoid the situation that the first switch 3 and the second switch 4 are not disconnected in time or abnormal conditions occur, the control system further includes a protection device 5 for controlling the connection or disconnection between the system output end and the power grid 8, so as to play a dual protection role for the control system and ensure the safety of the first energy storage system 1 and the second energy storage system 2.

[0037] Specifically, the control system further includes a main line 10 electrically connected to the system output end, a power grid branch line 11 connecting the main line 10 and the power grid 8, and a load branch line 12 connecting the main line 10 and the external load 9. The protection device 5 is arranged on the power grid branch line 11, that is, the protection device 5 is only responsible for the connection or disconnection between the PCS1 and PCS2 and the power grid 8.

[0038] Further, the protection device 5 is communicatively connected to the BMS1 or BMS2, that is, one of the BMS1 or BMS2 can control the disconnection or connection of the protection device 5.

[0039] In the specific implementation process, the protection device 5 is preferably a circuit breaker. Due to its characteristics of short - circuit or over - current protection, when BMS1 or BMS2 receives a current flowing from PCS1 or PCS2 to the power grid 8, BMS1 or BMS2 controls the circuit breaker to disconnect, so as to prevent the current from flowing reversely from the first energy storage system 1 or the second energy storage system 2 to the power grid 8 and causing an impact on the power grid 8.

[0040] The control system further includes a current sensor 6 provided on the power grid branch line 11 and used to detect whether there is a current flowing reversely to the power grid. The current sensor 6 is located on the side of the protection device 5 away from the power grid 9, that is, the current sensor 6 is located at the front end of the protection device 5, so as to facilitate the current sensor 6 to detect the current in time. Both the current sensor 6 and the protection device 5 are communicatively connected to BMS1, or both are communicatively connected to BMS2, so as to enable BMS1 or BMS2 to give an instruction to disconnect the protection device 5 in time after receiving the signal of the current sensor 6, so that PCS1 and PCS2 are disconnected from the power grid 8.

[0041] Further, the control system includes an inverter 7 provided on the main line 10. The inverter 7 realizes the direct - alternating current conversion of the current output by the battery system, so that the direct - current current output in the battery system becomes the alternating - current current meeting the requirements of the power grid 8 or the external load 9.

[0042] The overall control system is set as follows: the first energy storage system 1 and the second energy storage system 2 are respectively connected to PCS1 and PCS2. PCS1 and PCS2 are connected in parallel and then connected to the inverter 7 on the main line 10. Then, the output terminals of the inverter 7 are respectively connected to the power grid 8 and the external load 9. The power grid 8 and the external load 9 are in a parallel relationship. The current sensor 6 and the protection device 5 are used to control the connection or disconnection between the inverter 7 and the power grid 8.

[0043] The present invention also provides a control method for the above - mentioned control system, as Figure 2 and Figure 3 shown, for implementing the process of mutual charge - discharge between the first energy storage system 1 and the second energy storage system 2.

[0044] The control method includes: controlling the first energy storage system 1 to perform a discharge test and the second energy storage system 2 to perform a charge test.

[0045] Specifically, BMS1 controls PCS1 to make the first energy storage system 1 charge the second energy storage system 2. If at least one of BMS1 and BMS2 detects a stop signal, BMS1 and / or BMS2 control the first switch 3 and the second switch 4 to disconnect simultaneously, so that PCS1 and PCS2 stop operating simultaneously, to ensure the safe operation of the first energy storage system 1 and the second energy storage system 2.

[0046] The above shutdown signals include, but are not limited to, one or several of the following: the first energy storage system is fully charged, the first energy storage system is fully discharged, the second energy storage system is fully charged, the second energy storage system is fully discharged, PCS1 fails, and PCS2 fails.

[0047] Furthermore, as Figure 3 shown, after PCS1 and PCS2 are shut down simultaneously, if the first energy storage system 1 is fully discharged while the second energy storage system 2 is not fully charged, then control PCS2 to continue charging the second energy storage system 2 from the power grid 8 until it is fully charged; if the second energy storage system 2 is fully charged while the first energy storage system 1 is not fully discharged, then control PCS1 to continue supplying power to the external load 9 with the first energy storage system 1. To complete the test process of fully discharging the first energy storage system 1 and fully charging the second energy storage system 2.

[0048] In this embodiment, if both the current sensor 6 and the protection device 5 are communicatively connected to BMS1, and if the current sensor 6 detects current flowing from PCS1 to the power grid 8, then transmit the relevant information to the BMS1, and the BMS1 controls the protection device 5 to disconnect, preventing the current from flowing reversely to the power grid 8 and causing an impact on the power grid 8.

[0049] If both the current sensor 6 and the protection device 5 are communicatively connected to BMS2, and if the current sensor 6 detects current flowing reversely to the power grid 8, then the BMS2 controls the protection device 5 to disconnect, preventing the current from flowing reversely to the power grid 8 and causing an impact on the power grid 8.

[0050] Correspondingly, the control method further includes: performing a discharge test on the second energy storage system 2 and a charge test on the first energy storage system 1.

[0051] Specifically, the BMS2 controls PCS2 to charge the first energy storage system 1 with the second energy storage system 2. If at least one of the BMS1 and BMS2 detects a shutdown signal, then the BMS1 and / or BMS2 controls the first switch 3 and the second switch 4 to disconnect simultaneously, causing PCS1 and PCS2 to shut down simultaneously to ensure the safe operation of the first energy storage system 1 and the second energy storage system 2.

[0052] As Figure 3 shown, after PCS1 and PCS2 are shut down simultaneously, if the second energy storage system 2 is fully discharged while the first energy storage system 1 is not fully charged, then control PCS1 to continue charging the first energy storage system 1 from the power grid 8 until it is fully charged; if the first energy storage system 1 is fully charged while the second energy storage system 2 is not fully discharged, then control PCS2 to continue supplying power to the external load 9 with the second energy storage system 2. To complete the test process of fully charging the first energy storage system 1 and fully discharging the second energy storage system 2.

[0053] Similarly, if the current sensor 6 detects that current is passing through, then the BMS 1 or BMS 2 controls the protection device 5 to disconnect. The secondary protection of the current sensor 6 and the protection device 5 for the control system is the same as the above test process and will not be elaborated here.

[0054] In summary, for the control system of the energy storage system of the present invention, during the test process of mutual charge and discharge between the first energy storage system 1 and the second energy storage system 2, the BMS 1 or BMS 2 simultaneously controls the first switch 3 and the second switch 4 to control the PCS 1 and PCS 2 to shut down simultaneously, ensuring the operation safety during the test process of the first energy storage system 1 and the second energy storage system 2.

[0055] It should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0056] The series of detailed descriptions listed above are only specific descriptions of the feasible embodiments of the present invention, and are not used to limit the protection scope of the present invention. Any equivalent embodiments or changes made without departing from the technical spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A control system for an energy storage system, characterized in that: Comprising: A first energy storage system, the first energy storage system including BMS1, PCS1 electrically connected to the first energy storage system, a first switch for controlling the connection or disconnection of PCS1, and PCS1 is communicatively connected to BMS1; A second energy storage system, the second energy storage system including BMS2, PCS2 electrically connected to the second energy storage system, a second switch for controlling the connection or disconnection of PCS2, and PCS2 is communicatively connected to BMS2, wherein, the first switch and the second switch are both communicatively connected to BMS1 and BMS2 at the same time; during the process of mutual charging and discharging between the first energy storage system and the second energy storage system, if at least one of BMS1 and BMS2 detects a shutdown signal, then BMS1 and / or BMS2 controls the first switch and the second switch to be disconnected simultaneously, so that PCS1 and PCS2 are shut down simultaneously.

2. The control system for an energy storage system according to claim 1, characterized in that: The output ends of PCS1 and PCS2 are connected in parallel to form a system output end, and the system output end is electrically connected to the power grid and an external load respectively.

3. The control system for an energy storage system according to claim 2, characterized in that: The control system further includes a main line electrically connected to the system output end, a power grid branch line connecting the main line and the power grid, a load branch line connecting the main line and the load, and a protection device provided on the power grid branch line for controlling the connection or disconnection between the system output end and the power grid, and the protection device is communicatively connected to BMS1 or BMS2.

4. The control system for an energy storage system according to claim 3, characterized in that: The control system further includes a current sensor provided on the power grid branch line and used for detecting whether there is current flowing to the power grid, the current sensor is located on the side of the protection device away from the power grid, and the current sensor and the protection device are both communicatively connected to BMS1 or both communicatively connected to BMS2.

5. The control system for an energy storage system according to claim 3, characterized in that: The control system includes an inverter provided on the main line.

6. The control system for an energy storage system according to any one of claims 1 to 5, characterized in that: The first switch and the second switch are both dry contacts.

7. A control method for a control system of an energy storage system according to any one of claims 1 to 6, characterized in that: The control method includes: BMS1 controls PCS1 to charge the second energy storage system by the first energy storage system; or, BMS2 controls PCS2 to charge the first energy storage system by the second energy storage system; If at least one of BMS1 and BMS2 detects a shutdown signal, then BMS1 and / or BMS2 controls the first switch and the second switch to be disconnected simultaneously, so that PCS1 and PCS2 are shut down simultaneously.

8. The control method of the control system of the energy storage system according to claim 7, characterized in that: The shutdown signal includes one or more of the first energy storage system is fully charged, the first energy storage system is fully discharged, the second energy storage system is fully charged, the second energy storage system is fully discharged, PCS1 fails, and PCS2 fails.

9. The control method of the control system of the energy storage system according to claim 7, characterized in that: The output ends of PCS1 and PCS2 are connected in parallel to form a system output end, the system output end is electrically connected to the power grid and an external load respectively, after PCS1 and PCS2 are shut down simultaneously, If the first energy storage system or the second energy storage system is fully discharged, and the second energy storage system or the first energy storage system is not fully charged, then the power grid is used to control PCS2 to charge the second energy storage system or control PCS1 to charge the first energy storage system until fully charged; Or, If the second energy storage system or the first energy storage system is fully charged, and the first energy storage system or the second energy storage system is not fully discharged, then control PCS1 to supply power to the external load from the first energy storage system or control PCS2 to supply power to the external load from the second energy storage system until it is fully discharged.

10. The control method of the control system of the energy storage system according to claim 9, characterized in that: The control system further includes a current sensor for detecting whether there is current flowing into the power grid and a protection device disposed between the current sensor and the power grid. Both the current sensor and the protection device are communicatively connected to the BMS1 or both are communicatively connected to the BMS2. If the current sensor detects that current is passing through, then the BMS1 or the BMS2 controls the protection device to disconnect.

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