Dual power supply system and power supply method of energy storage system

Abstract

The application provides a dual-power supply system and a power supply method of an energy storage system, which comprises a battery direct-current side power supply circuit, an energy storage alternating-current side power supply circuit and an EMS energy management subsystem; an input end of the battery direct-current side power supply circuit is connected with an energy storage battery through a direct-current side micro-break switch, and an output end is connected with an electrical load; an input end of the energy storage alternating-current side power supply circuit is connected with a power grid through a first alternating-current side micro-break switch, and an output end is connected with the electrical load; the direct-current side micro-break switch and the first alternating-current side micro-break switch are both connected with the EMS energy management subsystem in control; a normally closed direct-current relay is connected in series in the battery direct-current side power supply circuit, normally closed contacts of the normally closed direct-current relay are connected with the direct-current side micro-break switch and the electrical load respectively, and a driving coil of the normally closed direct-current relay is connected to the energy storage alternating-current side power supply circuit. The application not only can prolong the standby time of the system power supply, but also is suitable for severe application environment, and does not need to increase air conditioners for heat dissipation, thereby reducing the system design cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of energy storage systems, in particular to a dual power supply system and a power supply method of an energy storage system. BACKGROUND

[0002] In an energy storage system project, an UPS (Uninterruptible Power Supply) is usually added as a power supply device for a control loop, which can maintain the continuous operation of the control loop for a certain period of time under abnormal external AC power supply, or plays a key role in power supply during the off-grid black start process of the system.

[0003] However, the built-in battery capacity of the UPS is limited and cannot be used for a long time, and after a certain period of use, the built-in battery capacity decays seriously, requiring frequent replacement of the built-in battery or the entire UPS. In addition, the UPS has high requirements for the environment, and an air conditioner needs to be added to provide a good operating environment, which greatly increases the system design cost. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a dual power supply system and a power supply method of an energy storage system to replace the power supply scheme of the UPS, which not only prolongs the standby time of the system power supply, but also is suitable for harsh operating environments without the need for additional air cooling, thereby reducing the system design cost.

[0005] To solve the above technical problems, the technical scheme adopted by the present application is:

[0006] A dual power supply system of an energy storage system, comprising a battery DC side power supply circuit and an energy storage AC side power supply circuit.

[0007] The input end of the battery DC side power supply circuit is connected to an energy storage battery through a DC side micro-break switch, and the output end is connected to an electrical load.

[0008] The input end of the energy storage AC side power supply circuit is connected to a power grid through a first AC side micro-break switch, and the output end is connected to the electrical load.

[0009] A normally closed DC relay is connected in series in the battery DC side power supply circuit, the normally closed contacts of the normally closed DC relay are connected to the DC side micro-break switch and the electrical load respectively, and the drive coil of the normally closed DC relay is connected to the energy storage AC side power supply circuit, for driving the normally closed contacts of the normally closed DC relay to open when there is voltage in the energy storage AC side power supply circuit.

[0010] To solve the above technical problems, another technical scheme provided by the present application is:

[0011] A dual power supply method of an energy storage system, applied to a dual power supply system of the energy storage system, comprising the steps of:

[0012] In the grid-connected mode, the first AC side micro-break switch in the energy storage AC side power supply circuit is closed, the AC power on the grid side is merged into a rectifier bridge stack through the first AC side micro-break switch, and the DC power output after rectification is used to supply power to the power load;

[0013] In the off-grid mode, there is no AC power input on the grid side, no voltage passes through the energy storage AC side power supply circuit, and the first AC side micro-break switch is disconnected. At this time, the DC side micro-break switch in the battery DC side power supply circuit is closed, the DC power on the energy storage battery side is output to the power load through the DC side micro-break switch and the normally closed contact of the normally closed DC relay;

[0014] When the grid side resumes work, the off-grid mode is converted into the grid-connected mode. At this time, the first AC side micro-break switch is closed again, the voltage passes through the energy storage AC side power supply circuit, the drive coil of the normally closed DC relay works, the normally closed contact of the normally closed DC relay in the battery DC side power supply circuit is driven to be disconnected, the battery DC side power supply circuit stops supplying power to the power load, and only the energy storage AC side power supply circuit supplies power to the power load.

[0015] The application has the advantages that the application provides a dual power supply system and a power supply method of an energy storage system. By controlling the on-off of the first AC side micro-break switch in the energy storage AC side power supply circuit and the DC side micro-break switch in the battery DC side power supply circuit, the power supply mode of the grid side in the grid-connected mode and the power supply mode of the energy storage battery in the off-grid mode are switched, the dual power supply of the energy storage system is realized, and the standby time of the system power supply is prolonged. A normally closed DC relay is introduced into the battery DC side power supply circuit, the drive coil of the normally closed DC relay is connected to the energy storage AC side power supply circuit, the normally closed contact of the normally closed DC relay is driven to be disconnected when the grid side resumes power supply, the power supply of the energy storage battery in the battery DC side power supply circuit is automatically disconnected, and the grid power supply is preferentially used. The UPS device is cancelled as a whole, is suitable for severe application environment, does not need to increase the air conditioner for heat dissipation, and effectively reduces the system design cost. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 The circuit principle diagram of the dual power supply system of the energy storage system of the embodiment of the application;

[0017] Figure 2 The grid side power supply principle diagram in the energy storage AC side power supply circuit of the dual power supply system of the energy storage system of the embodiment of the application;

[0018] Figure 3A battery internal power supply principle diagram in a battery DC side power supply circuit of a dual power supply system of an energy storage system according to an embodiment of the present application;

[0019] Figure 4 A battery external power supply principle diagram in a battery DC side power supply circuit of a dual power supply system of an energy storage system according to an embodiment of the present application;

[0020] Figure 5 A power supply principle diagram of an energy storage converter in an energy storage AC side power supply circuit of a dual power supply system of an energy storage system according to an embodiment of the present application;

[0021] Figure 6 A flow chart of a dual power supply method of an energy storage system according to an embodiment of the present application.

[0022] Label explanation:

[0023] PCS, energy storage converter; UR, rectifier bridge stack; FU, fuse;

[0024] K1, first AC side micro-break switch; K2, second AC side micro-break switch; K3, DC side micro-break switch; KM1, normally closed DC relay; KM2, high-voltage relay;

[0025] D1, first anti-reverse diode; D2, second anti-reverse diode; D3, third anti-reverse diode. DETAILED DESCRIPTION

[0026] To explain the technical content, the purposes and effects of the present application in detail, the following will be described in combination with the embodiments and the accompanying drawings.

[0027] Please refer to Figures 1 to 5 A dual power supply system of an energy storage system, comprising a battery DC side power supply circuit and an energy storage AC side power supply circuit;

[0028] The input end of the battery DC side power supply circuit is connected to an energy storage battery through a DC side micro-break switch, and the output end is connected to an electrical load;

[0029] The input end of the energy storage AC side power supply circuit is connected to a power grid through a first AC side micro-break switch, and the output end is connected to the electrical load;

[0030] A normally closed DC relay is connected in series in the battery DC side power supply circuit, the normally closed contact points of the normally closed DC relay are respectively connected to the DC side micro-break switch and the electrical load, and the drive coil of the normally closed DC relay is connected to the energy storage AC side power supply circuit, for driving the normally closed contact points of the normally closed DC relay to open when there is voltage in the energy storage AC side power supply circuit.

[0031] From the above description, the beneficial effects of the present application are that: by controlling the on-off of the first AC side micro-break switch in the energy storage AC side power supply circuit and the DC side micro-break switch in the battery DC side power supply circuit, the power supply mode of the grid side under grid-connected and the energy storage battery under off-grid is switched, the dual power supply of the energy storage system is realized, the standby time of the system power supply is prolonged; and a normally closed DC relay is introduced in the battery DC side power supply circuit, the driving coil of the normally closed DC relay is connected to the energy storage AC side power supply circuit, so that when the grid side restores power supply, the normally closed contact of the normally closed DC relay is driven to open, thereby automatically disconnecting the power supply of the energy storage battery in the battery DC side power supply circuit, and the grid power supply is preferentially adopted. The UPS device is cancelled as a whole, which is suitable for harsh application environment, does not need to increase air conditioning cooling, and effectively reduces the system design cost.

[0032] Further, the energy storage AC side power supply circuit further comprises an energy storage converter and a second AC side micro-break switch;

[0033] The AC end of the energy storage converter is connected to the first AC side micro-break switch and the second AC side micro-break switch in parallel to the power load.

[0034] The DC end of the energy storage converter is connected to the energy storage battery.

[0035] From the above description, in order to improve the performance of the energy storage system, the energy storage converter is added, which can on one hand run off-grid to output power to supply the power load when the grid side is abnormal, and on the other hand convert the AC power of the grid side into DC power to charge the energy storage battery when the power load is not used, so as to ensure that the energy storage battery has sufficient power, thereby further prolonging the power supply time of the energy storage system.

[0036] Further, the first AC side micro-break switch and the second AC side micro-break switch are mechanical interlocking switches.

[0037] From the above description, the first AC side micro-break switch and the second AC side micro-break switch adopt a mechanical interlocking mode, that is, only one of the two micro-break switches can be closed at the same time, or both are disconnected, when the grid side supplies power to the power load, the first AC side micro-break switch is closed, and the second AC side micro-break switch is in the open state under the mechanical interlocking structure, and the energy storage converter does not work to reduce the consumption of the grid side voltage; when the grid side is abnormal, that is, off-grid, the second AC side micro-break switch is closed, and the first AC side micro-break switch is in the open state under the mechanical interlocking structure, at this time, there is still no voltage in the energy storage AC side power supply circuit. The advantage of this is to reduce the impact when there is voltage in this branch, and after the subsequent energy storage converter is started, the power supply to the power load is stably maintained by the energy storage converter.

[0038] Further, the energy storage AC side power supply circuit is also connected in series with a rectifier bridge stack;

[0039] The input end of the rectifier bridge stack is connected to the first AC side micro switch and the second AC side micro switch through an AC bus, and the output end of the rectifier bridge stack is connected to the power load, for rectifying AC power from the grid side or the energy storage converter to DC power and outputting the DC power to the power load.

[0040] As can be seen from the above description, since the power load is usually powered by DC, a rectifier bridge stack is introduced to uncontrolledly rectify AC power from the grid side or the energy storage converter side to DC power and output the DC power to the power load.

[0041] Further, an EMS energy management subsystem is also included, and the energy storage battery includes an internal battery and an external battery;

[0042] The internal battery is connected to the normally closed DC relay through the DC side micro switch;

[0043] The external battery is connected to the normally closed DC relay through a first anti-diode;

[0044] A high-voltage relay is connected in series between the internal battery and the external battery, and the high-voltage relay is controlled by the EMS energy management subsystem;

[0045] The DC end of the energy storage converter is connected to the external battery.

[0046] As can be seen from the above description, the energy storage battery is usually equipped with a master control box to manage the battery, and the master control box contains a high-voltage relay inside. The internal battery is the front end of the high-voltage relay, and there is always voltage in the internal battery when the high-voltage relay does not act, i.e., the contact is not closed. The external battery is the rear end of the high-voltage relay, and there is voltage in the external battery only when the contact of the high-voltage relay is closed. Therefore, the energy storage battery is divided into an internal battery and an external battery according to the high-voltage relay. After the DC side micro switch is closed in the off-grid state, the internal battery power is transmitted to the power load through the normally closed DC relay to supply power to the EMS energy management subsystem. The EMS energy management subsystem starts to control the high voltage of the energy storage battery, i.e., controls the contact of the high-voltage relay to be attracted. At this time, the external battery has voltage. Then, the DC side micro switch is opened, and the external battery supplies power to the power load. The internal battery can provide a high-voltage signal for the power supply of the external battery, similar to an uninterrupted UPS, but does not provide continuous power supply for the power load. Therefore, the DC side micro switch can be opened after the external battery has voltage. At the same time, the first anti-diode can prevent short circuit caused by the inconsistency between the internal battery voltage and the external battery voltage during the process of increasing the voltage of the external battery, thereby playing a protection role.

[0047] Further, the DC side micro-break switch is further connected in series between the fuse and the inside of the battery.

[0048] As described above, the fuse is added in the battery DC side power supply circuit, which effectively protects the components in the circuit when the circuit is short-circuited, and further protects the energy storage system.

[0049] Further, the DC / DC converter is further included.

[0050] The output end of the rectifier bridge stack and the normally closed DC relay are connected to the power load through the DC / DC converter.

[0051] As described above, the DC / DC converter can convert the voltage of the grid side, the energy storage converter side and the energy storage battery side into the rated input voltage suitable for the power load, so as to supply power to the power load.

[0052] Further, the second anti-reverse diode is further connected in series between the rectifier bridge stack and the DC / DC converter.

[0053] Further, the third anti-reverse diode is further connected in series between the normally closed DC relay and the DC / DC converter.

[0054] As described above, the second anti-reverse diode and the third anti-reverse diode both prevent the current from flowing in the reverse direction in the circuit, thereby avoiding the short circuit of the circuit.

[0055] Please refer to Figure 6 A dual power supply method of an energy storage system, applied to the dual power supply system of the energy storage system, comprising the steps of:

[0056] In the grid-connected mode, the first AC side micro-break switch in the energy storage AC side power supply circuit is closed, the grid side AC power is input into the rectifier bridge stack through the first AC side micro-break switch, and the DC power output after rectification is used to supply power to the power load;

[0057] In the off-grid mode, there is no AC power input from the grid side, and the energy storage AC side power supply circuit has no voltage, and the first AC side micro-break switch is disconnected, at this time, the DC side micro-break switch in the battery DC side power supply circuit is closed, the DC power of the energy storage battery side is output to the power load through the DC side micro-break switch and the normally closed contact of the normally closed DC relay.

[0058] When the grid side recovers, the off-grid mode is converted into the grid-connected mode, at this time, the first AC side micro switch is closed again, the voltage in the energy storage AC side power supply circuit passes, the drive coil of the normally closed DC relay works, the normally closed contact of the normally closed DC relay in the battery DC side power supply circuit is driven to be disconnected, the battery DC side power supply circuit stops supplying power to the power load, and only the energy storage AC side power supply circuit supplies power to the power load.

[0059] From the above description, the beneficial effects of the present application are that: based on the same technical concept, the above-mentioned dual power supply system of an energy storage system provides a dual power supply method of an energy storage system, the mode of power supply by the grid side in the grid-connected mode and the mode of power supply by the energy storage battery in the off-grid mode are switched by controlling the on-off of the first AC side micro switch in the energy storage AC side power supply circuit and the DC side micro switch in the battery DC side power supply circuit, the dual power supply of the energy storage system is realized, and the standby time of system power supply is prolonged; and a normally closed DC relay is introduced into the battery DC side power supply circuit, the drive coil of the normally closed DC relay is connected to the energy storage AC side power supply circuit, so that the normally closed contact of the normally closed DC relay is driven to be disconnected when the grid side recovers, thereby automatically disconnecting the power supply of the energy storage battery in the battery DC side power supply circuit, and the grid power supply is preferentially used. The UPS device is cancelled as a whole, is suitable for harsh application environment, does not need to increase air conditioning cooling, and effectively reduces the system design cost.

[0060] The dual power supply system and power supply method of the energy storage system of the present application are used to replace the UPS as the control circuit power supply device in the traditional energy storage system to maintain the system continuous operation for a certain time under the abnormal external AC power supply, which is described below in combination with specific embodiments.

[0061] Please refer to Figure 1 , the first embodiment of the present application is:

[0062] A dual power supply system of an energy storage system, as shown in Figure 1 , comprises a battery DC side power supply circuit and an energy storage AC side power supply circuit.

[0063] The input end of the battery DC side power supply circuit is connected to the energy storage battery through a DC side micro switch K3, and the output end is connected to the power load; the input end of the energy storage AC side power supply circuit is connected to the grid through a first AC side micro switch K1, and the output end is connected to the power load; and a normally closed DC relay KM1 is connected in series in the battery DC side power supply circuit, the normally closed contact of the normally closed DC relay KM1 is connected to the DC side micro switch K3 and the power load at both ends, and the drive coil of the normally closed DC relay KM1 is connected to the energy storage AC side power supply circuit, so as to drive the normally closed contact of the normally closed DC relay KM1 to be disconnected when the voltage in the energy storage AC side power supply circuit passes.

[0064] That is, in the present embodiment, by controlling the on-off of the first AC side micro switch K1 in the energy storage AC side power supply circuit and the DC side micro switch K3 in the battery DC side power supply circuit, the mode of power supply by the grid side power supply in grid-connected mode and the mode of power supply by the energy storage battery in off-grid mode are switched, the dual power supply of the energy storage system is realized, and the standby time of the system power supply is prolonged; and a normally closed DC relay KM1 is introduced in the battery DC side power supply circuit, the drive coil of the normally closed DC relay KM1 is connected to the energy storage AC side power supply circuit, so that when the grid side power supply is restored, the normally closed contact of the normally closed DC relay KM1 is driven to open, thereby automatically disconnecting the power supply of the energy storage battery in the battery DC side power supply circuit, and the grid power supply is preferentially used. The UPS device is cancelled as a whole, which is suitable for harsh application environment, does not need to increase air conditioning cooling, and effectively reduces the system design cost.

[0065] Please refer to Figure 1 , the second embodiment of the present application is:

[0066] A dual power supply system of an energy storage system, based on the above embodiment one, in the present embodiment, as shown in Figure 1 , the energy storage AC side power supply circuit further includes an energy storage converter PCS and a second AC side micro switch K2.

[0067] Among them, the AC end of the energy storage converter PCS is connected to the load in parallel with the first AC side micro switch K1 through the second AC side micro switch K2, and the DC end of the energy storage converter PCS is connected to the energy storage battery.

[0068] That is, in the present embodiment, in order to improve the performance of the energy storage system, the energy storage converter PCS is added, which can on one hand output power to supply power to the load when the grid side is abnormal, and on the other hand can convert the AC power of the grid side into DC power to charge the energy storage battery when the load is not used, so as to ensure that the energy storage battery has sufficient power, thereby further prolonging the power supply time of the energy storage system.

[0069] Wherein, in the embodiment, the first AC side micro-break switch K1 and the second AC side micro-break switch K2 are mechanically interlocked switches. That is, the first AC side micro-break switch K1 and the second AC side micro-break switch K2 are mechanically interlocked, that is, only one of the two micro-break switches can be closed at the same time, or both are opened, when the power grid side supplies power to the power load, the first AC side micro-break switch K1 is closed, and the second AC side micro-break switch K2 is in an open state under the mechanical interlocking structure, and the energy storage converter PCS does not work to reduce the consumption of the power grid side voltage; when the power grid side is abnormal, that is, off-grid, the second AC side micro-break switch K2 is closed, and the first AC side micro-break switch K1 is in an open state under the mechanical interlocking structure, at this time, there is still no voltage passing through the energy storage AC side power supply loop, which has the advantage of reducing the impact when there is voltage in the branch. After the subsequent energy storage converter PCS is started and runs, the power supply to the power load is stably maintained by the energy storage converter PCS.

[0070] It is worth noting that the first AC side micro-break switch K1 and the second AC side micro-break switch K2 in the embodiment are only part of the energy storage AC side power supply loop. When it is necessary to convert the AC power of the power grid side into DC power to supply the energy storage battery by using the energy storage converter PCS, other charging circuits can be added according to actual needs, which are not limited here.

[0071] For example, as shown in Figure 1 In the embodiment, a rectifier bridge stack UR is also connected in series in the energy storage AC side power supply loop, and the input end of the rectifier bridge stack UR is connected to the first AC side micro-break switch K1 and the second AC side micro-break switch K2 through an AC bus, and the output end of the rectifier bridge stack UR is connected to the power load, for uncontrolled rectification of the AC power of the power grid side or the energy storage converter PCS to DC power output to supply power to the power load.

[0072] That is, since the power load usually adopts DC power supply, the AC power of the power grid side or the energy storage converter PCS side is uncontrolled rectified to DC power output by introducing a rectifier bridge stack UR to supply power to the power load.

[0073] At the same time, since the power supply voltage of the power load usually has requirements, as shown in Figure 1 The dual-power supply system of the energy storage system of the embodiment further includes a DC / DC converter, wherein the normally closed DC relay KM1 and the output end of the rectifier bridge stack UR are connected to the power load through the DC / DC converter. That is, the DC / DC converter can convert the voltage of the power grid side, the energy storage converter PCS side and the energy storage battery side into the rated input voltage suitable for the power load to supply power to the power load.

[0074] Please refer to Figure 1 The third embodiment of the present application is:

[0075] A dual power supply system of an energy storage system, on the basis of the first or second embodiment, in this embodiment, in order to perfect the control strategy, an EMS energy management subsystem is introduced, which can be used as a control center and also as an electrical load, which is powered by the dual power supply system of this embodiment.

[0076] In this embodiment, the energy storage battery includes an internal battery and an external battery, the internal battery is connected to the normally closed DC relay KM1 through the DC side micro switch K3, and the external battery is connected to the normally closed DC relay KM1 through a first anti-diode; at the same time, a high voltage relay KM2 is connected in series between the internal battery and the external battery, and the high voltage relay KM2 is connected to the EMS energy management subsystem; the DC end of the energy storage converter PCS is connected to the external battery.

[0077] That is, in this embodiment, since the energy storage battery is usually equipped with a master control box to manage the battery, and the master control box contains a high voltage relay KM2, the internal battery is the front end of the high voltage relay KM2, and when the high voltage relay KM2 does not act, that is, the contact is not closed, the internal battery always has voltage; and the external battery is the rear end of the high voltage relay KM2, and only when the contact of the high voltage relay KM2 is closed, the external battery has voltage, therefore, the energy storage battery is divided into internal and external according to the high voltage relay KM2, after closing the DC side micro switch K3 in off-grid state, the internal battery power is transmitted to the electrical load through the normally closed DC relay KM1 to power the EMS energy management subsystem, and the EMS energy management subsystem starts to control the high voltage of the energy storage battery, that is, controls the contact of the high voltage relay KM2 to attract, at this time the external battery has voltage, then the DC side micro switch K3 is opened, and the external battery supplies power to the electrical load. The internal battery can provide a high voltage signal for the power supply of the external battery similar to an uninterrupted UPS, but it does not provide continuous power supply for the electrical load, therefore, after the external battery has voltage, the DC side micro switch K3 can be opened; at the same time, the first anti-diode D1 can prevent short circuit caused by the inconsistency of the internal battery voltage and the external battery voltage during the high voltage buffering process of the external battery, and plays a protective role.

[0078] In addition, as Figures 2 to 6 In this embodiment, a fuse FU is connected in series between the DC side micro switch K3 and the internal battery, which can effectively protect the components in the circuit when a short circuit occurs, and further protect the energy storage system; a second anti-diode D2 is connected in series between the rectifier bridge stack UR and the DC / DC converter, and a third anti-diode D3 is connected in series between the normally closed DC relay KM1 and the DC / DC converter, in this embodiment, the second anti-diode D2 and the third anti-diode D3 both prevent current from flowing in the opposite direction in the circuit, avoid short circuit in the circuit, and perfect the performance of the energy storage system.

[0079] Referring to Figure 6 , the fourth embodiment of the present application is:

[0080] A dual power supply method of an energy storage system, applied to the dual power supply system of the energy storage system in the third embodiment, as shown in the figure, comprising the steps of: Figures 2 to 5

[0081] In grid-connected mode, the first AC side micro switch K1 in the energy storage AC side power supply circuit is closed, the grid side AC power is input into a rectifier bridge stack UR through the first AC side micro switch K1, and the DC power output after rectification is used to supply power to the power load;

[0082] In off-grid mode, there is no AC power input from the grid side, and no voltage passes through the energy storage AC side power supply circuit, so the first AC side micro switch K1 is disconnected. At this time, the DC side micro switch K3 in the battery DC side power supply circuit is closed, and the DC power from the energy storage battery is output to the power load through the DC side micro switch K3 and the normally closed contact of the normally closed DC relay KM1.

[0083] When the grid side resumes operation, the off-grid mode is converted to the grid-connected mode. At this time, the first AC side micro switch K1 is closed again, and the voltage passes through the energy storage AC side power supply circuit. The driving coil of the normally closed DC relay KM1 works, and the normally closed contact of the normally closed DC relay KM1 in the battery DC side power supply circuit is disconnected. The battery DC side power supply circuit stops supplying power to the power load, and only the energy storage AC side power supply circuit supplies power to the power load.

[0084] That is, in this embodiment, based on the same technical concept, in cooperation with the above-mentioned dual power supply system of an energy storage system, a dual power supply method of an energy storage system is provided. By controlling the on-off of the first AC side micro switch K1 in the energy storage AC side power supply circuit and the DC side micro switch K3 in the battery DC side power supply circuit, the power supply mode of the grid side in grid-connected mode and the energy storage battery in off-grid mode is switched. The dual power supply of the energy storage system is realized, and the standby time of the system power supply is prolonged. A normally closed DC relay KM1 is introduced into the battery DC side power supply circuit, and the driving coil of the normally closed DC relay KM1 is connected to the energy storage AC side power supply circuit. When the grid side resumes power supply, the normally closed contact of the normally closed DC relay KM1 is driven to be disconnected, so as to automatically disconnect the power supply of the energy storage battery in the battery DC side power supply circuit, and the grid power supply is preferred. The whole cancels the UPS device, which is suitable for harsh application environment and does not need to increase the air conditioner for heat dissipation, effectively reducing the system design cost.

[0085] As Figure 2 is the specific principle process diagram of the dual power supply method of an energy storage system in this embodiment, as Figure 3 ​As shown, when the grid side is normal, the grid side power supply voltage is normal, at this time, the first AC side micro switch K1 is closed, the grid side AC power is uncontrolled rectified by the rectifier bridge stack UR to DC voltage, and then through the second anti-reverse diode D2 to the DC / DC converter, and the DC / DC converter outputs 24V power supply voltage to supply power to the devices in the energy storage system.

[0086] When the grid side is abnormal, the energy storage system is in off-grid operation, at this time, the second AC side micro switch K2 is closed (it should be noted that although the second AC side micro switch K2 is closed at this time, since the energy storage converter PCS is not started, and the grid side is abnormal, at this time, there is no voltage passing through the loop in which the second AC side micro switch K2 is located, and the advantage of closing the second AC side micro switch K2 first is that after the voltage generated by the subsequent start of the energy storage converter PCS, the impact of the voltage can be effectively buffered), and the first AC side micro switch K1 is disconnected due to mechanical interlocking. Then, the DC side micro switch K3 is closed, the internal voltage of the battery passes through the fuse FU, the DC side micro switch K3, the normally closed DC relay KM1, the third anti-reverse diode D3 and the DC / DC converter in turn, and is converted by the DC / DC converter into 24V power supply voltage to supply power to the devices in the energy storage system temporarily, that is, as shown in Figure 4 .

[0087] At this time, the EMS energy management subsystem starts to work under the condition of internal battery power supply, controls the contact of the high-voltage relay KM2 to be attracted, and the high voltage outside the battery is turned on, at this time, the DC side micro switch K3 can be disconnected to convert the internal battery power supply to the external battery power supply, that is, as shown in Figure 5 .

[0088] Further, when the energy storage system controls the energy storage converter PCS to start off-grid operation, the AC bus in the energy storage AC side power supply loop has voltage passing through the second AC side micro switch K2 which has been closed originally, at this time, the drive coil of the normally closed DC relay KM1 detects that there is voltage in the energy storage AC side power supply loop, that is, the normally closed contact of the normally closed DC relay KM1 is disconnected, and the power supply loop outside the battery is also disconnected, and the devices in the energy storage system are powered by the energy storage converter PCS instead, that is, as shown in ​ .

[0089] The energy storage system runs stably, and the power is taken from the AC side to supply power to the power load, and when the energy storage system is shut down or the energy storage converter PCS is abnormally shut down, the power is converted to be taken from the DC side.

[0090] At the same time, if the grid side is restored to normal, the first AC side micro switch K1 can be closed again to restore the power supply to the power load by the grid side.

[0091] In summary, the application provides a dual power supply system and a power supply method of an energy storage system, which have the following beneficial effects.

[0092] 1. The UPS device is cancelled, the system does not need to increase the air conditioning cooling scheme, and the environmental adaptability of the system is improved.

[0093] 2. Compared with the previous UPS power supply, the dual power supply of alternating current and direct current and the multi-path power supply mode effectively avoid the situation that the system cannot run due to the failure of the UPS single device.

[0094] 3. In the off-grid application scenario, the power supply of the application is more stable and reliable. As long as the energy storage battery system has power, the system can be black started and run.

[0095] The above is only an embodiment of the application, and does not limit the patent range of the application. Any equivalent transformation, direct or indirect application in related technical fields using the content of the specification and drawings is also included in the patent protection range of the application.

Claims

1. A dual-power supply system for an energy storage system, characterized in that, This includes the battery DC-side power supply circuit and the energy storage AC-side power supply circuit; The input terminal of the battery DC power supply circuit is connected to the energy storage battery via a DC-side micro-circuit switch, and the output terminal is connected to the electrical load. The input end of the energy storage AC power supply circuit is connected to the power grid through a first AC micro-circuit switch, and the output end is connected to the electrical load. A normally closed DC relay is connected in series in the DC power supply circuit of the battery. The two ends of the normally closed contact of the normally closed DC relay are respectively connected to the DC side micro-break switch and the electrical load. The drive coil of the normally closed DC relay is connected to the AC power supply circuit of the energy storage, and is used to drive the normally closed contact of the normally closed DC relay to open when there is voltage passing through the AC power supply circuit of the energy storage. The energy storage AC power supply circuit also includes an energy storage converter and a second AC side micro-circuit switch. The AC terminal of the energy storage converter is connected in parallel to the electrical load via the second AC-side micro-break switch and the first AC-side micro-break switch; The DC terminal of the energy storage converter is connected to the energy storage battery; It also includes an EMS energy management subsystem, and the energy storage battery includes an internal battery and an external battery. The battery is internally connected to the normally closed DC relay via the DC-side micro-break switch. The battery is externally connected to the normally closed DC relay via a first anti-reverse diode. A high-voltage relay is connected in series between the inside and outside of the battery, and the high-voltage relay is controlled by the EMS energy management subsystem. The DC terminal of the energy storage converter is connected to the outside of the battery; The dual power supply method of the energy storage system includes the following steps: In grid-connected mode, the first AC side micro-break switch in the AC power supply circuit of the energy storage is closed, and the AC power from the grid side is fed into a rectifier bridge through the first AC side micro-break switch. After rectification, DC power is output to supply power to the electrical load. In off-grid mode, there is no AC power input on the grid side, and no voltage passes through the AC power supply circuit of the energy storage. The first AC side micro-break switch is open. At this time, the DC side micro-break switch in the DC power supply circuit of the battery is closed, and the DC power from the energy storage battery side is output to the electrical load through the normally closed contact of the DC side micro-break switch and the normally closed DC relay. When the grid side resumes operation, the off-grid mode is switched to the grid-connected mode. At this time, the first AC side micro-circuit switch is closed again, and voltage flows through the energy storage AC side power supply circuit. The drive coil of the normally closed DC relay is activated, driving the normally closed contact of the normally closed DC relay located in the battery DC side power supply circuit to open. The battery DC side power supply circuit stops supplying power to the electrical load, and only the energy storage AC side power supply circuit supplies power to the electrical load.

2. The dual-power supply system for an energy storage system according to claim 1, characterized in that, The first AC-side micro-break switch and the second AC-side micro-break switch are mechanically interlocked with each other.

3. The dual-power supply system for an energy storage system according to claim 1, characterized in that, A rectifier bridge is also connected in series in the AC power supply circuit of the energy storage; The input terminal of the rectifier bridge is connected to the first AC side micro-break switch and the second AC side micro-break switch via an AC bus. The output terminal of the rectifier bridge is connected to the electrical load, and is used to rectify the AC power stored on the grid side or the energy storage converter into DC power to supply the electrical load.

4. The dual-power supply system for an energy storage system according to claim 1, characterized in that, A fuse is connected in series between the DC-side micro-break switch and the inside of the battery.

5. The dual-power supply system for an energy storage system according to claim 3, characterized in that, It also includes DC / DC converters; The normally closed DC relay and the output of the rectifier bridge are both connected to the electrical load through the DC / DC converter.

6. The dual-power supply system for an energy storage system according to claim 5, characterized in that, A second anti-reverse diode is also connected in series between the rectifier bridge and the DC / DC converter.

7. The dual-power supply system for an energy storage system according to claim 5, characterized in that, A third anti-reverse diode is also connected in series between the normally closed DC relay and the DC / DC converter.

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