Energy storage device and system, and power system

1. An energy storage device, comprising:

at least two parallel-connected energy storage units, wherein

each energy storage unit comprises: a battery cluster and a power conversion system; and the battery cluster comprises at least two cells;

a direct-current side of the power conversion system is electrically connected to the battery cluster,

an alternating-current side of the power conversion system is configured to electrically connect to an input side of an alternating-current combiner cabinet,

an output side of the alternating-current combiner cabinet is configured to electrically connect to an alternating-current side of a transformer,

the power conversion system comprises a three-phase inverter bridge, a switch device, and a circuit breaker, and

an input end of the three-phase inverter bridge is electrically connected to the battery cluster, an output end of the three-phase inverter bridge is electrically connected to one end of the switch device, the other end of the switch device is electrically connected to one end of the circuit breaker, and the other end of the circuit breaker is configured to electrically connect to the input side of the alternating-current combiner cabinet.

2. The energy storage device according to claim 1 , wherein each energy storage unit further comprises: a first protection circuit; and the first protection circuit is configured to protect the power conversion system and the battery cluster; and

one end of the first protection circuit is electrically connected to the battery cluster, the other end of the first protection circuit is electrically connected to the direct-current side of the power conversion system, and the direct-current side of the power conversion system is electrically connected to the battery cluster through the first protection circuit.

3. The energy storage device according to claim 2 , wherein the first protection circuit comprises:

an isolation module, a safety module, a main control module, and an overcurrent protection module, wherein

one end of the isolation module is electrically connected to the battery cluster, the other end of the isolation module is electrically connected to one end of the safety module, the other end of the safety module is electrically connected to one end of the main control module, the other end of the main control module is electrically connected to the direct-current side of the power conversion system, and the overcurrent protection module is parallel-connected to the main control module.

4. The energy storage device according to claim 2 , wherein the first protection circuit comprises:

a safety module, a main control module, an overcurrent protection module, and an isolation module, wherein

one end of the safety module is electrically connected to the battery cluster, the other end of the safety module is electrically connected to one end of the main control module, the other end of the main control module is electrically connected to one end of the isolation module, the other end of the isolation module is electrically connected to the direct-current side of the power conversion system, and the overcurrent protection module is parallel-connected to the main control module.

5. The energy storage device according to claim 1 , wherein the alternating-current side of the power conversion system is configured to electrically connect to one end of a second protection circuit, and the other end of the second protection circuit is configured to electrically connect to the input side of the alternating-current combiner cabinet; and the alternating-current side of the power conversion system is configured to electrically connect to the input side of the alternating-current combiner cabinet through the second protection circuit.

6. The energy storage device according to claim 1 , wherein the switch device is a relay.

7. The energy storage device according to claim 1 , wherein the switch device is a contactor.

8. An energy storage system, comprising:

the energy storage device according to claim 1 ;

the alternating-current combiner cabinet, wherein the input side of the alternating-current combiner cabinet is electrically connected to the energy storage device; and

the transformer, wherein the alternating-current side of the transformer is electrically connected to the output side of the alternating-current combiner cabinet.

9. The energy storage system according to claim 8 , wherein the energy storage system further comprises a third protection circuit, the output side of the alternating-current combiner cabinet is electrically connected to one end of the third protection circuit, and the other end of the third protection circuit is electrically connected to the alternating-current side of the transformer.

10. The energy storage system according to claim 8 , wherein the alternating-current combiner cabinet comprises: an alternating-current circuit breaker corresponding to each energy storage unit; and

one end of the alternating-current circuit breaker is electrically connected to an alternating-current side of a power conversion system in the energy storage unit corresponding to the alternating-current circuit breaker; and the other end of the alternating-current circuit breaker is electrically connected to the alternating-current side of the transformer.

11. A power system, comprising:

an optical-to-electrical conversion system;

the energy storage system according to claim 8 , wherein the energy storage system is electrically connected to the optical-to-electrical conversion system; and

a power grid, wherein the power grid is electrically connected to the energy storage system.