The battery pack is an independent and reliable power source. It is not affected by the AC power supply. In the event of any accident in the power plant or substation, even in the case of power failure of the entire plant and the entire station AC power supply, the DC system can still be guaranteed. The electrical equipment works reliably and continuously, and the voltage is stable. At the same time, it can also be used as the accident lighting power supply for the whole plant and the whole station, and is the last barrier to ensure that the power supply is not interrupted.