Voltage stability control for DC microgrid with energy storage

In order to maintain the bus voltage stability of isolated DC microgrid, it is necessary to configure the energy storage system (ESS) to realize the balance of energy supply and demand. When there are multiple energy storage units (ESUs) in the dc microgrid, the overcharge or over discharge is avoided. Therefore, a new adaptive droop control is proposed according to the state of charge (SOC). Once the ESS is out of work due to fault or fully charged, the renewable energy source needs to switch from the maximum power point tracking (MPPT) mode to the droop control mode. Meanwhile, the demand side power is distributed automatically by renewable energy source according to its maximum output power, which can assure the bus voltage stability. The proposed strategy can be verified through real time digital simulator (RTDS) in an isolated DC microgrid.