Research on power scheduling strategy for microgrid in islanding mode

摘要

This article discussed and analyzed the power scheduling strategy for the energy management system (EMS), the microgrid central controller (MGCC), and the device units in the situation where the microgrid operates in the islanding mode. Since the output powers of inverters operate under the traditional droop parallel strategy, it cannot precisely match the reference powers scheduled by the EMS. The probable commanding confliction between the EMS and the MGCC will further result in a frequency flicker. Therefore, an improved power distributing strategy is proposed to divide the droop characteristic curves of inverters into two kinds. One of which with no frequency regulation mission is controlled by the EMS to be operated in constant power characteristic while the other one controlled by the MGCC maintains the system frequency. Thus, the output powers can follow the EMS instructions without being influenced by load disturbance. Corresponding verified experiments are meanwhile able to be performed on an experimental microgrid platform. It is demonstrated that the stabilization of voltage frequency can be achieved even in the situation of frequent load fluctuation and the constant power outputs of units can be also guaranteed as well.