A coordinated control strategy for suppressing transient power fluctuation of power conversion system and stabilizing AC bus voltage

Abstract

The PV / Storage microgrid (MG) is one of the main forms of effectively use of Solar energy. Energy storage based power conversion system (PCS) is responsible for maintaining the power balance and voltage / frequency in the islanded MG. However, the power input or output of PCS and the instantaneous stress of the converter current will be increased greatly when the load is suddenly changed, which may result in the PCS over current fault and power imbalance, and the bus voltage and frequency oscillation of MG, will threaten the system stability. In this paper, a coordinated control strategy for PCS and photovoltaic (PV) inverter based islanded hybrid MG is proposed to suppress the transient power fluctuation of PCS and stabilize the AC bus voltage. The differentials of active power output of PCS is calculated and used to compensate the d-axis current of PV inverter. In this way, the PV system is controlled to change the power output with PCS simultaneously, so as to achieve the purpose of suppressing PCS transient power fluctuations and stabilizing the AC bus transient voltage. The hybrid MG is simulated by MATLAB / Simulink, the effectiveness of the coordinated control strategy is verified by simulation results based on different scenarios.