A frequency stability control strategy for an islanded microgrid including intermittent renewable energy

diesel generator set(DGS)and battery energy storage system is proposed based on a virtual synchronous generator(VSG). First

a DGS equivalent mathematical model is built to illustrate the step response characteristics of the DGS output voltage and rotating speed in a synchronous rotating coordinate reference frame. Besides

on the basis of theoretical analysis of VSG control and frequency stability of the microgrid

the control approach to an energy storage converter with virtual inertia and virtual damping is designed using the rotor motion equation of the synchronous generator

the primary frequency regulation feature and the voltage reactive power regulation characteristic. Furthermore

the frequency response characteristics of the microgrid are compared with those of conventional current control

droop control and VSG control for the energy storage converter(ESC)based on the MATLAB/Simulink under fluctuations by loads. Finally

the proposed strategy is demonstrated in detail and validated with an islanded microgrid consisting of two VSGs and a DGS under various conditions. This work is supported by National Key Research and Development Program of China(No. 2016YFB0900300)and National Natural Science Foundation of China(No. 51677049).