Research of Virtual Impedance Control Strategy of Hybrid Renewable Energy Microgrid

Abstract

The principle of virtual impedance is analyzed in detail, and the simulation of parallel connection of inverter with different capacity is compared and analyzed in detail. The principle of virtual impedance is analyzed, and its derivation and analysis are carried out in detail. The simulation results show that the reactive power of parallel inverters with different capacities without virtual impedance cannot be distributed proportionally, and there is a large reactive circulation between inverters, which seriously threatens the safe and stable operation of micro grid. After the introduction of virtual impedance, reactive power distribution can be effectively improved, and the distribution effect is better with the increase of virtual impedance, but it will cause voltage sag of AC bus. This paper introduced the virtual impedance into the traditional droop control, make the output impedance and line impedance of the inverter are mainly inductive, so the droop control algorithm is implemented. This paper presented a new method based on the virtual impedance to adjust the frequency and voltage of the micro-grid bus to realize the adjustment of the voltage of the micro grid.