46 / 2021-10-08 16:22:54

Improved control strategy for parallel reactive power sharing on Virtual Synchronous Generator

Power electronics technology and application > Power converter topologies and design

Distributed power sources in medium and low voltage microgrids often lead to different line impedances due to different distances. Multiple inverters with the same reactive power capacity controlled by traditional virtual synchronous generators (VSGs) cannot achieve uniform distribution of load reactive power and will generate parallel circulation. This article proposes an improved multi-VSG parallel reactive power sharing control strategy. In this strategy, the load voltage secondary adjustment module is added to the reactive power-voltage loop to compensate for the voltage drop caused by the line impedance and the voltage primary adjustment characteristics when the reactive power capacity of the VSG is not equal to the reactive power consumption of the load, so as to achieve the non-difference control of load voltage. And the voltage compensation signal is added to enable the VSG to realize the uniform distribution of the reactive power in the steady state. In order to suppress the reactive circulating current as VSGs are running in parallel, an adaptive virtual impedance based on circulating current feedback is introduced. Finally, it is verified by simulation that when the system is stable, the load can work at the rated voltage and the power can be shared equally between the VSGs.