VSG parallel control strategy based on secondary voltage regulation

In view of the different distances of distributed power sources (DGs) in medium and low-voltage microgrids, the line impedance of each power source cannot meet the matching principle of inversely proportional to the capacity, so that parallel virtual synchronous generators (VSG) cannot allocate reactive power according to capacity. This paper proposes a VSG parallel control strategy based on secondary voltage regulation. In this strategy, a virtual complex impedance is first added to match the transmission impedance, thereby increasing the proportion of steady-state reactive power distribution of multiple VSGs in parallel and reducing transient transients. Power fluctuations. In island mode, to allow the load to work at the rated voltage when the VSG is running in parallel, the non-difference adjustment of the load voltage is achieved by adding a secondary voltage regulating module and connecting a PI regulator in series with a coefficient proportional to the capacity and the reactive power is distributed among the VSGs according to the capacity. Finally, it is verified by simulation that when the system is stable, the load can work under the rated voltage and the reactive power is distributed among the VSGs according to the capacity.