Optimization Design and Feature Research on VSG Control Strategy of Marine Photovoltaic Grid-connected Inverter

Aiming at improving the schedulability and stability of photovoltaic (PV) system that integrated within the ship power system (SPS), this paper proposes a virtual synchronous generator (VSG) based control strategy for the PV grid-connected inverter. The virtual inertia power is introduced into the reference power value by a first-order inertia function, so as to change the inertia and damping characteristics of the inverter and show similar operating features as those of traditional diesel synchronous generator (DG). Both droop control and logic threshold control strategies are applied to realize the automatic power distribution between the inverter and the generator. Under the simulation environment of PSCAD/EMTDC software, an original marine PV grid-connected power system model is established. The simulation cases are discussed under two typical operation conditions, which are depended on whether or not the power management system (PMS) is put into the utilization. Then, the active/reactive power distribution response and frequency fluctuation characteristics of these two power sources are compared by applying the traditional constant power (PQ) control and VSG control strategy respectively. The results show that this novelty VSG control strategy has immediate effectiveness in suppressing the frequency fluctuation of the power grid, and realizing the automatic and proportional output power adjustment for the grid-connected inverter, which can significantly improve the grid stability.