Research on Marine VSG Grid-connected Pre-synchronization Control Strategy

Compared with the land power grid, the capacity of the ship power system is smaller, and the frequent switching and start/stop of high-power converter devices and nonlinear loads will lead to the ship power grid in a non-ideal state with harmonics. At this time, the grid connection of photovoltaic power supply based on Virtual Synchronous Generator (VSG) control technology will lead to poor phase-locking performance and impulse current. However, due to the existence of phase-locked loop (PLL), the speed and accuracy of pre-synchronization of traditional VSG pre-synchronization con-trol strategy are easy to be disturbed when there are a large number of harmonics in ship power grid. In order to solve this problem, an improved pre-synchronization control strategy of marine VSG is proposed in this paper. Two PI regulators are used to replace PLL to reduce control parameters and effectively improve the speed of VSG pre-synchronization. Finally, the effect of this method on improving the grid-connected pow-er quality of marine distributed photovoltaic inverter is verified by simulation and experiment.