Dynamic Stability Study of Grid-Connected Inverter Based on Virtual Synchronizer under Weak Grid

Abstract

The power grid has the characteristics of a weak grid with an increase in new energy penetration in the power system. Power electronic-based renewable generation brings issues that weaken the entire system, including the loss of inertia. Low inertia and weak damping cause system oscillation. Virtual synchronous generator (VSG) technology gives power electronic equipment inertia-support capability but increases the complexity of control system parameter design. Many researchers have studied the design method of VSG considering the frequency disturbance of the power grid. The traditional VSG parameter design method ignores the influence of source-side and grid-side fluctuations on the transient stability of the system, resulting in the difference between the actual dynamic and static indicators and the design indicators of VSG in a weak grid. This paper analyzes a small-signal model based on power fluctuations and frequency fluctuations and proposes a control parameter design method that combines the influence of grid impedance to ensure the dynamic stability of the system under a weak power grid. The simulation and experimental results verify the correctness and feasibility of the control method.