Real-Time Optimization Method for Virtual Inertia Based on Energy Storage VSG Grid-Connected Control

Abstract

Grid-forming energy storage controlled in Virtual Synchronous Generator (VSG) has received widespread attention due to its ability to improve system inertia level and to support renewable energy’s friendly grid-connection. However, when using VSG control with fixed virtual inertia to deal with different frequency events, its virtual rotational speed and power angle are prone to significant oscillating and slow recovery. Therefore, this article proposes a method for dynamically optimizing virtual inertia in real-time based on status of virtual speed and power angle. Firstly, a mathematical model of energy storage based on VSG control was constructed, and the influence of virtual inertia on the transient processes of virtual speed and power angle was analyzed. Secondly, the optimization objective is to reduce virtual speed oscillation, power angle oscillation, and shorten transition time. The range of virtual inertia values is determined with system stability as the constraint. Then the optimization model is established. The particle swarm optimization algorithm is used to calculate the optimal inertia value in real time. Finally, a simulation model of a wind storage joint system with VSG control was constructed, and the effectiveness of the proposed method was verified