Coupling analysis on power‐frequency control loops for virtual synchronous generator based on relative gain array and Prony method

Abstract

AbstractWith the improvement of the penetration of power electronic equipment, a challenging scenario is arising in power‐frequency control system design of virtual synchronous generator (VSG). This affects the stability and control performance of the multi‐VSG grid‐connected system due to the undesirable dynamic coupling of the power‐frequency control loops. From this perspective, this paper proposes a systematic procedure for accurately evaluating the coupling of power‐frequency control loop, which is based on the relative gain array (RGA) and Prony analysis method. Firstly, the output admittance model of multi‐VSG grid‐connected system is established, and the transfer function matrices of output power and angular frequency are derived, respectively. Then, the variation law of coupling between control loops of VSG with different parameters is investigated by two methods: One is numerical analysis, and the other is RGA method which can determine the frequency band of coupling. Besides, the interaction between different VSG control strategies is compared and analyzed based on RGA. Subsequently, Prony analysis method is proposed to verify the results of RGA analysis. Finally, simulation and experimental results in a two‐machine grid‐connected system are presented to support the theoretical analysis and demonstrate the feasibility of the proposed method.