Online RLS Impedance Estimation - Based Adaptive Control of Virtual Synchronous Generators in Grid Forming Inverters

This article addresses the problem of poor dynamic performance of conventional virtual synchronous generators (VSGs) when switched to grid-connected mode (GCM) due to varying grid conditions. The proposed research involves an analysis of the coupling between active and reactive power and its dependence on grid conditions, leading to the proposal of an adaptive VSG (AVSG) control strategy based on online grid impedance estimation. The Recursive Least Square (RLS) method is proposed for real-time grid impedance estimation, allowing the AVSG to exhibit superior performance compared to conventional fixed-parameter-based controller designs. The effectiveness of the proposed control scheme is demonstrated by using the Simscape electrical library in MATLAB/Simulink. The major findings indicate that the AVSG ensures robust operation under both strong and weak grid conditions, with specified settling time and damping ratio and minimal overshoot. The conclusions reached demonstrates the effectiveness of the AVSG control strategy in improving the dynamic performance of VSGs in GCM, with potential for wider applications in renewable energy systems.