ANN-Based Grid Impedance Estimation for Adaptive Gain Scheduling in VSG Under Dynamic Grid Conditions

TL;DR

This paper introduces an ANN-based adaptive gain-scheduling control scheme for VSGs that accurately estimates grid impedance in real-time, ensuring stable operation under varying grid conditions.

Contribution

The paper presents a novel method combining ANN-based impedance estimation with adaptive gain scheduling for VSG control, improving stability and robustness.

Findings

Maintains consistent settling times and overshoot across grid conditions.

Accurately estimates unseen grid impedance values with minimal delay.

Validated in Simulink with superior performance over fixed-gain VSGs.

Abstract

In contrast to grid-following inverters, Virtual Synchronous Generators (VSGs) perform well under weak grid conditions but may become unstable when the grid is strong. Grid strength depends on grid impedance, which unfortunately varies over time. In this paper, we propose a novel adaptive gain-scheduling control scheme for VSGs. First, an Artificial Neural Network (ANN) estimates the fundamental-frequency grid impedance; then these estimates are fed into an adaptive gain-scheduling function to recalculate controller parameters under varying grid conditions. The proposed method is validated in Simulink and compared with a conventional VSG employing fixed controller gains. The results demonstrate that settling times and overshoot percentages remain consistent across different grid conditions. Additionally, previously unseen grid impedance values are estimated with high accuracy and minimal time delay, making the approach well suited for real-time gain-scheduling control.