Robust Adaptive Control of STATCOMs to Mitigate Inverter-Based-Resource (IBR)-Induced Oscillations

Abstract

The interaction among inverter-based resources (IBRs) and power network may cause small-signal stability issues, especially in low short-circuit grids. Besides, the integration of static synchronous compensators (STATCOMs) in a multi-IBR system for voltage support can deteriorate small-signal stability. However, it is still challenging to understand the impact mechanism of STATCOMs on IBR-induced oscillation issues and to design STATCOMs' control for damping these oscillation issues in a multi-IBR system, due to complex system dynamics and varying operating conditions. To tackle these challenges, this paper proposes a novel method to reveal how STATCOMs influence IBR-induced oscillation issues in a multi-IBR system from the viewpoint of grid strength, which can consider varying operating conditions. Based on this proposed method, we find critical operating conditions, wherein the system tends to be most unstable; moreover, we demonstrate that robust small-signal stability issues of the multi-IBR system with STATCOMs can be simplified as that of multiple subsystems under critical operating conditions, which avoids traversing all operating conditions and establishing system's detailed models. On this basis, an adaptive control-parameter design method is proposed for STATCOMs to ensure system's robust small-signal stability under varying operating conditions. The efficacy of proposed methods is validated by a 39-node test system