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-level grids. Besides, integrating static synchronous compensators (STATCOMs) in a multi-IBR system for voltage support can deteriorate small-signal stability. However, it is still challenging to fully understand the impact mechanism of STATCOMs on IBR-induced oscillation issues and to design optimal STATCOMs' control for dampening 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, critical operating conditions are identified, 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 exhaustive studies on many operating conditions with detailed system models. On this basis, an adaptive control-parameter design method is proposed for STATCOMs to ensure system robust stability under varying operating conditions. The proposed methods are validated by a modified IEEE39-node test system.