Integrating static synchronous compensators (STATCOMs) in a multiple inverter-based-resource (IBR) system for voltage support can deteriorate sub/sup-synchronous oscillation issues caused by the interaction among IBRs and power networks, especially in low short-circuit-level grids. However, it is still challenging to fully understand the impact mechanism of STATCOMs on IBR-induced oscillation issues and to effectively design 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. Furthermore, we investigate the robust small-signal stability of the multi-IBR system with STATCOMs by designing STATCOMs' control parameters to ensure the robust small-signal stability of multiple subsystems under critical operating conditions. This avoids exhaustive studies on many operating conditions with detailed system models. The proposed methods are validated on a modified IEEE 39-node test system. This paper provides an effective way of better understanding the interaction among diversified devices through power network, and coordinating their controls to ensure the system's robust small-signal stability in modern power systems integrated with large-scale power converters.

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