A Real-Time Wide-Area Control Framework for Mitigating Small-Signal Instability in Large Electric Power Systems

This paper proposes a framework for a real-time centralized controller for addressing small-signal instability related events in large electric power systems. The proposed system is meant to be a safety net type control strategy that will detect and mitigate small-signal stability phenomena as they emerge in the system. Specifically, it will use wide-area monitoring schemes to identify the emergence of growing or undamped oscillations related to interarea and/or local modes. The damping levels of the associated interarea and local oscillatory modes will be estimated by analyzing predefined sets of signals using algorithms such as the Multi-Prony method. When the Central Control Unit detects an oscillatory mode with low or negative damping ratio, say less than 1 percent, the controller will initiate strategically located thyristor devices into an aggressive damping enhancement mode for correcting the damping level of the problematic mode. The paper proposes the framework of the controller with preliminary discussions on the various components of the controller, including a) the detection of undamped oscillations, and b) the design of corrective control actions.