Design of Wide Area Damping Controller Based on Clustering of Inter-Area Oscillations

One of the biggest threats to power system stability is inter-area oscillations (IAOs). In long, interconnected tie lines, low-damping IAOs prevent rated power transfer. Hence IAOs must be identified and sufficiently damped to avoid these situations. Various controllers are available in the literature to dampen IAOs. However, as the operating point varies with time, performance of controller degrades. Hence, considering the operating point uncertainty, designing a wide-area damping controller (WADC) is necessary. This paper proposes a thyristorcontrolled series capacitor (TCSC) assisted WADC, which is a two-stage lead-lag power system stabilizer (PSS). The critical IAOs in interconnected system can vary with changes in operating scenarios. Hence, using the K-means algorithm, different clusters of IAOs are identified with their mean values. Then separate wide-area PSSs are designed for each cluster to improve the damping of their IAOs sets. Finally, the output of each wide area PSS is weighted using Gaussian distribution, i.e., wide area PSSs with high probability are assigned with higher weights, and that with low probability are assigned with lower weights. Finally, efficacy of the proposed methodology is demonstrated on 4-machine, 11-bus system.