Mitigation of Subsynchronous Resonance Induced by a Type III Wind System

This paper proposes an adaptive supplementary controller based on the multiple-model adaptive control (MMAC) approach to mitigate subsynchronous resonance (SSR) induced by a Type III wind system connected to a series-compensated transmission line. The proposed supplementary controller has two levels; the first level is a set of controllers designed using standard linear control methods, and the second level is a supervisory controller that selects the level-one controller based on the system conditions. A systematic approach is introduced for simultaneous coordination of parameters of the proposed supplementary controllers in a nonaggregated wind system. The aim of this coordination approach is to stabilize the system by moving the unstable modes to the left-hand plane while minimizing the controller gain values to reduce the sensitivity of the wind generator to the small disturbances. To evaluate the performance of the proposed controller, small-signal stability of the test system is studied using its comprehensive dynamic model. Time-domain simulation results show the effectiveness of the proposed supplementary controller to mitigate subsynchronous oscillations in a wide range of operating conditions.