Improved model-free adaptive wide-area coordination damping controller for multiple-input-multiple-output power systems

Wide-area power system stabiliser (WAPSS) has been proved to be an effective method to damp inter-area low-frequency oscillations by using synchronised-phasor measurements. However, negative interactions among the WAPSSs may happen when they are designed separately. The conventional model-based coordination design methods are difficult to get good damping performance because model identification of the high-order, non-linear and time-varying power system is difficult. In this study, an improved model-free adaptive control (MFAC) algorithm is proposed for WAPSS coordination design. With the consideration of the interactions among the controllers and system noises, a novel decoupled multiple-input-multiple-output power system description for WAPSS coordination design are given. The MFAC control law and adaption law for each subsystem are improved to satisfy the controller coordination design requirements. The closed-loop system stability and parameter settings of the improved MFAC algorithm are also analysed from a global perspective. Compared with model-based methods, the proposed MFAC algorithm can ensure the controllers cooperate with each other and perform well under various operating conditions without tedious system modelling. The effectiveness of the proposed controllers is tested on an interconnected large-scale power system in China. An MFAC-WAPSS control system for field application is also presented in this study to validate its practicality.