Stability analysis for control strategy of a STATCOM and TCSC control of nonlinear co-ordinated excitation with aperiodically sampled functional by an augmented Lyapunov Krasovskii method

This paper presents the transient stability analysis of a robust nonlinear co-ordinated generator excitation by thyri-stor controlled series capacitor (TCSC) controller and a control strategy of a static synchronous compensator (STATCOM) is proposed to improve of power system. This study analyses the stability of aperiodically sampled-data control systems with and without communication delays by application using a new augmented Lyapunov functional method, which compared with most of existing methods that commonly require each term of a Lyapunov Krasovskii functional(LKF) to be non-negative, the proposed method waives this requirement by introducing an augmented term. A nonlinear feedback law for the generator is found, which linearises and decouples the power system model. Robust nonlinear control theory is then employed to design the nonlinear co-ordinated controller that consists of two controllers is the generator excitation and the TCSC controllers. The proposed control strategy of the STATCOM was then tested on a single machine infinite busbar system. Simulation results show that the proposed controller can ensure transient stability of the power system in a critical fault clearing time, which may occur at the generator busbar terminal. These criteria are extended to investigate the stability of the systems with polytopic uncertainties and the exponential stability of the system.