Adaptive Excitation Control Of Power Systems Using The Improved Back-stepping Method

With the increasing capacity of power systems and the increasing complexity of network structure, stability problems is becoming more and more severe. Synchronous generator excitation control is an important means to improve the power system stability. Due to the high uncertainty, strong nonlinearity and highly coupling of the systems, linear control methods cannot achieve the desired control performance. Therefore, the fully consideration of the system uncertainty and the usage of advanced nonlinear control method during the excitation controller design will be extremely important to improve the dynamic performance of power systems.In this thesis, the improved Back-stepping method and inverse Back-stepping method are used to design excitation controllers of power systems and the following research results are obtained:1. An uncertain dynamic model of the power systems is established, where the nonlinearity and uncertainty of the systems are fully considered. The generator power is taken as state and the variables which are difficult to measure, such as damping coefficient, and other uncertain parameters are regarded as unknown parameters.2. By transforming the proposed dynamic model to strict feedback form, the improved Back-stepping method is adopted to design adaptive excitation controller. The estimator of the unknown parameters and excitation controller are put forward. The asymptotic stability of the closed loop system is proved. Simulation results show that compared to the traditional Back-stepping controller, the proposed excitation controller can improve the stability performance of power systems more effectively.3. The adaptive inverse optimal excitation controller problem of parameter uncertain power systems is investigated using Back-stepping method. The parameter estimator of the unknown parameters is designed. Then an adaptive inverse optimal excitation controller is put forward. The stability of the system is discussed as well. Simulation results show that compared to the traditional excitation controller, the proposed inverse optimal excitation controller is more efficient to improve the dynamic performance of the power systems.