| With the rapid development of the power industry,the interconnection between large power grids has become an inevitable trend in the development of modern power systems.While improving the efficiency of power generation and transmission,the structure of the power system has become more complex,and the stability of the system has been severely affected.Modern power system is a kind of complex dynamic system with strong coupling and strong nonlinearity.Under certain conditions,chaotic oscillation can easily occur,causing voltage instability or even voltage collapse,which greatly affects the safe and stable operation of power systems.Therefore,the chaotic oscillation phenomenon in the power system is analyzed and controlled in this thesis to ensure the normal and stable operation of the power system.In this thesis,a typical second-order power system is studied.Firstly,the parameter values that cause chaotic oscillation in power system are given,time domain diagram,attractor phase diagram and maximum Lyapunov exponent diagram are used to analyze the system.Then,the damping coefficient and the amplitude of the disturbance in the system are studied,and the influence of their different values on the operating state of the system is analyzed.Finally,combining adaptive control with global sliding mode control,an adaptive global sliding mode controller is designed to eliminate chaotic oscillation in the power system.The designed controller takes into account the problem that the system disturbance is difficult to determine under actual conditions,and enhances the practicality.Based on the second-order model,the influence of the excitation limiter on the system is considered,a fourth-order power system model considering excitation limitation is obtained and studied.Firstly,the existence of chaotic oscillation in the power system under certain parameters has been confirmed.The timing diagram,attractor phase diagram of the system under chaotic oscillation are given and the Lyapunov exponents are calculated.Then,the influence of the excitation limiter and the damping coefficient on the system operating state is analyzed.Finally,in view of the fact that the damping coefficient and mechanical power in the power system usually have uncertainty,an adaptive non-singular fast terminal sliding mode controller is designed to achieve rapid suppression of chaotic oscillation in the power system.By adding a continuous relay characteristic function to the controller,the effect of chattering on the control system is eliminated. |
