Nonlinear Controller Design Of STATCOM Based On Hamilton Theory

Modern power system is a typical hi-dimensional strong nonlinear dynamic system.The application of a variety of new electrical equipment and the incorporation of a large number of micro grid increase the complexity and uncertainty of power system,and also made the power system operation and control more complex.STATCOM is one of the core controllers of the flexible AC transmission system.It can continuously and precisely compensate the reactive power of the system,and improve the voltage quality and the stability of the power system.Hamilton system theory is an important control method in the field of nonlinear system control and it can effectively utilize the internal structure characteristics of the system.Therefore,considering the nonlinear characteristics of the system,the design of nonlinear controller with STATCOM based on the Hamilton system theory has great theoretical significance and practical value.A control strategy of STATCOM to restrain low frequency oscillation in multi-machine system is designed based on the generalized Hamilton theory.The Hamilton energy function with the oscillation energy concept is constructed,and the multi-machine equivalent system with STATCOM is expressed as a generalized Hamilton system.The control strategy aiming to reduce system oscillation energy is proposed which based on generalized Hamilton control theory.The simulation results show that the proposed model and strategy are correct and effective.The coordinated control problem of STATCOM and generator automatic voltage regulator in multi-machine power systems is discussed in the presence of external disturbances.STATCOM adopts a third order dynamical model which considers internal dynamics.The effects of STATCOM on the multi-machine power system are analyzed,and the dynamic model of the multi-machine system with STATCOM is established.The pseudo-generalized dissipative Hamilton form of the multi-machine system with the transfer conductance and the generator automa tic voltage regulator is completed.The nonlinear coordinated control strategy of automatic voltage regulator and STATCOM,which takes account of the impact of the transfer conductance,is designed by2 L disturbance attenuation method.The simulation results show that the proposed nonlinear coordinated controller can effectively guarantee the power angle stability and the voltage stability of the system.Nonlinear coordinated control of STATCOM and generator excitation is studied under the condition of considering the time delay of the wide area signal.The time delay is implicated in the coefficient of system dynamic equations by using Pade approximation.The electromagnetic power of multi-machine system which contains STATCOM is derived.The multi-machine power system with STATCOM and time-delay feedback excitation is represented as a form of pseudo-generalized dissipation Hamilton system based on the pseudo-generalized Hamilton theory.The nonlinear coordinated control strategy of STATCOM and generator excitation,which takes account of the impact of time delay and the transfer conductance,is designed by L2 disturbance attenuation method.The simulation results show that the proposed nonlinear robust coordinated contro ller by comparison with the traditional decentralized controller can effectively restrain the oscillation of the system and have indifference to time delay.