Electromechanical Disturbance Contoller Design Based On Hamilton Energy Function

Modern power system is a typical high-dimension,strongly nonlinear complex dynamic system,which is constantly subjected to various kinds of disturbance during normal operation.Therefore,the security and stability of power systems have been a focus of concern all the time.When a fault occurs in a power system,steam value controller can reduce the speed fluctuation and power angle swing caused by the imbalance between mechanical power and electrical power,which is conducive to reestablish synchronization with the power system.Excitation control can adjust generator terminal voltage and reactive power,which is one of the most frequently used and economical ways in power system control area.With the combination of the steam valve controller and traditional excitation controller,the convergence speed of the system after a disturbance will be improved,and a stable system would be established in a faster manner.In early power systems,the primary design method of controller is to linearize the nonlinear systems near the operation points.However,due to the strong nonlinearity of power systems,the controller designed by local linearity method can't meet the transient performance requirements after large disturbance.In recent years,nonlinear control has been widely used in power systems,and lots of achievements have been achieved.Hamilton energy function plays an important part in nonlinear theory.Aiming at generator models with steam valve controller,two effective control methods based on the Hamilton energy function have been proposed in this paper.At first,aiming at a single-machine infinite-bus system with steam-valve control,constant value realization,which is a pseudo generalized Hamilton realization with structure matrix as constant value,is used to express the system as pseudo Hamilton system,and the electro-mechanical disturbance controller of excitation and steam-value coordinate controlled are designed for the first time.Besides,for the single-machine infinite-bus system,the parameters of electro-mechanical disturbance controller based on Hamilton energy function is determined from the perspective of eigenvalues for the first time.Since no linearized methods are adopted during the controller design,nonlinear properties of the dynamic system can be well preserved and utilized.Compared with the single excitation controller and the traditional PID controller,the excitation and steam valve coordinate controlled electro-mechanical disturbance controller based on constant value realization can improve the convergence speed of the system after a disturbance.When the operation point changes,the disturbance controller can not only improve the convergence speed of the system,but also reduce the shift of the system frequency.Besides,a simulation based on a single machine infinite bus system is performed to verify the electro-mechanical disturbance controller,being effective and correct.Secondly,a multi-machine power system with transfer conductance and steam valve control is expressed into a pseudo-generalized Hamilton system based on Hamilton energy theory for the first time,and then the excitation and steam valve coordinate controlled electro-mechanical disturbance controller is designed through a modified L2-disturbance attenuation method,which has clear physical significance.The nonlinear property of the dynamic system is well maintained based on Hamilton energy function method,which avoids the difficulties of constructing Lyapunov function directly and yields a good control effect.The excitation and steam valve coordinate controlled electro-mechanical disturbance controller is verified to be effective and correct in this paper based on a WECC 3-machines 9-nodes system.The simulation shows that compared with the single excitation controller,the excitation and steam valve coordinate controlled electro-mechanical disturbance controller can improve the convergence speed of the system after a disturbance,reduce the shift of the system frequency and enhance the transient stability.