Wide-area Measurement Of Time-Varying Delay Power System Stability Analysis And Control

Due to the uncertainty of grid structure,parameters and external disturbances,the model of the system is difficult to describe accurately,which seriously affects the stability control effect.The problem of time-delay stability of power system has always been the field that scholars are tirelessly researching.How to reduce the conservativeness of the system and how to improve the stability margin of time-delay are the knowledge points involved in this paper,as follows:A time-varying delay power system model is constructed for the wide-area measurement system of communication delay.In order to obtain the time-delay stability margin value,an augmented Lyapunov-Krasovskii functional with triple integral term is established,and time-varying delay term,primary integral term,quadratic integral term,etc.are added to the augmented vector of the functional information.The integral inequality method of the free matrix inequality method and the auxiliary function is used to define the one-fold integral term and the double integral term in the augmented Lyapunov-Krasovskii functional derivation.Consider the relationship between h(t)and t-h(t)in the process of obtaining,so as to obtain more effective information and reduce the conservativeness of the system.Using MATLAB's YALMIP tool for processing and calculation,the results are applied to a typical second-order system,a single-machine infinity system,and an IEEE 4-machine 11-bus test system.Through simulation comparison,the obvious advantages of this method in reducing conservatism can be obtained.In the wide-area environment,considering the controller design problem of time-varying power system with communication delay,a memory controller and a memoryless controller are designed.Using the Lyapunov-Krasovskii functional,a method combining Bessel-Legendre integral inequality and inverse convex matrix inequality is proposed to estimate the integral term.The time-delay is divided and a free weight matrix is introduced to obtain more effective information in the functional model to reduce the conservativeness of the system.Then,based on this,the state feedback controller is designed,and the nonlinear term generated by this controller is processed by the adjustment parameter method.The conclusions obtained by the simulation operation are applied to the single-machine infinity system and the WECC 3-machine 9-bus test system.The example proves the superiority of this method in the wide-area measurement system.