Power System Time Delay Compensation And Optimal Design Of Wide Area Damping Controller

Low-frequency oscillation has become one of the main reasons affecting the normal operation of the power grid and suppressing the transmission capacity of the power system.The wide-area damping controller generates an additional excitation signal by using the wide-area signal selected by the wide-area measurement system,which can effectively suppress the interval low-frequency oscillation.However,the influence of time-delay factors in the process of wide-area signal measurement cannot be ignored.If the time-delay factors cannot be effectively dealt with,the control performance of the wide-area damping controller will be greatly disturbed,which will aggravate the system's interval oscillation and seriously Affect the normal operation of the power system.Therefore,this paper does the following work in the three aspects of time-delay power system modeling,power system time-delay compensation and wide-area damping controller optimization design,which has important theoretical research significance for ensuring stable operation of the power system in a wide-area environment.First,this paper studies the problem of linearization modeling of power system considering time delay.For the time-delayed power system model,the time-delay is expressed as an exponential term,which brings great problems to the linearization of the time-delay link.To solve this problem,first establish a linear model of open-loop power system and wide-area damping controller without considering time delay;then use the Pade approximation method to convert the time-delay exponential term into a Pade rational polynomial to establish a linear model of the time-delay term Finally,the simultaneous open-loop power system model,wide-area damping controller model and time-delay term model are obtained,and the linearized model of the closed-loop power system considering the time-delay is obtained.It is designed to study the power system time-delay compensation and the optimization design of the wide-area damping controller Provides a good foundation.Secondly,this paper studies the optimization design method of wide-area damping controller considering time delay.Aiming at the impact of the time-delay term on the performance of the wide-area damping controller,the unified Smith predictor is first used to compensate for the time-delay link,and the expression of the unified Smith predictor is calculated according to the open-loop power system model and added to the selected In the wide-area feedback loop,thereby reducing the impact of the time-delay term on the wide-area damping controller;then the performance index that comprehensively considers the electromechanical mode damping ratio and the difference in the speed of each generator is used as the target function to determine the parameters to be optimized,thereby establishing a wide-area Parameter optimization model of damping controller.Using the improved particle swarm algorithm to solve the optimal parameter configuration improves the problem that the traditional particle swarm algorithm is easy to fall into local convergence and the quality of the initial population,and directly and effectively obtain' the optimal configuration of its parameters.Finally,a new example of a 10-machine system model in New England is used as an example to verify the effectiveness of the method.Finally,this paper studies the optimization design method of the wide-area damping controller of the time-delay power system considering the model mismatch.First,based on the principle of linear auto-disturbance control,a unified Smith predictor combined with linear auto-disturbance control is designed to make up for the shortcoming of the unified Smith predictor that is greatly affected by model mismatch;The parameters of the controller and the wide-area damping controller are coordinated and optimized.The parameters to be optimized and the range of values in the optimal control model are determined according to the parameter tuning rules of the linear auto-disturbance controller;finally,the New England 10-machine system model is used as an example for the calculation example In the simulation,the time delay compensation performance of the unified Smith predictor and the linear auto-interference rejection-unified Smith predictor in the case of gain parameter mismatch,time constant mismatch and time delay size mismatch are compared,and the models of different degrees are analyzed The influence of the mismatched system verifies the effectiveness of the proposed method.