Optimal Control Strategy Of PSS Aided By Energy Storage Device In Power System

With the large input of high magnification regulator,the increase of power system load and the expansion of power grid scale,various disturbances often cause low frequency oscillation of power system.Power System Stabilizer(PSS)has been widely used as an additional controller of generator excitation system.Energy storage device can be used as a new way of energy consumption,and also participate in power grid frequency modulation and power flow control,effectively improving the stability of the power grid.When energy storage devices and power system stabilizers(PSS)are used together in power systems,if the parameters are not coordinated,they often fail to achieve good results.Therefore,the study of power system stabilizer(PSS)and energy storage device parameter optimization has important theoretical and practical value.In this paper,superconducting magnetic energy storage device(SMES)is selected as an additional measure of power system stabilizer(PSS)to suppress low-frequency oscillation.The low-frequency oscillation mechanism is studied by using single-machine infinite system,and in the system,the PSS and SMES are analyzed.At the same time,according to the mathematical model and working principle of PSS and SMES,the two are simplified and linearized.Combined the linearization model of the power system with eigenvalue analysis theory,linearized models of the single-machine infinity system and the 3machine 9 node system are established.The linearization model of the system is the basis for analysis of subsequent simulations.In order to optimize the parameters of PSS and SMES,this paper studies the shortcomings of bat optimization algorithm and improves the algorithm.Considering the shortcomings of the basic bat algorithm(BA),three improvements,namely,memory function,time-varying inertia weight and hybridization link,are added to the improved bat algorithm(IBA).The performance of the improved bat algorithm(IBA)is tested by typical test functions,which proves that the improved algorithm has the advantages of fast convergence and not easy to fall into local optimum.In theory,the improved algorithm can better solve the parameter optimization problem of power system stabilizer(PSS)and energy storage device.Finally,the simulation models of single machine infinite bus system and 3 machine 9 node system are built in MATLAB/Simulink simulation platform.The objective function designed considers the stability of frequency,power and voltage synthetically.The sum of the absolute values of generator speed deviation,electromagnetic power deviation and terminal voltage deviation is chosen as the objective function of the optimization algorithm.The PSS and SMES are optimized by using the improved bat algorithm.At the same time,the effect of suppressing low frequency oscillation on three different operating conditions is compared and analyzed under various operating modes of the system.It shows that SMES can not only aid PSS to suppress the low frequency oscillation of the system,but also improve the voltage stability of the generator terminal.