Identification And Suppression Of Low Frequency Oscillation Based On Wide Area Measurement Data

With the global rapid economy increasing and sharp population growth,electric power consumption increased continuously accordingly,which caused the power grid capacity to be aggravated constantly.At the same time,current power system has entered a cross-regional and interconnected large power grid period,the long-distance and large capacity of transmission line widely exist,which will be likely to bring out low frequency oscillation.If the phenomenon of low frequency oscillation is not inhibited effectively,it will cause a serial of system breakdown and a large area of power off,resulted the great economy losses.In recent years,the power system low frequency oscillation has become one of the key impacted points if power grid can operate reliably and safely.Therefore,how to identify the related parameters in the low frequency oscillation quickly and efficiently,and how to adjust the damper to suppress low frequency oscillation becomes particularly important,it will have a great significance in terms of robustness enhancement of power system.This paper had elaborated based on the negative damping mechanism of low frequency oscillation;established the mathematical model of single-machine infinite maximum system and multi-machine system;and processed further analysis of formation mechanism to low frequency oscillation on this basis.It analyzes the generator excitation system and the Power System Stabilizer(PSS)to find out the influence to low frequency oscillation in power system through simulation.For analysis of low frequency oscillation of power system,this paper comes up with using combination of improved mathematical morphology filter and Total Least Squares-Estimating Signal Parameter via Rotational Invariance Techniques(TLS-ESPRIT)to identify the modal parameter of low frequency oscillation based on wide area measurement data.The improved mathematical morphology filter can effectively eliminate the noise in the signal,retain the original features of the signal well and also improved the anti-interference performance of the proposed algorithm;At the same time,the TLS-ESPRIT which is improved has advantage such as simplify calculation,high accuracy and not easily influenced by subjective factors in the aspect of system set order.By the means of numerical simulation,the IEEE 4 machine 2 area system,EPRI-36 node system simulation and practical data of simulation analysis of grid verified the algorithm accuracy and effectiveness in the power system low frequency oscillation modal identification in this paper.In the optimal allocation of PSS,this paper has used the Singular Value Decomposition(SVD)method to reasonably allocated PSS installation location;In view of the PSS parameter setting problem,this article combined the advantages of global search of Artificial Fish Algorithm(AFSA)and advantages of local search of Bacteria Foraging Optimization(BFO)algorithm,and formed AFSA-BFO hybrid algorithm for PSS parameters setting;The simulation results had verified the rationality of the optimal allocation of PSS and the effectiveness of the PSS parameters setting;adaptive simulation shows that the method in this paper can effectively improve the robustness of the system.