Study On Harmonic State Estimation And Harmonic Source Location In Power System

In recent years,power electronic loads have been widely used in industry,transportation,electric power,communication,new energy and other systems,which a large number of harmonic currents have been injected into the power system,and the voltage has also been distorted.So,the harmonic problem is becoming more and more serious.And power harmonic will also cause harm to other electrical equipment connected to power grid and increase power loss.This dissertation firstly introduces the basic concept of harmonic distortion and analyzes the research background and meaning of the subject.Then the dissertation reviews the research status of harmonic analysis at home and abroad,including the ideas,advantages and disadvantages of various methods.Secondly,according to the harmonic impedance models of various common power components（equipment）in the power grid,the theoretical modeling and analysis are carried out,and the calculation method of the system harmonic impedance is studied.Thirdly,for dynamic harmonic estimation,Kalman filter（KF）,extended Kalman filter（EKF）,and unscented Kalman filter（UKF）algorithm are respectively studied by using the actual collection.The three algorithms were analyzed under the condition of no noise and noise,and the results show that the algorithms can effectively estimate harmonic parameters.Among them,UKF algorithm has the best estimation performance.Fourthly,the harmonic power flow calculation based on BIBC（node injection current-branch current）-BCBV（branch current-node voltage）method and the dynamic harmonic state estimation based on adaptive square root UKF（SRUKF）algorithm are studied respectively,and the two algorithms are verified by constructing IEEE 14 node system.The results show that the algorithms are effective.Finally,the dissertation analyzes the harmonic equivalent circuit model.The single harmonic source locating method is studied,and then the harmonic state estimation algorithm is adopted for harmonic source location.The example analysis has been carried on,and the results show that harmonic state estimation method based on adaptive SRUKF algorithm can identify multiple harmonic source in the node position.