Research On Harmonic Location Method And Its Application Based On Mahalanobis Distance And Harmonic Powe

With the further acceleration of the process of "carbon peaking and carbon neutralization",on the power side,wind power,photovoltaic and other new energy power generation equipment are connected to the grid on a large scale,and various forms of energy storage power stations supporting them have also become an important part of the grid;On the grid side,light DC and HVDC have become important means for regional grid interconnection and transmission of new energy power generation;On the load side,the proportion of non-linear loads such as electrified railways,electric vehicle charging stations and programmable industrial equipment is increasing.The above factors cause a large number of harmonic currents to be injected into the power system,and affects the the security and stability of the grid,as well as other loads.To solve the harmonic problem,the most important work is to find the harmonic source quickly and accurately.The increasingly complex source grid load brings great difficulty to the harmonic source location.In this thesis,by studying the harmonic characteristics of the main harmonic sources in the power system,combining statistical methods with traditional harmonic source location methods,a harmonic location method based on Mahalanobis distance and harmonic power is proposed.Firstly,the concept,standard and mechanism of harmonics are summarized,and the main problems caused by harmonics in the current power system are proposed;Secondly,typical nonlinear loads are classified and their harmonic characteristics are analyzed one by one;Thirdly,the statistical methods such as Mahalanobis distance and Euclidean distance and harmonic impedance method are studied,and a new harmonic location method is proposed by combining Mahalanobis distance method and harmonic power method.The constructed covariance matrix representing the correlation of the research object is solved by using Mahalanobis distance to obtain the substations,lines,nodes The number of monitoring points and data scale involved in the analysis will be greatly reduced due to spatial characteristics and time-domain characteristics.Then,the harmonic power flow method will be used to locate the above positive correlation elements.This method can effectively reduce the calculation amount of harmonic location and increase the accuracy of harmonic location.This method solves the problem that it is difficult to analyze the harmonic problems of complex power grids or large-scale regional power grids from a global perspective.In this thesis,two typical scenarios are selected to verify the proposed harmonic location method,namely,Bozhou area in Xinjiang,which includes electrified railway and new energy power generation,and Jinhua area power grid,which includes HVDC converter stations and a large number of nonlinear loads.Among them,the harmonic voltage of individual substations in the power grid of Bozhou area seriously exceeds the standard,while the shunt capacitors of substations in Jinhua area are frequently burnt.Through the actual measurement of power grids in two regions,the test data are sorted out,and the harmonic data of selected substations are analyzed using the Mahalanobis distance and harmonic power positioning method proposed in the thesis,which verifies the effectiveness of the method and provides a clear direction for solving the harmonic problems in the two regions.