Study Of Harmonic Source Identification Method Of Power System

With the acceptance of renewable energy,the use of facts control devices and nonlinear loads,harmonic pollution in power systems is becoming more and more serious,and complexity of harmonic problem is increased.Eliminating harmonics has always been the focus of power system field,and seeking a fast and accurate method for identifying harmonic source is an effective way to eliminate harmonics.For improving the power quality and ensuring the safety,stability and economic operation of the power system,it has important theoretical significance and practical value researching on the harmonic source identification method of power system.In order to solve the problem of identifying the harmonic source of power system in a fast way,based on comparison and analysis of typical harmonic source identification methods,a fast harmonic source identification method based on generalized Tellegen’s theorem is proposed.Firstly,harmonic analysis of bus is analyzed,and the number and content of main harmonic are determined.Secondly,mathematical model of the corresponding main harmonic network and mathematical model of the adjoint network are established.By using the generalized Tellegen’s theorem for simple and overall advantages of harmonic sensitivity,calculating the main harmonic sensitivity of each harmonic source on the bus,so as to achieve positioning of system of harmonic sources rapidly.For calculating the harmonic sources harmonic emission amount and harmonic responsibilities accurately,clearing harmonic source identification method,and considering the diversity and complexity of harmonic sources,this thesis divides harmonic source into single harmonic source and multi-harmonic sources.In order to calculate the harmonic emission of single harmonic source,using harmonic identification method which is based on partial least squares(PLS),the equivalent model of power grid is built.Then using in the public point of harmonic current voltage measurement(PCC),and through the principal component analysis to extract the dependent and independent variables and the principal component,which can maximum limit contains function,it can ensure the accuracy of mathematical modeling and get the regression coefficients in the equation,calculate every harmonic impedance and users harmonic emission quantity contained in the required system.Finally,the percentage of each harmonic on the bus common points in harmonic system can be calculated.According to the relationship between voltage vector and current vector,measures of linear superposition calculation among the projection of the harmonic voltage at the observation bus of each harmonic source are taken to calculate the harmonic contribution of harmonic source.Partial least squares(PLS)regression method is used to obtain the regression coefficients and the harmonic responsibility of each harmonic source is calculated.The simulation results of IEEE-30 node system are compared with the results of harmonic power flow calculation,the result shows that the method proposed in this thesis can accurately locate the harmonic source and accurately calculate the harmonic amount.At the same time,the validity of the proposed method is verified.