Comparative Study On Typical Anti-interference Methods For Measuring The Parameters Of Transmission Lines

Transmission line parameters are important parameters of power system.Accurate measurement of transmission line parameters is of great significance to improve the safe operation level of the power system.The induced voltages and induced currents are usually generated by the electromagnetic coupling between the lines which seriously affects the accuracy of parameter measurement of transmission lines.Many anti-interference methods for measuring the parameters of transmission lines are proposed in existing researches.However,each method is idealized and few factors are considered when using the methods.And there is no comparison between each anti-interference method.Therefore,it is difficult to select the most suitable measurement method in practical situation.In this paper,the characteristics and error sources of 6 typical anti-interference measurement methods of transmission lines were analyzed by their measuring methods and measuring process.The lumped parameter models of the 6 typical methods were established by using PSCAD,and the variation rules of the relative errors of the zero sequence parameter measurement results are obtained by setting the parameters of these error sources.And the influence of different conditions on the measurement results of various methods is analyzed.The model of long-distance transmission line based on distributed parameters was also established to analyze the relative error of the zero sequence parameter measurement of each anti-interference method.A model was also established in PSCAD to analyze the influence of each factor on the method of anti-interference measurement in the process of positive sequence parameter measurement.And the influence of the measuring instrument resolution on the measurement methods was analyzed when the measured line was withdrawn from normal operation and under normal operation,respectively.Then two typical strong interference environments were set up,and 6 anti-interference methods were used to measure the parameters respectively.Through the comparison of the simulation results,the orders of the measurement errors of the 6 anti-interference methods in the two cases were obtained.In this way,the most suitable anti-interference measurement method was found in each interference environment.Theoretical analysis and simulation test results show that,when there are many running line coupling near the tested line and the interference is basically the same,the increment method is the best in measuring line impedance parameters.And the second is the interference method and the reverse-phase method.When the interference near the tested line is changing frequently,the best measurement method is non-power frequency method.By the way,the harmonic method provides the highest measurement accuracy in the situation of measuring the capacitance parameters of the lines.The results of this paper can provide a reference for the selection of anti-interference measurement methods for transmission line impedance parameters in strong interference environment.