Research On Practical Calculation Method And Actual Measurement Criterion Of Transmission Line

The transmission line is an important part of the power system,and its parameters directly affect the work of power system power flow calculation and relay protection setting.As the scale of the power grid continues to expand,the degree of automation of the power system continues to increase,and the accuracy requirements of the power grid for transmission line parameters continue to increase.In order to better carry out the engineering parameter measurement work,the thesis carried out research and exploration from three aspects: the theoretical calculation method of transmission line parameters,whether the zero-sequence mutual inductance parameters need to be measured theoretically,and engineering software development.First,the thesis studies the theoretical calculation formula of transmission line parameters.Through model simulation and formula analysis,the factors such as soil resistivity,ground wire type,ground wire grounding method,pole tower structure,line direction,and mutual inductance line operation mode are all The influence of order parameters.Investigate the actual situation of transmission lines in Northeast China.Based on the survey results and the methods used in engineering surveys,improve the traditional theoretical calculation method based on the above several influencing factors to make it more accurate and practical.Next,the thesis qualitatively and quantitatively analyzes the influence of zerosequence mutual inductance parameters on the protection of grounding distance.Deduced the calculation formula of measuring impedance error and protection range change without compensating the zero-sequence mutual inductance parameters,and analyzed the change of the influence of zero-sequence mutual inductance on the distance protection when the line is erected differently,the strength of the support system is different,and the operation mode is different.According to the law,under the different structures,the zero-sequence mutual inductance is the most "serious" situation for distance protection,and various situations are simulated and verified in ATP-EMTP.According to the above conclusions,the theoretical judgment basis for judging whether the zero-sequence mutual inductance parameters of the line need to be measured is put forward,and the general criterion applicable to the general situation is derived based on the engineering practice.Finally,the paper develops and designs the transmission line parameter calculation software for engineering measurement work.Its main functions include calculating transmission line parameters,judging the accuracy of the measured parameter results,judging whether the zero-sequence mutual inductance parameters need to be measured,and the already invested transportation line parameters and related Information query.The software has high accuracy of engineering practicality.