Review of Live Measurement for Power Frequency Parameters of Transmission Lines

The live measurement of line parameters (LMLPs) has great application prospects. However, up to now, the application of LMLPs in engineering is very rare. In view of this problem, the paper analyzes the influencing factors of the accuracy of LMLPs, and puts forward that the error of measuring small signal by VT and CT should be paid attention to. The signal increment method and non-power frequency method are the two main methods for LMLPs. Combined with the non-power frequency method, signal increment method can further resist strong electromagnetic interference and improve the measurement accuracy. It is feasible to generate large zero sequence signals by operatng the single-phase circuit breaker on line, and there is no overvoltage and safety risk. Finally, the problems to be solved in the popularization and application of LMLPs are summarized: improving the power of the test power supply, miniaturization and light weight; clarifying the small signal measurement accuracy of VT and CT, and quantifying the system error of LMLPs. The corresponding suggestions are given, which provides a technical reference for the popularization and application of live line parameter measurement.