Live Line Measuring the Impedance Parameters of Transmission Lines Based on Interference Sources

Based on GPS technology, a new differential equation method (DEM) of live line measuring the parameters of transmission lines with mutual inductance is proposed. The new method uses only the inductance voltages or inductance currents between lines as the measurement sources. No extern voltage source is applied in measurements, so this method can also be called as an interference measurement method. The mathematical model of the new method is explained in detail. An example of live line measuring six 500 kV transmission lines with mutual inductances in North-East China power grid is given. Comparison of results between the DEM and the Increment Equation Method (IEM) is also shown. The field measurement results prove that the new method can meet the need of live line measurement of transmission lines´ inductance parameters.