A Real Time Measurement Method of Leakage Conductance in Distribution Network

With the full current compensation arc suppression coil in the distribution network, the application range is gradually expanded, the requirements for the accuracy of the line-to-ground leakage conductance measurement also increase. To suppress or eliminate the ferromagnetic resonance overvoltage caused by the saturation of the voltage transformer, a damping resistor is usually installed on the triangular side of the secondary opening of the voltage transformer or on the side of the neutral point in practical applications. The paper considers that the neutral point is grounded by the series damping resistor of the arc suppression coil, a method for real-time measurement of ground leakage conductance in a resonant grounding distribution network is proposed. The non-power frequency specific frequency current signal is injected into the distribution network through the zero-sequence voltage transformer of the distribution network, and the signal injection unit is equivalent to the current source. The voltage signal measured by the voltage transformer inside the arc suppression coil. According to the relationship between the injected characteristic current and the return characteristic voltage, the leakage conductance of the distribution network to the ground is calculated. In the PSCAD/EMTDC simulation environment, the proposed real-time measurement method for ground leakage conductance is simulated and analyzed. The measurement method has high measurement accuracy was shown. And it can eliminate the influence of the internal impedance of the voltage transformer and the addition of the damping resistance, the measurement process is safe and simple.