A Novel Measuring Method of Capacitance to Ground in Resonant Grounding System

In order to accurately and effectively realize the arc-suppression coil tuning, it is urgent to improve the measuring accuracy of the capacitance to ground in resonant grounding system. Because the existing measuring method does not consider the damping resistance which is connected in the grounding loop of arc-suppression coil, a novel measuring method of capacitance to ground in resonant grounding system was proposed in this paper. First, a variable-frequency current signal is injected into the system by the zero-sequence voltage transformer of the distribution network. Then the returned voltage signal will be measured by the voltage transformer inside the arc-suppression coil. After establishing the variable-frequency equivalent circuit which considers the damping resistance, the capacitance to ground can be calculated accurately. Finally, the effectiveness of this method was proved by the PSCAD/EMTDC, which showed that this method has high precision, which eliminates the negative influence of damping resistance.