Ground capacitance measuring instrument in transformer substation power distribution system

The utility model discloses a ground capacitance measuring instrument in a transformer substation power distribution system. The instrument comprises a signal acquisition device, a main controller and an H bridge inverter circuit, wherein the signal acquisition device is used to collect current and voltage signals in an arc suppression coil; the main controller possesses control, analysis and operation functions; the H bridge inverter circuit is used to provide a conversion current signal for a power grid. The signal acquisition device, the main controller and the H bridge inverter circuit are successively connected. An input terminal of the signal acquisition device and an output terminal of the H bridge inverter circuit are connected to a power grid arc suppression coil grounding device. Compared to a traditional single phase metal grounding method, by using the instrument of the utility model, a grounding fault does not need to be made on purpose and a system risk is avoided; aiming at a near resonant point operation mode in which a damping resistor is additionally installed and a far away resonant point operation mode in which the damping resistor is not additionally installed of the current arc suppression coil, two different measuring modes of a two-point method and a frequency conversion method are designed respectively. System ground capacitance measuring precision is guaranteed and negative effects are not brought to the system simultaneously.