Direct earth capacitance gauge in converting station power distribution system

Abstract

The invention discloses a direct earth capacitance gauge in a converting station power distribution system. The direct earth capacitance gauge comprises a signal acquisition device, a master controller, and an H-bridge inverter circuit, wherein the signal acquisition device is used for acquiring current signals and voltage signals in an arc suppression coil, the master controller has control, analysis, and operation functions, and the H-bridge inverter circuit is used for supplying converting signals for an electric network. The signal acquisition device, the master controller, and the H-bridge inverter circuit are successively connected, wherein an input end of the signal acquisition device and an output of the H-bridge inverter circuit are connected with a grounding device of the electric network arc suppression coil. Compared with a traditional single-phase metal grounding method, the method of the direct earth capacitance gauge is free of manufacturing fault intentionally, avoids system risk, and aims at that the arc suppression coil has a running mode added with damping resistance close to resonance point and a running mode without being added with the damping resistance far from the resonance point at present, and then two different measuring ways, namely a two-point method and a variable-frequency method, are respectively designed. Can not only precision of direct earth capacitance of the system be guaranteed, but also the direct earth capacitance gauge cannot bring negative influence to the system.

Description

technical field [0001] The invention relates to a ground capacitance measuring instrument in a power distribution system of a substation. Background technique [0002] When a single-phase ground fault occurs in the power grid, the arc suppression coil grounding can use the inductance current generated by the arc suppression coil to compensate the capacitance current of the ground point, reduce the recovery speed of the fault phase voltage, and automatically extinguish the arc at the ground point. Therefore, it is an important condition to accurately measure the capacitance value of the system to the ground to generate the correct inductive current for the arc suppression coil, thereby compensating the capacitance current of the grounding point, so that the arc at the grounding point is automatically extinguished, and the residual grounding current is smaller. The traditional measurement of capacitive current is mainly single-phase metal grounding method. Under the condition...

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Problems solved by technology

The problem with this method is that ground faults are deliberately created to increase system risk. If a ground fault occurs in other phases during measurement, it will evolve into a very harmful phase-to-phase short circuit, so this method is not applicable in practice.

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