Neutral-point earth-free distributing network direct-to-ground capacitance current measuring method

Abstract

This invention discloses a measurement method of the neutral earth-free distribution network towards the direct earth capacitance. It has such steps as injecting stable current signal from the open-delta of bus-bar potential transformer of the substation, measuring the open-delta voltage and the second star side-voltage. It detects the current of the direct earth capacitance of the distribution network according to the injected current signal and the measured voltage signal. This invention thoroughly avoids the influence of the short circuit of the open-delta of bus-bar potential transformer of the substation and the injected signal frequency toward the measuring result without changing the first connection and influencing the good running of the distribution network. It has such merits as safe, convenient, accurate and it completely settles the technical puzzle of the measuring accuracy of the short circuit of the open-delta of bus-bar potential transformer of the substation towards error current of the distribution network.

Description

technical field [0001] The invention relates to a method for measuring the ground capacitance current of a neutral point ungrounded distribution network. Background technique [0002] At present, there are two main methods for measuring the ground-to-ground capacitance current of the neutral point ungrounded distribution network by injecting signals into the power grid through voltage transformers: [0003] One is to inject the frequency conversion signal through the delta side of the voltage transformer of the substation bus, and connect an inductor in parallel on the delta side of the voltage transformer, and calculate the capacitance current value of the distribution network to ground by finding the resonant frequency; [0004] The other is to inject two or three signals of different frequencies through the delta side of the voltage transformer of the substation bus, measure the signal voltage and signal current, establish a system of equations, and solve the capacitance ...

AI Technical Summary

Problems solved by technology

[0006] In order to solve the technical problem of low test accuracy existing in the existing neutral point ungrounded distribution network ground capacitance current measurement method, the present invention provides an accurate neutral point ungrounded distribution network ground capacitance current measurement method, Solve the problem that the short-circuit impedance of the substation bus voltage transformer and the selection of the frequency of the injection signal affect the test accuracy, and improve the accuracy of the measurement of the capacitance current of the distribution network to the ground

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