Method for measuring grounding parameters of grounding power distribution network through arc suppression coil series resistor

Abstract

The invention provides a method for measuring ground parameters of a grounding power distribution network through an arc suppression coil series resistor. The method is suitable for an arc suppressioncoil series resistor grounding power distribution network. The method comprises: injecting a non-power-frequency characteristic frequency constant-current signal into a power distribution network ata connection point between any one of a bus, a neutral point or a feeder line of the power distribution network and the ground; measuring the returned characteristic frequency voltage signal from theneutral point zero-sequence voltage transformer of the power distribution network, changing the frequency of the constant-current signal, searching the resonance angular frequency of the zero-sequenceequivalent circuit of the power distribution network, and calculating the ground capacitance and the ground leakage conductance of the power distribution network. According to the invention, injection positions of a plurality of constant current signals are provided, the limitation that the constant current signals must be injected from the secondary side of the voltage transformer is avoided, the influence of damping resistance in a ground parameter measurement process can be eliminated, high-precision measurement of ground parameters of the resonant grounding power distribution network is realized, and the measurement does not influence normal operation of the power distribution network.

Description

technical field [0001] The invention belongs to the field of distribution network measurement, and in particular relates to a method for measuring ground parameters of a distribution network grounded through an arc suppressing coil series resistance. Background technique [0002] The medium and low voltage distribution network in my country generally adopts the resonant grounding method (that is, the neutral point is grounded through the arc suppression coil). my country's current "Code for Design of Overvoltage Protection and Insulation Coordination of AC Electrical Installations" clearly stipulates that for 6kV ~ 66kV systems using neutral point resonance grounding, the ground fault residual current shall not exceed 10A. However, with the increase in the proportion and length of cables in the distribution network, the line-to-ground capacitive current increases significantly, resulting in a sharp increase in fault current levels. There are also literatures pointing out th...

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Problems solved by technology

Invention patent 2017109911831 proposes an online measurement method for the capacitance current of the distribution network. Although it can eliminate the influence of the series damping resistance of the arc suppression coil and the internal impedance of the voltage transformer, the injection method is limited, the formula is relatively complicated, and it can only be obtained separately. Ground capacitance, since the formula is directly derived from the injection signal and the return signal, when the injection signal is weak and the measured return signal has a slight error, it will cause a huge error in the result

[0004] Therefore, there is an urgent need for a method for measuring the ground parameters of the distribution network grounded through the arc suppression coil series damping resistance to solve the problems that cannot be solved by the existing technology

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