Power distribution network multivariable characteristic parameter dynamic correlation fault judgment method

Abstract

A power distribution network multivariable characteristic parameter dynamic correlation fault judgment method comprises the steps that the displacement voltage of a neutral point of a power distribution network, three-phase voltages ua, ub and uc and zero-sequence currents ij of all feeder lines are detected in real time, if the neutral point of the power distribution network has a grounding resistor, the current ib of a resistor branch is detected, and in a time period deltaT1, whether a single-phase earth fault occurs in the power distribution network or not is judged according to the correlation change of each variable. After an earth fault processing device is started, different methods are adopted to judge the fault property and whether the fault is successfully processed or not according to different variable relationships.

Description

technical field [0001] The invention belongs to the field of single-phase ground fault processing of distribution network, and is mainly used for the judgment of the ground fault, the nature of the fault, and the judgment of whether the ground fault processing is successful. Background technique [0002] When the ground fault processing device handles the ground fault, it is necessary to judge whether it is a single-phase ground fault, because there are many other faults with similar characteristics to the single-phase ground fault; only after the fault is accurately judged can the ground fault processing device be started to correct The ground fault is processed. At present, it is generally based on the magnitude of the neutral point displacement voltage of the power grid as the judgment of the single-phase ground fault and the ground fault processing device is started. However, changes in the operation mode of the distribution network will also cause the distribution networ...

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Problems solved by technology

[0003] In order to solve the judgment problem of the ground fault processing device when a single ground fault occurs in the distribution network, a multi-variable correlation judgment method for a single-phase ground fault in the distribution network is invented. The ground fault processing device detects the neutral point displacement voltage of the distribution network in real time u N , three-phase voltage u a , u b , u c , each feeder zero-sequence current i j , when there is a grounding resistance at the neutral point of the distribution network, the detection resistance branch current i b and other variable characteristic parameters and their time period 1 The dynamic increment of these characteristic parameters, if in the time period 1 The stable increment of the neutral point displacement voltage of the internal distribution network conforms to ≥γ, distribution network three-phase voltage u a , u b , u c The increment of the zero-sequence current in the feeder is not greater than zero or less than zero at the same time, and the stable increment of the maximum zero-sequence current in the feeder complies with Δi mmax0 ≥δ, if there is a grounding resistance branch at the neutral point of the distribution network, the current i of the neutral point resistance branch of the distribution network b The steady increment of Δi corresponds to b ≥β, it is determined that a single-phase ground fault has occurred in the distribution network, and at this time the ground fault processing device enters the fault start to process the single-phase ground fault; ΔT 1 is the sampling time interval of each relevant variable by the ground fault processing device, 1 γ is the standard value of stable increment of the neutral point displacement voltage of the power grid; δ is the standard value of stable increment of the largest zero-sequence current in the feeder; β is the stable incremental standard value of the neutral point resistance branch current volume standard value

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