Distributed method for collecting zero-sequence current concerning load variation

Abstract

The invention discloses a method for collecting distributed zero-sequence current concerning load variation in the technical field of fault line selection and positioning of a power system. The method comprises the following steps: assembling current transformers in phases, transmitting detected current to an error setter and a synthesizer; setting detected current of each phase by the error setter to acquire the maximum error delta I (L max) and determine a radius r of a voltage error circle; determining collected zero-sequence current 3I'0 by the synthesizer by taking the phase of head end zero sequence voltage as a reference phase; comparing sizes of the 3I'0 with the delta I (L max) by a comparer, outputting phase information of the current to a direction indicator when the 3I'0 is more than the delta I (L max), and ensuring that the direction indicator maintains the indication result; transmitting a locking signal to the direction indicator by a locking device when the 3I'0 is less than the delta I (L max), not outputting the phase information, and leading the direction indicator not to indicate; and completing flow direction determination of the zero sequence current of all collection points, and performing fault line selection and fault positioning according to the indication result. The method ensures the accuracy of flow direction determination of the current through locking the zero sequence current when unbalance current is small.

Description

technical field [0001] The invention belongs to the technical field of fault line selection and location in electric power systems, and in particular relates to a distributed zero-sequence current collection method considering load changes. Background technique [0002] The problem of fault location and line selection after a single-phase ground fault occurs in a small current system has always been a problem that is not easy to solve in the power system. Therefore, some scholars have proposed a fault line selection location method based on zero-sequence current phasors. This location method is based on the fact that when a single-phase ground fault occurs in an ungrounded system, the zero-sequence current phase of the fault path lags behind the zero-sequence voltage, and the zero-sequence voltage of the non-fault path The current phase is ahead of the zero-sequence voltage, so the fault section can be gradually judged according to the current flow direction of the collected...

AI Technical Summary

Problems solved by technology

[0004] The purpose of the present invention is to propose a distributed zero-sequence system that considers load changes for the failure of line selection and location due to low accuracy of zero-sequence current collection when the neutral point is not grounded. Current collection method

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