Power distribution zero-sequence current constant value self-optimization protection method

Abstract

The invention relates to the technical field of power transmission and distribution relay protection, in particular to a power distribution zero-sequence current constant value self-optimization protection method, which comprises the following steps: analyzing impedance change from a detection point to a power supply end by taking three-phase voltage and current vectors simultaneously detected atthe head end and the tail end of an automatic section as criteria to obtain a theoretical zero-sequence current value; performing through-flow test on each phase, measuring remote measurement, obtaining a correction coefficient, adjusting a zero-sequence current theoretical value of a monitoring point according to the correction coefficient, obtaining a four-order zero-sequence protection constantvalue, performing zero-sequence current protection in four orders, positioning a fault section by adopting an optical fiber communication technology, and realizing millisecond-level fault isolation.

Description

technical field [0001] The invention relates to the technical field of relay protection for power transmission and distribution, and more specifically, to a protection method for self-optimizing fixed value of zero-sequence current in power distribution. Background technique [0002] With the deepening development of my country's distribution network technology field, the concept of "smart grid" has been continuously proposed. The distribution network full feeder gradually begins to deepen the development of distribution network automation technology from the plain area to the coastal area, and realizes the intelligent self-healing of the distribution network full feeder line. For isolated grounding Due to unbalanced faults, the current distribution network feeder mostly adopts zero-sequence overcurrent protection based on a small resistance grounding system, and an intelligent switch with three remote (telemetry, remote signaling, remote control) functions is set through each...

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Problems solved by technology

[0003] Chinese patent CN107611943 discloses a small resistance grounding system feeder adaptive zero-sequence current protection method. The method includes two parts: fixed value setting and adaptive zero-sequence current protection. When the zero-sequence current exceeds the value of the fixed value setting, start Adaptive zero-sequence current protection action, this method uses the positive sequence, negative sequence and zero-sequence current of the fault feeder, the phase voltage before and after the fault, the zero-sequence compensation coefficient and the zero-sequence system impedance to correct the current zero-sequence current to single The zero-sequence current when a single-phase ground fault occurs on the circuit line without load, overcomes the problem of protection refusal caused by the reduction of the zero-sequence current of the feeder when multiple circuit lines have the same phase-to-ground fault at the same time, but this scheme identifies the fault section. The time is long, and errors such as zero-sequence current transformer excitation current and software calculation cannot be effectively eliminated

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