A method and device for single-phase ground leakage line selection in industrial and mining low-voltage power grids

Abstract

The invention discloses a single-phase grounding leakage line selection method and device of the industrial and mineral low-tension electrical network. A single-phase leakage line selection module of the device comprises a zero-sequence fundamental-wave frequency-multiplication phase discriminating device, a zero-sequence voltage signal u0 processing circuit, a fault discriminating start voltage signal u0q processing circuit, a three-phase electrical network insulation level monitoring signal Ujy processing circuit and multiple zero-sequence current signal i0 processing circuit. According to the invention, frequency multiplication is directly carried out on the fundamental-wave zero-sequence current and voltage signals, the signals after frequency multiplication is sued for selecting and discriminating the single-phase grounding leakage fault, and such method is used for the first time domestically. Via the zero-sequence fundamental-wave frequency-multiplication phase discrimination method, selection time for the single-phase grounding leakage fault is shortened to less than or equivalent to 10ms which is greatly shorter than the protective motion time prescribed in the standard JB6314-92, and the technical problem that rapid and accurate leakage selection cannot be realized in the industrial and mineral low-tension multilevel electrical network with the zero-sequence reactor compensation function.

Description

technical field [0001] The present invention relates to a power grid fault line selection method and device, in particular to a single-phase ground leakage line selection method and device for industrial and mining low-voltage power grids, especially to single-phase ground leakage selection for industrial and mining low-voltage power grids with neutral point non-effective grounding systems The invention relates to a line protection device and a single-phase ground leakage fault line selection method for a single-phase ground line selection device of a medium-voltage power grid in a small-current grounding system, belonging to the field of power system single-phase ground fault detection and relay protection, and electrical safety technical meaning. Background technique [0002] At present, my country's industrial and mining 380-1140V low-voltage power grids and 3.3KV-35KV medium-voltage power grids widely use neutral point non-grounding systems, which can be roughly divided i...

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Problems solved by technology

Zero-sequence reactor compensation is used to reduce the capacitive current of single-phase earth leakage, so that the industrial and mining low-voltage power grid is the same as the resonant grounding system of 6KV ~ 35KV medium-voltage power grid, but the realization of single-phase earth leakage line selection protection is slower than that of medium The single-phase grounding line selection of the high-voltage resonant grounding system is complicated, difficult, and difficult to realize. For example, the zero-sequence admittance method, residual incremental method, signal injection method, transient component method, and five-order Harmonic method, etc., cannot be used in leakage protection of industrial and mining low-voltage power grids

[0006] So far, the "leakage selection principle" of various types of single-phase earth leakage protection devices used in my country's industrial and mining low-voltage power grids are basically based on the principle of zero-sequence power direction or the method of comparing the absolute value of zero-sequence current. The principle used is outdated and outdated, so the accuracy and reliability of leakage protection are relatively poor, and the protection action time cannot meet the requirements of multi-level leakage protection for low-voltage power grids, and the total leakage detection relay (such as TY-82 type) must be abolished. The zero-sequence reactor compensation function is the premise, which also does not meet the provisions of 4.2.1 and 5.15 of the JB6314-92 standard

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