A Grounding Protection Method for Improving Transverse Selectivity of 6~10kv Power Grid in Coal Mine

Abstract

T he invention discloses a ground protection method for improving transverse selectivity of a coal mine 6-10kV power grid, and belongs to power grid ground protection methods. The method includes: (1) respectively building intelligent subsidiary substations in various converting substations on the ground and under wells, and building a station control layer of a regional centralized control center on the ground as a common station control layer of the intelligent subsidiary substations; (2) collecting bus zero-sequence voltage and zero-sequence current of each branch by the intelligent subsidiary substations, gathering multiple line information by a merging unit, and sorting and sending the information to a process layer network; acquiring zero-sequence fault information of each branch by protection measurement-control device of the intelligent subsidary substations, and determining a branch with faults by ground protection software; (3) determining the fault branch by centralized computing phase information of bus zero-sequence voltage and zero-sequence all-current of each branch; and (4) issuing a trip order to an intelligent terminal by the protection measurement-control device of the intelligent subsidiary substations, and turning off a corresponding switch by the intelligent terminal. Accordingly, ground protection action accuracy is guaranteed, and reliability and safety of power supply system operation are improved.

Description

technical field [0001] The invention relates to a grounding protection method for a power grid, in particular to a grounding protection method for improving the lateral selectivity of a coal mine 6-10kV power grid. Background technique [0002] Most coal mine power grids are powered by cables, and the environment is harsh. Single-phase leakage or single-phase grounding faults often occur on cable lines. These failures may cause personal electric shock or cause gas and coal dust explosions, and even cause the electric detonator to detonate in advance. Therefore, practical grounding protection measures must be taken to improve the safety and reliability of coal mine power supply. [0003] At present, the grounding protection suitable for coal mine power grid can be divided into additional DC power detection type, zero sequence voltage type, zero sequence current type and zero sequence current direction type according to its working principle. Each grounding protection princi...

AI Technical Summary

Problems solved by technology

However, based on the traditional substation grounding protection device, the information collection method is single, and the single-device microcomputer protection can only use the fault information obtained by itself, and cannot realize the sharing of the underlying data of the whole station. Only the zero-sequence voltage and the zero-sequence full current of one branch are calculated each time. The phase relationship of the ground fault increases the calculation time of the ground protection software, and it is difficult to achieve coordination among the protection devices, and the ground fault protection has low lateral selectivity

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