Grounding and line selection method for low current grounding system

Abstract

The invention discloses a ground line selection method for a small current grounding system. The method solves the problem that the prior line selection method is low in sensitivity and generates errors in line selection. The method comprises the following steps: 1, single-circuit lines and double-circuit lines are numbered and placed in a microcomputer; 2, the microcomputer judges whether the system is grounded or not and identifies a grounding phrase of the system; 3, according to the number of the single-circuit lines and the double-circuit lines, the microcomputer calculates a grounding transfer characteristic formula with zero sequence current which is measured during the normal operation of the system, zero sequence current of the single-circuit lines, zero sequence voltage of a bus and zero sequence current of the double-circuit lines which are measured when the system is grounded, and zero sequence voltage of a bus, zero sequence current of the double-circuit lines and zero sequence current of the single-circuit lines which are measured during grounding transfer of the system; the result of the calculation is compared with grounding current IJ passing through a split phase switch of the grounding phase during grounding transfer to determine a fault line. The method has the advantages of the characteristics of high sensitivity and accurate line selection and great significance on accurate identification of grounding circuit, grasp of grounding and arc-suppression coil conditions of the system, and promotion and improvement of safe and reliable operation of the system.

Description

technical field [0001] The invention relates to a grounding line selection method for a power system, in particular to a grounding line selection method for a small current grounding system. Background technique [0002] At present, in the 3.3 kV to 66 kV power grid of the power system, the line selection methods using zero-sequence current and zero-sequence voltage as parameters are: 1) the fundamental wave zero-sequence current ratio amplitude ratio method; 2) based on zero-sequence power 3) Line selection based on harmonic components; 4) Line selection based on the first half-wave of the transient process. In these line selection methods, due to the influence of factors such as system operation mode, line length, zero-sequence current transformer imbalance and grounding degree, there are problems such as low sensitivity and wrong line selection. In addition, in order to understand and master the grounding parameters of the system, it is necessary to carry out a simulated...

AI Technical Summary

Problems solved by technology

In these line selection methods, due to the influence of factors such as system operation mode, line length, zero-sequence current transformer imbalance and grounding degree, there are problems such as low sensitivity and wrong line selection.

In addition, in order to understand and master the grounding parameters of the system, it is necessary to carry out a simulated grounding test in the system, and it needs to pass through many testing instruments and repeated tests of different contents; and there is a certain risk in carrying out this work

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