Arc grounding fault modeling and analyzing method based on piecewise linear equivalence

Abstract

The invention discloses an arc grounding fault modeling and analyzing method based on piecewise linear equivalence. A high-precision nonlinear arc light high-resistance grounding fault model is established based on a logarithmic arc model. Expression of arc nonlinear volt-ampere characteristics at a fault point is achieved through piecewise linear equivalence, solving of a nonlinear arc light high-resistance grounding fault state equation is achieved based on piecewise linear equivalence, and analytical expressions of fault zero-mode voltage and zero-mode current at a feeder line outlet underthe underdamping and overdamping conditions are given; the arc light high-resistance grounding fault model established by the invention is high in precision; the piecewise linear equivalence providedby the invention can realize the nonlinear expression of the arc, can obtain the analytical expression of the fault electrical quantity, and provides sufficient theoretical support for the subsequentdesign of the arc light high-resistance grounding fault detection algorithm of the neutral point arc suppression coil grounding power distribution system with both reliability and sensitivity.

Description

technical field [0001] The invention belongs to the field of relay protection for distribution line systems of electric power systems, and in particular relates to a modeling and analytical expression method for arc light high-resistance grounding faults of power distribution systems grounded through arc-suppression coils based on segmented linear equivalents. Background technique [0002] my country's medium-voltage distribution network is mostly grounded by the neutral point through the arc-suppression coil. Due to the large number of branch lines in the distribution network and the complex and diverse natural geographical environment, the probability of single-phase faults is high, about Accounting for about 80% of the total number of failures. With the extensive use of existing fault detection technologies based on traveling waves and transient quantities, the positive dynamic rate of fault detection has been improved, especially for metallic or low transition resistance ...

AI Technical Summary

Problems solved by technology

Researchers often regard the transition resistance between the line and the earth as a fixed resistance, and give the analytical expression of the relevant fault electrical quantity based on the fixed resistance model. This kind of modeling and analysis method seriously ignores the nonlinearity caused by the arc. , the accuracy needs to be improved

At the same time, in the process of obtaining the analytical expression, the zero-state response process during the fault is mostly used to replace the full response process of the fault, and the zero-input response process affected by the energy storage of the equivalent capacitance and inductance before the fault is ignored

In addition, although relevant literature has proposed a series of arc models to characterize the nonlinearity of single-phase ground fault arcs, such modeling and analysis methods do not pay enough attention to high resistance. , The arc model of the analytical expression of the arc current can only obtain the analytical expression of the relevant electrical quantity at the fault point, but cannot obtain the analytical expression of the faulty electrical quantity at the outlet of the feeder

The insufficiency of the existing fault modeling and analysis methods leads to certain defects in the relevant fault detection algorithm based on its design, which will cause the fault to exist for a long time and cannot be discovered in time, and develop into a more serious two-phase short circuit, or even Three-phase short-circuit faults may even cause fires, damage electrical equipment, and cause electric shock casualties, etc.

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