Line selection method for single-phase earth fault of power distribution network

Abstract

The invention discloses a line selection method for a single-phase earth fault of a power distribution network. The method comprises the steps of measuring zero sequence voltage of a power distribution network bus, switching a parallel resistor, connected in parallel with an arc suppression coil, of an electric structure if the amplitude of the zero sequence voltage of the power distribution network bus is greater than 15% of that of A phase voltage of the power distribution network during normal operation, measuring sampling values of the zero sequence voltage of the power distribution network bus and sampling values of zero sequence currents of power distribution network feeder lines at sampling times, selecting any cycle of sampling values of the zero sequence voltage of the power distribution network bus and sampling values of the zero sequence currents of the power distribution network feeder lines, sequentially calculating line selection power coefficients of the power distribution network feeder lines, and selecting the power distribution network feeder line of which the line selection power coefficient is less than zero and the absolute value of the line selection power coefficient is maximum as a fault feeder line. A fault line selection result of the method is not influenced by factors such as a feeder line type, a fault location, line parameters, transition resistance, an earth fault type and line length, is adapted to a complicated power distribution network operating environment, and is good in practicability.

Description

Technical field [0001] The invention relates to the technical field of fault line selection for a power system distribution network, in particular to a single-phase ground fault line selection method for a distribution network. Background technique [0002] After a single-phase grounding fault occurs in the feeder of the distribution network, due to the compensation effect of the inductive current provided by the arc suppression coil, the zero-sequence current flowing through the faulted feeder is small and the fault characteristics are not obvious, resulting in a relatively large selection of the faulty feeder in the distribution network. Great difficulty. The current feeder methods of distribution network are mainly divided into steady-state method and transient method. The steady-state method mainly uses the steady-state fundamental frequency or the harmonic electrical signals generated by the single-phase grounding of the distribution network feeder to complete the fault lin...

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Problems solved by technology

The steady-state method mainly uses the steady-state fundamental frequency or harmonic electrical signals generated by the single-phase grounding of the distribution network feeder to complete the fault line selection function. The influence of this method often fails in line selection and cannot meet the practical needs of the site

The steady-state method is based on the fact that the transient component of the fault zero-sequence current is much larger than the steady-state value, and uses the transient zero-mode voltage and current in a certain selected frequency band to complete the function of fault line selection. The line selection accuracy is high, but the transient state The method has too high requirements on the reliability of hardware and algorithms, and cannot adapt to the complex operating environment of the distribution network, and cannot adapt to the practical needs of the site.

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