Method for hybrid circuit combined distance measurement of power distribution network based on single-ended fault information

Abstract

The invention relates to a method for hybrid electric power circuit fault distance measurement of a power distribution network, in particular to a method for hybrid circuit combined distance measurement of the power distribution network based on single-ended fault information. The method for hybrid circuit combined distance measurement comprises the steps that firstly, high-frequency traveling wave components of a fault current signal and a fault voltage signal of a hybrid circuit are decomposed; secondly, the wave velocity of traveling waves transmitted in an overhead line and a cable is measured offline; thirdly, preliminary fault distance measurement is conducted according to a correlation coefficient analytical method; fourthly, final fault distance measurement is conducted according to a wave tip combining method; fifthly, a fault distance measurement result is verified. According to the method, only the fault information measured at one end of the circuit is used, initial wave tips and various reflecting wave tips of the traveling waves can be effectively extracted when a fault occurs, the method can be applied to the occasions without the double-ended traveling wave distance measurement function, accurate fault distance measurement is achieved, and the defects of fault distance measurement in the hybrid circuit of an existing power distribution network are overcome. According to the method, on the basis that fault distance measurement is achieved through the current traveling waves, a voltage traveling wave distance measurement result is comprehensively considered, and the reliability and the accuracy of distance measurement judgment are improved.

Description

technical field [0001] The invention relates to a hybrid power line fault ranging method suitable for a distribution network, in particular to a combined distance measuring method for a hybrid line of a distribution network based on single-end fault information. Background technique [0002] Due to the shortage of urban land resources and the influence of surrounding buildings, most urban power grids now use underground cable lines, while the surrounding lines are still dominated by overhead lines, which has led to the emergence of a large number of overhead line-cable hybrid transmission lines. Due to the imperfect manufacturing process, harsh operating environment and product quality defects, etc., the insulation level of the cable is often reduced, resulting in cable operation failure. Because the quality of insulators on overhead lines is not good enough, or they are damaged by external forces, etc., line faults are often caused. Therefore, the accurate fault location o...

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Problems solved by technology

[0004] However, the mixed line structure of the distribution network is complex and the line types are not uniform. Using the single-ended traveling wave method to realize its fault location is faced with the following problems: Refraction and reflection will occur at the connection, accompanied by traveling wave attenuation, making it difficult to distinguish the head of the fault traveling wave; (2) In overhead lines and cables, the propagation speed of traveling waves is obviously different, and it is impossible to measure distance directly like a single-structure high-voltage line; (3) In particular, after the reflected wave in the traveling wave propagates through the short-distance cable lines in the distribution network, it undergoes multiple refraction and reflection, and the amplitude of the measured wave head obtained is seriously attenuated, which is easily affected by interference signals, and the ranging accuracy may not be good. precise

Affected by the above problems, there is no mature and reliable fault location method for hybrid lines in distribution network

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