Fault positioning method for overhead cable hybrid line

Abstract

The invention, which belongs to the technical field of power fault location, discloses a fault positioning method for an overhead cable hybrid line. The method comprises: installing fault current detecting devices at a hybrid line bus and all connection points and determining a fault branch of an overhead cable hybrid line according to directions of fault current signals detected by the fault current detecting devices; determining a fault point position based on a calculation formula of the fault point position under the condition of knowing the fault branch; and establishing an overhead-cablehybrid line simulation model and verifying correctness of the fault point position based on the fault types of all detection points in the simulation model. With the method, the fault point can be located quickly and accurately; faults can be eliminated timely; and power supply can be restored. And thus the power supply reliability of the entire system is improved.

Description

technical field [0001] The invention relates to the technical field of power fault location, in particular to a fault location method for overhead-cable hybrid lines. Background technique [0002] At present, power cable lines are mostly used as power transmission equipment in urban areas. When the lines leave the city, they are changed to overhead lines, resulting in the emergence of high-voltage transmission lines with multiple cables and overhead lines. After a fault occurs on the line, the dispatcher mainly relies on the fault location data to determine the range of line inspection. Due to the large error of the existing fault location device, the range of line inspection issued by the dispatcher is relatively large. Whether it is an overhead line or a cable line, most of its faults do not have obvious burn marks, which not only brings difficulties to the troubleshooting of fault points. From the existing experience of fault recovery operation, the time spent on finding...

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Problems solved by technology

[0003] The document with the announcement number CN 105044551 B provides a method for fault location of an overhead line-high voltage cable hybrid line, including: (1) respectively measuring the three-phase voltage and current phasors of the M and N terminals on both sides of the line, and using the symmetrical component method Calculate the negative-sequence voltage, negative-sequence current, positive-sequence voltage, and positive-sequence current on both sides respectively; (2) judge the fault type according to the negative sequence voltage; (3) if it is an asymmetrical fault, the two-terminal electrical and the three-phase voltage and current phasors on the N side to calculate the negative-sequence voltage amplitude of each point along the line, and the point where the negative-sequence voltage amplitude is equal is the fault point; (4) If it is a three-phase symmetrical fault, the positive-sequence voltage change The fault location is carried out by comparing the magnitude of the positive sequence voltage. The point where the amplitude of the positive sequence voltage is equal is the fault point. However, this location method lacks the corresponding model support and cannot verify the rationality of the location method.

[0004] The document with the notification number CN 105137289 B discloses a traveling wave fault location method suitable for high-voltage overhead line-cable hybrid lines, which installs traveling wave acquisition devices at both ends of the tested hybrid line, and uses the two The traveling wave acquisition device collects and calculates the injection traveling time difference, the closing traveling time difference, and the fault traveling wave time difference respectively. Using the characteristic that the wave velocity of the traveling wave signal is constant in the overhead line section or cable section, by judging the fault traveling time difference and Whether each injection travel time difference satisfies the judgment condition and the order of satisfying the judgment condition to accurately and quickly determine the line section where the fault point of the tested hybrid line is located, and then accurately locate the fault point position of the tested hybrid line through calculation, but the The literature lacks corresponding models and examples for relevant theoretical support, which needs further improvement

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