Method and device for positioning single-phase ground fault section of power distribution network based on transient signal prony algorithm

Abstract

The application provides a positioning method and a positioning device for a single-phase ground fault section of a power distribution network based on a transient signal prony algorithm. The positioning method comprises the following steps in sequence: accurately capturing zero-sequence current transient signals of the zero-sequence current in one cycle before exceeding the starting value and in four cycles after exceeding the starting value through terminals in different positions on a circuit; extracting the transient high-frequency component signal which plays a lead role in the fault transient signals through the prony algorithm; and analyzing the section of the fault point according to the transient high-frequency component signals. The positioning device comprises terminals and a master station, wherein the terminals are arranged on overhead line poles and towers or cable ring main units; the input ends of the terminals are used for receiving phase current signals from the CT (Computed Tomography) secondary sides of power distribution lines (including overhead lines and cables) and combining the phase current signals into the zero-sequence current signals; the input ends of the terminals are connected with the master station in an optical fiber communication way or a mobile communication way; the master station is built in a transformer substation or a control center and comprises an optical fiber communication module and a mobile communication module; and the master station is used for receiving the signals transmitted by the terminals. The method and device provided by the application are mature in technology and high in reliability.

Description

technical field [0001] This application belongs to the technical field of power system automation, and specifically relates to a section positioning method for a single-phase ground fault in a distribution network and a positioning device based on the positioning method. When a phase-to-ground fault occurs, accurately locate the fault section. Background technique [0002] The 3-60kV distribution network in my country widely adopts the non-effective neutral point grounding method, also known as the small current grounding system, and most of the faults in the small current grounding system are single-phase grounding faults. When a single-phase ground fault occurs, the ground current is very small, and it can continue to run for 1 to 2 hours under the fault condition, but the fault point must be found as soon as possible, which raises the problem of fault location. [0003] The problem of fault location in the distribution network has not been well resolved for a long time, ...

AI Technical Summary

Problems solved by technology

When a single-phase ground fault occurs, the ground current is very small, and it can continue to run for 1 to 2 hours under the fault condition, but the fault point must be found as soon as possible, which raises the problem of fault location

[0003] The problem of fault location in the distribution network has not been well resolved for a long time. The method of manual line inspection is often still used on site. Manual line inspection not only consumes a lot of manpower and material resources, but also prolongs the power outage time and affects the safety of power supply.

At present, there are three methods for automatic positioning on site. The first method is to inject a high-frequency signal from the PT and detect the signal along the line to determine the fault location. However, because the distributed capacitance of the line forms a path for the high-frequency signal, the positioning is not correct when it is grounded through a resistor. precise

The second method is to use the fault indicator. Since the fault indicator can only measure the phase current and cannot measure the zero-sequence current, it is better for short-circuit faults, but the accuracy of single-phase ground fault location is very low.

The third method is to install a smart switch with a built-in CT. Although this method can measure the zero-sequence current, the terminals and master stations operating on the market have simple algorithms that only judge whether the steady-state zero-sequence current exceeds a fixed value. The positioning accuracy of the arc suppression coil grounding system is very low

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