CN102969685A - Method for improving lightning prevention and resisting level of overhead power distribution line - Google Patents

Abstract

The invention discloses a method for improving lightning prevention and resisting level of an overhead power distribution line, and belongs to the field of overhead power distribution lines. The method for improving lightning prevention and resisting level of the overhead power distribution line comprises the following content: accelerating line insulation transformation; installing a lightening prevention insulator on a straight line pole additionally; installing an overvoltage protection circuit additionally on an angle pole; installing arresters additionally on a high-voltage side and a low-voltage side of a power distribution transformer; carrying out a spot check on grounding resistors of lightning hardware fittings and a line overvoltage protector regularly, and recovering unqualified grounding devices of the grounding resistors; and carrying out a spot check on grounding resistors of lightning hardware fittings and a line overvoltage protector regularly, and recovering unqualified grounding devices of the grounding resistors. The method for improving lightning prevention and resisting level of the overhead power distribution line is set about fundamentally, accelerates upgrading, is beneficial to improving the technique equipment level of the integral line, is simple and feasible, is convenient to implement, contributes to popularization, and can be widely applied to the field of the running of the overhead power distribution line and lightning prevention management.

Description

A Method of Improving the Anti-lightning Strike Level of Overhead Distribution Lines

technical field

The invention belongs to the field of overhead power distribution lines, in particular to a method for improving the safety of overhead power distribution operation.

Background technique

Distribution lines are widely distributed, and towers are mostly high-standing objects on the ground, which are very vulnerable to lightning strikes.

In the summer of 2010, lightning caused a power supply company's distribution lines to trip 138 times, of which 4 times were disconnected, causing a large-scale power outage.

The results of theoretical calculations show that every 100km transmission and distribution lines are struck by lightning 4.5 to 5 times a year. The professional statistical data of power supply enterprises show that more than 70% of the outages in the power supply system are caused by lightning strikes on the lines.

How to improve the lightning protection level of distribution lines is an urgent and important problem faced by power supply enterprises.

Judging the performance of line lightning protection is mainly measured by lightning tripping rate and lightning resistance level. The former refers to the average number of lightning tripping per 100km per year, and the latter refers to the maximum lightning current amplitude of lightning strikes the insulation of the line without flashover . The lower the former and the higher the latter, it means that the performance of lightning protection is good.

Two conditions must be met to cause the tripping of the line: first, the amplitude of the lightning current is greater than or equal to the lightning resistance level of the line, causing power frequency flashover of the insulation; second, when the power frequency flashover becomes a stable power frequency arc; on the transmission line The atmospheric overvoltages that appear generally include induced lightning overvoltages and direct lightning overvoltages.

Contents of the invention

The technical problem to be solved by the present invention is to provide a method for improving the anti-lightning strike level of overhead power distribution lines, which is simple, easy to implement, and has obvious effects.

The technical solution of the present invention is to provide a method for improving the lightning protection level of overhead distribution lines, which is characterized in that the lightning protection level method includes the following content: speed up the insulation transformation of the line; install lightning protection on the straight pole Insulators; install line overvoltage protectors on corner poles; install lightning arresters on the high and low voltage sides of distribution transformers; conduct random testing of lightning protection fittings and grounding resistance of line overvoltage protectors, and restore unqualified grounding resistance G.

The method of anti-lightning strike level also includes: regularly spot-testing the grounding resistance of lightning protection fittings and line overvoltage protectors, and restoring grounding devices with unqualified grounding resistance.

The arrester described in it is a zinc oxide arrester.

Compared with prior art, the advantages of the present invention are:

1. Start from the root and speed up the replacement, which will help to improve the technical equipment level of the overall line;

2. Simple, easy to implement, easy to be accepted, and helpful for promotion.

Detailed ways

The present invention will be further described below.

The invention provides a method for improving the anti-lightning strike level of overhead power distribution lines, which is characterized in that the method for anti-lightning strike level includes the following contents: speeding up the line insulation transformation; installing lightning protection insulators on straight poles; Install line over-voltage protectors on poles; install lightning arresters on the high and low-voltage sides of distribution transformers; conduct random sampling tests on the grounding resistance of lightning protection fittings and line over-voltage protectors, and restore grounding devices with unqualified grounding resistance.

The method of anti-lightning strike level also includes: regularly spot-testing the grounding resistance of lightning protection fittings and line overvoltage protectors, and restoring grounding devices with unqualified grounding resistance.

The arrester described in it is a zinc oxide arrester.

By taking the above measures, the overall lightning protection level of the line has been improved.

In recent years, lightning strike disconnection accidents have shown a downward trend year by year. This year, under the circumstance of relatively frequent lightning strikes, there were only 4 lightning strike disconnection accidents of 10kV lines within a power supply company, which was 50% lower than that in 2004.

Several relatively mature protection measures against lightning strike and disconnection of distribution lines:

1. Lightning protection insulators:

Conductive discharge insulator strips the insulation layer at the fixed place of the insulated wire, and installs an arc discharge gap and a specially designed metal wire clip.

The power-frequency freewheeling current caused by lightning flashover ignites an arc on the metal clamp until it is cut off by the tripping of the line switch, so as to avoid fusing the insulated wire and burning the insulator. It is maintenance-free and relatively inexpensive, with the downside of breaking the insulation.

2. Zinc oxide arrester (MOA):

The application of MOA lines to limit lightning overvoltage is also a measure widely adopted by power companies in recent years. It can effectively cut off power frequency freewheeling, limit lightning overvoltage and induced overvoltage of distribution lines. The disadvantage is that the protection range is small; the investment cost of the installation of the whole line is relatively large; at this time, the insulation layer must be broken, and absolute

The wire core of the edge wire enters water, and the sag of the wire is electrochemically corroded, resulting in disconnection; due to long-term exposure to power frequency voltage, it will cause aging of the valve plate, etc., and timely maintenance is required.

3. Overhead lightning conductor:

The traditional method is to use the shielding of the overhead lightning conductor to protect the distribution overhead insulated line, and the induced voltage can be reduced to 1/(1-k) (k is the product of the lightning conductor, the coupling system between the conductors and the impact coefficient). This method has a better effect and requires no maintenance, but the anti-circling lightning effect is poor, and it is easy to form a line counterattack.

4. Line overvoltage protector:

The line overvoltage protector absorbs the working principle of the current-limiting arc-extinguishing angle adopted in Japan, the United States, Europe, etc., and quickly cuts off the power-frequency continuous current through the current-limiting element, and does not need to trip the circuit breaker to extinguish the arc, which can effectively limit the lightning overvoltage , the quality of power supply will not be affected and the power supply will not be interrupted, which can effectively prevent accidents such as damage to insulators, lightning breakage of overhead insulated conductors, etc., and reduce switch tripping accidents caused by lightning strikes. It is equivalent to MOA with an outer gap, usually No operating voltage, easy installation, no need for broken wires, no maintenance, and longer life. However, it can only protect the lightning overvoltage that breaks down the insulated wire, and it cannot protect other overvoltages on the line. It needs to be limited by the MOA near the wire terminal or power equipment.

The invention can be widely used in the fields of operation and lightning protection management of overhead power distribution lines.

Claims (3)

1. A method for improving the anti-lightning strike level of overhead distribution lines, characterized in that the method for the anti-lightning strike level comprises the following: Accelerate the transformation of line insulation; Install lightning protection insulators on straight poles; Install a line overvoltage protector on the corner pole; Install lightning arresters on the high and low voltage sides of the distribution transformer; The grounding resistance of lightning protection fittings and line overvoltage protectors shall be randomly tested regularly, and the grounding device with unqualified grounding resistance shall be restored. 2. According to the method for improving the anti-lightning strike level of overhead distribution lines according to claim 1, it is characterized in that the method for said anti-lightning strike level also includes: The grounding resistance of lightning protection fittings and line overvoltage protectors shall be randomly tested regularly, and the grounding device with unqualified grounding resistance shall be restored. 3. The method for improving the anti-lightning strike level of overhead distribution lines according to claim 1, characterized in that said arrester is a zinc oxide arrester.