CN104682304A - Suburb 10kV power distribution line differentiated lightning-protection method - Google Patents

Abstract

The invention relates to a suburb 10kV power distribution line differentiated lightning-protection method. The method comprises the following steps: step 1: collecting electric parameters of a typical suburb 10kV power distribution line and lightning parameters of a line region; step 2: carrying out lightning risk evaluation on the typical suburb 10kV power distribution line; step 3: designing a suburb 10kV power distribution line differentiated lightning-protection scheme according to lightning risk evaluation, line lightning fault counting and a differentiated lightning-protection principle; and step 4: estimating the lightning-protection effect of the suburb 10kV power distribution line differentiated lightning-protection method to determine a finally-adopted differentiated lightning-protection measure. Compared with the prior art, the suburb 10kV power distribution line differentiated lightning-protection method provided by the invention can be used for specifically carrying out differentiated lightning protection on the suburb 10kV power distribution line according to economical, blocked and dredged differentiated lightning-protection principles.

Description

A Differentiated Lightning Protection Method for Suburb 10kV Distribution Lines

technical field

The invention relates to lightning protection technology for 10kV power distribution lines, in particular to a differential lightning protection method for 10kV power distribution lines in suburban areas.

Background technique

Operation experience at home and abroad shows that lightning strikes are the main reason for tripping 10kV lines, which seriously threatens the safe and stable operation of the distribution network and reduces the reliability of power supply. In recent years, the country has mainly carried out detailed investigation and research on lightning strike accidents, lightning activity distribution characteristics and related topography of typical high-voltage and ultra-high-voltage transmission lines. State Grid Corporation of China has proposed differentiated lightning protection technology and Strategies, such as the invention of a patented method for differential lightning protection of transmission lines (application number: 201310112586.6). However, in the past, differential lightning protection methods for transmission lines were used. Only the lightning protection effect of single lightning protection measures on 10kV distribution lines was analyzed, and there was no differential lightning protection method for suburban 10kV distribution lines.

Contents of the invention

In order to overcome the shortcomings of the existing lightning protection method for 10kV distribution lines in suburban areas, the present invention provides a differentiated lightning protection method for 10kV distribution lines in suburban areas.

The present invention takes the following technical solutions to achieve the above object:

A suburban 10kV distribution line differential lightning protection method, characterized in that the method comprises the following steps:

Step 1: Collect the electrical parameters and lightning parameters of the typical suburban 10kV distribution lines;

Step 2: Conduct lightning strike risk assessment of typical suburban 10kV distribution lines;

Step 3: Design a differentiated lightning protection scheme for suburban 10kV distribution lines based on lightning risk assessment, line lightning fault statistics, and differentiated lightning protection principles;

Step 4: Evaluate the protection effect of the differential lightning protection method for 10kV distribution lines in the suburbs to determine the final differential lightning protection measures.

In the step 1, the electrical parameters of the 10kV distribution line that need to be obtained are the tower height and grounding resistance, the geometric layout of the tower head, the line span and insulation level, the wire diameter and the DC resistance information, and the lightning parameters in the line area are the lightning current amplitude Probability distribution, lightning current waveform and ground flash density information.

In the step 2, the lightning strike risk of the 10kV distribution line is assessed by using the electrical geometric model, the EMTP electromagnetic transient calculation and the IEEE procedure method.

In the step 3, the differentiated lightning protection principles are divided into economic type, blocking type and dredging type.

The economical type is the lowest cost of lightning protection measures, the blocking type is to minimize the line lightning trip rate, and the dredging type is to minimize the line lightning failure rate.

In the step 4, the finally adopted differentiated lightning protection measures are determined according to the power supply reliability standard requirements of the power grid company and the user.

Compared with the prior art, the present invention can perform differentiated lightning protection for suburban 10kV distribution lines according to the principles of economical, blocking and diverting lightning protection

Description of drawings

Fig. 1 is a flowchart of an embodiment of the present invention;

Fig. 2 is the present invention Schematic diagram of the result of a concrete straight bar.

Detailed ways

Below in conjunction with embodiment and accompanying drawing the method of the present invention is described in detail, present embodiment implements according to the technical scheme of the present invention, has provided detailed implementation and specific process, but protection scope of the present invention is not limited to this embodiment.

As shown in Fig. 1, a kind of suburban 10kV distribution line differential lightning protection method, described method comprises the following steps:

Step 1: Calculate the electrical parameters and lightning parameters of the typical suburban 10kV distribution lines. As shown in Figure 2 The height of the tower head and pole is shown in the figure. The grounding resistance of the tower is 10Ω. The line span is 60m, the typical value of the 10kV line in Shanghai Power Grid. There are 20 lines in total, with a total length of 1200m. The three-phase wire adopts ZS-JKLYJ-10/150 type insulated wire, the outer diameter of the wire is 14.6mm, the DC resistance is 0.2Ω/km, the soil resistivity is 100Ω m, and no lightning protection measures are used PS-15 pin support insulator, 50 % The critical flashover voltage is 105kV. The shielding of buildings reduces the number of direct lightning strikes on the line, and the increased number of lightning strikes around the line leads to an increase in the tripping rate of induced lightning. The surrounding area of the suburban line is open, and the shielding factor of the building is taken as 0.

The lightning current amplitude distribution function adopts the average distribution of the lightning location system in Shanghai from 2003 to 2011:

$\mathrm{<span\; class="notranslate">\; P</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}}{\mathrm{<span\; class="notranslate">\; 26.7</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2.3</span>}}}$

In the formula, I _F represents the magnitude of the first lightning current, kA.

The Heidler function widely used in the world is used as the lightning current model:

$\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}}}{\mathrm{<span\; class="notranslate">\; \&eta;</span>}}\frac{{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; no</span>}}}{<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; ]</span>}{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}$

In the formula, I _p is the lightning current amplitude, kA; η is the current amplitude coefficient, take η=1; n is the current steepness coefficient, take n=5; τ ₁ and τ ₂ are the wave head and wave tail respectively, The waveform is 3.83/77.5μs recommended by IEEE standard. For the density of ground flashes, the average density of ground flashes in the Shanghai area from 2003 to 2011 was measured by the lightning positioning system as 4.76 times/km2/year.

Step 2: Conduct lightning strike risk assessment for 10kV distribution lines in typical urban areas. Using electrical geometric model, EMTP electromagnetic transient calculation combined with IEEE regulation method to evaluate the lightning strike risk of 10kV distribution line, it is obtained that the direct strike trip rate before the line lightning protection transformation is 12.35 times/100km/year, and the counterattack trip rate is 7.48 times/100km/year. The trip rate is 12.86 times/100km/year, and the total trip rate is 32.6 times/100km/year. It can be concluded that the current line is mainly at risk of direct strike and induced lightning tripping.

Step 3: According to lightning risk assessment, line lightning fault statistics and differentiated lightning protection principles, design a differentiated lightning protection method for 10kV distribution lines in urban areas.

The purpose of the economical differentiated lightning protection principle is to minimize the cost of lightning protection measures. The current line is mainly at the risk of direct strike and induction lightning tripping. For existing lines, only lightning arresters can be installed (choose to install three-phase line lightning arresters, and the installation distance is 240m, that is, every 4 For new 10kV lines in the suburbs, FXBW10/70 composite insulators can be used (50% critical flashover voltage is 195kV) + lightning arresters are installed (three-phase line lightning arresters are installed, the installation distance is 360m, that is, the difference is installed every 6 gears) chemical lightning protection measures.

The purpose of the principle of blocking differential lightning protection is to minimize the lightning trip rate of the line, and the lightning protection method of lightning arrester (installation of three-phase line arrester, installation interval of 360m, that is, every 6 gears) + lightning protection line can be used.

The purpose of the differential lightning protection principle is to minimize the lightning trip rate of the line. A large number of lightning protection gaps or lightning protection post insulators are installed to reduce the lightning disconnection rate. However, it is necessary to use a longer gap to control the lightning trip rate and greatly reduce lightning strikes. Disconnection rate, using improved lightning protection gap, 50% critical flashover voltage is 110kV.

Step 4: Evaluate the protection effect of the differential lightning protection method for 10kV distribution lines in urban areas.

It is calculated that the line is economical and differentiated lightning protection. For the existing line, choose to install three-phase line lightning arresters. The installation distance is 240m, that is, every 4 gears are installed. After the transformation, the direct strike trip rate is 10.71 times/100km/year, and the counterattack trip rate is 5.95 times /100km/year, the induction trip rate is 2.14 times/100km/year, and the total trip rate is 18.80 times/100km/year, which reduces the total line trip rate by 42%. For newly built 10kV lines in the suburbs, the differential lightning protection measures of FXBW10/70 composite insulators (50% critical flashover voltage of 195kV) + installation of lightning arresters (installation of three-phase line lightning arresters with an installation distance of 360m, that is, every 6 gears) can be used. After the transformation, the direct trip rate is 4.84 times/100km/year, the counterattack trip rate is 1.93 times/100km/year, the induction trip rate is 0.58 times/100km/year, and the total trip rate is 7.35 times/100km/year, which reduces the total line trip rate by 77 %.

Calculated the blocking type differential lightning protection method, lightning arrester (three-phase line lightning arrester installed, the installation distance is 360m, that is, installed every 6 gears) + lightning protection line after transformation, the direct strike trip rate is 0 times/100km/year, and the counterattack trip rate is 2.51 times/100km/year, the induction trip rate is 2.01 times/100km/year, and the total trip rate is 4.52 times/100km/year, reducing the total line trip rate by 86%.

According to the calculation of the dredging type differential lightning protection method, the direct strike trip rate after transformation is 12.35 times/100km/year, the counterattack trip rate is 7.19 times/100km/year, the induction trip rate is 11.42 times/100km/year, and the total trip rate is 30.95 times/100km /year, reducing the total tripping rate of the line by 5%.

Because it is a key user and has high requirements for power supply reliability and power quality, FXBW10/70 composite insulators are used for new lines (50% critical flashover voltage is 195kV) + lightning arresters are installed (three-phase line lightning arresters are installed, and the installation distance is 360m. Install every 6 gears) Differentiated lightning protection measures.

Claims (6)

1. a suburban 10kV power distribution line differentiation lightning protection method, is characterized in that, described method comprises the following steps: Step 1: Collect the electrical parameters and lightning parameters of the typical suburban 10kV distribution lines; Step 2: Conduct lightning strike risk assessment of typical suburban 10kV distribution lines; Step 3: Design a differentiated lightning protection scheme for suburban 10kV distribution lines based on lightning risk assessment, line lightning fault statistics and differentiated lightning protection principles; Step 4: Evaluate the protection effect of the differential lightning protection method for the 10kV distribution lines in the suburbs to determine the final differential lightning protection measures. 2. a kind of suburban 10kV distribution line differential lightning protection method according to claim 1, is characterized in that, in described step 1, need to obtain the electrical parameter of 10kV distribution line to be tower height and grounding resistance, tower head Geometric layout, line span and insulation level, wire diameter and DC resistance information, lightning parameters in the line area are lightning current amplitude probability distribution, lightning current waveform and ground flash density information. 3. a kind of suburban 10kV power distribution line differentiation lightning protection method according to claim 1, it is characterized in that, in described step 2, adopt electrical geometry model, EMTP electromagnetic transient calculation to evaluate 10kV power distribution in conjunction with IEEE regulation method Line lightning risk. 4. A method for differential lightning protection of suburban 10kV power distribution lines according to claim 1, characterized in that, in said step 3, the differential lightning protection principles are divided into economic type, blocking type and dredging type. 5. a kind of suburban 10kV power distribution line differentiation lightning protection method according to claim 4, it is characterized in that, described economic type is that the cost of lightning protection measures is the lowest, and described blocking type is to reduce line lightning tripping rate to the greatest extent, The dredging type is to minimize the lightning failure rate of the line. 6. A kind of suburban 10kV power distribution line differentiated lightning protection method according to claim 1, it is characterized in that, in said step 4, according to the standard requirement of power grid company and user to power supply reliability, determine the final adopted difference Lightning protection measures.