CN106451307A - Lightning shielding method for 10-KV power distribution overhead line - Google Patents

Abstract

The invention belongs to the field of distribution network construction, and in particular relates to a method for lightning protection of 10KV power distribution overhead lines. a. First collect the information of the 10KV power distribution overhead line, the information of the power distribution line includes the height of the tower, the distance of the tower, the height of the lightning protection line, the installation position of the lightning arrester and the insulation level of the line; b. According to the collected 10KV distribution For the information of electrical overhead lines, use PSCAD and EMTDC to establish relevant models and construct a line with 7 base towers; c, calculate the number of flashovers on both sides of the line; d, calculate the tower height to lightning tripping rate according to the number of line flashovers and the influence of the line insulation level on the lightning tripping rate, and then select the appropriate height of the tower and the insulator. The present invention has the purpose of achieving the optimal lightning protection effect at the lowest cost. This method is simple to operate and can be operated by those skilled in the art. It is suitable for Large-scale promotion and use.

Description

Lightning Protection Method for 10KV Power Distribution Overhead Line

technical field

The invention belongs to the field of distribution network construction, and in particular relates to a method for lightning protection of 10KV power distribution overhead lines.

Background technique

With the continuous development of science and technology, electricity has brought rapid changes to people's lives. In order to ensure that people can use electricity, the construction of distribution network led by State Grid Corporation and China Southern Power Grid Corporation is in full swing. , 10KV distribution lines, as the distribution lines directly in contact with the user end, play a pivotal role in the construction of the entire distribution network. The main reason for the most frequent lines is lightning strikes. Lightning strikes will not only interrupt power distribution lines, but also cause damage to power distribution equipment and user equipment, and even cause personal casualties, causing serious losses to industrial and agricultural production.

In order to solve the lightning strike problem of 10KV power distribution overhead lines, various methods have been proposed, for example, installing lightning arresters, lightning conductors, improving the insulation of lines, etc. However, although the above methods can play a certain role However, it has a certain blindness. In order to achieve the effect of lightning protection, people generally set these devices, which increases the cost of distribution network construction, and cannot effectively provide a reasonable method for the line. Make the cost of lightning protection at the lowest and achieve the best effect of lightning protection.

Contents of the invention

The present invention aims at the technical problem of blindness in the lightning protection measures of the 10KV power distribution overhead line mentioned above, and proposes a lightning protection method for the 10KV power distribution overhead line with reasonable design, simple method, good lightning protection effect and low lightning protection cost.

In order to achieve the above object, the technical solution adopted in the present invention is a method for lightning protection of 10KV power distribution overhead lines, comprising the following effective steps:

a. First collect the information of the 10KV power distribution overhead line, the information of the power distribution line includes the height of the tower, the distance of the tower, the height of the lightning protection line, the installation position of the lightning arrester and the insulation level of the line;

b. According to the collected information of 10KV power distribution overhead lines, use PSCAD and EMTDC to establish relevant models and construct a line with 7 base towers;

c. Calculate the number of flashovers on both sides of the line, the calculation formula is:

Among them, N _i is the number of line flashovers caused by lightning strikes per year (24 thunderstorm days) on a 100km line, P is the lightning current distribution probability in areas where the annual average thunderstorm day is more than 20 days, hd is the height of the conductor from the ground, and γ is the lightning strike density ( According to the value of DL/T620-1997), S is the distance between the lightning strike point and the line, and d is the distance between the lightning strike point and the center point of the tower;

d. Calculate the influence of the tower height on the lightning trip rate and the line insulation level on the lightning trip rate according to the number of line flashovers, and then select a suitable height tower and insulator.

As preferably, in the c step, Wherein, α=I _min /S, wherein, Imin is the minimum flicker current when the line flickers.

Preferably, it also includes erecting lightning arresters on the lines with N _i ≧8, and the grounding resistance of the control tower is less than 30'Ω.

Preferably, it also includes erecting a lightning protection line on the line with N _i ≧8, and the height of the lightning protection line from the top of the tower is 0.3m.

Compared with prior art, advantage and positive effect of the present invention are,

1. The present invention provides a lightning protection method for 10KV power distribution overhead lines, which effectively combines factors such as lightning strike points, flicker currents, and heights of conductors, and combines optimized formulas to provide an optimization method for the erection of 10KV power distribution overhead lines. The purpose of achieving the optimal lightning protection effect at the lowest cost, the method is simple to operate, can be operated by anyone skilled in the art, and is suitable for large-scale promotion and use.

detailed description

In order to understand the above-mentioned purpose, features and advantages of the present invention more clearly, the present invention will be further described below in conjunction with the examples. It should be noted that, in the case of no conflict, the embodiments of the present application and the features in the embodiments can be combined with each other.

In the following description, many specific details are set forth in order to fully understand the present invention. However, the present invention can also be implemented in other ways than described here. Therefore, the present invention is not limited to the specific embodiments disclosed below. limit.

Embodiment 1. This embodiment provides a lightning protection method for 10KV power distribution overhead lines. Specifically, Dong'e County is taken as an example. The annual average thunderstorm days in Dong'e County are 24 days. The Dong'e County Power Supply Company serves Dong'e County for 10 days. Townships, 1 provincial-level economic development zone, 507 administrative villages, and 130,000 customers. By the end of 2015, Dong'e had 2 220 kV substations, 9 110 kV substations, and 16 35 kV substations; 265.84 kilometers of transmission and transformation lines of 35 kV and above, 906.04 kilometers of 10 kV lines, and 956.64 kilometers of 0.4 kV lines.

In this embodiment, taking the Dongcheng District Line of Dong’e County as an example, the Dongcheng Line uses LJ-70 conductors, the safety factor K=2.5, and the total length is 5.06km. Stress rods, among them, corner rods and tension rods are 3 bases in total. Except for 1 rod using 15m rods, the others are all 12m rods with a large span. There are 6 lightning arresters, and the wires of the whole line are arranged in a triangle.

According to the collected data, use PSCAD and EMTDC to build relevant models and construct a 7-base tower line. PSCAD is responsible for interface graphics, and EMTDC is responsible for simulation calculations. PSCAD and EMTDC have been used in the power industry for 30 years. Therefore, in this paper In the embodiment, no detailed description is added.

In the process of model calculation, the height of the conductor is 11m, the parameters of the inductance and capacitance of the conductor are taken at high frequency 10 ⁶ HZ, the electrical parameters of the conductor are calculated using the existing line parameter calculation program, and the grounding resistance of the tower is taken as 30'Ω, the tower inductance is 0.84μH/m. Since the line adopts S-210/Z ceramic cross-arm, when the induced lightning overvoltage Ug exceeds 50% discharge voltage of the line insulator, the insulator will flashover. Combined with the electromagnetic field method, the minimum flashover current of the lightning strike and the level of the line can be calculated The relationship between the distances is Since S ² ≧hd ² , the formula can also be simplified as I _min =α.S, where According to the probability curve of the lightning current amplitude exceeding I currently used in general areas in our country, the selected empirical formula lgp=-I/88 is deduced P is the distribution probability of lightning current in areas with an annual average thunderstorm day greater than 20 days, according to the formula Among them, N _i is the number of line flashovers caused by lightning strikes per year (24 thunderstorm days) on a 100km line, P is the lightning current distribution probability in areas where the annual average thunderstorm day is more than 20 days, hd is the height of the conductor from the ground, and γ is the lightning strike density ( According to the value of DL/T620-1997), in this embodiment, the value of γ is 0.07, S is the distance between the lightning strike point and the line, and d is the distance between the lightning strike point and the center point of the tower, which can be obtained through derivation and calculation of the final formula ,

If the height of the pole is 15 meters, the average distance between the conductor and the ground is hd=11m, α=0.76, and N _i =9.5 is calculated; if the height of the pole is 12 meters, the average distance between the conductor and the ground is hd=9.5m, α=0.88 , the calculated N _i =8.1, when the height of the pole is 15 meters, the lightning trip rate is 14% lower, with the height of the pole as 10 meters, the average distance hd = 7.8m from the wire to the ground, calculated α = 1.07, calculated Ni=6.8, compared with the pole height of 15 meters, the lightning tripping rate is 28% lower. From the above calculations, it can be seen that the height of the overhead pole tower of the 10KV power grid in Dong'e County is preferably 10 meters, and at this height, there is no need to install a lightning arrester and lightning conductors.

Since in this embodiment, the insulator uses S-210/Z porcelain cross-arm, when the insulator selects S-280/Z porcelain cross-arm, calculate the number of flashovers,

If the height of the pole is 15 meters, the average distance between the conductor and the ground is hd = 11m, and α = 280/25hd = 1.01 is calculated, and N _i = 7.1. If the height of the pole is 12 meters, the average distance between the conductor and the ground is hd = 9.5 m, calculated α = 280/25hd = 1.17, calculated Ni = 6.1, the lightning tripping rate is 14% lower.

Based on the above calculations, it can be seen that among the 10KV overhead lines of Dong'e County Power Supply Company, the pole tower is preferably 10m pole, and the insulator is preferably S-280/Z porcelain cross-arm. The reduction of the lightning protection effect also means the best.

The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention to other forms. Any skilled person who is familiar with this field may use the technical content disclosed above to change and modify the equivalent of equivalent changes The embodiments are applied to other fields, but any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention still belong to the protection scope of the technical solutions of the present invention without departing from the content of the technical solutions of the present invention.

Claims (4)

1. a kind of method that 10KV distribution overhead line is taken shelter from the thunder is it is characterised in that include following effective procedure：

A, collect the information of 10KV distribution overhead line first, the information of described distribution line includes the height of shaft tower, shaft tower Distance, the dielectric level of the height of lightning conducter, the installation site of arrester and circuit；

B, according to the information collecting 10KV distribution overhead line, set up related model using PSCAD with EMTDC and construct one The circuit of bar 7 base shaft tower；

C, calculate the flashover number of times of circuit both sides, computing formula is：

$N_i=1.78\underset{2hd}{\overset{\mathrm{\∞}}{\∫}}p\frac{24\mathrm{\γ}100}{1000}ds$

Wherein, N_iFor 100km circuit annual (24 thunderstorm days) because thunderbolt causes line flashover number of times, P is annual thunderstorm day More than the lightning current distribution probability in 20 days areas, for wire away from ground level, γ is lightning strike density (according to DL/T620-1997 to hd Value), S is the distance of lightning strike spot and circuit, and d is the distance of lightning strike spot and shaft tower central point；

D, calculated according to line flashover number of times the impact highly to tripping rate with lightning strike for the shaft tower and line insulation level to thunderbolt jump Lock rate, and then choose shaft tower and the insulator of proper height.

2. the method that 10KV distribution overhead line according to claim 1 is taken shelter from the thunder it is characterised in that in described step c,Wherein, α=I_min/ S, wherein, when there is flicker for circuit in Imin, minimum flicker electric current.

3. the method that 10KV distribution overhead line according to claim 2 is taken shelter from the thunder is it is characterised in that be additionally included in Ni 8 Circuit on set up arrester, control shaft tower earth resistance be less than 30 ' Ω.

4. the method that 10KV distribution overhead line according to claim 3 is taken shelter from the thunder is it is characterised in that also include Ni's 8 Lightning conducter is set up on circuit, the height apart from head of mast of described lightning conducter is 0.3m.