CN101272040B - A Method of Lightning Protection Configuration for Transmission Lines Using Lightning Damage Distribution of Power Grid - Google Patents

Abstract

The invention relates to a method using lightning disturbance distribution to carry out lightening protection configuration of the transmission line, which adopts a computer to processing to the lightening automatic monitoring data, establishes a database and uses a geographical information system and the database as an analysis platform; the method also adopts a grid method to compute lightening parameters and sets an amplitude range for dangerous lightning currents of the lightening disturbance of the objects according to the lightning stroke against ability and the characteristics of ground objects, and acquires the correspondent lightning disturbance distribution according to the amplitude range for dangerous lightning currents and the lightening data computed by the computer; by adopting the reliable index in operation confirmed by the transmission line and the statistic data of the lightning stroke flashover types, the method sets critical density value in the lightning disturbance distribution which can cause lightning strike flashover: the method computes the scale and distribution of the lightning disturbance based on the critical density value and confirms the lightning-proof configuration of the transmission line based on the scale and distribution of the lightning disturbance. The invention can be adopted to judge the correspondent area and probability of 'shielding failure flashover' and 'back flashover' of the transmission line and can effectively configure the correspondent lightning-proof measures of the transmission line based on the characteristics of the two lightning disturbances, thus improving the performance-price ratio.

Description

A Method of Lightning Protection Configuration for Transmission Lines Using Lightning Damage Distribution of Power Grid

technical field

The invention relates to lightning protection technology for transmission lines, in particular to a method for lightning protection configuration of transmission lines by utilizing lightning damage distribution.

Background technique

Lightning protection configuration is the necessary protective measures and technical means to make overhead lines effectively deal with lightning strikes. The lightning protection configuration of existing transmission lines is mainly in accordance with the method recommended by the current power industry regulations "Overvoltage Protection and Insulation Coordination of AC Electrical Installations" (DL/T620-1997), that is, according to the definition of lightning days manually recorded by the Meteorological Department for a long time According to the intensity of lightning activity, the lightning protection configuration is determined in combination with the insulation structure of the transmission line. In terms of specific measures, the anti-backlash flashover is to reduce the grounding resistance of the tower or strengthen the line insulation, and the anti-shield flashover is to reduce the Lightning wire protection corner. The results of engineering tests prove that this method has obvious shortcomings: "thunder day" itself cannot fully characterize the characteristics of lightning activities, that is, a thunder day cannot fully represent the frequency of specific lightning occurrences, so its guiding role is very limited; in recent years, it has gradually The ground flash density (fl/km ² /a) representing the lightning distribution is used to replace the lightning day. The applicant found in the research that due to the structural characteristics of the power grid itself and the insulation characteristics represented, not all lightning may cause high-voltage overhead transmission. The flashover of the high-voltage overhead transmission line can only be caused by part of the lightning that is called dangerous; the actual distribution of this part of the lightning that is harmful to the power grid is not equal to the distribution of the lightning density on the ground; neither of the above two methods can Correctly express the two types of lightning accidents that may occur on the transmission line, "counterattack" and "shielding", that is, it cannot be judged that the "shielding flashover" that occurs when the shielding of the lightning conductor fails and the lightning strike caused by the lightning conductor or the top of the tower The area corresponding to the "counter-flashover" and the probability of lightning damage, and the lightning protection measures required for the corresponding transmission lines cannot be configured corresponding to the two characteristics of lightning damage, resulting in the current situation that the cost performance of lightning protection measures has always been very low.

Contents of the invention

The object of the present invention is to improve the deficiencies of the prior art, and propose a method for lightning protection configuration of transmission lines by using the lightning damage distribution of the power grid.

The technical solution of the present invention is to use a computer to process the lightning automatic monitoring data, establish a database, use the geographic information system (GIS for short) and the database as the analysis platform, use the grid method to count the lightning parameters, and aim at the ground objects to resist lightning strikes Ability and its characteristics, set the range of the dangerous lightning current amplitude of the object lightning damage, and use the lightning data of the computer statistics according to the range of the dangerous lightning current amplitude to obtain the corresponding lightning damage distribution of the power grid, which is characterized in that the transmission line is used to determine Statistical data of operational reliability indicators and lightning flashover types, set the critical density value in the distribution of lightning damage that can cause lightning flashover, and use the critical density value as a criterion to calculate the classification and distribution of lightning damage The basic steps to determine the lightning protection configuration of the transmission line are as follows:

(1) First, the lightning automatic monitoring data is stored in the database according to time, location, lightning current amplitude and polarity, main discharge and sequence discharge, and the computer program is used to process the data in the database. Determine the corresponding area of the lightning automatic monitoring data on the digital map, and divide the selected area on the digital map into equal-area grids; the computer counts the data of each grid; and assigns the lightning monitoring data to the lightning topic Attributes and geographic attributes, each grid automatically divided has the same coordinate system geographic attributes as the lightning monitoring data; the lightning parameters calculated by the grid method are associated with the area where the grid is located, and each grid is set as a lightning statistical unit; Transfer the thematic data in the database to the corresponding network according to the geographical attributes as a statistical sample, and count the number of lightning occurrences in each grid;

(2) According to the insulation structure of the power grid, the range value of the dangerous lightning current amplitude that can cause flashover of the insulator string of the transmission line is used as the criterion, and the current amplitude attribute of the lightning in each grid is counted, and the ones other than the criterion are excluded Data, and then divide the annual lightning times of each grid by the grid area to obtain the lightning damage distribution of the grid; the grid insulation structure includes the grid voltage level, transmission line structure, and terrain factors;

(3) Classify the records of lightning flashover events of transmission lines that have occurred according to the special attributes of time of occurrence, location coordinates, flashover type, and voltage level, store the data in the lightning fault database in the computer, and record lightning flashover events According to its thematic attributes, it is transferred to the grid corresponding to the lightning damage distribution of the power grid in turn, and the connected grid is marked with the grid as the center to obtain the historical lightning damage area of the power grid. Regions and power grids shield historical lightning-damaged areas;

(4) Use computer to calculate the corresponding geographical distribution layer for the distribution of power grid counterattack lightning damage and the historical lightning damage area of power grid counterattack for each voltage level, the distribution of power grid shielding lightning damage and the historical lightning damage area of power grid shielding strike, and then use the geographic information system Obtain the distribution map of power grid comprehensive counter-attack lightning damage and the distribution map of power grid comprehensive shielding lightning damage;

(5) According to the lightning protection reliability control index of the transmission line, that is, the number of trips/(100 kilometers · 40 lightning days), and the statistical data of lightning flashover types, set the distribution of lightning damage that can cause shielding flashover and counter flashover In the critical density value, the critical density value is used as a criterion to calculate the lightning damage distribution grid ground flash density value, and respectively calibrate the exceeding value and the non-exceeding value;

(6) Statistical lightning damage distribution grid, set four levels of lightning damage areas according to different combinations of counterattack and shielding exceeding the standard value and not exceeding the standard value, among them, there are data areas with counterattack not exceeding the standard value and shielding attack not exceeding the standard value It is set as level 1 lightning damage area, the data area with counterattack exceeding standard value and shielding attack not exceeding standard value is set as level 2 lightning damage area, and the data area with counter attack not exceeding standard value and shielding attack exceeding standard value is set as level 3 lightning damage area. Harmful area, the data area with counterattack exceeding the standard value and shielding attack exceeding the standard value is set as a level 4 mine damage area;

(7) Carry out the lightning protection configuration of the transmission line with the lightning damage zone of four levels of above-mentioned setting: Wherein,

a. For Class 1 mine damage area, carry out conventional lightning protection configuration according to DL/T620-1997;

b. For Level 2 lightning hazard areas, strengthen the configuration of anti-reflection flashover of transmission lines, the grounding resistance value of transmission line towers, the grounding resistance of 110kV-500kV line towers in mountainous areas should not be higher than: 15Ω, and the grounding resistance in plain areas should not be higher. Higher than 7Ω; or to enhance the insulation strength of transmission lines, composite insulators are required: under the premise of meeting the requirements of wind deflection and wire-to-ground distance, the dry arc distance of composite insulators used for 500kV lines is not less than 30 pieces of suspension porcelain insulators or glass insulators The structural length of composite insulators used for 220kV lines should not be less than the structural length of 14 suspended porcelain insulators or glass insulators; the dry arc distance of composite insulators used for 110kV lines should not be less than the structural length of 7 suspended porcelain or glass insulators ;Required number of pieces for porcelain and glass insulators: 30 to 32 pieces for 500kV; 15 pieces for 220kV; 9 pieces for 110kV;

c. For Level 3 lightning hazard areas, strengthen the configuration of transmission line anti-shielding flashover and reduce the protection angle of lightning protection lines. Newly built 110kV ~ 500kV lines should erect double overhead ground wires on the whole line, and 500kV and 220kV should adopt negative angle protection. 110kV line protection angle should be less than 10°;

d. For Level 4 lightning hazard areas, it is necessary to simultaneously strengthen the anti-counterattack flashover and Rao strike flashover configurations of transmission lines, and jointly adopt the lightning protection configurations for Level 2 and 3 lightning hazard areas.

The advantage of the present invention is that the area and probability corresponding to the "shielding flashover" and "counter-attack flashover" of the transmission line can be judged by using the present invention, and corresponding to the two lightning damage characteristics, the corresponding power transmission can be effectively configured. Line lightning protection measures to improve cost performance. The realization method of the present invention is simple and clear, and has good operability and practicability.

Description of drawings

Fig. 1, functional block diagram of the present invention.

Detailed ways

Below, the present invention will be described in further detail in conjunction with the accompanying drawings.

As shown in Figure 1, the present invention uses the automatic monitoring data of the lightning location system as a statistical sample, uses a computer processing program to input the automatic monitoring data into a computer with a geographic information system (abbreviated as GIS) processing function, sets up a database, and uses geographic information The system and database are analysis platforms, and the grid method is used to count lightning parameters. According to the ability and characteristics of ground objects to resist lightning strikes, set the range of dangerous lightning current amplitudes of object lightning hazards, and then according to this range, use the lightning data processed by computer statistics to obtain the corresponding distribution of lightning hazards in the power grid, and use the operation determined by transmission lines Statistical data of reliability index and lightning flashover type, set the critical density value in the distribution of lightning damage that can cause lightning Classification and distribution to determine the lightning protection configuration of transmission lines.

Combining the shielding characteristic current and counterattack characteristic current of power grids of various voltage levels, a dangerous current data analysis system is established, and the required data and analysis results are determined by grid method, and the analysis results are compared, verified and corrected by lightning accident records. The lightning damage distribution of the corresponding object is obtained. According to the distribution of lightning damage and the corresponding reliability index, the critical density value corresponding to the distribution of lightning damage is determined. According to the density value, the lightning damage area of the power grid is divided into four levels, and targeted lightning protection measures are configured for these four levels of lightning damage areas. It adopts the following steps: (1) The lightning automatic monitoring data is stored in the database through the computer according to the time, position, lightning current amplitude and polarity thematic attribute data. Use a computer with GIS processing function, use special software, set the program to divide the target object—the selected area on the digital map into equal-area grids, set each grid as a lightning statistical unit, and use the data in the lightning database The data is compared with the corresponding grid in geography, and the thematic data in the lightning database is transferred to the corresponding grid as a statistical sample according to the geographical attributes, and the number of ground lightning in each grid is counted. (2) Set the shielding dangerous current range value and the counterattack dangerous current range value according to the grid insulation margin. Perform amplitude comparison according to this range, remove the data in each grid whose lightning current amplitude is outside the range of shielding and counterattack dangerous currents, and divide the remaining number of lightning strikes by the corresponding grid area to obtain the power grid shielding lightning damage Distribution and Lightning Damage Distribution of Grid Counterattack. (3) At the same time, the history of lightning flashover accident records of the power grid is stored in the computer according to the time of occurrence, the longitude and latitude coordinates of the lightning strike point, the type of flashover, and the voltage level, and the lightning strike fault database of the power grid is established. Comparing the data of the lightning strike fault database with the corresponding geographical grid, the shielding fault point and the counterattack fault point are respectively transferred to the corresponding geographic grid according to the latitude and longitude coordinates of the geographical information, and centered on the grid, the Adjacent grids are marked to obtain the historical lightning damage area of the power grid shielding and the historical lightning damage area of the grid counterattack; (4) the lightning damage distribution of the power grid shielding and the historical lightning damage area of the shielding power grid are obtained to obtain the lightning damage distribution of the integrated power grid, Combining the lightning damage distribution of the power grid counterattack and the historical lightning damage area of the power grid counterattack, the distribution map of the integrated power grid counterattack lightning damage is obtained. (5) According to the existing lightning protection reliability control index (that is, the lightning strike trip rate, unit time/(100 kilometers · 40 lightning days)), the lightning protection calculation is carried out to obtain the lightning damage of the power grid corresponding to the reliability index of each voltage level The density value of the grid on the distribution map, the density value of the dangerous lightning in this grid is the critical density value, and the critical density value is used as a criterion to compare the density value of the grid. On the lightning damage map of the power grid, the grid The grid area whose density value exceeds the critical density value is marked as the over-standard area, and the grid area whose density value does not exceed the critical density value is marked as the non-over-standard area. According to the nature of lightning damage, the critical density value is divided into critical shielding dangerous lightning density value and critical counterattack dangerous lightning density value. According to the corresponding lightning damage area is divided into the shielding exceeding the standard area and the shielding not exceeding the standard area, the counterattack exceeding the standard area and the counterattack not exceeding the standard area. (6) Combining these four areas, the areas on the lightning damage distribution map of the power grid are classified into four levels of lightning damage areas: the intersection of the counterattack no-exceeding area and the shielding area not exceeding the standard is called the first-level lightning damage area, and the counterattack area does not exceed the standard area. The intersection of the exceeding standard area and the shielding non-exceeding area is called the second-level lightning damage area, the intersection of the counterattack non-exceeding area and the shielding exceeding the standard area is called the third-level lightning damage area, and the intersection of the counterattack exceeding the standard area and the shielding exceeding the standard area is called 4 Level mine damage area. (7) According to the nature of the lightning damage in the fourth-level lightning damage area, carry out targeted lightning protection configuration. If the corresponding shielding critical density value (criterion) is not exceeded, the severity of lightning damage is relatively low. According to the Chinese power industry standard "Overvoltage Protection and Insulation Coordination of AC Electrical Installations" (DL/T 620-1997), routine Although the grid dangerous lightning density corresponding to the second-level lightning damage area does not exceed the corresponding shielding critical density value (criterion), it exceeds the corresponding counterattack critical density value (criterion). Industry regulation DL/T 620-1997 In addition to the conventional lightning protection configuration, it is necessary to install special lightning protection measures for counterattack, such as reducing grounding resistance, strengthening insulation, etc.; grid dangerous lightning density corresponding to level 3 lightning damage area It does not exceed the corresponding counterattack critical density value, but exceeds the corresponding shielding critical density value. In addition to the conventional lightning protection configuration according to the Chinese Electric Power Industry Regulations DL/T 620-1997, it is also necessary to install special shielding protection Lightning protection measures, such as reducing the protection angle, etc.; the grid dangerous lightning density value corresponding to the level 4 lightning damage area exceeds both the corresponding counterattack critical density value and the corresponding shielding critical density value, which means that the lightning damage is relatively serious In the area, in addition to the conventional lightning protection configuration according to the regulations of China's electric power industry DL/T 620-1997, other lightning protection measures against shielding and counterattack should be installed, and the lightning protection of level 2 and 3 minefields should be comprehensively used measure.

The lightning protection configuration of transmission lines using the four levels of lightning damage areas set above is specifically implemented as follows:

a. For Class 1 mine damage area, carry out conventional lightning protection configuration according to DL/T620-1997;

b. For Level 2 lightning hazard areas, strengthen the configuration of anti-reflection flashover of transmission lines, the grounding resistance value of transmission line towers, the grounding resistance of 110kV-500kV line towers in mountainous areas should not be higher than: 15Ω, and the grounding resistance in plain areas should not be higher. Higher than 7Ω; or to enhance the insulation strength of transmission lines, composite insulators are required: under the premise of meeting the requirements of wind deflection and wire-to-ground distance, the dry arc distance of composite insulators used for 500kV lines is not less than 30 pieces of suspension porcelain insulators or glass insulators The structural length of composite insulators used for 220kV lines should not be less than the structural length of 14 suspended porcelain insulators or glass insulators; the dry arc distance of composite insulators used for 110kV lines should not be less than the structural length of 7 suspended porcelain or glass insulators ;Required number of pieces for porcelain and glass insulators: 30 to 32 pieces for 500kV; 15 pieces for 220kV; 9 pieces for 110kV;

c. For Level 3 lightning hazard areas, strengthen the configuration of transmission line anti-shielding flashover and reduce the protection angle of lightning protection lines. Newly built 110kV ~ 500kV lines should erect double overhead ground wires on the whole line, and 500kV and 220kV should adopt negative angle protection. 110kV line protection angle should be less than 10°;

d. For Level 4 lightning hazard areas, it is necessary to simultaneously strengthen the anti-counterattack flashover and Rao strike flashover configurations of transmission lines, and jointly adopt the lightning protection configurations for Level 2 and 3 lightning hazard areas.

The acquisition data processing of the lightning damage distribution map and criterion of the power grid mentioned above can be processed on one computer, and can also be processed on multiple computers through network connection for data exchange processing. Therefore, statistical data resources are effectively obtained for the present invention, and statistical data resource sharing is achieved.

The collected automatic monitoring data of the lightning location system of North China Power Grid and the data of lightning strike accidents of the power grid, which contain geographic attributes, are input by computer, and processed by computer programs. in:

1. Determination of the lightning damage distribution map of the power grid

(1) Selection of dangerous current range

The occurrence of power grid lightning damage has its unique characteristics. Affected by the insulation level of the power grid, only ground lightning in certain current amplitude ranges can cause lightning strikes, and lightning currents with different amplitudes have different damage degrees.

Determining the range of dangerous currents is a prerequisite for determining the distribution of lightning damage in the power grid. The selection of dangerous currents is based on the lightning withstand performance of most transmission lines in the power grid and determined by using existing calculation methods. The insulation level of power grids with different voltage levels is significantly different. For power grids of the same voltage level, the performance of anti-shielding and counterattack will also be significantly different due to different application environmental conditions. The protective measures are different, so different shielding dangerous current ranges and counterattack dangerous current ranges are proposed for different voltage levels. At the same time, for the same voltage level, the range of dangerous current is also different when the tower type is different, the grounding resistance is different, and the protection angle is different. The range of dangerous current should be selected so that the dangerous current of most transmission lines falls within the selected dangerous current range. . The range (start and stop value) of the counterattack dangerous current is solved according to the current electric power industry regulations "Overvoltage Protection and Insulation Coordination of AC Electrical Installations" (DL/T620-1997). Determined according to the electrical geometric model.

For the 500kV power grid, it is assumed that 28 insulators are used, U _50% is 2420kV, and the span is 450m; the grounding resistance of the adjacent tower is 15Ω, and the calculation results are shown in Table 1. It can be seen from the calculation results that the impact of power frequency voltage on the lightning withstand level is very large. In the case of considering the influence of power frequency voltage (which is consistent with the actual situation), the lightning withstand level drops by an average of 18% compared with that without considering the power frequency voltage.

Therefore, for a 500kV transmission line, the lower limit of the counterattack dangerous current can be taken as 134kA (standardized line requirements meet 15Ω), and considering more general results, take 125kA.

Similarly, for 220kV transmission lines, the lower limit of counter-attack dangerous current can be 75kA.

Table 1 Calculation results of back-attack lightning withstand level of 1500kV line

According to the rules and regulations: the general 220kV shielding lightning resistance level is 14.0kA (corresponding to U _50% is 1400kV).

The shielding critical current is calculated for the two typical transmission lines in Table 2, and the results are shown in Table 3. The analysis of 7 220kV power grid lightning tripping accidents in Chengde area in June 2006 includes 4 shielding accidents. The calculation results of shielding current are shown in Table 4.

Combining Table 3 and Table 4, it can be seen that the current value of shielding for 220kV transmission lines calculated by the stroke distance method is generally about 15-40kA. Further survey and statistics of lightning shielding in Shanxi Provincial Power Grid and Hebei Southern Power Grid show that the size of the shielding current sample is generally within the range of shielding dangerous current in this study.

Under comprehensive consideration, the 220kV shielding dangerous current range is taken as [10kA, 40kA].

In the same way, the dangerous current range of 500kV grid shielding is taken as [20kA, 50kA].

Table 2 Parameters of two typical 220kV transmission lines

Tower type Gap (m) Height of wire hanging point to ground (m) The height of the hanging point of the lightning conductor to the ground (m) Horizontal distance from wire hanging point to tower center (m) The horizontal distance from the hanging point of the lightning protection line to the center of the tower (m) Insulator string length (m) SZ₂ 358 30 40 13 8.5 2.34 SJ₂ 306 30.5 41.5 7.2 3.8 2.34

Table 3 Calculation results of maximum shielding current

Table 4220kV line shielding current calculation (example)

(2) Determination of the lightning damage distribution map of the power grid

Firstly, the lightning damage distribution of the counter-strike power grid and the lightning damage distribution of the shielding power grid should be determined. Taking the start and end values of the above-mentioned dangerous current as the dangerous current range, count the number of ground flashes with lightning current amplitude within this range in each grid under the 0.2°×0.2° grid, and then divide it by the corresponding grid area to obtain the dangerous current range of each grid. Lightning density value.

Count the lightning density in the range of 125kA and above in each grid, and obtain the lightning damage distribution of the North China 500kV power grid; count the lightning density in the range of 20kA to 50kA in each grid, and obtain the 500kV North China Distribution of power grid shielding lightning damage; count the lightning density in each grid with amplitude within the range of 75kA and above, and obtain the distribution of lightning damage in North China 220kV power grid; count the ground lightning with amplitude in the range of 10kA to 40kA in each grid Density, get lightning damage distribution of 220kV power grid in North China.

Then determine the historical lightning damage area of the counterattack power grid and the historical lightning damage area of the shielding power grid. Operation experience is the verification and summary of all measures and basic theories, and it is a concrete manifestation of the combination of power grid and nature. The distribution of lightning damage should first be supplemented by operation experience on the basis of the distribution of dangerous lightning. Based on the four-year lightning accident records in North China from 2000 to 2007, a lightning fault database with geographic attributes was established. From 2000 to 2007, there were 43 lightning faults on 500kV transmission lines in North China, and 74 lightning faults on 220kV transmission lines. Mark the counterattack fault point and shielding fault point on the geographic electronic map of North China respectively, find the grid that intersects with it, and select the grid and its adjacent two grids to form the counterattack historical power grid lightning damage area and shielding Historical power grid lightning damage area.

Finally, the lightning damage distribution map of the counter-attack power grid and the lightning damage area of the counter-attack historical power grid, the lightning damage distribution map of the shielding power grid and the historical lightning damage area of the shielding power grid are respectively combined to form a comprehensive lightning damage distribution map of the counter-attack power grid and a lightning damage distribution map of the comprehensive shielding power grid Distribution. These two power grid historical lightning damage areas are superimposed on the lightning damage distribution map of the counterattack power grid and the lightning damage distribution map of the shielding power grid respectively, and the historical fault area in the two maps is rendered with the attribute adjacent to the area upward.

2. Determination of critical density value (selection of criteria)

Take the 256# tower of the 500kV Tuoyuan primary circuit line and the 50# tower of the 220kV Panzun line of the North China Power Grid as examples for calculation.

The calculation of the lightning trip rate is based on the method recommended by the Chinese electric power industry standard "Overvoltage Protection and Insulation Coordination of AC Electrical Installations" (DL/T 620-1997), and is carried out according to formula (1).

N=N _L η(gP ₁ +P _α P ₂ ) (1)

对于山区线路，

Among them, N is the lightning strike tripping rate, N _L is the annual number of lightning strikes per 100 kilometers under 40 lightning days, N _L =0.28(b+4h), b is the distance between two lightning protection lines, h is the average height of lightning protection lines; g is the stroke rate; η is the arc building rate, P ₁ is the lightning current probability exceeding the lightning resistance level when lightning strikes the top of the tower, P ₂ is the probability of dangerous current shielding; P _α is the shielding rate, for plain lines,

For mountain routes,

Define the dangerous lightning density as N _gc , the counterattack dangerous lightning density as N _gc1 , and the shielding dangerous lightning density as N _gc2 , then

N _gc1 = N _g P ₁ , N _gc2 = N _g P ₂ ,

counter trip rate

Shielding trip rate

Lightning trip rate N＝n _r +n _f

Calculated according to the reliability control index set by the State Grid Corporation, the State Grid Corporation set the 500kV line reliability control index as 0.14 times/(100 kilometers · 40 lightning days), and the 220kV line reliability control index as 0.315 times/( 100 kilometers · 40 thunder days). For the distribution of reliability control index on shielding tripping rate and counterattack tripping rate, it is carried out according to operating experience. For 500kV lines, counterattack tripping accidents and shielding tripping accidents account for 30% and 70%, respectively. For 220kV lines, counterattack tripping Accidents and shielding trip accidents account for 50% each.

A. Calculation of the critical density value for the 256# tower of the 500kV Tuoyuan primary circuit line of the North China Power Grid

The parameters of the tower are as follows: ZKI type, the height of phase A is 40.66m, the middle distance of phase A is 12.4m, double lightning protection lines, the distance between lightning protection lines is 21.3m, and the height of lightning protection lines is 49.5m. Here the ground slope is 10°.

Then it can be calculated that the average height of the lightning protection line h=49.5-2/3*9.5=43.167(m), the protection angle α=11.198°, and the shielding rate P _α =0.0037.

Critical counterattack dangerous lightning density value:

${\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; gc</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0.14</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; 30</span>}<span\; class="notranslate">\; \%</span><span\; class="notranslate">\; \&times;</span>\frac{\mathrm{<span\; class="notranslate">\; 10</span>}}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; b</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 4</span>}\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; \&times;</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&eta;</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; g</span>}}<span\; class="notranslate">\; \&times;</span>\frac{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}}{\mathrm{<span\; class="notranslate">\; 40</span>}}<span\; class="notranslate">\; \&ap;</span>\mathrm{<span\; class="notranslate">\; 0.006</span>}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; /</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; km</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; a</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>$

(T _d is taken as 26 according to the location of 256# tower and 0.15° grid)

Critical shielding hazard lightning density value:

${\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; gc</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0.14</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; 70</span>}<span\; class="notranslate">\; \%</span><span\; class="notranslate">\; \&times;</span>\frac{\mathrm{<span\; class="notranslate">\; 10</span>}}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; b</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 4</span>}\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; \&times;</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&eta;</span>}<span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}}<span\; class="notranslate">\; \&times;</span>\frac{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}}{\mathrm{<span\; class="notranslate">\; 40</span>}}<span\; class="notranslate">\; \&ap;</span>\mathrm{<span\; class="notranslate">\; 1.026</span>}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; /</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; km</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; a</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>$

Inquiring from the distribution of lightning strike back strike and lightning strike distribution of the power grid, it is found that the dangerous lightning density of the grid where the tower is located is greater than the critical counterattack dangerous lightning density value, and the shielding dangerous lightning density is also greater than the critical shielding dangerous lightning density value value, so the location of this tower is not only the counterattack exceeding the standard area, but also the shielding attack exceeding the standard area, that is, it is a level 4 mine damage area.

B. Calculation of critical density value for 54# tower of 220kV Jiangxing Line 1 in North China Power Grid

The parameters of the tower are as follows: Z43-L type, the height of the tower is 38.25m, double lightning protection lines, the distance between lightning protection lines is 6m, the arc sag of lightning protection lines is 6.9m, and the protection angle is 13°. The terrain here is the top of a mountain.

Then it can be calculated that the average height of the lightning protection line h=38.25-2/3*6.9=33.65(m), and the shielding rate P _α =0.0038.

Critical counterattack dangerous lightning density value:

${\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; gc</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; .</span>\mathrm{<span\; class="notranslate">\; 315</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; 50</span>}<span\; class="notranslate">\; \%</span><span\; class="notranslate">\; \&times;</span>\frac{\mathrm{<span\; class="notranslate">\; 10</span>}}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; b</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 4</span>}\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; \&times;</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&eta;</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; g</span>}}<span\; class="notranslate">\; \&times;</span>\frac{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}}{\mathrm{<span\; class="notranslate">\; 40</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0.042</span>}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; /</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; km</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; a</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>$

(T _d is 30 according to the position of the tower and the 0.15° grid)

Critical shielding hazard lightning density value:

${\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; gc</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; .</span>\mathrm{<span\; class="notranslate">\; 315</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; 50</span>}<span\; class="notranslate">\; \%</span><span\; class="notranslate">\; \&times;</span>\frac{\mathrm{<span\; class="notranslate">\; 10</span>}}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; b</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 4</span>}\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; \&times;</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&eta;</span>}<span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}}<span\; class="notranslate">\; \&times;</span>\frac{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}}{\mathrm{<span\; class="notranslate">\; 40</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; .</span>\mathrm{<span\; class="notranslate">\; 764</span>}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; /</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; km</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; a</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>$

Inquiry from the distribution of lightning strike back strike and lightning strike distribution of the power grid, it is found that the dangerous lightning density of the grid where the tower is located is greater than the critical counterattack dangerous lightning density value, and the shielding dangerous lightning density is less than the critical shielding dangerous lightning density value , so the location of this tower is the counterattack exceeding the standard area, and the shielding attack does not exceed the standard area, that is, this is the second-level mine damage area.

3. Lightning protection configuration scheme

According to the above-mentioned critical lightning density calculation for each tower, and then compare the shielding dangerous lightning density and counterattack dangerous lightning density values at the corresponding positions on the lightning damage distribution map of the power grid to judge the level of the lightning damage area where the tower is located According to the method of configuring lightning protection measures according to the level of lightning damage, the production department of North China Power Grid installed targeted installations on 10 500kV transmission lines including the Shachang double-circuit line and 15 220kV transmission lines including the Chenglong single-circuit line in 2007. A total of 1,420 sets of anti-shielding lightning rods and side pins were installed, 121 line arresters were installed, 1,003 bases of grounding devices were modified, 257 bases of grounding and grounding modules were added, and 166km of continuous grounding bodies were installed.

Claims (2)

1. utilize damage to crops caused by thunder to distribute and carry out the method for transmission line lightning protection configuration, adopt computer that the thunder and lightning automatic monitoring data is handled, set up database, with GIS-Geographic Information System and database is analysis platform, adopt gridding method statistics lightning parameter, and resist thunderbolt ability and feature thereof at ground object, set the dangerous amplitude of lightning current scope of object damage to crops caused by thunder, and adopt the thunder and lightning data of computer statistics according to this danger amplitude of lightning current scope, obtaining corresponding electric network thunderstorm damage distributes, it is characterized in that, adopt the operational reliability index that transmission line determines and the statistics of lightning stroke flashover type, the critical density value during the damage to crops caused by thunder that setting can cause lightning stroke flashover distributes, with this critical density value is criterion, the classification and the distribution of statistics damage to crops caused by thunder again according to damage to crops caused by thunder classification and distribution, are determined transmission line lightning protection configuration; In conjunction with each electric pressure electrical network shielding characteristic current, counterattack characteristic current, set up the dangerous currents data analysis system, adopt gridding method to determine required data and analysis result, to analysis result adopt that the lightning strike accident record compares, verification and correction, the damage to crops caused by thunder that obtains respective objects distributes; Critical density value according to damage to crops caused by thunder distributes and reliability index is determined corresponding damage to crops caused by thunder distribution accordingly is divided into level Four according to this density value with the electric network thunderstorm damage zone, and this level Four damage to crops caused by thunder district is carried out specific aim lightning protection measure configuration, and the basic step of employing is as follows:

(1) at first, deposit the thunder and lightning automatic monitoring data in database by time, position, amplitude of lightning current and polarity, main discharge and time continuous thematic attribute data that discharges by computer classes; Employing has the computer program of GIS-Geographic Information System processing capacity to determine the corresponding region of thunder and lightning automatic monitoring data on numerical map, the selection area on the numerical map is carried out the homalographic grid divide; By computer the data information of each grid is added up; And make the lightning monitoring data be given thunder and lightning special topic attribute and geographical attribute, each grid of dividing has and lightning monitoring data same coordinate system geographical attribute automatically; The region, the related grid place of lightning parameter of adopting gridding method to count, setting each grid is a thunder and lightning statistic unit; Thematic data in the database is called in map network as statistical sample by geographical attribute, add up each grid and the thunder and lightning number of times occurs;

(2) according to the line insulation structure, the dangerous amplitude of lightning current value range of insulator string generation flashover that can cause transmission line is as criterion, add up the current amplitude attribute of thunder and lightning in each grid, reject the data outside the criterion, again with each grid year the thunder and lightning number of times divided by the grid area, obtain electric network thunderstorm damage and distribute; The line insulation structure comprises line voltage grade, transmission line framework, orographic factor; Set shielding dangerous currents value range, counterattack dangerous currents value range according to line insulation nargin; Carry out amplitude relatively according to this scope, amplitude of lightning current in each grid is rejected in shielding, the outer data of counterattack dangerous currents value range, dodge number of times by the ground of remainder and obtain respectively divided by corresponding grid area that electrical network shielding damage to crops caused by thunder distributes and electrical network is strikeed back the damage to crops caused by thunder distribution;

The record of the transmission line lightning stroke flashover incident that (3) will take place is classified by the thematic attribute of time of origin, position coordinates, flashover type, electric pressure, its storage is advanced the lightning fault database in the computer, the lightning stroke flashover incident is called in the grid that its corresponding electric network thunderstorm damage distributes according to its thematic attribute successively, with this grid is the center, the grid that links to each other is carried out mark, obtain the historical damage to crops caused by thunder of electrical network zone, be divided into electrical network by fault point character and strike back historical damage to crops caused by thunder zone, the historical damage to crops caused by thunder of electrical network shielding zone;

(4) the electrical network counterattack damage to crops caused by thunder distribution and the electrical network of each electric pressure are strikeed back historical damage to crops caused by thunder zone, electrical network shielding damage to crops caused by thunder distributes and the historical damage to crops caused by thunder of electrical network shielding zone goes out corresponding geographic distribution layer with COMPUTER CALCULATION, uses GIS-Geographic Information System to obtain electric network synthetic counterattack damage to crops caused by thunder distribution map, electric network synthetic shielding damage to crops caused by thunder distribution map respectively again;

(5) promptly trip number of times/(hundred kilometers 40 thunder and lightning days) according to transmission line lightning protection reliability control index, with lightning stroke flashover type statistics data, critical density value during the damage to crops caused by thunder that setting can cause shielding flashover and counterattack flashover distributes, with this critical density value is criterion, the ground of the grid that statistics damage to crops caused by thunder distributes dodges density value, demarcates the exceed standard value and the value that do not exceed standard respectively;

(6) statistics damage to crops caused by thunder distribution grid, exceed standard value and four other damage to crops caused by thunder districts of level of the value various combination that do not exceed standard setting according to counterattack and shielding, wherein, have counterattack the do not exceed standard data area of value of value and shielding that do not exceed standard and be set at 1 grade of damage to crops caused by thunder district, have counterattack the do not exceed standard data area of value of value and shielding that exceeds standard and be set at 2 grades of damage to crops caused by thunder districts, have counterattack the exceed standard data area of value of value and shielding that do not exceed standard and be set at 3 grades of damage to crops caused by thunder districts, have counterattack the exceed standard data area of value of value and shielding that exceeds standard and be set at 4 grades of damage to crops caused by thunder districts;

(7) carry out the lightning protection configuration of transmission line with other damage to crops caused by thunder district of four levels of above-mentioned setting.

2. the method for utilizing damage to crops caused by thunder distribution carrying out transmission line lightning protection configuration according to claim 1 is characterized in that, carries out the lightning protection configuration of transmission line with other damage to crops caused by thunder district of four levels of above-mentioned setting: wherein,

A. for 1 grade of damage to crops caused by thunder district, carry out conventional lightning protection configuration by DL/T620-1997;

B. for 2 grades of damage to crops caused by thunder districts, strengthen the configuration of the anti-counterattack of transmission line flashover, the requirement of powerline pole tower ground resistance value, the 110kV-500kV overhead line structures are not higher than at the earth resistance in mountain area: 15 Ω, the earth resistance in the plains region is not higher than 7 Ω; Perhaps strengthen the dielectric strength of transmission line, require composite insulator: under the prerequisite that satisfies windage yaw and the requirement of lead distance to the ground, the 500kV circuit uses the dry arcing distance of composite insulator to be not less than the structure length of 30 suspended porcelain insulators or glass insulator; The 220kV circuit uses the dry arcing distance of composite insulator to be not less than the structure length of 14 suspended porcelain insulators or glass insulator; The 110kV circuit uses the dry arcing distance of composite insulator to be not less than the structure length of 7 suspension type porcelain or glass insulator; Require porcelain or glass insulator to select for use sheet number: 500kV to select 30 to 32; 220kV selects 15; 110kV selects 9;

C. for 3 grades of damage to crops caused by thunder districts, strengthen the configuration of the anti-shielding flashover of transmission line, reduce the lightning conducter shielding angle, newly-built 110kV～500kV circuit should set up the double joint overhead ground wire completely, 500kV and 220kV should adopt the negative angle protection, and 110kV route protection angle should be adopted below 10 °;

D. for 4 grades of damage to crops caused by thunder districts, strengthen transmission line anti-counterattack flashover and the configuration of shielding flashover simultaneously, unite the lightning protection configuration of adopting 2,3 grades of damage to crops caused by thunder districts.

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