CN104392055B - Combined type composite material shaft tower lightning protection Optimization Design - Google Patents

Abstract

The invention discloses a combined composite material tower lightning protection optimization design method, which includes: 1. Obtaining the structural information of the tower; 2. Establishing the wave impedance model of the ground wire crossarm and the tower body, and establishing the segmental concentrated inductance of the grounding downconductor 3. Determine the possible flashover path according to the structure of the tower head, and establish an insulation flashover model based on the pilot method; 4. Establish a grounding resistance model that considers the lightning current impact effect; 5. According to the above models, the connection forms an overall 6. Calculation of lightning resistance level and lightning tripping rate, 7. Iterative calculation and parameter update. The invention continuously improves the geometric structure of the composite material pole tower through iterative means, thereby improving the technical economy of the composite material pole tower under the premise of ensuring the lightning resistance performance.

Description

Optimal Design Method for Combined Composite Tower Lightning Protection

technical field

The invention relates to the technical field of lightning protection for power transmission lines, in particular to a combined composite material tower lightning protection optimization design method.

Background technique

With the rapid expansion of the grid scale, power construction consumes more and more resources such as land and steel. For a long time, the iron towers widely used in transmission lines are heavy, and the transportation and assembly are inconvenient, which greatly increases the construction cost and operation and maintenance cost of the line. Composite materials have many advantages such as good electrical insulation, high strength, corrosion resistance, and environmental friendliness. Using composite materials to make the tower head can improve the electromagnetic field distribution of the tower head and greatly improve the insulation performance. Replacing steel with composite materials can reduce the width of transmission line corridors and reduce the amount of steel used.

Composite materials have many advantages, and the towers made of them are quite different from ordinary iron towers. The lightning resistance performance is closely related to the geometric structure of the tower. The design structure of the existing combined composite material towers is generally conservative in design ideas, that is, the lightning resistance performance is given priority. cost.

References: People's Republic of China Electric Power Industry Standard "DL/T6201997 Overvoltage Protection and Insulation Coordination of AC Electrical Installations";

"Experimental Research on the Characteristics of 110kV Transmission Line Composite Towers" Hu Yi, Liu Ting, Liu Kai, Deng Shicong, Li Hanming, Hu Guangsheng High Voltage Technology, Volume 37, Issue 4, 2011;

"Research on Line Insulation Flashover Criterion Based on Continuous Pilot", Xiao Ping, Wang Fen, Huang Fuyong, Zhou Weihua, Wang Guoli, Xiong Jingwen, Anyi, Power Grid Technology, Volume 36, Issue 11, 2012;

"Calculation Model of Tower Grounding Body Impulse Grounding Resistance Based on ATP-EMTP", Xu Wei, Liu Xun, Huang Weichao, Electric Power Construction, Volume 31, Issue 5, 2010;

References: Li Xiaolan, Yin Xiaogen, Yu Renshan, He Junjia, "Calculation of Shielding Trip Rate Based on Improved Electrical Geometric Model", Journal of High Voltage Technology, Volume 32, Issue 3, 2006

Contents of the invention

The purpose of the present invention is to provide a combined composite material tower lightning protection optimization design method, the method continuously improves the geometric structure of the composite material tower through iterative means, thereby improving the technical economy of the composite material tower under the premise of ensuring the lightning resistance performance sex.

In order to achieve this goal, the combined type composite material tower lightning protection optimization design method designed by the present invention is characterized in that it includes the following steps:

Step 1: Obtain the length l _g of the ground wire cross arm of the combined composite material tower, the radius r _A of the ground wire cross arm, and the air distance from the first phase conductor to the ground down conductor from the typical design drawing of the combined composite material tower Gap distance D ₁ , the air gap distance D ₂ from the second phase conductor to the grounding down conductor, the air gap distance D ₃ from the third phase conductor to the grounding down conductor, the vertical distance h ₁ from the cross arm of the ground wire to the upper conductor , the vertical distance h ₂ between the cross arm of the upper layer conductor and the cross arm of the lower layer conductor, the height h ₃ of the steel pipe rod, the distance l ₁ from the first phase conductor to the upper ground wire of the same side ground wire cross arm, and the distance between the first phase conductor and the same side For the distance l ₂ of the third phase conductor, consult the reference "DL/T6201997 Overvoltage Protection and Insulation Coordination of AC Electrical Installations" to obtain the composite material impact flashover characteristic parameters and air impact flashover characteristic parameters of the above-mentioned typical combined composite material pole tower , query the reference "DL/T6201997 Overvoltage Protection and Insulation Coordination of AC Electrical Installations" to obtain the inductance value L ₀ per unit length of the grounding down conductor;

Step 2: Calculate the wave impedance Z _A of the crossarm of the ground wire by the following formula 1;

${\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 60</span>}\mathrm{<span\; class="notranslate">\; ln</span>}<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}}{{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

Among them, r _A is the radius of the ground cross-arm, and h _A is the height of the ground cross-arm, that is, h _A =h ₁ +h ₂ +h ₃ ;

Calculate the wave impedance Z _T of the steel pipe rod by the following formula 2;

${\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 60</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; ln</span>}\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\sqrt{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}}{{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

Wherein, h ₃ is the height of the steel pipe rod, and r _T is the mean value of the top section and the bottom section radius of the steel pipe;

The grounding down-conductor is divided into upper and lower parts that are connected to each other at the position where the upper conductor crossarm is located, and the inductance value L _g1 of the upper part of the grounding down-conductor is calculated by the following formula 3:

L _g1 =L ₀ *h ₁ (3)

Among them, L ₀ is the inductance value per unit length of the grounding down-conductor, h ₁ is the vertical distance from the cross-arm of the ground wire to the cross-arm of the upper layer conductor, that is, the length of the upper part of the grounding down-conductor;

The inductance value L _g2 of the lower part of the grounding down conductor is calculated by the following formula 4:

L _g2 =L ₀ *h ₂ (4)

Among them, L ₀ is the inductance value per unit length of the grounding down conductor, h ₂ is the vertical distance from the cross arm of the upper layer conductor to the cross arm of the lower layer conductor, that is, the length of the lower part of the grounding down conductor;

The wave impedance Z _A of the above-mentioned ground wire crossarm, the wave impedance Z _T of the steel pipe pole, the inductance value L _g1 of the upper part of the ground down conductor, and the inductance value L _g2 of the lower part of the ground down conductor constitute the ground wire cross arm, steel pipe Lightning strike simulation model of pole and grounding downconductor;

Step 3: The developed length x of the leader in the insulation gap of the combined composite material tower is obtained by the following formula 5, where the insulation gap L of the combined composite material tower is the distance D ₁ between the first phase conductor and the grounding down conductor, and the second The distance D ₂ between the second-phase conductor and the grounding down-conductor, the distance D ₃ between the third-phase conductor and the grounding down-conductor, the distance l ₁ from the first phase conductor to the grounding wire on the cross arm of the same side grounding wire and The distance l ₂ from the first phase conductor to the third phase conductor on the same side, gap flashover may occur in the gap corresponding to each distance in the above step;

$\frac{\mathrm{<span\; class="notranslate">\; dx</span>}}{\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; ku</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; u</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 5</span>}<span\; class="notranslate">\; )</span>$

Among them, t is the development time of the leader in the insulation gap of the combined composite material tower, k is the empirical coefficient obtained by fitting the results of the impulse discharge experiment, E ₀ is the initial field strength of the leader in the insulation gap L of the combined composite material tower, u (t) is the voltage value of the insulation gap L of the combined composite material tower at each time period from the start of the combined composite material tower simulation lightning strike to the occurrence of flashover or the end of the simulated lightning strike. The voltage value is passed through the existing combined composite material tower lightning strike simulation Extracted from the software, the empirical coefficient k obtained from the fitting of the above impulse discharge experiment results and the initial field strength E ₀ of the composite composite tower insulation gap L, according to the composite material of the typical composite composite tower obtained in step 1 The characteristic parameters of impact flashover and air impact flashover are calculated by using the existing method in the literature "Research on Line Insulation Flashover Criterion Based on Continuous Leader", and dx/dt is the leader development speed in the insulation gap of composite material tower , the above formula 5 forms the insulation flashover model of the combined composite material tower;

Step 4: Obtain the grounding resistance value R _ch of the combined composite material tower under the action of lightning impact through the following formula 6;

${\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; ch</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}{\sqrt{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; I</span>}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; g</span>}}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 6</span>}<span\; class="notranslate">\; )</span>$

Among them, R _o is the grounding resistance value of the combined composite material tower under power frequency current, I is the amplitude of the impact current flowing through the grounding body of the combined composite material tower under the action of lightning impulse, and I _g is the minimum current value to ionize the soil , the above R _o is the typical value recorded in the reference "DL/T6201997 Overvoltage Protection and Insulation Coordination of AC Electrical Installations", and I _g is the reference "Calculation Model of Impulse Grounding Resistance of Tower Grounding Body Based on ATP-EMTP" The typical value of , I is the value calculated in real time by the existing combined composite material tower lightning strike simulation software, and the above formula 6 forms the combined composite material tower lightning impact grounding resistance model;

Step 5: The above-mentioned ground wire cross-arm lightning strike simulation model, steel pipe pole lightning strike simulation model, grounding downconductor lightning strike simulation model, insulation flashover model of combined composite material tower and combined composite material tower lightning impact grounding resistance model follow the steps 1. The structural form connection combination of the typical design diagram of the combined composite material tower, that is, the lightning strike simulation model of the whole base composite material tower;

Step 6: Use the ATP-EMTP simulation software to calculate the counter-strike lightning resistance level and shielding lightning resistance level of the whole-base composite material tower through the lightning strike simulation model of the whole-base composite material tower;

Step 7: Calculate the counter-attack tripping rate BSTOR _c by the following formula 7 using the above-mentioned counter-attack lightning resistance level:

BSTOR _c = NgP ₁ η (7)

Among them, the N is the number of lightning strikes per 100 kilometers of the line corridor, which is calculated by the method given in the reference "DL/T6201997 Overvoltage Protection and Insulation Coordination of AC Electrical Installations", and the g is the query reference "DL /T6201997 Overvoltage Protection and Insulation Coordination of Alternating Current Electrical Installations "acquired stroke rate, the said P ₁ is the probability that the amplitude of lightning current exceeds the counter-attack lightning withstand level, which is determined by the counter-attack lightning withstand level obtained in step 6 according to the reference " It is calculated by the existing method of DL/T6201997 Overvoltage Protection and Insulation Coordination of AC Electrical Installations, and the said η is the arc establishment rate obtained from the reference document "DL/T6201997 Overvoltage Protection and Insulation Coordination of AC Electrical Installations";

Use the above shielding lightning resistance level to calculate the shielding trip rate SFTOR _c through the following formula 8:

${\mathrm{<span\; class="notranslate">\; SFTOR</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}}{\mathrm{<span\; class="notranslate">\; 10</span>}}<span\; class="notranslate">\; (</span>\underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{<span\; class="notranslate">\; \&Integral;</span>}_{{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; k</span>}}}^{{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; max</span>}\mathrm{<span\; class="notranslate">\; k</span>}}}{\mathrm{<span\; class="notranslate">\; P</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; I</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; D.</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; I</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; iGO</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; \&eta;</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 8</span>}<span\; class="notranslate">\; )</span>$

The shielding tripping rate SFTOR _c is calculated according to the improved electrical geometric model, the total shielding tripping rate is the sum of the shielding tripping rates of each phase, N _d is the given ground lightning density value, and I _2k is the shielding lightning resistance of the kth phase Level, where k is 1 or 2 or 3, the lightning shielding level of the kth phase is calculated by the ATP-EMTP simulation software through the existing method, I _smaxk is the maximum lightning shielding current of the kth phase, where k is 1 or 2 Or 3, the maximum lightning current of the kth phase is obtained by calculating the corresponding wire coordinates and ground wire coordinates in the improved electrical geometric model, P ^' (I) is the probability distribution density of the lightning current amplitude, and is the lightning current amplitude The derivative of the value probability distribution function P(I), the lightning current amplitude probability distribution function P(I) is determined by the reference "DL/T6201997 Overvoltage Protection and Insulation Coordination of AC Electrical Installations", D _k is the kth The projected distance of the exposed arc of the phase conductor, the projected distance of the exposed arc of the kth phase conductor under the corresponding lightning current is obtained according to the existing method in the improved electrical geometric model, and the above η is the query reference "DL/T6201997 Overvoltage of AC Electrical Installations" Arc establishment rate obtained from Protection and Insulation Coordination;

Use the following formula 9 to calculate the final lightning tripping rate of the tower:

LTOR _c = BSTOR _c + SFTOR _c (9)

That is, the final lightning tripping rate of the tower is equal to the sum of the counterattack tripping rate and the shielding tripping rate;

Step 8: Compare the final lightning tripping rate LTOR _c of the tower with the specified index LTOR _r on the lightning tripping rate in the reference "110(66)kV~500kV Overhead Transmission Line Operation Specification";

When the final lightning tripping rate LTOR _c of the tower is less than the specified index _{LTOR r} of the lightning tripping rate, it means that the structural parameters of the tower are safe. The air gap distance D ₁ from the grounding down conductor, the air gap distance D ₂ from the second phase conductor to the grounding down conductor, the air gap distance D ₃ from the third phase conductor to the grounding down conductor, and adjust the ground wire cross arm The vertical distance h 1 to the upper conductor cross arm, the vertical distance h ₂ from the upper conductor cross arm to the lower conductor cross arm, and the height h _{3 of} the steel pipe pole, realize the final lightning tripping rate LTORc of the tower while reducing the amount of composite materials Increase;

When the final lightning tripping rate LTOR _c of the tower is greater than the specified index LTOR _r of the lightning tripping rate, by increasing the length _lg of the ground wire crossarm of the combined composite material tower, the air from the first phase conductor to the grounding down conductor Gap distance D ₁ , air gap distance D ₂ from the second phase conductor to the grounding down conductor, and D ₃ air gap distance from the third phase conductor to the grounding down conductor to improve the insulation level of the combined composite material tower and reduce the protection angle, thereby reducing the value of the final lightning tripping rate LTOR _c of the tower.

Beneficial effects of the present invention:

The combined composite material tower lightning strike calculation simulation model proposed by the present invention obtains the structure information of the pole tower and establishes the ground wire crossarm lightning strike simulation model, the steel pipe pole lightning strike simulation model, the ground downconductor lightning strike simulation model, and the combined composite material Insulation flashover model of tower and combined composite material tower lightning impulse grounding resistance model. The simulation model established by the above method will more accurately reflect the situation of the composite tower being struck by lightning, and provide a basis for power grid operation and maintenance personnel to grasp the lightning protection performance of the composite tower. At the same time, the above method continuously improves the geometric structure of the composite material tower through iterative means, thereby improving the technical economy of the composite material tower under the premise of ensuring the lightning resistance performance.

Description of drawings

Figure 1 is a schematic diagram of the combined composite material tower head and the whole tower;

Fig. 2 is a side view of the cross-arm part of the ground wire in Fig. 1;

Among them, 1—cross arm of ground wire, 2—first phase wire, 3—ground down conductor, 4—second phase wire, 5—third phase wire, 6—cross arm of upper layer wire, 7—lower layer wire Cross arm, 8—steel pipe pole, 9—ground wire.

detailed description

Below in conjunction with accompanying drawing and specific embodiment the present invention is described in further detail:

A combined composite material tower lightning protection optimization design method, it comprises the following steps:

Step 1: Obtain the length l _g of the ground wire cross arm 1 of the combined composite material tower, the radius r _A of the ground wire cross arm 1 , and the first phase conductor 2 to the grounding down conductor from the typical design drawing of the combined composite material tower The air gap distance D 1 of line 3, the air gap distance D ₂ of the second phase conductor 4 to the grounding down conductor 3, the air gap distance D ₃ of the third phase conductor 5 to the grounding down conductor ₃ , and the grounding cross arm 1 The vertical distance h 1 to the upper conductor cross arm 6, the vertical distance h ₂ from the upper conductor cross arm 6 to the lower conductor cross arm 7, the height h ₃ of the steel pipe pole ₈ , the first phase conductor 2 to the same-side ground wire cross arm 1 For the distance l 1 of the ground wire 9 and the distance l ₂ of the first phase conductor ₂ to the third phase conductor 5 on the same side, consult the reference "DL/T6201997 Overvoltage Protection and Insulation Coordination of AC Electrical Installations" to obtain the above typical combined formula For composite material impact flashover characteristic parameters and air impact flashover characteristic parameters of composite material towers, query the reference "DL/T6201997 Overvoltage Protection and Insulation Coordination of AC Electrical Installations" to obtain the inductance value L ₀ per unit length of the grounding downconductor, such as As shown in Figures 1 and 2;

Step 2: Calculate the wave impedance Z _A of the ground crossarm 1 by the following formula 1;

${\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 60</span>}\mathrm{<span\; class="notranslate">\; ln</span>}<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}}{{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

Among them, r _A is the radius of the ground cross arm 1, and h _A is the height of the ground cross arm 1, that is, h _A =h ₁ +h ₂ +h ₃ ;

Calculate the wave impedance Z _T of the steel pipe pole 8 by the following formula 2;

${\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 60</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; ln</span>}\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\sqrt{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}}{{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

Wherein, h ₃ is the height of the steel pipe rod 8, and r _T is the mean value of the top section and the bottom section radius of the steel rod pipe 8;

The grounding downconductor 3 is divided into upper and lower parts that are connected to each other at the position where the upper conductor cross arm 6 is located. The inductance value L _g1 of the upper part of the grounding downconductor 3 is calculated by the following formula 3. The inductance value L _g2 of the downline 3 is calculated by the following formula 4;

L _g1 =L ₀ *h ₁ (3)

Among them, L ₀ is the inductance value per unit length of the grounding downconductor, h ₁ is the vertical distance from the grounding crossarm 1 to the upper conductor crossarm 6, that is, the length of the upper part of the grounding downconductor 3;

L _g2 =L ₀ *h ₂ (4)

Among them, _L0 is the inductance value per unit length of the grounding downconductor, and h2 is the vertical distance between the upper conductor crossarm ₆ and the lower conductor crossarm 7, that is, the length of the lower part of the grounding downconductor 3;

The wave impedance Z _A of the above-mentioned ground wire cross arm 1, the wave impedance Z _T of the steel pipe rod 8, the inductance value L _g1 of the upper part of the ground down conductor 3 and the inductance value L _g2 of the lower part of the ground down conductor 3 constitute the ground wire Lightning strike simulation model of crossarm 1, steel pipe pole 8 and grounding downconductor 3;

Step 3: The developed length x of the leader in the insulation gap of the combined composite material tower is obtained by the following formula 5, where the insulation gap L of the combined composite material tower is the distance D ₁ between the first phase conductor 2 and the grounding downconductor 3 , the distance D ₂ between the second phase conductor 4 and the grounding down conductor 3 , the distance D 3 between the third phase conductor 5 and the grounding down conductor ₃ , the first phase conductor 2 to the same-side grounding crossarm 1 The distance l1 of the upper ground wire 9 and the distance l2 _of the first phase conductor ₂ to the third phase conductor 5 on the same side, gap flashover may occur in the gap corresponding to each distance in the above step;

$\frac{\mathrm{<span\; class="notranslate">\; dx</span>}}{\mathrm{<span\; class="notranslate">\; dt</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; ku</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; u</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 5</span>}<span\; class="notranslate">\; )</span>$

Among them, t is the development time of the leader in the insulation gap of the combined composite material tower, k is the empirical coefficient obtained by fitting the results of the impulse discharge experiment, E ₀ is the initial field strength of the leader in the insulation gap L of the combined composite material tower, u (t) is the voltage value of the insulation gap L of the combined composite material tower at each time period from the start of the combined composite material tower simulation lightning strike to the occurrence of flashover or the end of the simulated lightning strike. The voltage value is passed through the existing combined composite material tower lightning strike simulation Extracted from the software, the empirical coefficient k obtained from the fitting of the above impulse discharge experiment results and the field strength E 0 at the beginning of the leader's initial field strength E ₀ for the insulation gap L of the combined composite material tower, according to the composite material of the typical combined composite material tower obtained in step 1 The characteristic parameters of impact flashover and air impact flashover are calculated by using the existing method in the literature "Research on Line Insulation Flashover Criterion Based on Continuous Leader", and dx/dt is the leader development speed in the insulation gap of composite material tower , the above formula 5 forms the insulation flashover model of the combined composite material tower;

Step 4: Obtain the grounding resistance value R _ch of the combined composite material tower under the action of lightning impact through the following formula 6;

${\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; ch</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}{\sqrt{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; I</span>}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; g</span>}}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 6</span>}<span\; class="notranslate">\; )</span>$

Among them, R _o is the grounding resistance value of the combined composite material tower under power frequency current, I is the amplitude of the impact current flowing through the grounding body of the combined composite material tower under the action of lightning impulse, and I _g is the minimum current value to ionize the soil , the above R _o is the typical value recorded in the reference "DL/T6201997 Overvoltage Protection and Insulation Coordination of AC Electrical Installations", and I _g is the reference "Calculation Model of Impulse Grounding Resistance of Tower Grounding Body Based on ATP-EMTP" The typical value of , I is the value calculated in real time by the existing combined composite material tower lightning strike simulation software, and the above formula 6 forms the combined composite material tower lightning impact grounding resistance model;

Step 5: The above-mentioned ground wire crossarm 1 lightning strike simulation model, steel pipe pole 8 lightning strike simulation model, grounding downconductor 3 lightning strike simulation model, the insulation flashover model of the combined composite material tower and the combined composite material tower lightning impact grounding resistance The model is connected and combined according to the structural form of the typical design drawing of the combined composite material tower in step 1, that is, the lightning strike simulation model of the whole base composite material tower is formed;

Step 6: Use the ATP-EMTP simulation software to calculate the counter-strike lightning resistance level and shielding lightning resistance level of the whole-base composite material tower through the lightning strike simulation model of the whole-base composite material tower;

Step 7: Calculate the counter-attack tripping rate BSTOR _c by the following formula 7 using the above-mentioned counter-attack lightning resistance level:

BSTOR _c = NgP ₁ η (7)

Among them, the N is the number of lightning strikes per 100 kilometers of the line corridor, which is calculated by the method given in the reference "DL/T6201997 Overvoltage Protection and Insulation Coordination of AC Electrical Installations", and the g is the query reference "DL /T6201997 Overvoltage Protection and Insulation Coordination of Alternating Current Electrical Installations "acquired stroke rate, the said P ₁ is the probability that the amplitude of lightning current exceeds the counter-attack lightning withstand level, which is determined by the counter-attack lightning withstand level obtained in step 6 according to the reference " It is calculated by the existing method of DL/T6201997 Overvoltage Protection and Insulation Coordination of AC Electrical Installations, and the said η is the arc establishment rate obtained from the reference document "DL/T6201997 Overvoltage Protection and Insulation Coordination of AC Electrical Installations";

Use the above shielding lightning resistance level to calculate the shielding trip rate SFTOR _c through the following formula 8:

${\mathrm{<span\; class="notranslate">\; SFTOR</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}}{\mathrm{<span\; class="notranslate">\; 10</span>}}<span\; class="notranslate">\; (</span>\underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{<span\; class="notranslate">\; \&Integral;</span>}_{{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; k</span>}}}^{{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; max</span>}\mathrm{<span\; class="notranslate">\; k</span>}}}{\mathrm{<span\; class="notranslate">\; P</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; I</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; D.</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; I</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; iGO</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; \&eta;</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 8</span>}<span\; class="notranslate">\; )</span>$

The shielding tripping rate SFTOR _c is calculated according to the improved electrical geometric model (EGM), the total shielding tripping rate is the sum of the shielding tripping rates of each phase, N _d is the given ground flash density value, I _2k is the kth phase The shielding lightning resistance level, where k is 1 or 2 or 3, the kth phase lightning shielding level is calculated by the ATP-EMTP simulation software through the existing method, I _smaxk is the maximum shielding lightning current of the kth phase, where k is 1 or 2 or 3, the maximum lightning current of the kth phase is obtained by calculating the corresponding wire coordinates and ground wire coordinates in the improved electrical geometric model, P'(I) is the probability distribution density of the lightning current amplitude, and is The derivative of the lightning current amplitude probability distribution function P(I), the lightning current amplitude probability distribution function P(I) is determined by the reference "DL/T6201997 Overvoltage Protection and Insulation Coordination of AC Electrical Installations", D _k is the corresponding lightning The projected distance of the exposed arc of the kth phase conductor flowing down, the projected distance of the exposed arc of the kth phase conductor under the corresponding lightning current is calculated according to the existing method in the improved electrical geometric model, and the above η is the query reference "DL/T6201997 AC Electrical Installation Over-voltage protection and insulation coordination" to obtain arc building rate;

Use the following formula 9 to calculate the final lightning tripping rate of the tower:

LTOR _c = BSTOR _c + SFTOR _c (9)

That is, the final lightning tripping rate of the tower is equal to the sum of the counterattack tripping rate and the shielding tripping rate;

Step 8: Compare the final lightning tripping rate LTOR _c of the tower with the specified index LTOR _r on the lightning tripping rate in the reference "110(66)kV~500kV Overhead Transmission Line Operation Specification";

When the final lightning tripping rate LTOR _c of the tower is less than the specified index _{LTOR r} of the lightning tripping rate, it indicates that the structural parameters of the tower are safe. The air gap distance D 1 from the conductor 2 to the grounding down conductor 3, the air gap distance D ₂ from the second phase conductor 4 to the grounding down conductor 3, the air gap distance D ₃ from the third phase conductor 5 to the grounding down conductor ₃ , and adjust the vertical distance h 1 from the ground wire cross arm 1 to the upper layer wire cross arm 6, the vertical distance h ₂ from the upper layer wire cross arm 6 to the lower layer wire cross arm 7, and the height h ₃ of the steel pipe rod ₈ , so as to reduce the composite The amount of materials increases the final lightning tripping rate LTORc of the tower at the same time;

When the final lightning tripping rate LTOR _c of the tower is greater than the specified index LTOR _r of the lightning tripping rate, by increasing the length _lg of the ground wire crossarm 1 of the combined composite material tower, the first phase conductor 2 to the grounding down conductor 3 air gap distance D ₁ , the air gap distance D 2 from the second phase conductor 4 to the grounding down conductor 3 , and the air gap distance D ₃ from the third phase conductor 5 to the grounding down conductor ₃ to improve the combined composite material tower The insulation level and the protection angle are reduced, thereby reducing the value of the final lightning tripping rate LTOR _c of the tower. When the value is selected according to the geometric parameters of the ordinary iron tower for the first time, the insulation strength of the composite material tower has a higher margin.

In the above-mentioned technical solution, in the step 7, the number of lightning strikes per 100 kilometers of the given line corridor is N=N _g *(b+4h)/10, where b is the distance between two lightning conductors of the composite material tower, and h is The average height of lightning conductors for composite towers. The given flash density value N _d is 2.78 times/km ² *year.

Before adjusting the parameters, it is necessary to use the idea of the control variable method to understand the influence of each variable on LTOR _c , so as to facilitate the grasp of the range of parameter adjustment. Until LTOR _c is slightly smaller than LTOR _r , the geometric parameters of composite towers can meet the needs of lightning protection, and the geometric parameters at this time are the optimal structural parameters for lightning protection.

Through continuous iterative calculations, the optimal geometric parameters that meet the needs of lightning protection can be obtained, and the corresponding towers use the least amount of composite materials and the highest technical and economical efficiency. The present invention is applicable to 110kV single-circuit "upper" type combined composite material towers, and is also applicable to combined composite material towers with other voltage levels and other structural forms.

The content not described in detail in this specification belongs to the prior art known to those skilled in the art.

Claims (3)

1. a combined type composite material shaft tower lightning protection Optimization Design, it is characterized in that, it comprises the steps:

Step 1: the length l obtaining the ground wire cross-arm (1) of combined type composite material shaft tower from the modular design figure of combined type composite material shaft tower _g, ground wire cross-arm (1) radius r _a, first-phase wire (2) is to the air gap distance D of down conductor (3) ₁, second-phase wire (4) is to the air gap distance D of down conductor (3) ₂, third phase wire (5) is to the air gap distance D of down conductor (3) ₃, ground wire cross-arm (1) is to topping wire cross-arm (6) vertical interval h ₁, topping wire cross-arm (6) is to the vertical interval h of lower layer conductor cross-arm (7) ₂, steel pipe pole (8) height h ₃, first-phase wire (2) is to the distance l of the upper ground wire (9) of homonymy ground wire cross-arm (1) ₁, first-phase wire (2) is to the distance l of the third phase wire (5) of homonymy ₂inquiry list of references " overvoltage protection of DL/T6201997 alternating-current electric device and Insulation Coordination " obtains composite impact flashover property parameter, the air impulse sparkover characteristics parameter of the box-like composite material pole tower of above-mentioned classical group, and inquiry list of references " overvoltage protection of DL/T6201997 alternating-current electric device and Insulation Coordination " obtains down conductor unit length inductance value L ₀;

Step 2: the wave impedance Z being calculated ground wire cross-arm (1) by following formula 1 _a;

$Z_A=60\ln \left(\frac{2h_A}{r_A}\right)---\left(1\right)$

Wherein, r _afor the radius of ground wire cross-arm (1), h _afor the height of ground wire cross-arm (1), i.e. h _a=h ₁+ h ₂+ h ₃;

The wave impedance Z of steel pipe pole (8) is calculated by following formula 2 _t;

$Z_T=60(\ln \frac{2\sqrt{2}{h}_3}{r_T}-1)---\left(2\right)$

Wherein, h ₃for the height of steel pipe pole (8), r _tfor the tip section of steel pole pipe (8) and the average of bottom section radius;

The position of described down conductor (3) residing for topping wire cross-arm (6) is that boundary is divided into interconnective upper and lower two parts, the inductance value L of upper part down conductor (3) _g1calculated by following formula 3;

L _g1＝L ₀*h ₁(3)

Wherein, L ₀for down conductor unit length inductance value, h ₁for ground wire cross-arm (1) is to topping wire cross-arm (6) vertical interval, i.e. the length of upper part down conductor (3);

The inductance value L of lower part down conductor (3) _g2calculated by following formula 4:

L _g2＝L ₀*h ₂(4)

Wherein, L ₀for down conductor unit length inductance value, h ₂for topping wire cross-arm (6) is to the vertical interval of lower layer conductor cross-arm (7), i.e. the length of lower part down conductor (3);

The wave impedance Z of above-mentioned ground wire cross-arm (1) _a, steel pipe pole (8) wave impedance Z _twith the inductance value L of upper part down conductor (3) _g1and the inductance value L of lower part down conductor (3) _g2constitute the lightning stroke simulation model of ground wire cross-arm (1) lightning stroke simulation model, steel pipe pole (8) lightning stroke simulation model and down conductor (3);

Step 3: the guide obtained in combined type composite material shaft tower clearance for insulation by following formula 5 develops length x, wherein combined type composite material shaft tower clearance for insulation L is the distance D between first-phase wire (2) and down conductor (3) ₁, distance D between second-phase wire (4) and down conductor (3) ₂, distance D between third phase wire (5) and down conductor (3) ₃, first-phase wire (2) is to the distance l of the upper ground wire (9) of homonymy ground wire cross-arm (1) ₁with the distance l of first-phase wire (2) to the third phase wire (5) of homonymy ₂, likely there is gap flashover in the gap in above-mentioned step corresponding to each distance;

$\frac{\mathrm{dx}}{\mathrm{dt}}=\mathrm{ku}\left(t\right)[\frac{u\left(t\right)}{L-x}-E_0]---\left(5\right)$

Wherein, t is the time of the guide's development in combined type composite material shaft tower clearance for insulation, and k is the experience factor of impulsive discharge experimental result matching gained, E ₀for the field intensity that combined type composite material shaft tower clearance for insulation L guide is initial, u (t) terminates the magnitude of voltage of interior each time period for combined type composite material shaft tower clearance for insulation L starts extremely generation flashover or simulation thunderbolt in combined type composite material shaft tower simulation thunderbolt, and this magnitude of voltage obtains by extracting in existing combined type composite material shaft tower thunderbolt simulation software; The experience factor k of above-mentioned impulsive discharge experimental result matching gained and the initial field intensity E of combined type composite material shaft tower clearance for insulation L guide ₀, utilize the existing method in document " research based on the line insulation flashover criterion of continuous leader " to calculate according to the composite impact flashover property parameter of the box-like composite material pole tower of the classical group obtained in step 1, air impulse sparkover characteristics parameter; Dx/dt is the guide's speed of development in composite material pole tower clearance for insulation, and above-mentioned formula 5 forms the insulation flashover model of combined type composite material shaft tower;

Step 4: obtain the grounding resistance R of combined type composite material shaft tower under lightning impulse effect by following formula 6 _ch;

$R_{\mathrm{ch}}=\frac{R_0}{\sqrt{1+I/I_g}}---\left(6\right)$

Wherein, R _ofor the grounding resistance of combined type composite material shaft tower under power current, I is the dash current amplitude that lightning impulse flows by action crosses box-like composite material pole tower grounding body, I _gthe minimum current value making soil that ionization occur, above-mentioned R _ofor the representative value recorded in list of references " overvoltage protection of DL/T6201997 alternating-current electric device and Insulation Coordination ", I _gfor the representative value recorded in list of references " the tower grounding body impulse earthed resistance computation model based on ATP-EMTP ", I is the value calculated in real time by existing combined type composite material shaft tower thunderbolt simulation software, and above-mentioned formula 6 forms combined type composite material shaft tower lightning impulse stake resistance model;

Step 5: the insulation flashover model of above-mentioned ground wire cross-arm (1) lightning stroke simulation model, steel pipe pole (8) lightning stroke simulation model, down conductor (3) lightning stroke simulation model, combined type composite material shaft tower is connected combination with combined type composite material shaft tower lightning impulse stake resistance model according to the version of the modular design figure of combined type composite material shaft tower in step 1, namely forms the lightning stroke simulation model of integral basis composite material pole tower;

Step 6: use ATP-EMTP simulation software to calculate counterattack lightning withstand level and the shielding lightning withstand level of integral basis composite material pole tower by the lightning stroke simulation model of integral basis composite material pole tower;

Step 7: utilize above-mentioned counterattack lightning withstand level to calculate counterattack trip-out rate BSTOR by following formula 7 _c:

BSTOR _c＝NgP ₁η(7)

Wherein, described N is thunderbolt number of times in every 100 kilometers of line corridor; calculate by reference to given method in document " overvoltage protection of DL/T6201997 alternating-current electric device and Insulation Coordination "; described g be inquiry list of references " overvoltage protection of DL/T6201997 alternating-current electric device and Insulation Coordination " obtain hit bar rate, described P ₁for amplitude of lightning current exceedes the probability of counterattack lightning withstand level, this probability is calculated according to the existing method of list of references " overvoltage protection of DL/T6201997 alternating-current electric device and Insulation Coordination " by the counterattack lightning withstand level obtained in step 6, and described η is the probability of sustained arc that inquiry list of references " overvoltage protection of DL/T6201997 alternating-current electric device and Insulation Coordination " obtains;

Above-mentioned shielding lightning withstand level is utilized to calculate back flash-over rate SFTOR by following formula 8 _c:

${\mathrm{SFTOR}}_c=\frac{N_d}{10}\left(\underset{k=1}{\overset{3}{\mathrm{\&Sigma;}}}{\&Integral;}_{I_{2k}}^{I_{\text{s max k}}}{P}^{\&prime;}\left(I\right)D_k\left(I\right)\mathrm{dI}\right)\mathrm{\&eta;}---\left(8\right)$

Back flash-over rate SFTOR _ccalculate according to the electric geometry method improved, total back flash-over rate is each phase back flash-over rate sum, N _dfor given CG lightning density value, I _2kfor kth phase shielding lightning withstand level, wherein k is 1 or 2 or 3, and this kth phase shielding lightning withstand level is that ATP-EMTP simulation software calculates by existing manner, I _smaxkfor the mutually maximum around shocking electric current of kth; wherein k is 1 or 2 or 3; the mutually maximum around shocking electric current of this kth is that wire coordinate corresponding in the electric geometry method improved and ground line coordinates calculating are obtained; P ' (I) is amplitude of lightning current probability distribution density; it is the derivative of amplitude of lightning current probability distribution function P (I); amplitude of lightning current probability distribution function P (I) is determined, D by list of references " overvoltage protection of DL/T6201997 alternating-current electric device and Insulation Coordination " _kfor kth phase conductor under corresponding lightning current exposes arc projector distance, under this corresponding lightning current, kth phase conductor exposure arc projector distance is obtained according to the existing mode in the electric geometry method improved, and described η is the probability of sustained arc that inquiry list of references " overvoltage protection of DL/T6201997 alternating-current electric device and Insulation Coordination " obtains;

Following formula 9 is utilized to calculate the final tripping rate with lightning strike of shaft tower:

LTOR _c＝BSTOR _c+SFTOR _c(9)

Namely the tripping rate with lightning strike that shaft tower is final equals counterattack trip-out rate and back flash-over rate sum;

Step 8: compare the tripping rate with lightning strike LTOR that shaft tower is final _cwith the set quota LTOR about tripping rate with lightning strike in list of references " 110 (66) kV ~ 500kV overhead transmission line operations specification " _rsize;

As the tripping rate with lightning strike LTOR that shaft tower is final _cbe less than the set quota LTOR of described tripping rate with lightning strike _rtime, tower structure parameter safety is described, by reducing the length l of the ground wire cross-arm (1) of combined type composite material shaft tower _g, first-phase wire (2) is to the air gap distance D of down conductor (3) ₁, second-phase wire (4) is to the air gap distance D of down conductor (3) ₂, third phase wire (5) is to the air gap distance D of down conductor (3) ₃, and adjust ground wire cross-arm (1) to topping wire cross-arm (6) vertical interval h ₁, topping wire cross-arm (6) is to the vertical interval h of lower layer conductor cross-arm (7) ₂, steel pipe pole (8) height h ₃, achieving the tripping rate with lightning strike LTORc simultaneously making tower final at the consumption reducing compound substance increases;

As the tripping rate with lightning strike LTOR that shaft tower is final _cbe greater than the set quota LTOR of described tripping rate with lightning strike _rtime, by increasing the length l of the ground wire cross-arm (1) of combined type composite material shaft tower _g, first-phase wire (2) is to the air gap distance D of down conductor (3) ₁, second-phase wire (4) is to the air gap distance D of down conductor (3) ₂, third phase wire (5) is to the air gap distance D of down conductor (3) ₃improve the dielectric level of combined type composite material shaft tower and reduce shielding angle, thus reducing the final tripping rate with lightning strike LTOR of shaft tower _cvalue.

2. combined type composite material shaft tower lightning protection Optimization Design according to claim 1, is characterized in that: in described step 7, thunderbolt times N=N in every 100 kilometers of given line corridor _g* (b+4h)/10, wherein b is the spacing of composite material pole tower two lightning conducters, and h is the average height of composite material pole tower lightning conducter.

3. combined type composite material shaft tower lightning protection Optimization Design according to claim 1, is characterized in that: described given CG lightning density value N _dbe 2.78 times/km ²* year.