CN104635087A - Inspection method for grounding safety performance of power transmission wire pole tower during lightning wire insulation erection - Google Patents
Inspection method for grounding safety performance of power transmission wire pole tower during lightning wire insulation erection Download PDFInfo
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- CN104635087A CN104635087A CN201510066561.6A CN201510066561A CN104635087A CN 104635087 A CN104635087 A CN 104635087A CN 201510066561 A CN201510066561 A CN 201510066561A CN 104635087 A CN104635087 A CN 104635087A
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Abstract
The invention discloses an inspection method for grounding safety performance of a power transmission wire pole tower during lightning wire insulation erection. According to the method, through simulated analysis and value calculation, the condition that the ground entering current of the power transmission wire pole tower reaches the maximum value when reaching the insulator critical break-through state is provided, in addition, the existing measuring method for step voltage and contact voltage is combined, the actual maximum step voltage and the contact voltage for the pole tower grounding obtained through calculation are given, the comparison is performed with the allowable maximum value specified in the regulation, and whether the pole tower grounding meets the specified safety requirement or not is inspected. The inspection method has the advantages that the inspection on the grounding safety performance of a power transmission wire pole tower during the lightning wire insulation erection can be realized, the problem of too high step voltage and contact voltage of the pole tower grounding due to lightning wire insulation erection can be discovered in time, in addition, the grounding transformation is guided, and the safety of personnel and equipment is ensured.
Description
Technical field
The present invention relates to the method for inspection of electric power line pole tower grounding safety performance when lightning conducter insulation is set up, it is that lightning conducter insulating Design or transformation are carried out in ice-melt that the method is applicable to transmission line of electricity, belongs to Hyper-Voltage of Power Systems field.
Background technology
The icing of transmission line of electricity will cause load of roadway to increase the weight of, will cause time serious broken string or fall tower, have impact on the safe operation of China's electrical network, in order to carry out ice-melt to lightning conducter, lightning conducter has been carried out Insulation Transformation or design by a lot of transmission line of electricity.After lightning conducter Insulation Transformation, when transmission line of electricity generation ground short circuit fault, because short-circuit current cannot flow into lightning conducter by insulator, cause and increased by the earth current of tower grounding pole, step voltage and touch voltage raise, and affect the safety of the person and equipment near shaft tower.Existing research mainly concentrates on the loss of various factors on lightning conducter and the impact of induced voltage.After lightning conducter insulation erection, when transmission line of electricity generation power frequency short trouble, the Changing Pattern puncturing rule and shaft tower earth current of lightning conducter insulation is still not clear, and existing code and documents and materials do not find the method for inspection of lightning conducter insulation erection rear bar tower grounding safety performance yet.
The present invention is by simulation analysis and numerical evaluation, after giving lightning conducter insulation erection, during lightning conducter insulator breakdown, required minimum short-circuit current is with pole tower ground resistance Changing Pattern, find that the earth current of this shaft tower increases with the increase of short-circuit current before lightning conducter insulator breakdown, when reaching the critical breakdown conditions of insulator---when namely the voltage of tower grounding system reaches the voltage breakdown of lightning conducter insulator, earth current reaches maximal value.When after lightning conducter insulator breakdown, due to the shunting action of lightning conducter, earth current sharply reduces, even if now increase the amplitude of short-circuit current again, and the amplitude of shaft tower earth current when shaft tower earth current is also difficult to again reach insulator critical breakdown conditions.Finally, when the present invention proposes that when lightning conducter insulator is in critical breakdown conditions, shaft tower earth current is power transmission line power frequency short circuit, this shaft tower can reach maximum earth current amplitude, and the method for inspection of electric power line pole tower grounding safety performance when proposing a kind of lightning conducter insulation erection.
Summary of the invention
The method of inspection of electric power line pole tower grounding safety performance when the object of the present invention is to provide lightning conducter insulation to set up, when using the method to may be used for the insulation erection of inspection transmission line of electricity lightning conducter, whether the step voltage difference of overhead line structures ground connection and touch voltage difference meet safety requirements.
Transmission line of electricity lightning conducter insulation erection schematic diagram as shown in Figure 1, J
i, J
i＇ represents the lightning conducter insulator of corresponding shaft tower; R
ifor shaft tower stake resistance (wherein i=1,2,3 ... ..n); R
0, R
0＇ is two ends substation ground network resistance; I
kfor whole short-circuit currents of short dot; I
k1, I
k2for the short-circuit current of both sides transformer station supply short dot; I
d1, I
d2the short-circuit current of transformer station is returned for flowing through lightning conducter; I
z1, I
z2for flowing back to the short-circuit current of transformer grounding neutral point; I
1, I
2for flowing through the short-circuit current of substation ground network.
As can be seen from Figure 1, when there is power frequency short circuit, if lightning conducter insulator J
ndo not puncture, short-circuit current I
kall will flow into the earth by shaft tower, now earth current increases with the increase of short-circuit current, pass through simulation analysis, obtain lightning conducter clearance for insulation puncture front and back shaft tower earth current with short-circuit current Changing Pattern as shown in Figure 1: setting pole tower ground resistance in figure is 10 ohm, the voltage breakdown of lightning conducter insulator is 66kV, therefore the minimum short-circuit current I that punctures of clearance for insulation
krelational expression I is met with pole tower ground resistance R
k.× R>=66kV.When short-circuit current is less than 6.6kA, the voltage at lightning conducter insulator two ends is less than voltage breakdown, and now earth current is exactly short-circuit current.When short-circuit current is greater than 6.6kA, the voltage at lightning conducter insulator two ends is greater than voltage breakdown, and earth current reaches 6.6kA.Now lightning conducter insulator breakdown, lightning conducter shunting causes the earth current flowing through shaft tower sharply to reduce, although afterwards short-circuit current liter is caused tens of kA, earth current is still less than 6.6kA.
Can be seen by above-mentioned demonstration, when after lightning conducter insulation erection, because circuit power frequency short-circuit current cannot pass through line residual current, can only enter ground by tower grounding pole, now earth current is short-circuit current.When earth current and pole tower ground resistance acting in conjunction, when making shaft tower earth potential liter reach lightning conducter insulator breakdown voltage, shaft tower earth current reaches maximal value, now lightning conducter insulator breakdown, lightning conducter shunting action causes shaft tower earth current sharply to reduce, even if now short-circuit current is risen to tens of kiloampere, shaft tower earth current when earth current is still less than that insulator is critical to be punctured.
If insulator breakdown voltage constant, the relation of shaft tower earth current when insulator is critical to be punctured and stake resistance can be obtained, after therefore determining pole tower ground resistance, the maximum earth current of shaft tower can be calculated by following formula:
U in formula
maxfor insulator frequency breakdown voltage, R
nfor the stake resistance of this shaft tower, I
dfor the maximum earth current of shaft tower, consider in earthed system, step voltage is directly proportional to earthed system voltage to touch voltage, and earthed system voltage equals earth current is multiplied by stake resistance, after the maximum earth current of shaft tower is determined, can in conjunction with the measurement result of step voltage and touch voltage, by calculating maximum stride voltage and Maximum Contact voltage, thus the security performance of electric power line pole tower ground connection during the insulation erection of inspection lightning conducter.
The technical solution adopted for the present invention to solve the technical problems comprises the following steps:
The method of inspection of electric power line pole tower grounding safety performance during lightning conducter insulation erection, the present invention is characterised in that, it comprises the following steps:
The first step, collects the basic ground connection data of electric power line pole tower, comprises the frequency breakdown voltage U of this transmission line of electricity lightning conducter insulator
0, maximum single-phase short circuit current I
0, short circuit duration T
0, the stake resistance R of shaft tower
0, the soil resistivity ρ near shaft tower;
Second step, measures the 6.4th article of method provided in directive/guide with reference to DL/T 475-2006 earthing device characterisitic parameter, measures the step potential difference U of this tower grounding device
sC, contact potential difference U
tC, I
minjected total earth current of shaft tower by equipment during for measuring;
3rd step, with reference to the 3.4th article of formula provided in the grounding design of DL/T 621-1997 alternating-current electric device, calculates the maximum stride voltage difference U that this shaft tower allows
sMAXwith Maximum Contact voltage difference U
tMAX;
4th step, calculates maximum stride voltage difference and Maximum Contact voltage difference in this shaft tower real work situation by following formula; I in formula
sfor actual shaft tower earth current, work as I
0* R
0<U
0time, I
s=I
0; Work as I
0* R
0>=U
0time, I
s=U
0/ R
0;
5th step, compares the result of the result of calculation of the 4th step and the 3rd step, only has and work as U
s<U
sMAXand U
t<U
tMAX, this tower grounding security performance meets the demands, otherwise does not all meet the grounding design of DL/T 621-1997 alternating-current electric device.
In above-mentioned steps, if this transmission line of electricity lightning conducter insulator is with sparking distance in parallel in the first step, and the frequency breakdown voltage of sparking distance in parallel is less than the frequency breakdown voltage of insulator, now U
0for the voltage breakdown of sparking distance in parallel.
In above-mentioned steps, if this transmission line of electricity lightning conducter insulator is with lightning arrester connected in parallel in the first step, lightning arrester is under power-frequency overvoltage effect during conducting, and the residual voltage at two ends is less than the frequency breakdown voltage of insulator, now U
0for lightning arrester residual voltage now.
In above-mentioned steps, in the first step, the stake resistance of shaft tower is measured by such as code DL/T 887-2004 shaft tower power frequency earthing resistance or code DL/T 475-2006 earthing device characterisitic parameter is measured method that directive/guide provides and carried out in-site measurement and obtain, or is calculated by the computing formula provided in code.
In above-mentioned steps, the 3rd step and the permission maximum stride voltage difference described in the 5th step and Maximum Contact voltage difference formula; Calculate with the formula provided in the grounding design of GB 50065-2011 alternating-current electric device 4.2.2 article, or calculate with the permission maximum stride voltage difference provided in domestic and international other standards and Maximum Contact voltage difference formula, the parameter of collecting in a first step then needs to adjust according to the permission maximum stride voltage difference provided and Maximum Contact voltage difference formula desired parameters.
Beneficial effect of the present invention is, can realize testing to electric power line pole tower grounding safety performance during lightning conducter insulation erection, Timeliness coverage lightning conducter insulation erection causes tower grounding step voltage and the too high problem of touch voltage, and guide and carry out grounding reconstruction, guarantee the safety of personnel and equipment.
Accompanying drawing explanation
The present invention is further illustrated below in conjunction with drawings and Examples.
Accompanying drawing 1 is transmission line of electricity lightning conducter insulation erection situation, J in figure
i, J
i＇ represents the lightning conducter insulator of corresponding shaft tower; R
ifor shaft tower stake resistance (wherein i=1,2,3 ... ..n); R
0, R
0＇ is two ends substation ground network resistance; I
kfor whole short-circuit currents of short dot; I
k1, I
k2for the short-circuit current of both sides transformer station supply short dot; I
d1, I
d2the short-circuit current of transformer station is returned for flowing through lightning conducter; I
z1, I
z2for flowing back to the short-circuit current of transformer grounding neutral point; I
1, I
2for flowing through the short-circuit current of substation ground network.
Embodiment
Below by case study on implementation, composition graphs 1, the method for inspection of electric power line pole tower grounding safety performance during lightning conducter insulation erection, the present invention is characterised in that, it comprises the following steps:
The first step, collects the basic ground connection data of electric power line pole tower, comprises the frequency breakdown voltage U of this transmission line of electricity lightning conducter insulator
0for 60kV, maximum single-phase short circuit current I
0for 12kA, short circuit duration T
0be 0.5 second, the stake resistance R of shaft tower
0be 30 ohm, the soil resistivity ρ near shaft tower is 500 Ω m;
Second step, measures the 6.4th article of method provided in directive/guide with reference to DL/T 475-2006 earthing device characterisitic parameter, measures the step potential difference U of this tower grounding device
sC, contact potential difference U
tC, I
mbeing injected total earth current of shaft tower during for measuring by equipment, injecting the electric current of 0.5A at the scene, measure and obtain step potential difference U
sCfor 80mV, contact potential difference U
tCfor 90mV.
3rd step, with reference to the 3.4th article of formula provided in the grounding design of DL/T 621-1997 alternating-current electric device, calculates the maximum stride voltage difference U that this shaft tower allows
sMAXwith Maximum Contact voltage difference U
tMAX
According to physical condition, obtain the maximum stride voltage difference U allowed
sMAXfor 306V, Maximum Contact voltage difference U
tMAX494V.
4th step, calculates maximum stride voltage difference and Maximum Contact voltage difference in this shaft tower real work situation by following formula; I in formula
sfor actual shaft tower earth current, work as I
0* R
0<U
0time, I
s=I
0; Work as I
0* R
0>=U
0time, I
s=U
0/ R
0;
According to data collection and test case, I
0* R
0=120kV, U
0=60kV, so the I that satisfies condition
0* R
0>=U
0, now I
s=U
0/ R
0=2kA, obtaining this shaft tower maximum stride voltage and touch voltage when actual generation power frequency short trouble is U
s=320V, contact potential difference U
t=360V.
5th step, compares the result of the result of calculation of the 4th step and the 3rd step, only has and work as U
s<U
sMAXand U
t<U
tMAX, this tower grounding security performance meets the demands, otherwise does not all meet the grounding design of DL/T 621-1997 alternating-current electric device, according to this data collection and test case, finds, finds U
t<U
tMAXbut U
s> U
sMAX, i.e. in the security performance of this tower grounding, touch voltage reaches the requirement of code, but the requirement that step voltage provides slightly larger than the grounding design of code DL/T 621-1997 alternating-current electric device, therefore this shaft tower step voltage exceeds standard, and needs to transform ground connection.
In above-mentioned steps, if this transmission line of electricity lightning conducter insulator is with sparking distance in parallel in the first step, and the frequency breakdown voltage of sparking distance in parallel is less than the frequency breakdown voltage of insulator, now U
0for the voltage breakdown of sparking distance in parallel.
In above-mentioned steps, if this transmission line of electricity lightning conducter insulator is with lightning arrester connected in parallel in the first step, lightning arrester is under power-frequency overvoltage effect during conducting, and the residual voltage at two ends is less than the frequency breakdown voltage of insulator, now U
0for lightning arrester residual voltage now.
In above-mentioned steps, in the first step, the stake resistance of shaft tower can be measured by such as code DL/T 887-2004 shaft tower power frequency earthing resistance or code DL/T 475-2006 earthing device characterisitic parameter is measured method that directive/guide provides and be carried out in-site measurement and obtain, and also can or be calculated by the computing formula provided in code.
In above-mentioned steps, the 3rd step and the permission maximum stride voltage difference described in the 5th step and Maximum Contact voltage difference formula; Can calculate with the formula provided in the grounding design of GB 50065-2011 alternating-current electric device 4.2.2 article, can also or calculate with the permission maximum stride voltage difference provided in domestic and international other standards and Maximum Contact voltage difference formula, the parameter of collecting in a first step then needs to adjust according to the permission maximum stride voltage difference provided and Maximum Contact voltage difference formula desired parameters.
Claims (5)
1. the method for inspection of electric power line pole tower grounding safety performance when lightning conducter insulation is set up, it is characterized in that, it comprises the following steps:
The first step, collects the basic ground connection data of electric power line pole tower, comprises the frequency breakdown voltage U of this transmission line of electricity lightning conducter insulator
0, maximum single-phase short circuit current I
0, short circuit duration T
0, the stake resistance R of shaft tower
0, the soil resistivity ρ near shaft tower;
Second step, measures the 6.4th article of method provided in directive/guide with reference to DL/T 475-2006 earthing device characterisitic parameter, measures the step potential difference U of this tower grounding device
sC, contact potential difference U
tC, I
minjected total earth current of shaft tower by equipment during for measuring;
3rd step, with reference to the 3.4th article of formula provided in the grounding design of DL/T 621-1997 alternating-current electric device, calculates the maximum stride voltage difference U that this shaft tower allows
sMAXwith Maximum Contact voltage difference U
tMAX;
4th step, calculates maximum stride voltage difference and Maximum Contact voltage difference in this shaft tower real work situation by following formula; I in formula
sfor actual shaft tower earth current, work as I
0* R
0<U
0time, I
s=I
0; Work as I
0* R
0>=U
0time, I
s=U
0/ R
0;
5th step, compares the result of the result of calculation of the 4th step and the 3rd step, only has and work as U
s<U
sMAXand U
t<U
tMAX, this tower grounding security performance meets the demands, otherwise does not all meet the grounding design of DL/T 621-1997 alternating-current electric device.
2. the method for inspection of electric power line pole tower grounding safety performance when lightning conducter insulation according to claim 1 is set up, it is characterized in that, in the first step, this transmission line of electricity lightning conducter insulator is with sparking distance in parallel, and the frequency breakdown voltage of sparking distance in parallel is less than the frequency breakdown voltage of insulator, now U
0for the voltage breakdown of sparking distance in parallel.
3. the method for inspection of electric power line pole tower grounding safety performance when lightning conducter insulation according to claim 1 is set up, it is characterized in that, in the first step, this transmission line of electricity lightning conducter insulator is with lightning arrester connected in parallel, lightning arrester is under power-frequency overvoltage effect during conducting, the residual voltage at two ends is less than the frequency breakdown voltage of insulator, now U
0for lightning arrester residual voltage now.
4. the method for inspection of electric power line pole tower grounding safety performance when lightning conducter insulation according to claim 1 is set up, it is characterized in that, in the first step, the stake resistance of shaft tower carries out in-site measurement by the method that such as code DL/T 887-2004 shaft tower power frequency earthing resistance is measured or code DL/T 475-2006 earthing device characterisitic parameter measurement directive/guide provides and obtains, or is calculated by the computing formula provided in code.
5. when lightning conducter insulation according to claim 1 is set up, the method for inspection of electric power line pole tower grounding safety performance, is characterized in that, the 3rd step and the permission maximum stride voltage difference U described in the 5th step
sMAXwith Maximum Contact voltage difference U
tMAX; The formula provided in 4.2.2 article in the grounding design of GB 50065-2011 alternating-current electric device is adopted to calculate, or calculate with the permission maximum stride voltage difference provided in domestic and international other standards and Maximum Contact voltage difference formula, the parameter of collecting in a first step then needs to adjust according to the permission maximum stride voltage difference provided and Maximum Contact voltage difference formula desired parameters.
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| CN112348359A (en) * | 2020-11-06 | 2021-02-09 | 长沙理工大学 | Method for determining safety design index of steel pipe tower grounding device of urban power transmission line |
| CN113420399A (en) * | 2021-06-30 | 2021-09-21 | 国网河南省电力公司电力科学研究院 | Insulating joint lightning induction voltage calculation method, device, equipment and medium |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN107656144A (en) * | 2017-11-14 | 2018-02-02 | 国网山东省电力公司电力科学研究院 | A kind of comprehensive detection system and method for transmission line of electricity earthed system |
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| CN112054530B (en) * | 2020-09-24 | 2023-11-21 | 云南电网有限责任公司电力科学研究院 | Full compensation system direct resistance design method and system based on fault phase residual voltage |
| CN112348359A (en) * | 2020-11-06 | 2021-02-09 | 长沙理工大学 | Method for determining safety design index of steel pipe tower grounding device of urban power transmission line |
| CN113420399A (en) * | 2021-06-30 | 2021-09-21 | 国网河南省电力公司电力科学研究院 | Insulating joint lightning induction voltage calculation method, device, equipment and medium |
| CN113420399B (en) * | 2021-06-30 | 2022-09-09 | 国网河南省电力公司电力科学研究院 | Insulating joint lightning induction voltage calculation method, device, equipment and medium |
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