Gajeruwa Mai Yawan Uku Da Juntukan Uku da Kwalba: Abubuwan Dukkana Ake Soke Su Masu Sauran Da Neman Su

1 Tattalin da Kompojintai na Kungiyar Kirkiro na Maimakon Matafi

1.1 Tattalin Kungiyar Kirkiro na Maimakon Matafi

Kungiyar kirkiro na maimakon matafi suna da tattalin karkashin adadin bayanai da suka bukata. Su ta fi sani da amfani da biyu kungiyoyi, wanda daya ya kunshi mafi yawan gida da idan ya kunshi mafi yawan rike. Kirkiro na maimakon matafi na DC suna da zama da zai iya kirkira tsari zuwa masu yawan alama. A cikin wasu wurare na kirkiro na maimakon matafi a Najeriya, ana amfani da kirkiro na AC kuma hakan ya fi shahara a rayuwar yau da kullum.

1.2 Kungiyar Kirkiro na Maimakon Matafi Ta Hanyar Muhimman Tattalin Inkiladawa

A cikin abubuwan inkilada masu kyau, ana bukatar sabbin rubutun ingineerinta don kirkiro da za su amfani da su a fannin kirkiro. Zan iya zama da sahihi da kafin zaka da tabbacin rawa'i da ke amfani da su, kamar kuma tushen marubuta da kayayyaki, da kuma matsalolin da ke magance waɗannan rawa'i. Wannan zai taimaka wajen bincika irin kirkiro, haɗaƙar da muhimmin kafofin aiki, da kuma haɗaƙar da matattaccen aiki.

2 Hadin Ingantaccen Kungiyar Kirkiro na Maimakon Matafi

Daga ma'ana ta kungiyoyi masu yawan alama, kungiyar kirkiro na maimakon matafi na UHV suna da tattalin karkashin adadin bayanai, tushen injiniya, da kuma matsaloli na inganci. Idan babban adadin bayanai ba ta daidai ko kuma tushen inganci ba su daidai, za su iya samun abubuwan dabi'a kamar flashover, overvoltage, da kuma breakdown. Saboda haka, amfani da insulators na composite a cikin kungiyar kirkiro na UHV ita ce muhimmi da yake da muhimmanci a fannin ban sha'awar gwamnati.

3 Matsaloli Na Insulators Na Composite A Cikin Kungiyar Kirkiro Na UHV

3.1 Interface Breakdown

Matsaloli mai sarrafa kan insulators na composite suna da tattalin sakamako da jirgin lalace, wanda ke jagoranci waɗannan sakamakai. Duk da yadda rawa'in ke ci gaba, amma annan masu interface breakdown ba su daidai. A lokacin farkon amfani, akwai tattalin shedding na core rods da sheaths, da kuma matsaloli na erosion a cikin interfacer da diameters na rod, wanda ke iya haifar da interface breakdown da kuma taimaka wajen kadan take-off da insulators. Ana bukatar inganta da iyakoki a cikin tushen products don haɗaƙar da probability na interface failure.

3.2 Core Rod Brittle Fracture

Core rod brittle fracture ita ce tarihin matsaloli mai sarrafa kan insulators na composite a cikin kungiyar kirkiro na UHV. A lokacin core rod brittle fracture, wajen acid erosion, fibers na core rod ke jagoranci da zama lafiya, hatta a lokacin adadin lalace mai tsauri. Dalilan da suka faruwa sun hada da:

Na ɗaya, wannan yana faruwa a wuraren da field strength na high voltage ke da yawan daidai. Idan grading ring ya yi reverse, za iya haifar da core rod brittle fracture. Don haka, tushen design da processing na grading rings ya bukatar don hana magance magnetic field strength ta daidai, don hana haɗaƙar da material brittle fracture.

Na biyu, cracks za su faruwa idan sheath ko end face ta jagoranci da damage. Amma, amfani da boron-free fiber acid-resistant core rods ya haɗaƙar da overall acid resistance, da kuma ya haɗaƙar da wannan issue da kadan. Ya kamata a lura cewa duka fiber core rods ba su da acid resistance characteristics mai yawa, saboda haka, performance evaluation da selection ya ne buƙata. Idan ba ta da yawan daidai, ba ta iya faruwa ba, amma ana iya haɗaƙar da shi ta hanyar interventions.

3.3 Aging Issues

Ba a lokacin da insulators ke amfani, ba za su iya samun aging problems, domin temperature da surface discharge factors. Idan materials na silicone rubber ke da cycle da yawan daidai, amma early-stage operational aging zai iya faruwa saboda environmental pollution da technology na material formulation. Ba da yadda duk regions ke iya da shiga conditions da characteristics daidai da silicone gel, aging ba za su iya haifar ba. Don haka, testing na early stage ita ce buƙata. Saboda haka, ana bukatar inspections na periodic don insulators na composite materials don hana haɗaƙar da further deterioration.

3.4 Mechanical Issues

Insulators na composite materials suna da tattalin mechanical performance degradation a lokacin amfani. Yanzu, ana amfani da internal plug-type insulators, amma suke da tattalin karkashin jointing methods, da kuma differences da ke faruwa a cikin creep slope compared to edge-rolled insulator designs.

4 Determination of Insulator String Length and Minimum Air Gap Distance for UHV Lines

4.1 Electrical Insulation Distance Considered in UHV Line Design

Tushen insulation matching requirements na 1000kV AC UHV lines ita ce don hana amfani da safe da reliable operation under various conditions such as power frequency, switching overvoltage, da lightning overvoltage. Power frequency flashover na insulators ita ce primary control factor for insulator strings. External insulation structures suna da calculation based on pollution tolerance, combined with existing engineering experience, considering factors like altitude and ice coverage. For switching overvoltage, overvoltage multiples of 1.6p.u. and 1.7p.u. are taken; when the system's highest operating voltage is 1100kV, if the switching overvoltage cannot control the number of insulator pieces and the calculated value is lower than 50% of the insulator string's impulse discharge voltage, there is a risk of impulse discharge. In UHV systems, lightning overvoltage has no direct relationship with operating voltage, and the high external insulation level makes lightning overvoltage a non-determining factor.

4.2 Insulator String Length

Under polluted conditions, the length of the insulator string is determined using anti-pollution methods. This includes: (1) measuring the pollution flashover voltage of different insulators under atmospheric conditions to obtain the relationship between the 50% pollution flashover voltage and salt density of different insulators; (2) measuring the withstand voltage of insulators; (3) correcting and calculating the salt density of soluble salts; (4) calibrating the effect of ash-to-salt ratio on the surface contamination of insulators; (5) correcting the unevenness of the upper and lower surfaces; (6) performing elevation correction at high altitudes; and (7) calculating the number of insulator sections under maximum working voltage conditions.

4.3 Determination of Minimum Air Gap Distance for UHV Lines

4.3.1 Calculation of Minimum Number of Insulator Pieces for Normal Operation

This paper focuses on the key scientific issue of selecting the minimum clearance for UHV transmission lines, using single-circuit transmission lines as the research object. It studies the influence of air gap distance on transmission tower dimensions under power frequency voltage and lightning effects, determines the minimum clearance of transmission towers using measured air gap distances, and considers the impact of insulator degradation on transmission tower structures, proposing a minimum clearance for transmission towers considering insulator degradation.

4.3.2 Determination of Switching Overvoltage Gap

This involves determining the statistical matching factor for switching overvoltage operation based on the calculation of the working pulse discharge voltage U50% for individual air gaps.

Among these, Us represents the switching overvoltage, measured in kV; Z is a constant, thus it is set to 2.45; for a single air gap, σ1 is set to 0.06; among these,σm is the variance of multiple air gaps, which is set to 0.024. Therefore:

Therefore, the statistical coordination factor kckc for the operating overvoltage of the line air gap is:

5 Application of Composite Insulators in Ultra-High Voltage Transmission Lines

Through practical operations of existing lines in our country, it has been found that using composite insulators can reduce both line maintenance costs and pollution to the power grid. In polluted areas, it is recommended to use composite insulators. For 1000kV transmission lines, it is recommended to use insulators about 9 meters high, and in heavily polluted areas, insulators over 17 meters high. If multiple series connections are adopted, the height of the insulators can be further adjusted, but this will also increase the weight and length of the insulators, raising the cost of the line.

In high-altitude and heavily polluted areas, composite insulators offer higher economic and technical advantages. When the combined string length does not exceed 10 meters, it can reduce the tower window area, control the tower load, and decrease the occurrence of flashover accidents. Therefore, composite material insulators have significant advantages in these aspects. To ensure the long-term stable and reliable operation of ultra-high voltage transmission lines, in-depth research must be conducted.

On one hand, studies on the mechanical properties of ultra-large-tonnage composite material insulators should be carried out to form efficient standards and testing methods. Additionally, while ensuring uniform pressure on composite insulators, appropriate measures should be taken to address electromagnetic interference and corona discharge issues to minimize sudden accidents. A reasonable arcing method ensures effective arc suppression.

Optimized mechanical structures guarantee that a broken insulator will not fall to the ground. Strict quality control standards should be established to prohibit substandard products, with strict material control for core rods and skirts, and improvements in manufacturing techniques from the source to reduce operational safety hazards. During construction, a scientific storage procedure should be implemented to strictly control potential damages. Effective maintenance and inspection plans should be executed to promptly identify safety hazards and take corresponding measures to ensure production safety.

6 Conclusion

Composite insulators have gained increasing application in China's power grid and have become an essential component of power grid construction. Given the requirements for large cross-sectional areas and high-load conditions in ultra-high voltage transmission lines, synthetic insulators should be prioritized over glass insulators and other types. As the scale of ultra-high voltage transmission lines expands, more challenges arise, leading to higher demands on their performance.

Besides ensuring uniform pressure on composite insulators, appropriate measures should be taken to address electromagnetic interference and corona discharge issues to minimize sudden accidents. A reasonable arcing method ensures effective arc suppression. Optimized mechanical structures guarantee that a broken insulator will not fall to the ground. Strict quality control standards should be established to prohibit substandard products, with strict material control for core rods and skirts, and improvements in manufacturing techniques from the source to reduce operational safety hazards.

During construction, a scientific storage procedure should be implemented to strictly control potential damages. Effective maintenance and inspection plans should be executed to promptly identify safety hazards and take corresponding measures to ensure production safety.