Talakawa na Gas-Insulated Switchgear Don Yankin Dukkana Tsakiya
Gas-insulated ring main units sun fiye da shugaban da ke gaba da shugabanni da suka da yawan da suka da yawan da za ta iya canzawa da suke kisan kasa ga tattalin arzikin jama'a. Wadannan wurare suna amfani da su don tattalin arziki na 12~40.5 kV, tattalin arziki na biyu na farko, da kuma tattalin arziki na tsakiyar tattalin arziki, tun daga cikin masu amfani da su don hanyar kontrola da kuma inganci na arziki. Suna da kyau don instalata a kan tashar substation.
A cikin tattalin da kuma yanayin arziki, suna tabbatar da zan iya ci gaba da rayuwarsa da za ta iya canzawa da suke kisan kasa ga tattalin arzikin jama'a. Masu muhimmanci na wadannan wurare suna amfani da circuit breakers ko kuma kombinasiyar load switches da fuses, wadanda suna da kyau saboda tsari mai sauƙi, yawan da suka da yawan da za ta iya canzawa da suke kisan kasa, nau'in da yaɗuwa da kuma inganci na arziki. Suna da amfani a cikin tashar substation da kuma tashar substation a kan tattalin arziki na biyu na farko kamar tattalin arziki na mafi girma, tattalin arziki na mafi girma, tattalin arziki na mafi girma, da kuma tattalin arziki na mafi girma. Duk insuwar gas da ke amfani a cikin wadannan wurare suna da kyau saboda nau'in da yaɗuwa da kuma kyaukkyaukan al'umma, wanda ya ba su da amfani a cikin tattalin arzikin jama'a.
Masu muhimmanci na wadannan wurare suna instalata a kan tanki mai sarrafa da gas mai insuwa (wanda ake kira "gas compartment"). Gas compartment shine masu muhimmanci na gas-insulated ring main units. Yadda aka yi shine in tabbatar da cewa masu muhimmanci na tsafta suna yi aiki da baya ba da waɗannan abubuwan da ke faruwa a kan tattalin arziki, kamar nasara, lafiya, da kuma nasara. Yana da kyau saboda tsari da kuma aiki na arziki. Duka abubuwan da ke cikin gas compartment suna da kyau saboda gas compartment. Gas compartment yana da cikakken bayanai da kuma gas density monitoring devices, kamar pressure gauges ko kuma density meters, wadanda suna amfani da su don bincike bayanai na gas compartment.
Wannan rubutu ya nuna masu amfani da mechanical da electrical performance na ring main units a kan tattalin arziki na mafi girma.
1. Common High-Altitude Design Schemes for Gas-Insulated Ring Main Units and Existing Issues
Gas-insulated ring main units suna da designs mai insuwa, inda main conductive circuits suna da insulated system mai kyau, wanda ya samu gas compartments, fully insulated bushings, da kuma fully insulated cable terminations. Saboda haka, tsari da lafiya na gas compartment ba sa iya faruwa ba a kan tattalin arziki, gas density da kuma humidity suna daidai. Idan a nemi, insulation performance ba sa iya faruwa ba a kan tattalin arziki, nasara, ko kuma gas mai nasara. Duk da haka, insulation performance na bushings da kuma cable terminations, wadanda suka yi aiki da insulating materials kamar epoxy resin da silicone rubber, ba sa iya faruwa ba a kan tattalin arziki. Superficially, conventionally designed gas-insulated ring main units appear adaptable to plateau environments, leading many manufacturers to believe they meet high-altitude operational requirements and deploy them directly in such regions.
Currently, two primary technical schemes are used when applying gas-insulated ring main units in high-altitude environments:
1.1 Direct Deployment in High-Altitude Areas
Design Concept: This approach relies on the principle that the main conductive circuit is fully enclosed by the insulated system (sealed gas compartment, fully insulated bushings, and cable terminations), making insulation performance unaffected by high-altitude conditions.
Existing Issues: In actual operation, reduced external atmospheric pressure at high altitudes increases the pressure differential between the interior and exterior of the gas compartment. This causes significant bulging deformation of the compartment, affecting the mechanical performance of electrical components such as circuit breakers and disconnectors. This may lead to operational jamming and changes in mechanical characteristics.
1.2 Reduced Factory Gas Pressure Setting
Design Concept: To address the increased internal-external pressure differential at high altitudes, this scheme reduces the gas pressure inside the compartment at the factory. When the unit arrives at high-altitude sites, the reduced atmospheric pressure causes the pressure differential to rise to the value required by technical specifications, making the pressure gauge display the required operational pressure.
Existing Issues: This design effectively reduces the density of the insulating gas inside the compartment. Although the pressure gauge shows the designed value at high altitudes, the insulation performance of gases is intrinsically linked to gas density according to the Paschen curve (see Fig. 1) formulated by German physicist Friedrich Paschen. The Paschen curve plots the function derived from Paschen’s Law. Its physical meaning: The breakdown voltage U (kV) is a function of the product of electrode distance d (cm) and gas pressure P (Torr), expressed as U = apd / [ln(Pd) + b] (see Fig. 1), where a and b are constants.
The curve’s primary significance: For a fixed insulation distance, increasing pressure or reducing pressure toward vacuum (e.g., 10⁻⁶ Torr) both raise the gap breakdown voltage. At near-vacuum pressures, reduced vacuum level (i.e., increased air density) makes electrical breakdown between electrodes easier. Beyond a certain pressure threshold, insulation performance gradually improves as pressure rises. In this phase (beyond point a in Fig. 1), reducing pressure—and thus gas density—lowers the breakdown voltage, meaning insulation performance deteriorates. The operational pressure range of gas-insulated ring main units falls entirely within this region (the section beyond point a in Fig. 1).
1.3 Summary of Issues with Conventional High-Altitude Designs
Increased pressure differential between the interior and exterior of the gas compartment causes greater deformation of the compartment, affecting the mechanical operation and performance of switches.
Under increased internal-external pressure differential conditions, pressure relief devices are more prone to activation.
Maimaituji da dabbobi suna neman farkon maimaituji daga kasa zuwa gida na zafi. Maimaitujin da suka da yawan tsari suke yi amfani da muhimmanci na tsari don maimaituji. Ba za su iya tabbatar da adadin gas mai saukarwa a cikin zafi domin hawa masu shirya, amma abubuwan gas mai saukarwa suna da alaka da yadda ake tsaftace.
Yawan tsari na jihohi a hawa masu shirya ya haifar da yadda ake tsaftace abubuwan tsaftaci na gida na zafi.
2. Tashar Tashar Gas-Insulated Ring Main Units Don Hawa Masu Shirya
Na wannan bayanin, wanda gas-insulated ring main units (da kabilu mai tsaftaci da suka faɗa da gas compartments, bushings mai tsaftaci, da kuma cable terminations mai tsaftaci) ba su iya haifar da tsaftacin a fannin, ana iya haifar da abubuwan da ke faruwa a hawa masu shirya: yadda farkon maimaituji daga kasa zuwa gida na zafi ya haifar da, ba su iya haifar da adadin gas mai saukarwa a cikin zafi, da kuma buƙatun da suka buƙata da adadin gas mai saukarwa. Saboda haka, tushen mafi muhimmanci na tashar gas-insulated ring main units don hawa masu shirya yana cikin tashar gas compartment da kuma tashar pressure relief device, da kuma tashar abubuwan tsaftaci na gida na zafi a hawa masu shirya.
2.1 Tashar Gas Compartment Da Pressure Relief Device Don Hawa Masu Shirya
Don lada abubuwan matsalolin masu ilimi, wannan rubutu ta ba da tashar gas-insulated ring main units na hawa masu shirya, wanda babu da tashar na musamman ko kuma tashar na musamman na pressure reduction. Wannan ring main unit ta da tashar na musamman a cikin abubuwan:
(1) Yadda Ake Zama Gas Compartment
Don lada yadda farkon maimaituji daga kasa zuwa gida na zafi ya haifar da, an zama gas compartment. Wannan ta tabbatar da gas compartment ya haifar da yadda ake tsaftace, ta haka ta ba da tsaftacin masu shirya ga abubuwan high-voltage components da suka faɗa a cikinsu.
Idan an amfani da International Standard Atmosphere model, za a iya kula maimaituji na jihohi a matsayin:
P = P₀ × (1 – 0.0065H/288.15)^5.256
idi P shine maimaituji na jihohi a matsayin hawa, P₀ shine maimaituji na jihohi a riyar tasiri, H shine hawa.
Idan an yanke misali na hawa 4000 m:
P = P₀ × (1 – 0.0065 × 4000 / 288.15)^5.256 ≈ 0.064 MPa.
Idan an yanke misali na 10 kV SF₆ gas-insulated ring main unit, tashar maimaituji na gas compartment a wurare da ba su da hawa masu shirya yana da 0.07 MPa. Idan an duba yadda maimaituji na jihohi ya haifar da a hawa masu shirya, za a iya kula tashar maimaituji na gas compartment a hawa 4000 m a matsayin:
P₁ = P₀ – 0.064 + 0.07 = 0.107 MPa.
(2) Tashar Pressure Relief Device Don Hawa Masu Shirya
Kafin a duba national standard GB/T 3906—2020 "AC metal-enclosed switchgear and controlgear for rated voltages above 3.6 kV and up to and including 40.5 kV", Section 7.103 ta ce gas compartment na gas-insulated ring main units ya kamata a tsafta 1.3 times tashar maimaituji (P₁) na 1 minute bila da pressure relief device suka faɗa. Idan maimaituji ya haifar da 1.3 times (P₁) zuwa 3 times (P₂) tashar maimaituji, pressure relief device ya kamata suka faɗa. Wannan ta haramta idan ta hakan da tashar manufacturer. Bayan test, gas compartment ya kamata ya haifar da yadda ake tsaftace amma ba suka ɗauki.
Tashar strength na gas compartment da pressure relief device da kyau a cikin national standards. Gas compartments da pressure relief devices don hawa daban-daban za su iya kula da tashar haka:
P₁ = 0.107 × 1.3 = 0.139 MPa
P₂ = 0.107 × 3 = 0.321 MPa
Na tashar strength na gas compartment, wanda an zama da steel plates masu tsakiyar ko kuma stiffeners, gas compartment ya kamata a tsafta yadda farkon maimaituji daga kasa zuwa gida na zafi ya haifar da a hawa masu shirya. Wannan ta haramta abubuwan mechanical da electrical performance na high-voltage switches da suka faɗa a cikin gas compartment saboda haifar da yadda ake tsaftace, ta haka ta ba da tsaftacin a matsayin maimaituji na gas compartment da kuma tsaftacin a hawa masu shirya kamar yadda ake tsaftace a wurare da ba su da hawa masu shirya.
Na tashar kula da experimental validation, yadda ake zama thickness da strength na pressure relief diaphragm ya haifar da yadda ake tsaftace pressure tolerance capability. Wannan ta haramta gas compartment’s pressure relief range ta hakan da tashar pressure range requirements, ta haka ta haramta pressure relief device suka faɗa saboda yadda farkon maimaituji daga kasa zuwa gida na zafi ya haifar da a hawa masu shirya. Wannan ta haramta internal insulation level da kuma electrical performance na ring main unit.
2.2 Tashar Gas Density Indication Device Don Hawa Masu Shirya
Gas density indication device ta amfani da sealed-type density meter. Abubuwan da ta barazan ba su iya haifar da yadda tsari ya haifar da ko kuma yadda maimaituji na jihohi ya haifar da.
Don gas-insulated ring main units na hawa masu shirya, density meter da ake zaba don gas compartment shine sealed-type full-condition density meter, wanda babu da yadda tsari ko hawa su iya haifar da. Tsarin da take da ita shine compensation element a cikin density meter wanda ya haifar da temperature compensation (ba su iya haifar da tsari). Amma, head na density meter ta da tashar sealed structure inda chamber na sealed ta hakan da maimaituji na jihohi. Barazan maimaituji na density meter ta hakan da farkon maimaituji daga kasa zuwa gida na zafi zuwa maimaituji na jihohi.
Wannan takawa taimakawa cewa kyauki na gas mai sarrafa da ake kammala a gas compartment yana nuna hakuriyar gas da ke cikin compartment. Wannan irin bayanai ba zama da gaba-gaban ladan hanyar tsari ko kasa, wanda ya fi shiga masu ilimi ga yankunan da suka da kasa.2.3 Takawa na Fully Insulated Bushings don Gas-Insulated Ring Main Units a Yankunan da Suka da Kasa
Idan an yi nasara a gas compartment da kuma abubuwa masu maida aiki, yankunan da suka da kasa suna iya haifar da abubuwan da ake kammala a gwargwadon gas kamar incoming/outgoing line bushings da cable terminal joints. Ingantaccen aiki na wannan abubuwan da ake kammala a gwargwadon gas suna da alaka da inganci na insulating material da kuma creepage insulation strength relative to ground. A yankunan da suka da kasa, tsari na hawa ya kace creepage insulation strength relative to ground. A fannin aiki, gas-insulated ring main units masu takawa na musamman suna iya jawo jirgin aiki na power frequency withstand voltage tests don abubuwan da ake kammala a gwargwadon insulating (kamar insulating bushings ko top-expansion busbars) bayan ake koyar da su a yankunan da suka da kasa.
Don in haifar da wannan, wannan rubutu ta rage take kan takawa na sabbin bayanai don fully insulated bushings a gas-insulated ring main units a yankunan da suka da kasa: add grounded shielding layer zuwa outer surface of such insulating components. Wannan takawa ta tabbatar da electric field uniformity da kuma in sa ki karfi ground discharge from the main circuit busbars.
A project na outdoor 10 kV switching station a Nagqu, Tibet, babban kamfanin ta samu matsalolin a lokacin da suka yi acceptance testing inda aiki na equipment yana iya jawo jirgin aiki na power frequency withstand voltage test of 29 kV/1 min relative to ground. Ba a dogara grounded shielding layer zuwa outer insulation of incoming/outgoing bushings and external busbars of the gas compartment, aiki na equipment ta taimaka da national standard requirement of 42 kV/1 min for power frequency withstand voltage relative to ground.
2.4 Mafarin Tekunukan Mai Tsarki
Muhimmancin takawa na gas-filled insulated ring main units a yankunan da suka da kasa sun hada:
Yara ingantaccen gas compartment tare da increase steel plate thickness ko add stiffeners to meet requirements for pressure tolerance range and deformation limits caused by increased internal-external pressure differential at high altitudes.
Yara ingantaccen takawa na pressure relief diaphragm a pressure relief device na gas compartment. Ba a dogara reinforcement, it satisfies the pressure tolerance range requirements for the pressure relief device under increased internal-external pressure differential at high altitudes.
Adopt sealed-type density meters for pressure indication devices. Their displayed values remain unaffected by temperature changes or external atmospheric pressure variations, making them suitable for high-altitude environments.
Design a grounded shielding layer on the outer surface of external insulating components of the gas compartment to improve electric field uniformity and prevent ground discharge from main circuit busbars.
3. Ma'anarsa na Takawa na Gas-Insulated Ring Main Unit a Yankunan da Suka da Kasa
Wannan takawa scheme ya taimakawa gas-insulated ring main units da za su iya duni ma'ana da yankunan da suka da kasa. Tare da yara ingantaccen gas compartment, improving pressure tolerance capability of pressure relief devices, enabling accurate measurement of internal gas density, and rationally designing related insulating components, the ring main unit achieves complete technical adaptability to high-altitude environments. Wannan taimakawa mechanical and electrical performance of the ring main unit and enables normal operation of gas-insulated ring main units in high-altitude environments.
Yankunan da suka da kasa a China suna da yawan tsari, wanda ya bazu damar aiki na power equipment da za su iya duni ma'ana da yankunan da suka da kasa. Standardization and rationality of product design urgently need improvement. Actual environmental variations in high-altitude regions impose new requirements on product design. This technical scheme provides a new design theory and methodology, representing a meaningful exploration.
