Tambayar da kisa na ƙarfin dacewa masu tashin hanyoyi na SF₆ 500kV da kuma yadda ake bincike da kuma gudanar da shi
A cikin gwamnati na gajeruwar zabe, insulating pull-rod shine wani abu mai muhimmanci a kan insulanta da kuma tushen shiga. Yana bukata a samun inganci sosai a cikin halayyar da kuma siffofin jiragen. Duk da yake insulating pull-rods ba suka faruwa ne kadan, amma idan an faruwa, za a iya haifar da matsaloli masu yawa ga gajeruwar zabe.
Gajeruwar zabe na 550kV a cikin wani makarantar noma na biyu, tana da shugaban fage horizontal, model 550SR-K da kuma mekanisim mai karfi. Tana da tasirin kusa 63kA, tsari mai yawan 550kV, tsari mai yawan lafiya 4000A, tsari mai yawan kusa 63kA, tsari mai yawan harshe mai kyau da ke dace 1675kV, tsari mai yawan harshe mai kyau da ke shiga 1300kV, da kuma tsari mai yawan harshe mai kyau da ke shiga ta hanyar layi 740kV. Insulating rod na gajeruwar zabe tana da epoxy resin, da tsari mai yawan 15mm, faɗa 40mm, da kuma tsarin 1.1-1.25g/cm³.
Tarihin Faruwar
Wani makarantar noma ya baka shiga bayanen ita ce na ƙasa na 4. Bayanan shiga na makarantar tana cika a Figura 1. Komputar na ƙungiyar ya bude gajeruwar zabe 5032, sannan ya bude gajeruwar zabe 5031. Komputar na ƙungiyar ta baki shekaru kamar "TV Open-Circuit Alarm" da "5031 Circuit Breaker Protection Device Abnormality". Idan a yi nufin sa, akwai TV open-circuit alarm a cikin device na protection da kuma device na safety-control na gajeruwar zabe 5031. Nufin komputar na ƙungiyar ta baki cewa, zuwa voltage transformers a cikin T-zone na gajeruwar zabe 5032 da 5031, Uab= 0, Uca = 306kV, da Ubc = 305kV. Nufin sa a kan gafara tana baki cewa, gajeruwar zabe 5032 da 5031 suna cikin hali na budede.
Makamiyar iyali suna oya tsari na winding na biyu na phase C a kan 55V da kuma phases A da B a kan 0V a terminal box na voltage transformer body a cikin T-zone na gajeruwar zabe 5032 da 5031. An yi takaitaccen cewa, an faruwa a phase C na gajeruwar zabe 5031.
Tarihin Nufin Gafara
Idan an faruwa, makarantar ta baka shiga bayanen ita ce na ƙasa don tabbatar da wurin faruwar. Tana baka shiga bayanen ita ce na ƙasa don tabbatar da sababin faruwar. Tana tattaune ƙungiyar na ƙasa don tabbatar da gajeruwar zabe 5031 a cikin hali na maintenance. Idan makamiyan gajeruwar zabe suna samu gafara, suka yi nufin operating mechanism na gajeruwar zabe 5031. Suka baki cewa, wurin operating rod na mechanism tana cikin hali na normal "budede", da kuma ba a samu abu mai ci gaba a cikin mechanism, cikin Figura 2. An yi takaitaccen cewa, faruwar tana samu karfi daga cikin gajeruwar zabe.
Saboda closing resistance na gajeruwar zabe tana da tsari mai yawa da grounding resistance, idan hali na gajeruwar zabe a cikin wuri tana da tsari mai yawa, grounding resistance na gajeruwar zabe tana da tsari mai yawa da sakamakon biyu. Suna oya tsari na grounding resistance na gajeruwar zabe 5031 na biyu bayan an bude grounding isolating switches a biyu. Hasashen oyi tana cewa, Phase A tana da 273.3 μΩ, Phase B tana da 245.8 μ&Ω;, da Phase C tana da 256.0 μ&Ω;. Ba a samu abu mai ci gaba a Phase C.
Idan gajeruwar zabe 5031 tana cikin hali na maintenance, gas recovery process na gajeruwar zabe 5031C tana faru, da kuma an yi girman shiga bayanen ita ce na ƙasa. Upper flange na gajeruwar zabe 5031C tana kawo har zuwa. Nufin sa tana baki cewa, moving da static contacts na gajeruwar zabe tana cikin hali na budede, structure na gajeruwar zabe tana da damu, da kuma ba a samu abubuwa ko alama mai ci gaba. Suna oya contact resistance bayan moving da static contacts na gajeruwar zabe a kan 0.6 &Ω; (a cikin hali na normal), da kuma ba a samu electrical connection bayan moving da static contacts da insulating pull-rod, cikin Figura 3.
Bayan an kawo upper flange da kuma lower access hole na gajeruwar zabe don nufin sa, an samu alama mai ci gaba a cikin gas chamber. An samu brown-black powdery substances a kasa gas chamber da kuma a wurin bottom explosion-proof membrane, cikin Figura 4.
Sun yi manual slow-closing test a gajeruwar zabe 5031C-phase. Operation na closing tana da damu, da kuma ba a samu abu mai ci gaba. Bayan an kammala manual slow-closing, sun yi nufin exterior na body na gajeruwar zabe. Suna baki cewa, akwai discharge marks biyu a insulating pull-rod na gajeruwar zabe. Wanda mafi yawa tana da crack, cikin Figura 5. Akwai tracking marks a surface na insulating pull-rod, da kuma alama tana haɗa a duk insulating pull-rod.
Bayan an yi nufin insulating pull-rod da kuma ba a samu abu mai ci gaba, sun yi manual slow-opening test a gajeruwar zabe 5031C-phase. Operation na opening tana da damu. Bayan an kammala opening, sun yi nufin insulating pull-rod, da kuma ba a samu abu mai ci gaba. Suna amfani da borescope don yi nufin interior na gajeruwar zabe, da kuma ba a samu abu mai ci gaba.
Tarihin Takaitaccen Sababin Faruwar
Bayan an kawo insulating pull-rod na faruwa, suna nufin da kuma oya. Pull-rod tana da tsari mai yawan 570mm, faɗa 40mm, da tsari mai yawan 15mm. Akwai discharge-burned spots biyu a duk insulating pull-rod, wadannan suna cikin 182mm da 315mm daga ƙaramin. Wanda mafi yawa tana da crack da tsari mai yawan 53mm. Akwai tracking channel da take haɗa holes na biyu a cikin pull-rod.
Suna oya insulation na faulty insulating pull-rod. Idan an oya a multimeter, insulation bayan adjacent holes na ƙaramin tana da damu. Insulation bayan inner-side holes na biyu a ƙaramin tana da 1.583M&Ω;. Idan an oya a insulation resistance meter, resistance value tana da 643k&Ω; (a tsari mai yawan 1010V), da kuma insulation bayan outer-side holes na biyu a ƙaramin tana da 1.52T&Ω; (a tsari mai yawan 5259V). Don insulating pull-rod na normal, insulation bayan inner-side holes na biyu a tsari mai yawan 5259V tana da 5.26T&Ω;.
Daga hasashen nufin sa, zan iya tabbatar da cewa, insulation na insulating pull-rod na gajeruwar zabe 5031C-phase tana da faruwa, da kuma tana da conductivity a tsari mai yawa da yawa.
Idan an kawo insulating pull-rod na gajeruwar zabe 5031C-phase don nufin sa, suna baki cewa, saboda ƙaramin pull-rod ba a samu air holes, akwai long air holes a cikin tracking channel, cikin Figura 6.
Overall breakdown; second, the material proportioning or curing time of the insulating pull-rod did not meet the relevant requirements, resulting in uneven insulation strength of different parts of the insulating pull-rod. Under a strong electric field, the areas with lower insulation were first punctured, and then other low-insulation areas followed, ultimately leading to the overall breakdown of the insulating pull-rod.
Handling Measures
General Handling
Ba da tabbacin sababin faruwar gajeruwar zabe 5031C-phase, makarantar tana tattaune don kawo insulating pull-rod na C-phase. Ba da kammalowa, gas chamber tana da shiga, da kuma an faruwa gas zuwa tsari mai yawan 0.45MPa, da kuma an rage shi zuwa 24 hours. Sannan, an yi routine tests, including measuring the moisture content in the gas chamber, checking the closing resistance, conducting characteristic tests, and performing gas leak detection. Ba da kammalowan routine tests, an yi AC withstand voltage and partial discharge tests for the 5031 circuit breaker in both the open and closed states. Accessories tana da shiga, da kuma an yi application don shiga bayanen ita ce na ƙasa.
AC Withstand Voltage and Partial Discharge Tests
Test voltage tana faruwa daga spare line 3E. Idan kowane three-phase secondary circuits of all current transformers (TAs) on both sides of the 5031 circuit breaker and the 5032 circuit breaker tana da short-circuited and grounded at the main body. Also, the secondary circuits of all TAs on the spare line 3E tana da short-circuited and grounded at the main body, and the voltage transformers within the test range tana kawo. AC withstand voltage and partial discharge tests tana faruwa when the 5031 circuit breaker tana cikin hali na closed and open states.
For the 500kV GIS equipment in the power station, the highest operating voltage , the phase voltage , the factory test voltage , and the maximum on-site withstand voltage , with a duration of .
As shown in Figure7, the sequence of the closing withstand voltage and partial discharge tests is as follows: The GIS was aged and purified at a voltage of for 5 minutes, and the busbar was aged and purified at a voltage of for 3 minutes. The AC withstand voltage test was then increased to and maintained for 60 seconds. The voltage was then rapidly reduced to , and the partial discharge of the gas chamber of the 5031 circuit breaker was tested for 3 minutes. After the test, the voltage was rapidly reduced to 0kV.
As shown in Figure 8, the test procedure for the open-circuit withstand voltage and partial discharge measurement is as follows: The test voltage was uniformly increased to and maintained for 60 seconds. After the withstand voltage test was completed, the voltage was rapidly reduced to , and the partial discharge of the gas chamber of the 5031 circuit breaker was tested. After the test, the voltage was rapidly reduced to 0kV.
Conclusion
The quality of the insulating pull-rods of 500kV SF₆ tank-type circuit breakers is of great significance for the safety of circuit breakers and the security of the power grid. Equipment manufacturers should exercise strict quality control. Before equipment assembly, partial discharge tests should be carried out on insulating pull-rods, and material inspections can be conducted using methods such as flaw detection if necessary. After the circuit breakers are put into operation, regular live partial discharge detection work should be carried out using methods like very high frequency and ultrasonic testing. At the same time, offline partial discharge live detection should be combined with circuit breaker maintenance. For circuit breakers with abnormal partial discharge levels, analysis of SF₆ gas decomposition products can be carried out simultaneously to diagnose the insulation health of SF₆ circuit breakers at an early stage, preventing equipment failures and ensuring the safe and stable operation of the power grid.
