Vegera heyî û tendansa çêdilana lîsterekên SF6 bi tenzîlî ya bikamîn

Bihayên darchîna barkî, ya jî bîrûyên darchîna barkî, hewceyên dargûnî û xebîtkirina arkê yên piştgirîdan hene. Wan dikarin ne ji bo derdîn û derbendîn karanî yên tîk û barkî yên darchîna barkîyan bikin dekane û wan dikarin, di dema ku serbestiya ek sisteman biguhere, bi amûran parzûma û cihazên otomatîk da hatine kirin da ku çereka derdîn werdigire, wêjîya nikarîna nîrvan bike û guhertina serbestiya bisekin. Ev ên pîvanî ye ji bo pêk kirina safta kirkerdina sisteman.

Bihayên darchîna barkî yên evoluzyon pirindivandî yên bîrûyên darchîna barkî yên dilî, bîrûyên darchîna barkî yên havî, bîrûyên darchîna barkî yên vakî û bîrûyên darchîna barkî yên SF₆ an. Lê zanistan, du yekemîn nav tipliyên bi tevahî digerandin û bîrûyên darchîna barkî yên SF₆ li gorî du yekemîn nav tipliyan herî ziyade serkarde. Bîrûyên darchîna barkî yên SF₆ li salên 1970'în girîng serkarde. Wan hexafluoride sulfur (SF₆) ji bo rewanîna arkê bikar dihin. Tipli bîrûyeyê vê gotara hewceyên dargûnî mezin hene. Di şertên dargûnî yên azad de, hewceyên dargûnî yan hundede divê bist dah jor hatine. Van ji bo serkirina ên pîvanî û safta kirkerdina sisteman împortan in û li ser bîra malpera û feydiya cîmisîyêda da pîvanîn hene.

1. Performansa Bîrûyên Darchîna Barkî yên SF₆

Bîrûyên darchîna barkî yên SF₆ ji bo rewanîna arkê û rewanîna dargûnî gasa SF₆ bikar dihin. Performansa rewanî û xebîtkirina arkê yên wan zi bîrûyên darchîna barkî yên dilî bi tevahî herî ziyade ne. Karakteristikên bîrûyên darchîna barkî yên sulfur hexafluoride (SF₆) wek hejmara:

• Hewceyên xebîtkirina arkê mezin, hewceyên dargûnî mezin û hewceyên dargûnî yên unit fracture mezin. Ji ber vê yekê, di rastaya li vir eynîn sathê rengînê de, ji bo serkarke navnîşkirina bîrûyên dargûnî yên series zêdetir dibistin, performansa malpera hilkaşîn bike.

• Cihanî malpera elektrikî. Wan dikarin derdîn da full capacity 50kA 19 jor bisekin û derdîn total 4200kA bike. Cihêza malpera dirêj û ji bo karbûnên serkarînê ve pêk e.

• Performansa malpera dargûnîya ber. Ji ber electronegativity SF₆ gas, wan hewceyên xebîtkirina electronên azad mezin hene. Ark ên form kirin di SF₆ de destûrê ji bo formkirina "structure of arc column" (core û sheath). Diffusion plasma ionized li ser kirin, ji bo recombination effective ion. Derdîn total 80-100kA, hata 200kA heta. Dema xebîtkirina arkê qetir, girîng 5-15ms. Li vir eynîn, performansa malpera dargûnî ji bo derdîn revese, near-zone faults, unloaded long lines û no-load conditions transformer da herî ber e.

• Performansa dargûnîya ber. Hewceyên dargûnî SF₆ hundede 5-10 jor hewceyên hewlê ne.

• Gas SF₆ colorless, odorless, non-toxic, non-flammable û gas stabîl e ku bi tevahî ne bi şevên din serkarde. Li vir eynîn, di dema ku bîrûyê vekirîne, pressure increase li ser kirin di dema arkê vekirîne qetir ne, ji bo kirina operaçeyên tevahî û bisekinîna serbestiya eksplozîyonê.

2. Çavkanîna Bîrûyên Darchîna Barkî yên SF₆
2.1 Bîrûyên Darchîna Barkî yên SF₆ Double-pressure

Du sistem gas SF₆ (sistem high-pressure û sistem low-pressure) di nav bîrûyê de set kirin. Tenha di dema vekirînê de, high-pressure chamber ji bo control blowing valve bi low-pressure chamber flow kirin da ku gas flow high-pressure form bike. Pas ku dargûnî vekirîne, blowing valve bicerabike. Prinsip ark extinguishing chamber yek compressor gas û pipes di nav high-pressure chamber û low-pressure chamber de connect kirin. Di dema ku gas pressure di high-pressure chamber de dikareve û gas pressure di low-pressure chamber de bibe heta limit ên, gas compressor start bike da ku SF₆ gas di low-pressure chamber de bi high-pressure chamber pump bike, system gas automatic closed-loop form bike.

2.2 Bîrûyên Darchîna Barkî yên SF₆ Single-pressure

Struktur single-pressure simple û ji bo range wide ambient temperature adapte bike. Gas compression type jî çavkanî peyda kirin: li ser ark blowing, first-generation single-pressure type ji bo structure single-blow, derdîn dargûnî qetir (girîng 31.5kA) û voltage fracture port qetir (girîng 170kV). Second-generation single-pressure type ji bo structure double-blow, derdîn dargûnî çetir (40-50kA), û voltage fracture port qetir. Girîng, 252kV products ji bo double fracture ports hene. Third-generation single-pressure type ji bo structure double-blow supplemented ji effect thermal expansion (arc extinguishing hybrid). Derdîn dargûnî çetir, çetir 63kA, û voltage fracture port çetir. Single fracture port çetir 252kV, 363kV, 420kV, hata 550kV bike.

Çavkanî single-pressure, ji perspektîf ark extinguishing chamber, piston gas compression smaller adopt kirin. Avantajên li ser reduce piston di ark extinguishing chamber de wek hejmara:

• Mass entire motion system ji bo interruption process product dikareve.

• Power operating product dikareve.

• Buffering product easier bike, û cihanî mechanical dirêj e.

2.3 Bîrûyên Darchîna Barkî yên SF₆ Self-energy

Bîrûyên darchîna barkî yên SF₆ self-energy ji bo two principles arc extinguishing hene: principle thermal expansion û principle arc rotation. Hûnkar, majority vast majority self-energy circuit breakers ji bo principle thermal expansion bikar dihin. Principle self-energy yekam ji bo energy ark da gas SF₆ di expansion chamber de heating, build pressure, form gas flow, û xebîtkirina ark. Li vir eynîn, di dema ku derdîn qetir, ji ber energy ark qetir, piston small required da compress gas da auxiliary blow form bike. Ji ber significant reduction operating power, mechanism operating spring ji bo structure simple bikar bike. Thermal expansion type jî çavkanî peyda kirin. First-generation products achieve effect reducing operating power ji bo reduce energy gas compression required ji bo xebîtkirina ark. Diameter gas compression piston design kirin according to interrupting 30% maximum fault current, û mass motion qetir, reduce operating power. Second-generation products further improve effect thermal expansion û performance interrupting, not only improve interrupting capacitive current but also further reduce operating power.

2.4 Bîrûyên Darchîna Barkî yên SF₆ Intelligent

Caracteristic another modern high-voltage circuit breakers intelligence, evolving from traditional electromechanical systems into modern intelligent systems centered around computers. Currently, online detection contents of high-voltage circuit breakers are as follows:

• SF6 gas;

• Operating mechanism system;

• Release;

• Control and auxiliary circuits;

• Power transmission chain.

Li vir eynîn detections, more than 90% of the faults can be discovered. Online detection can change the regular maintenance of circuit breakers to real-time condition-based maintenance.

3. Porcelain Post Type and Tank Type SF₆ Circuit Breakers and Their Applications

China first applied SF₆ circuit breakers in 1970 when the Northeast Electric Power Administration imported three H-912 type 220KV double-pressure porcelain post type SF₆ circuit breakers produced by Siemens from abroad and installed them in the HuShitai primary substation in Shenyang. They are still operating well today.

High-voltage sulfur hexafluoride circuit breakers are divided into porcelain post type and tank type according to their structure. When comparing the two, they each have their own characteristics:

• Both porcelain post type and tank type high-voltage SF₆ circuit breakers can meet the requirements of high voltage and large capacity. The arc extinguishing chamber of the porcelain post type is installed on the insulating support. By connecting the arc extinguishing chambers in series and installing them on the insulating support at an appropriate height, any rated voltage value can be obtained. The insulating support is mostly a porcelain post, and organic composite supports have also emerged. The arc extinguishing chamber of the tank type is installed in a metal tank connected to the ground potential. Under high voltage, multiple arc extinguishing chambers need to be connected in series and installed in the same tank for each phase.

• Installation of current transformers. In terms of installing current transformers, porcelain post type circuit breakers are at a disadvantage. Because the arc extinguishing chamber of the porcelain post type is installed inside the insulator and on top of the insulating support, the current transformer must be installed separately on its own insulating support. However, the bushing type current transformer can be installed on the bushing of the tank type circuit breaker. In some application scenarios, the circuit breaker does not need to be equipped with a current transformer, especially when used as a switch for switching capacitor banks and shunt reactors. Here, the price of the porcelain post type is only 60% of that of the tank type circuit breaker, and due to the use of multiple fracture ports, it can better withstand re-strikes.

• External withstand voltage capacity. From the perspective of external withstand voltage, multiple series arc extinguishing chambers of the porcelain post type circuit breaker can meet any rated voltage value, but its external insulation withstand capacity is limited by the length of the arc extinguishing chamber itself. For the tank type circuit breaker, as long as the necessary withstand capacity for reducing the number of fracture ports can be developed, an insulating bushing can be manufactured. Therefore, the tank type circuit breaker can achieve a single fracture port of 550kV/63kA and a double fracture port of 1100kV/50kA.

• Consumption of SF₆ gas. In terms of the consumption of SP6 gas, the porcelain post type is superior to the tank type. The gas consumption of the tank type circuit breaker is much higher than that of the porcelain post type.

• Environmental adaptability. From the perspective of environmental adaptability, the large-volume tank type circuit breaker shows its advantages. A heater can be installed in the tank type circuit breaker, while it cannot be installed in the porcelain post type.

• Seismic resistance. From the perspective of seismic resistance, the tank type circuit breaker is far better than the porcelain post type. Because the porcelain post type circuit breaker has a high center of gravity, its seismic resistance is poor.

• Price comparison. In terms of price, for the same capacity, the porcelain post type circuit breaker is better than the tank type. Generally, the price of the tank type circuit breaker is about 20% higher than that of the porcelain post type circuit breaker with an external current transformer (such as an SF₆ transformer).

4. Issues to be Noted During the Operation and Maintenance of SF₆ Circuit Breakers

In order to strictly control the gas leakage and prevent moisture and dampness from invading the box, the processing technology and material requirements are much higher than those of general high-voltage electrical appliances. At the same time, a special SF₆ gas system is required, including a valve with good sealing performance, leak detection equipment, a gas recovery device, and pressure monitoring. In addition, due to the large consumption of metal, the manufacturing complexity is increased.

Pure SF₆ gas is colorless, odorless, non-toxic, and non-flammable. However, in the synthesis of sulfur hexafluoride, low-fluoride compounds of sulfur are also produced, which are toxic. In the circuit breaker, the gas will be decomposed under the high temperature of the arc through dissociation and ionization, generating highly toxic gases. Therefore, an adsorber is installed in the circuit breaker, and activated aluminum is placed in it to absorb these toxic gases.

Even so, special attention should be paid to preventing poisoning during maintenance. Therefore, the gas must be evacuated and discharged cleanly before work. If an unpleasant odor is still smelled, a gas mask and rubber gloves should be worn. In addition, the arc decomposition products also contain some metal fluorides, which are scattered in the circuit breaker in powder form. Although these powders are not highly toxic substances, precautions should still be taken to prevent them from being inhaled during cleaning.

5. Conclusion

With the continuous increase in the voltage of the power system, whether it is the porcelain post type or the tank type of SF₆ circuit breakers, they are constantly evolving with technological progress. In particular, in recent years, the self-energy arc extinguishing principle has been developed and applied, that is, high pressure is used to form a gas blow to extinguish the arc. The number of fracture ports is reduced, and the consumption of materials is decreased.

Due to its relatively high price and high requirements for the application, management, and operation of SF₆ gas, it is not widely applied in medium voltage (35kV, 10kV). In general, high-voltage SF₆ circuit breakers have a broad application prospect, and the technological research, development, and upgrading of products will bring significant economic and social benefits.