Ang mga high-voltage SF₆ circuit breakers mao ang pinaka gamit nga switchgear sa mga substation. Regular nga pag-inspeksyon ug pag-maintenance nianhi makatabang sa pag-ensuro sa stable nga operasyon sa sistema sa kuryente. Sa wa pa, sa field sa pag-maintenance sa substation, lalo na sa panahon sa pag-maintenance sa high-voltage SF₆ circuit breakers, adunay daghang hazard points (tulad sa poisoning, electric shock, etc.), nga seriozo nga nag-banta sa personal nga seguridad sa mga workers. Batasan niini, ang paper niini gipag-analisa gikan sa perspektibo sa location ug safety control technologies, uban ang layo nga objetivo nga mapabuto ang seguridad sa operasyon sa pag-maintain sa substation ug mapakita ang accident rate.
1 Pagsusi sa Working Principles ug Characteristics
1.1 Physical ug Chemical Properties sa SF₆ Gas
Ang molekula sa SF₆ gisusok pinaagi sa usa ka sulfur atom ug siyam ka fluorine atoms, may atomic weight nga 146.06, 5.135 beses mas dako kay sa hangin. Ubos 150°C, ang gas sa SF₆ nagpakita og maayo nga chemical inertness ug wala mag-react sa common nga metals, plastics, ug uban pang materyales sa circuit breakers. Kini gitawag isip walay kulay, walay odor, non-toxic, ug transparent nga non-combustible gas, nga karaniwan dili mog-breakdown (insoluble sa transformer oil ug sparingly soluble sa tubig). Sa wa pa, pinaagi sa pag-bukas ug pag-tupi sa switches, ang gas sa SF₆ mobreakdown bahin sa epekto sa discharge ug arcs, nga nagbuhat og decomposition products sa form sa gas o powdery, tulad sa metal fluorides, SOF₂, SO₂F₄, etc., nga ekstremong masama sa lawas. Sa diin, ang gas sa SF₆ mobreakdown ug dissociate pinaagi sa epekto sa arcs (molecules sa polyatomic structure mobreakdown ngadto sa single atoms o charged particle gases), ug ang internal changes nakapagtubag sa pagtaas sa iyang thermal ug electrical conductivity.
1.2 Working Principle sa High-voltage SF₆ Circuit Breakers
Ang SF₆ circuit breaker gisusok pinaagi sa tulo ka vertical porcelain insulator units, baw taas may gas-blast arc-extinguishing chamber. Ang disenyo niini nagbutang sa circuit breaker compact, samtang may maayo nga insulation ug arc-extinguishing performance. Ang gas-blast arc-extinguishing chamber mao ang core component sa high-voltage SF₆ circuit breaker, ug ini full sa gas sa SF₆ pinaagi sa pipes nga konektado sa tulo ka arc-extinguishing chambers. Sa panahon sa pag-bukas sa circuit breaker, ang controllable contact mo-separate gikan sa fixed contact, nagbuhat og arc. Sa wa pa, ang gas sa SF₆ sa arc-extinguishing chamber quick nag-blow ngadto sa arc pinaagi sa pipes, paggamit sa gas's insulation ug arc-extinguishing properties aron quick moputli ang arc. Kasagaran, ang spring operating mechanism ug ang iyang single-box control equipment mao ang key components para sa pag-drive ug pag-control sa movement sa contacts sa high-voltage SF₆ circuit breaker. Kini kasagaran gisusok pinaagi sa springs, connecting rods, transmission mechanisms, microprocessors, o programmable logic controllers. Sa panahon sa circuit breaker gibukas o tupi, ang control equipment mag-release og instruction aron ang spring operating mechanism mobiya ug drive ang movable contact movida ngadto.
1.3 Performance Characteristics sa High-voltage SF₆ Circuit Breakers
Kumpara sa hangin ug transformer oil, ang gas sa SF₆ may characteristics sa high insulation strength, excellent arc-extinguishing performance, ug small volume, ug may broad application prospects sa high-voltage power field.
- Blocking effect: Ini full play sa arc-blowing effect sa gas flow. Ang arc-extinguishing chamber small sa size, simple sa structure, large sa breaking current, short sa arcing time, wala reignition sa panahon sa pag-bukas sa capacitive o inductive current, ug low over-voltage.
- Long electrical life: Ini can continuously break 19 times sa full capacity sa 50kA, may cumulative breaking current sa 4200kA, long maintenance cycle, ug suitable para sa frequently-operated scenarios.
- High insulation strength: Ang gas sa SF₆ can pass various insulation tests sa large margin sa 0.3MPa. Pagkatapos sa cumulative breaking current reach 3000kA, ang every breaking port can withstand a power-frequency voltage sa 250kV sa loob sa 1 minute sa 0.3MPa, ug can still withstand a power-frequency voltage sa 166.4kV kung ang pressure sa gas sa SF₆ gi-reduce sa zero gauge pressure.
- Good sealing performance: Ang water content sa gas sa SF₆ relatively low. Ang arc-extinguishing chamber, resistors, ug supports can be divided into independent gas compartments para sa pag-prevent sa dirt ug moisture sa pag-enter sa interior sa circuit breaker.
- Small operating power ug smooth buffering: Ang transmission ratio sa working cylinder sa mechanism ug arc-extinguishing contact 1∶1, ug ang mechanism has stable characteristics. Ang stability sa characteristics sa mechanism can reach 3000 times (10000 times sa test environment), ug ang operating noise less than 90dB.
2 Pagsusi sa Hazard Points sa Substation Maintenance Sites
2.1 Types ug Characteristics sa Hazard Points
Ang mga hazard points sa substation maintenance sites mainly include four types: electrical hazards, mechanical hazards, chemical hazards, ug environmental factors. Kini nga mga hazard points may directly o indirectly threaten the personal safety sa maintenance personnel.
- Electrical hazards: Caused by equipment insulation damage o operational errors, mainly manifested as high voltage ug arcs. Since the circuit breaker carries high voltage during operation ug has capacitive ug inductive effects, residual charges may still exist even when it is in the open-circuit state, leading to electric shock injuries. Arcs may generate high temperatures ug cause fires.
- Mechanical hazards: The hazards mainly come from the mechanical components of the equipment. If not properly operated ug maintained, one may be pinched or bumped by rotating or moving parts.
- Chemical hazards: SF₆ gas is stable at room temperature, but it begins to decompose under the action of arcs, corona, etc. Inhaling the generated gas may cause dizziness, pulmonary edema, or even death.
- Environmental hazards: Performing maintenance in weather such as thunderstorms ug strong winds not only increases the difficulty of maintenance work but also brings uncontrollable risks to maintenance personnel. In addition, problems such as poor ventilation ug small space in the maintenance environment may also increase the danger of on-site maintenance.
2.2 Analysis sa Causes sa Hazard Points
The causes of hazard points sa substation maintenance sites mainly include equipment-related, human-related, ug environmental factors. With the increase in the number of maintenance operations, the degree of equipment wear and tear increases, leading to a decline in electrical performance ug a higher risk of accidents.
Due to the uneven quality of maintenance personnel, some of them lack sufficient understanding of the equipment structure ug working principles, ug may be negligent during actual operations. For example, due to a lack of sufficient vigilance, personnel may accidentally touch live parts or use tools inappropriately, which may directly trigger safety accidents.
For SF₆ circuit breakers, the hazards mainly stem from their chemical properties. Toxic substances generated under specific conditions are likely to accumulate indoors due to environmental limitations, further increasing the level of danger.
3 Hazard Point Location ug Safety Control Technologies
3.1 Hazard Point Location Methods
- Fiber optic sensing technology: Fiber optic sensing technology has excellent insulation performance ug anti-electromagnetic interference ability. It can effectively monitor the structural health ug electrical parameters of SF₆ circuit breakers, collect ug analyze data in real-time, ug promptly detect potential faults ug safety hazards.
- Wireless sensor network: A wireless sensor network is composed of a large number of sensor nodes. Its main purpose is to monitor environmental parameters, equipment status, ug the location information of maintenance personnel in real-time. The network has the characteristics of self-organization, self-adaptation, ug anti-interference, ug can adapt to the complex ug changeable environmental conditions on-site, realizing real-time monitoring ug location of hazard points.
- Machine vision ug infrared thermal imaging technology: Machine vision technology can identify ug locate potential hazard points, such as exposed cables ug damaged equipment, by capturing ug analyzing on-site images; while infrared thermal imaging technology can monitor the temperature distribution of equipment in real-time ug accurately locate fault points ug potential risk points.
3.2 Hazard Point Prediction Model Based on Data Analysis
At present, intelligence, digitalization, automation, ug integration are the main trends of China's power grid, ug the application of artificial intelligence ug big data technologies has accelerated this development process. During the maintenance of SF₆ circuit breakers, a hazard point prediction model based on data analysis is established, which mainly includes four steps: data collection, data preprocessing, feature engineering, ug model training.
- Data collection: Obtained through various sensors, operation records of monitoring equipment, etc. To improve the accuracy of the model, a large amount of comprehensive data should be collected as much as possible.
- Data preprocessing: Preprocess the original data (outlier detection ug processing, data transformation, etc.) to improve data quality ug lay the foundation for subsequent feature engineering ug model training.
- Feature engineering: After preprocessing is completed, useful features for hazard point prediction need to be selected from a large amount of data. These features should have good discrimination ug predictive ability to improve the accuracy of the model.
- Model training: SVM (Support Vector Machine) is a commonly used classification ug regression analysis method. It separates different categories of data by finding the optimal hyperplane, maximizing the classification interval between the two types of data.
3.3 Safety Control Technology Strategies
To improve the accuracy ug practicality of location technologies, big data ug artificial intelligence technologies should be utilized, ug machine learning algorithms should be applied to intelligently identify ug predict hazard points in substation maintenance sites, providing more accurate location information for maintenance personnel ug reducing the risk of accidents. In substation maintenance sites, data from various sensors should be fused to improve the accuracy of location ug the accuracy of the model. Applying augmented reality (AR) technology, which integrates virtual information with the real world, can enable maintenance personnel to better understand the equipment structure ug thus solve the problem of operational errors. Relevant parties should strengthen the management of on-site maintenance work ug strictly follow the operation procedures for maintenance (see Figure 1). At the same time, develop intelligent wearable devices for maintenance personnel to obtain their location information in real-time ug monitor them in real-time to ensure safety.
4 Conclusion
In substation maintenance sites, accurately identifying ug locating hazard points is the key to ensuring the safety of SF₆ circuit breaker maintenance sites. Through in-depth research on the working principles ug characteristics of SF₆ circuit breakers, it is found that chemical factors are the main non-negligible hazard points during their maintenance process. To effectively deal with risks, new technologies, new concepts, ug new methods should be used for pre-event prevention, predicting potential risks in advance, ug providing early-warning information for maintenance personnel to ensure the smooth progress of maintenance operations.
