Ang mga Kasamtangan nga Aplikasyon ug mga Tindog sa Hinabang hinggil sa Solid-Insulated Ring Main Units (RMUs)

1.Kasamtangan nga Pag-aplikar sa Solid-Insulated Ring Main Units sa Medium-Voltage Distribution Networks

1.1 Widespread Application in Urban Residential Areas

Ang mga pangunahon nga komponente sa medium-voltage ring main units (RMUs) naglakip sa load switches ug fuses. Kini nga mga yunit naghulagway og daghang abilidad sama sa simple nga struktura, compact nga sukat, ug kaayo gamay nga gastos. Sa wala pa, sila maayo ug epektibo sa pag-improve sa kalidad sa kuryente ug pagtaas sa reliability ug seguridad sa power supply. Ang obserbasyon mibangon nga ang pinakataas nga rated current alang sa medium-voltage RMUs mao ang 1250A, ug ang typical value mao ang 630A. Sumala sa insulation media, ang RMUs kasagaran gisukod sa duha ka klase: air-insulated ug SF₆ gas-insulated. Kasagaran sila gigamit para sa switching sa load currents ug interrupting sa short-circuit currents, ug padayon mopasabot og certain control ug protection functions.

1.2 Vacuum Load-Switch RMUs Provide Reliable Isolation Gaps

Ang mga load switch nga gigamit sa air-insulated RMUs adunay apat ka klase: gas-generating, compressed-air, vacuum, ug SF₆. Sa tanan niini, ang SF₆ load switches ang primary switches sa air-insulated RMUs. Ang mga load switch sa sealed enclosures kasagaran adunay tulo ka operational positions: load interruption, reliable grounding, ug circuit isolation.

1.3 Enhanced Practical Application Level

Kasagaran, ang RMUs adunay compact nga disenyo. Sumala kini nga katangian, ang pipila ka load switches (kasagaran high-voltage switches) adunay simple nga struktura ug equipped og high-voltage fuses. Ang normal nga operasyon sa RMUs kasagaran gidepende sa load switches, samtang ang short-circuit currents maayo ug epektibo nga gi-interrupt sa fuses. Ang epektibo nga pagsulay sa duha ka komponente naka-maximize sa replacement sa circuit breakers, bag-o naa ra gyud limitasyon sa specific capacity ranges.

2.Development Trends and Technical Characteristics of Solid-Insulated Ring Main Units

2.1 Effective Application of Encapsulated Pole Technology

Ang epoxy resin kasagaran gigamit isip primary insulating material sa solid insulation, ug ang vacuum ang arc-quenching medium. Aron maayo ug epektibo ang pag-abli sa functions sama sa load ug current isolation, ang operating mechanism kinahanglan maayo ug epektibo nga gisulay aron makontrol ang power distribution system, ug maprotektahan ang equipment ug safety sa mga personal. Ang solid insulation maayo ug epektibo sa pag-reduce sa phase-to-ground insulation distance sa loob sa switchgear, ang air insulation gaps gikurta gikan sa 125mm hangtod sa sulod ka mga milimetro. Bisan walay SF₆ gas, ang overall volume mas gamay kaysa sa traditional C-GIS. Padayon, ang paggamit sa relatively simple nga operating mechanism maayo ug epektibo sa pag-reduce sa number sa components, ug nag-improve sa reliability sa equipment.

2.2 Technical Characteristics of Solid-Insulated RMUs

Sumala sa air-insulated RMUs uban sa SF₆ switches ug SF₆ gas-insulated RMUs, ang solid-insulated RMUs adunay daghang abilidad: Unsa, ang housing structure mas simple. Tungod sa pag-eliminate sa pressure vessels, pressure gauges, filling valves, ug uban pang gas-related components, ang reliability sa RMUs maayo ug epektibo nga ginausab, ang maintenance costs gitawag, ug ang operational condition sa switch maayo ug epektibo nga ginausab. Second, ang primary switch equipped og isolation component, nga naghatag og clearly visible break. Ang solid insulation kasagaran gigamit ang epoxy resin sleeves ug insulating tubes. Kini nga materyales maayo ug epektibo sa pag-reduce sa SF₆ liquefaction sa cold regions ug pag-reduce sa adverse effects gikan sa thermal expansion sa high-temperature areas, nga nagpakita og broad applicability sa extreme environments.

3.Issues Requiring Attention in Solid-Insulated Ring Main Units

3.1 Insulation and Surface Coating Technology

Sumala sa mechanism sa partial discharge formation, ang internal discharges sa solid insulation kasagaran gihatagan sa presence sa voids. Ang kasamtangan nga sealing techniques kasagaran involve preheating metal molds, placing preheated components sa mold, slowly injecting under vacuum, ug curing. Kini nga proseso dili efficient ug costly. Ang incomplete bubble removal mao ang nagresulta sa numerous voids sa solid insulation, kasagaran magresulta sa partial discharge sa panahon sa operasyon, kasagaran nagresulta sa long-term cracking sa insulation components ug affecting the safe and reliable operation of equipment.

Bisan, advanced, high-quality, ug efficient epoxy resin encapsulation technology kinahanglan ipasabot. Padayon, tungod kay ang surface shielding direktang makaapekto sa performance sa equipment, ang issue sa surface shielding—i.e., surface shielding technology—kinahanglan i-address sa panahon sa design ug production. Ang purpose sa metallizing sa surface sa insulation materials mao ang paghatag og reliable grounding sa solid insulation components, minimize the impact of environmental factors, ug enhance product performance. Kasagaran, significant portion sa solid-insulated RMUs sa market wala proper surface treatment, resulta mao ang high partial discharge levels sa supplied products.

3.2 Lack of Operation and Maintenance Experience

Ang solid-insulated RMUs usa ka relatively new technology. Tungod sa lack of scientific ug reasonable trial operation arrangements sa power grids, ang kasamtangan nga total operational volume gamay, ang operational time maayo, ug provincial grid connections incomplete. Bisan, sa high-temperature, high-humidity, coastal, high-rainfall, ug large diurnal temperature variation regions, practical issues kinahanglan i-address. Comprehensive work experience kinahanglan i-accumulate nationwide aron makonduktar ug targeted ug forward-looking improvements sa solid-insulated RMUs, continuously enhancing product safety ug stability.

3.3 Development of Solid-Insulated RMU Equipment

Sa recent years, sumala sa rapid development sa China's distribution network, ang technical level sa distribution system significantly improved. Ang SF₆ gas kasagaran gigamit sa medium-voltage RMUs. Sumala sa China's current development status, ang SF₆ gas best overall performance. Bisan, sumala sa increasing awareness sa environmental protection ug importance sa natural conservation, ang extensive use sa SF₆ gas sa RMUs may cause certain environmental hazards ug potential risks sa human health. Bisan, reducing the use of SF₆ gas RMUs ug promoting solid-insulated RMUs will be a primary goal for the development of high-voltage switchgear. Domestic manufacturers have anticipated this trend ug have gradually begun developing ug producing solid-insulated RMU products.

3.4 Optimization of Insulation Module Structure Design

Ang structural design sa insulation modules kinahanglan, sumala sa functional, inspection, ug installation requirements, aim to reduce material consumption ug prevent residual stress. Ang presence sa residual stress mao ang nagresulta sa internal ug external cracks sa solid insulation components, kasagaran magresulta sa partial discharge sa panahon sa operasyon ug potential insulation breakdown. Bisan, in-depth research sa overall structure, thickness, ug transitions sa insulation modules necessary, with consideration given to heat dissipation concepts.

3.5 Research and Design of Shielding Layers

Ang primary purpose sa external design mao ang plan metal shielding grounding: first, sa event sa insulation failure, confine short-circuit faults sa phase-to-ground only, reducing arc energy ug fault risk; second, maintain insulation performance sa any environment without requiring cleaning sa module's outer surface, ensuring unchanged electric field distribution even with metallic foreign objects inside the cabinet.

4.Development Directions for Solid-Insulated Ring Main Unit Technology

4.1 Development of New High-Performance Insulating Materials

Bisan ang epoxy resin performs well as a solid insulation material, ang casting process in vacuum ceramic arc-quenching chambers can damage raw materials. Bisan, developing advanced epoxy resins that surpass current material characteristics essential. In 2014, ang journal Science published an article on the discovery of a new recyclable thermosetting polymer, marking a significant advancement in the recycling of "polysalicylate" thermosetting plastics. This polymer exhibits high recyclability, addressing the issue that thermosetting plastics were previously non-recyclable. In the next decade, new products will increasingly utilize recyclable thermosetting materials.

4.2 Research on Internal Component Interface Connection Methods

Since solid-insulated RMUs are manufactured by encapsulating main circuit conductors ug mounting parts within solid insulation, the inflexibility of embedded components necessitates standardized connections between different cast elements. The overall configuration of the RMU is linear, ug connecting conductors must be cast with epoxy resin, requiring a certain degree of freedom during product rationalization. To address this, an interface technology using silicone rubber material for gate-to-conductor connections is proposed. This method enables standardization, allowing components to be interconnected ug reasonably configured, reducing the design complexity of the overall insulated enclosure.

4.3 Market Promotion Prospects for Solid-Insulated RMUs

Solid-insulated RMUs feature a simple structure, compact size, non-toxicity, pollution-free operation, ug environmental friendliness, aligning with the global green development concept. Bisan, for a product to be successful, manufacturers must profit from sales, making market application a key focus. Understanding ug meeting user needs critical to the successful introduction of new products. The application prospects of solid-insulated products are analyzed based on user requirements.

4.3.1 Products Meeting Consumer Needs

During use, users first require that product technical parameters comply with relevant standards (technical specifications, national ug industry standards, etc.) ug obtain certification from the national power industry. As no specific standards currently exist for solid-insulated products, manufacturers must assist in establishing national or industry standards. It is reported that by December 31, 2002, claims for approximately 15 million tons of solid-insulated products had been filed.

4.3.2 High User Requirements for Distribution Network Products

Medium-voltage distribution equipment is a fundamental component widely used in power grids. With the continuous expansion of grid infrastructure, demand for medium-voltage equipment as a bridge between main networks ug end-users is growing. Users require products with long service life, strong environmental adaptability, compliance with environmental standards, compact size, easy ug quick installation, economic convenience, ug a reliable operational history.

Solid-insulated RMUs have compact dimensions, with single load switch cabinet units measuring 860mm (depth) × 420mm (width) × 1200mm (height) or 850mm (depth) × 500mm (width) × 1600mm (height). Their size falls between that of air-insulated switchgear. Based on the above technical performance, solid-insulated RMUs provide enhanced personal safety. Bisan, due to their relatively short operational history, only a limited number of units are currently in service across several Chinese factories. Given the limited operational data, it is currently impossible to evaluate the aging of epoxy insulation or determine inspection cycles.

Some domestic equipment manufacturers guarantee a product lifespan of over 20 years through advanced production facilities (workshops, molds, ug automated laser welding). This represents a competitive advantage. Economically, current production of solid-insulated enclosures requires significant investment in specialized equipment, molds, ug materials, resulting in higher market prices. Additionally, as power systems primarily use equipment bidding with a focus on low prices, SF₆ RMU modules have become increasingly cost-competitive, making it difficult for solid-insulated RMUs to gain market dominance in the short term.

4.3.3 Product Environmental Requirements

In most regions, users require normal operating environments not exceeding 40°C ug not below -10°C. Bisan, the increasing frequency of natural disasters globally has raised user demands. For example, RMUs installed in harsh environments must be fully enclosed ug maintenance-free, ensuring complete insulation. Circuit breaker equipment must exhibit strong environmental adaptability, dust ug moisture resistance, short-term immersion protection, ug enhanced vibration resistance.

Casting internal components of circuit breakers with epoxy resin significantly increases the dielectric strength of insulating materials, preventing degradation due to vibration during transportation ug use. Compared to gas-insulated RMU products, some manufacturers have conducted tests in Qinghai ug coastal humid regions, as well as at altitudes around 4000m, achieving IP68 protection ratings. Therefore, solid-insulated RMU products better meet environmental requirements.

5.Conclusion

Based on the current development status of solid-insulated RMUs in China, the insulation technology is relatively mature, effectively addressing the shortcomings of air-insulated ug gas-insulated RMUs, ug suitable for special environments such as high-altitude regions. The adoption of solid-insulated RMUs can effectively promote the development of China's power grid ug contribute to sustainable socioeconomic development. With growing attention to environmental protection, it can be confidently stated that solid-insulated RMUs have broad application prospects.