Pagsusi sa Standards ug Structural Performance sa gikombinadong distribution equipment
Pangutana ug Klasipikasyon sa mga Combined Power Distribution Devices
Adunay daghang klase sa combined power distribution devices. Ang kasagaran nga gigamit mao ang packaged substations, box-type transformers, pre-assembled substations, combined transformers, European-style box substations, ug American-style box substations.
Relevant Standards para sa Combined Power Distribution Devices
Ang kasamtangan nga epektibo nga relevant standards alang sa combined power distribution devices sa China mahimong maglakip sa: ang national standard GB/T 17467-1998 High-voltage/Low-voltage Prefabricated Substations, ang mechanical industry standard JB/T 10217-2000 Combined Transformers, ug ang ordering standard sa power industry DL/T 537-2002 Selection Guidelines for High-voltage/Low-voltage Prefabricated Box-type Substations.
Nadumala ang International Electrotechnical Commission (IEC) ang standard IEC1330-1995 High-voltage/Low-voltage Prefabricated Substations niadtong 1995. Ang national standard GB/T 17467-1998 High-voltage/Low-voltage Prefabricated Substations nagkabug-at sa IEC1330 standard. Sa kini nga standard, ang prefabricated substation gi-define isip "equipment nga naka-pass sa type tests ug gigamit aron mopasabot og electrical energy gikan sa high-voltage system ngadto sa low-voltage system. Inklusibo kini sa transformers, low-voltage ug high-voltage switchgear, connection lines, ug auxiliary equipment nga nahimutang sa usa ka casing".
Sa mechanical industry standard JB/T 10217-2000 Combined Transformers, ang standard definition sa combined transformer mao: "usa ka transformer nga nagkuha sa transformer body, switchgear, fuses, tap-changers, ug corresponding auxiliary equipment".
Ang ordering standard sa power industry DL/T 537-2002 Selection Guidelines for High-voltage/Low-voltage Prefabricated Box-type Substations gibag-o ang orihinal nga DL/T 537-1993 Technical Conditions for Ordering 6-35kV Box-type Substations, mahimo ang power industry standard sa box-type substations consistent sa IEC 1330-1995. Ang pagkakaiba tali sa DL/T 537-2002 ug IEC 1330-1995 (o GB/T 17467-1998) makita sa Table 1.
Ang uban nga domestic standards mahimong recommended standards. Tungod sa iba't ibang karakteristikas sa tanang industriya, adunay unique features ang bawg standard. Ang ordering standard sa power industry gi-consider gikan sa perspective sa user, batasan sa international (national) standards, ug gidugangan ang content nga ipasabot sa Table 1, naghatag og mas detalyado nga basehan alang sa selection sa equipment.
Klasipikasyon sa Combined Power Distribution Devices
Bagama may mga nabanggit nga standards, ang naming sa combined power distribution devices sa practical applications dili uniform, ug ang klasipikasyon usab nagbago-bago. Adunay duha ka pangunahing kategorya: ang una mao ang define lang sa pre-assembled substations isip European-style box substations; ang ikaduha mao ang collectively call tanang combined power distribution devices isip pre-assembled substations, ug pagkatapos divide ang pre-assembled substations sa "European-style box substations" ug "American-style box substations". Ang pipila ka suppliers, aron mapasabot ang panginahanglan sa iba't ibang users, adunay product nga may duha ka ngalan.
Struktura ug Performance Analysis
European-style Prefabricated Substation
Niadtong 1970s, ang China midala og 6-10kV integrated power distribution equipment gikan sa European countries sama sa France ug Germany. Kini nga bag-ong equipment nag-integrate sa tulo ka main components sa substation (high-voltage switchgear, transformer, ug low-voltage distribution cabinet) sa usa ka enclosure, na-establish ang konsepto sa prefabricated substation.
Niadtong Disyembre 1993, ang former Ministry of Electric Power nadumala ang industry standard DL/T 537-1993 "Technical Specifications for 6-35kV Prefabricated Substations". Sa Article 3.1 sa kini nga standard, gi-define nga: "A compact complete power distribution assembly consisting of high-voltage distribution equipment, power transformers, low-voltage distribution equipment, and electric energy metering devices enclosed in one or multiple cabinets shall be termed as a prefabricated substation, abbreviated as cabinet-type substation." Naggikan sa European designs, kini nga configuration naging commonly known isip European-style prefabricated substation.
Pagkahuman nadumala ang National Standard GB/T 17467-1998 "High-voltage/Low-voltage Prefabricated Substations" niadtong 1998, ang official terminology nagsulay sa "prefabricated substation". Pero ang users ug manufacturers padayon mosulti kini nga installations isip cabinet-type substations o European-style substations sa common practice.
Structural Characteristics:
Ang European-style substation kasagaran naglakip sa tulo ka functional compartments:
High-voltage chamber
Low-voltage chamber
Transformer chamber
Duha ka primary configurations ang gigamit:
Linear layout: Standard configuration
Triangular layout: Gi-adopt para sa complex low-voltage circuit requirements
Performance Advantages over Conventional Substations:
Load proximity optimization:
Reduces power supply radius by 40-60%
Decreases cable investment costs by 25-35%
Lowers line losses by 15-20%
Space efficiency:
Occupies approximately 10% of traditional substation footprint
Reduces civil engineering costs by 60-70%
Simplified installation:
Field construction time reduced by 50-60%
Technical Limitations and Solutions:
Ang encapsulation design nag-present og critical thermal management challenges:
Restricted heat dissipation elevates internal temperature (typical ΔT increase: 8-12°C)
Potential thermal impacts on component stability (estimated performance degradation: 3-5% per 10°C rise)
Industrial mitigation strategies include:
Advanced ventilation systems:
Labyrinth-structured enclosure walls
Axial-flow exhaust fans (typically 200-400 CFM capacity)
Thermal enhancement measures:
Radiator optimization (surface area increased by 20-30%)
Heat-resistant insulation materials (Class H or higher)
These solutions, while effective, introduce:
Structural complexity (manufacturing cycle extension: 15-20%)
Additional energy consumption (auxiliary systems: 5-8% of total load)
Acoustic emissions (typical noise level increase: 3-5 dBA)
Recent Technological Advancements:
Leading manufacturers have achieved breakthrough developments in thermal management:
Novel heat dissipation configurations for transformers (improved efficiency: 12-15%)
Optimized enclosure aerodynamics (temperature reduction: 6-8°C)
Certified high-capacity designs (≥800kVA) without forced ventilation
Compliance with GB 1094.11 dry-type transformer thermal limits (maximum winding temperature rise: 100K)
These innovations maintain compliance with national standards while achieving:
Energy savings (fan power reduction: 100%)
Noise level reduction (4-7 dBA)
Enhanced operational reliability (MTBF improvement: 20-25%)
American-style Box Substations (Combined Transformers)
Niadtong 1990s, ang American-style compartmentalized three-phase distribution transformers nadala sa Chinese market. Sumala sa American National Standard (ANSI) C57.12.26-1992 Standard for Pad-Mounted Compartmentalized Self-Cooled Three-Phase Distribution Transformers with High-Voltage Plug-in Connectors, ang high-voltage cables gitugok sa transformer pinaagi sa cable connectors sa high-voltage compartment, ug ang low-voltage cables gitugok sa low-voltage terminals pinaagi sa bolts sa low-voltage compartment. Ang oil tank sa pad-mounted compartmentalized distribution transformer equipped sa high-voltage fuses ug four-position load switches. Ang transformer makapuyo isip terminal o sa loop network, protecting ug controlling ang power supply status sa high-voltage side sa transformer.
Ang mga manufacturer sa transformer sa China migsumbit sa low-voltage circuit breakers ug electricity meters sa low-voltage compartments sa American-style products, transforming sila isip combined power distribution devices. Kini nga mga devices wide use sa residential communities. Aron ma-distinguish sila gikan sa European-style box substations, sila gitawag isip American-style box substations, o known isip combined transformers. Ang mechanical industry standard JB/T 10217-2000 Combined Transformers expounds sa standard definition sa combined transformers (as mentioned above). Sa 3.7, gitawag ang "high-and low-voltage compartments" isip "spaces where the high-and low-voltage cable terminations and the operation and control parts of electrical components are enclosed by steel plates, relying on the oil tank walls". Kini usa sa structural differences gikan sa European-style box substations.
Kini nga standard nag-classify sa combined transformers (American-style box substations) sa duha ka types sumala sa oil tank structure: common-tank type ug separate-tank type. Sa common-tank type, ang high-voltage electrical components mag-share sa transformer oil tank sa transformer body, denoted sa letter ZG. Sa separate-tank type, ang high-voltage electrical components sama sa load switches gitugok sa separate oil tank, ug ang uban pa sa high-voltage electrical components ug ang transformer body gitugok sa another oil tank. Ang oil circuits sa duha ka oil tanks wala mag-connect, denoted sa letter ZF.
Common-tank Combined Transformers
Bisan parehas ang advantages sa European-style box substations, ang common-tank combined transformers adunay additional advantages:
Smaller Footprint: Occupies approximately 3/5 of the area of a European-style box substation.
Better Heat Dissipation: The transformer is directly exposed, which is beneficial for heat dissipation. The structure is relatively simple, and the selling price is relatively low (about 3/5 of that of a European-style box substation).
Convenient Transportation and Installation: Smaller in volume, making transportation and installation more convenient.
Under the Chinese context, American-style box substations directly imported from abroad have the following deficiencies:
Transformer Oil Degradation: When the high-voltage load switch operates, the arc generated is likely to cause the decomposition of the transformer oil, affecting the overall service life of the American-style box substation.
Phase-loss Operation: When a high-voltage fuse blows, it may cause the transformer to operate under phase-loss conditions.
Limited High-voltage Circuit Functionality: The high-voltage circuit has relatively simple functions, which does not fully meet the requirements of current electrical operation regulations. For example, the high-voltage load switch has no obvious disconnection point.
To address these issues, domestic manufacturers have made several improvements. As mentioned above, low-voltage circuit breakers (usually intelligent air-circuit breakers) are added to the low-voltage compartments of American-style box substations to achieve multiple fault protections such as over-load, under-voltage, short-circuit, and grounding. This eliminates the phenomenon of high-voltage fuses blowing due to short-circuits or over-loads in low-voltage feeder lines, avoiding the phase-loss operation of the transformer. Secondly, the high-voltage part has been redesigned. For example, in terms of high-voltage protection, American-style box substations use load switches to cut off the load power supply and rely on backup protection fuses and plug-in fuses for full-range power protection.
Separate-tank Combined Transformers
So far, most of the American-style box substations produced by transformer manufacturers belong to the ZG-type common-tank combined transformers. To eliminate the shortcomings of common-tank combined transformers mentioned above, domestic transformer manufacturers have separated high-voltage components such as load switches and backup protection fuses from the transformer oil tank. High-flash-point oil is injected into the small compartments of high-voltage components such as load switches, and ordinary No. 25 oil is injected into the transformer oil tank. This not only solves the problem of transformer oil aging caused by operating the load switch but also addresses the heat-dissipation problem caused by using high-flash-point oil in the entire transformer oil tank (due to its high viscosity).
Adoption of Amorphous Alloy Transformers
The transformer is the largest-sized and most heat-generating component in a box-type substation. Its structural characteristics and the level of losses are directly related to the overall design of the box-type substation.
In 1996, China successfully developed and produced non-crystalline distribution transformers below 500 kVA, but the production volume was small, and large-scale production was not achieved. In 1998, Shanghai Xindian Electric Company introduced the design and manufacturing technology of amorphous transformers from General Electric (GE) in the United States for large-scale production. Currently, there are more than 20 amorphous transformer manufacturers. The no-load loss of amorphous alloy iron cores is 20% of that of the S9 series, showing a very significant energy-saving effect.
The ANSI distribution transformer standards also play a role in the broader context of transformer technology and market. However, the main factor restricting the adoption of amorphous alloy transformers in domestic box-type substations is the price, which requires the country to implement corresponding incentive policies. In fact, there are many incentive policies for using amorphous alloy transformers at home and abroad. According to Taiwanese manufacturers, the Taiwan region has formulated strict standards for non-crystalline alloy transformer products. Wherever users purchase amorphous alloy transformers, they can receive subsidies based on the transformer capacity, with a reward of tens of thousands of New Taiwan Dollars given per kW.
Comparison between European-style and American-style Box Substations
As mentioned above, both American-style and European-style box substations share advantages in terms of volume, floor area, and environmental coordination. American-style box substations, which are often designed with reference to ANSI distribution transformer-related norms, even have certain advantages over European-style ones in aspects such as floor area, price, and heat dissipation. For instance, in the case of the DXB(W)-1.10 type box substation, the high-and low-voltage bushings, tap-changers, oil conservators, and oil drain valves of the transformer are installed on one side wall, each enclosed in separate high-and low-voltage equipment compartments. The transformer thus forms part of the box substation's casing, while the remaining three side walls are equipped with corrugated heat sinks exposed to the air. This improves the heat-dissipation conditions and reduces certain losses.
However, since the heat-dissipation parts of American-style box substations are exposed to the air for a long time, new problems such as material corrosion due to the natural environment arise, affecting the overall service life of the equipment. Moreover, in summer, the temperature of the heat sinks of American-style box substations can reach above 80-90°C, posing a risk of scalding to people who accidentally get close to them.
European-style box substations using amorphous alloy transformers are newly developed products by domestic manufacturers. They represent a technological advancement following the amorphous alloy combined transformers (including common-tank and separate-tank types). With improvements in other heat-dissipation designs, they achieve natural cooling while meeting the national temperature-rise requirements, eliminating the energy consumption and noise of ventilation fans. Thus, amorphous alloy European-style box substations possess excellent technical characteristics.
Conclusion
With the further promotion of standards, the naming of combined power distribution devices should become more unified. The development of technology and the improvement of manufacturing processes and structures make American-style and European-style box substations more advantageous compared to traditional substations. They are better adapted to the market's demands for miniaturization, environmental coordination, multi-functionality, and reliable power supply of power distribution equipment. If the use of environmentally-friendly and energy-saving materials such as amorphous alloys can receive certain policy incentives, the technical and economic performance of domestic box substations will be further enhanced.
