Analisis sa Klasipikasyon ug mga Tendensya sa Pagkamato sa High-Voltage/Low-Voltage Prefabricated Substations
1. Pagpasilip
Ang mga prefabricated substation nga may mataas o mababang boltya, na kasagaran gisulti og "prefabricated substations", gisulat usab isip "prefab substations" o "box substations". Sa Tsina, giila kini sa daghang mga ngalan sama sa "combined substations", "combined transformers", "factory-assembled compact substations", "box-type high-voltage power receiving units", ug "prefabricated compact substations". Nobyembre 1995, ang International Electrotechnical Commission (IEC) miingon sa IEC 1330 standard nga "high-voltage/low-voltage prefabricated substations". Ang kasamtangan nga standard GB/T 17467—2020 High-voltage/Low-voltage Prefabricated Substations usab naggamit sa termino nga "high-voltage/low-voltage prefabricated substations", nga gisulti sa mas maong pag-usab isip "prefabricated substations" sa sumala nga teksto.
Ang pangunahon nga katangian sa prefabricated substations mao kini:
Ang disenyo ug pagbuhat sa produkto mahimong matapos sa factory.
Gibasehan sa type tests isip gihatagan sa standard GB/T 17467.
Gipagtumong pinaagi sa factory tests.
Ang basic composition niini nagsilbi sa tulo ka functional units, ang transformer room, high-voltage switch room, ug low-voltage switch room. Ang key components nga gibuhos sa sulod (sa standard, ang transformers, high-voltage switchgear, low-voltage switchgear, etc. gitakda isip key components) gibasehan sa type tests ug factory tests nga qualified. Kini gibuhos sa usa ka shared housing o box aron makabuo og prefabricated substation product. Ang typical scheme gibasehan sa type tests isip gihatagan sa requirements sa GB/T 17467, ug padalhon sa users para sa installation ug paggamit human ma-pass ang factory tests. Kini nagrepresentar sa basic structural form sa typical prefabricated substation.
Sa practical applications, ang automation devices, communication units, video surveillance systems, control power supply systems, fire protection systems, etc. gibuhos sa prefabricated substations, nahimong importanteng components o supplements aron mapugos ang functional requirements sa prefabricated substations sa uban-uban nga working conditions.
Ang pangunahon nga advantages sa prefabricated substations kasagaran ang high integration, small footprint, short construction period, flexible site selection, strong environmental adaptability, convenient installation ug paggamit, safe ug reliable operation, low investment, ug quick results.
Sa recent years, ang prefabricated substations nakakita og rapid development ug extensive application sa new energy power generation ug energy storage fields sama sa wind power ug photovoltaic power generation, enabling the transmission or exchange of electrical energy.
Application scenarios sa prefabricated substations: Sa distribution network, ang prefabricated substations magpadali sa distribution sa electrical energy pinaagi sa voltage reduction aron mapugos ang requirements sa end-users; sa power generation system, sila magpadali sa transmission sa electrical energy gikan sa power generation side to the grid pinaagi sa voltage boosting ug grid connection.
Ang rated capacity ug voltage level sa transformer nga gibuhos sa prefabricated substations mao ang importanteng indicators sa measurement sa scale ug configuration sa substation. Kasagaran, para sa prefabricated substations nga may transformer rated capacity nga around 10,000 kV·A ug voltage level nga 40.5 kV ug below, ang transformer ug switchgear o uban pang equipment gibuhos sa usa ka whole, o i-padala sa site sa separate modules ug pagkatapos ibuhos sa usa ka whole.
Kon ang transformer capacity adunay 31,500 kV·A, ang supporting switchgear ug uban pang auxiliary equipment gibuhos sa box sa prefabricated substation, tungod kay ang main transformers gibuhos sa outdoor. Adunay duha o dugang pa ka main transformers, nga sa dili pa matapos igbuhos sa usa ka complete substation, enabling the transmission or exchange of electrical energy.Kini nga article nagclassify sa prefabricated substations gikan sa industry development direction o ang main characteristics sa product, ug ginanalyse ang ilang development trends sa field sa substation.
2.Konventional nga Mga Paraan sa Pagkategorya sa Prefabricated Substations
Sa practical applications, ang prefabricated substations may daghang variation sa rated capacity ug structural characteristics sa transformer, rated voltage level, key components, material ug structural form sa box, application scenarios, ug main purposes. Tungod kay adunay difference sa application fields, ang industry standards ug product verification methods usab nagdiffer. Ang sumusunod nagkategorya sa prefabricated substations gikan sa uban-uban nga dimensions o based sa ilang main characteristics.
1) Classification batas sa Rated Voltage Level sa High-voltage Side
Ang prefabricated substations gikategorya batas sa rated voltage level sa high-voltage side sa: high-voltage prefabricated substations, medium-voltage prefabricated substations, ug low-voltage prefabricated substations. Ang rated voltage sa high-voltage side sa high-voltage prefabricated substations 110 kV ug above, sa medium-voltage prefabricated substations 3.6 hangtod 40.5 kV, ug sa low-voltage prefabricated substations 1.14 kV ug below.
Ang high-voltage prefabricated substations kasagaran gibuhos close sa center sa electrical load. Kasagaran sila mogamit og substation construction mode nga kombinado sa modular manufacturing ug on-site construction. Ang ilang features mao ang high voltage level sa high-voltage side sa transformer, large single-unit capacity, ug relatively large number of primary ug secondary supporting equipment.
Ang medium-voltage prefabricated substations kasagaran gamiton sa power generation systems, sa terminals sa distribution network, o sa temporary power supply scenarios. Ang ilang scheme configuration relatively simple, ang transformer capacity relatively small, ug ang manufacturing process relatively straightforward.Ang low-voltage prefabricated substations kasagaran gibuhos sa secondary control equipment, auxiliary equipment, o low-voltage switchgear sa sulod aron mapugos ang specific functional requirements.
2) Classification batas sa Usage o Installation Environment
Silag ikategorya sa indoor prefabricated substations ug outdoor prefabricated substations batas sa usage o installation environment. Ang commonly mentioned prefabricated substations kasagaran ang outdoor type. Tungod kay sa uban-uban nga factories, buildings, o sa tabi sa indoor electrical equipment nga may relatively small power load, ang supporting prefabricated substations mao ang indoor prefabricated substations. Ang ilang usage environment o protection level relatively better kay sa outdoor prefabricated substations, ug ang product itself may slightly lower requirements sa environmental protection ug safety.
3) Classification batas sa Product Installation Method
Silag ikategorya sa fixed prefabricated substations ug mobile prefabricated substations batas sa product installation method. Kasagaran, ang prefabricated substations fixedly installed sa foundation, ug ang ilang installation position remains unchanged during use.
Sa uban-uban nga application scenarios, sama sa mines, oil fields, construction sites, ug temporary maintenance power supply scenarios, kon ang construction progress advances, ang location sa prefabricated substation kasagaran mosusi. Adunay duha ka types sa mobile prefabricated substations: wheeled prefabricated substations ug skid-mounted prefabricated substations. Kon ang power supply position sa prefabricated substation mosuli, sila mahimo mopadala pinaagi sa trailer o semi-trailer.
4) Classification batas sa Material Gisulti sa Box Manufacturing
Batad sa different materials gisulti sa manufacture sa box sa prefabricated substations, sila mahimong ikategorya sa steel plate type, non-metallic type, stainless steel plate type, aluminum alloy type, color steel composite plate type, Jinbang plate type, magnesium-aluminum-zinc-coated plate type, container type, etc. Ang main characteristic mao ang materials o structural forms sa boxes sa prefabricated substations may vary, aron mapugos ang different needs sa users o usage requirements.
5) Classification batas sa Box Appearance o ang Degree of Matching sa Environment
Batad sa special requirements sa prefabricated substations sa surrounding usage environment, sila mahimong ikategorya sa ordinary type, landscape type (sama sa example, ang box surface may styles imitating Chinese ancient architecture, European architecture, artistic modeling, o affixed landscape paintings), etc. Sama sa example, ang prefabricated substation gisulti sa park may shape nga pavilion o building nga match sa park environment, ug ang surface decorated sa landscape paintings o different color tones.
6) Classification batas sa Different Installation Methods
Batad sa degree of combination tali sa prefabricated substation ug foundation, sila mahimong ikategorya sa above-ground prefabricated substations, semi-buried prefabricated substations, ug fully-buried prefabricated substations.Ang above-ground prefabricated substation installs the entire prefabricated substation sa top sa foundation. Sa semi-buried prefabricated substation, ang high-voltage switch room ug low-voltage switch room sa tulo ka basic functional rooms located sa above sa foundation, while ang transformer room located sa below ug sinks sa foundation.
Ang overall volume sa product relatively small. Ang fully-buried prefabricated substation means that ang entire product sinks sa foundation, with only inspection manhole openings o ventilation holes exposed sa above sa foundation. This type of product particularly suitable for the city center o densely populated core areas, reducing the visual impact sa product sa usage environment ug enhancing the safety and reliability sa product operation.
7) Classification batas sa Different Arrangement Methods sa Functional Rooms
Batad sa different arrangements o combinations sa tulo ka basic functional rooms (high-voltage room, low-voltage room, ug transformer room) sa prefabricated substations, sila mahimong ikategorya sa "eye"-shaped prefabricated substations, "character-pin"-shaped prefabricated substations, "H"-shaped prefabricated substations, "dumbbell"-shaped prefabricated substations, "field"-shaped prefabricated substations, etc.
Sa "eye" -shaped prefabricated substation, ang transformer room arranged sa middle, while ang high-voltage room ug low-voltage room arranged sa both sides. Its overall layout similar sa "Chinese characters" sa Chinese characters. Sa prefabricated substation sa shape sa "needle", ang tulo ka functional rooms arranged together, similar sa shape sa Chinese character "".
Sa "H" type prefabricated substation, ang high-voltage room ug low-voltage room made into separate boxes, ug ang live parts sa liquid-immersed transformer completely enclosed ug placed sa between sa two boxes. In addition, mesh shielding adopted sa both sides sa transformer for simple protection ug isolation, which improves the heat dissipation conditions during the operation sa transformer. Sa prefabricated substation sa shape sa "dumbbell", actually a set sa high-voltage switch cabinets, two sets sa transformers ug low-voltage switch cabinets.
The high-voltage room located sa middle sa box, while ang transformer room ug low-voltage room respectively sa both sides sa transformer room. The overall layout sa each functional room in the shape sa "dumbbell". Sa "field" -shaped prefabricated substation, ang low-voltage room divided into two independent compartments (the low-voltage switch room ug the automation room). Together sa high-voltage room ug transformer room, the overall layout takes on the shape sa Chinese character“Word”.
8) Classification batas sa Customary Appellation
Batad sa main characteristics ug customary appellations sa product, ang prefabricated substations ikategorya sa European-style substations, American-style substations, ug Chinese-style substations.
Ang key units (high-voltage switchgear, low-voltage switchgear, transformers) sa prefabricated substations all standard products nga finalized after type tests. Initially, sila mainly introduced from European countries such as Germany, commonly known as "European-style substations". Their main features include the interconnection ug combination sa key components, flexible ug changeable design schemes, ug relatively convenient capacity expansion sa transformer. Currently, sila widely used sa both the distribution network ug power generation systems.
According to the standard JB/T 10217, an American-style substation is a prefabricated substation in which the high-voltage switch is installed in the transformer oil tank ug the transformer oil is used as the insulation ug arc-extinguishing medium, while the low-voltage switch is installed in the low-voltage box. For example, the 10 kV economical prefabricated substation represented by the American Cooper Company is commonly known as an "American-style substation".
The main feature of an American-style substation is that the high-voltage load switch, transformer core, coil, etc. are immersed in the same oil tank, ug the transformer oil is jointly used as the insulation, arc-extinguishing, ug cooling medium. It adopts dual-fuse protection, ug the fuses have current ug temperature dual-sensitive characteristics, which greatly improve the sensitivity ug reliability sa transformer protection. The main advantages of American-style substations are small size, compact structure, simplicity, ug economy.
However, their disadvantages are also evident, such as the rapid decline in the insulation performance sa transformer oil, a simple scheme, ug low flexibility. The arc generated by the breaking ug closing sa high-voltage switch will cause the deterioration sa transformer oil quality. Currently, 10 kV American-style substations are rarely used in the distribution network ug have been classified as products that are being phased out or restricted.
After modification ug upgrading, 10 kV American-style substations have increased the voltage level to 35 kV ug are applied in new energy power generation systems. Due to their compact structure, small footprint, ug low manufacturing cost, they are increasingly being promoted ug used.
In recent years, the prefabricated substations used in new energy systems such as wind power ug photovoltaic power generation mainly function to transmit electrical energy from the power generation side with a lower voltage level to a 35 kV high-voltage substation. The transformer capacity is getting larger ug larger. If designed in the form sa "European-style substations", the transformer is installed in the transformer room in a closed manner, ug it is difficult to dissipate the generated heat to the outside.
Additional equipment such as fans or heat exchangers is required to address this issue. Therefore, a prefabricated substation with a relatively compact structure ug a liquid-immersed transformer installed outside the box has emerged. Its main features are: the transformer is installed outdoors, which solves the problems sa safety protection ug heat dissipation sa transformer, ug the manufacturing cost is significantly reduced. It appears somewhat similar to an "American-style substation" in appearance, but it essentially still belongs to a "European-style substation". When it first appeared in the industry, it was named a "compact prefabricated substation". Since it was first successfully developed in China ug applied to actual engineering projects, it has been commonly known as a "Chinese-style substation" in the industry. However, its product features are more in line with the requirements sa GB/T 40823 standard.
3. Development Trends sa Prefabricated Substations
The development trends sa prefabricated substations analyzed from the following different aspects.
1) Diversification sa Box Manufacturing Materials ug Structural Forms
The most intuitive ug noticeable change is that the structural forms sa boxes sa prefabricated substations are showing a trend sa diversification, which can be observed from the shape, color, ug material sa boxes. The box should be in harmony sa surrounding environment. For example, European-style substations generally sink 1 m underground, ug the above-ground part is not higher than 1.5 m, which neither affects the long-distance view nor causes accidental injuries if children climb up to play. The materials used are non-metallic, which are environmentally friendly ug easily coordinated sa surrounding environment.
Common materials sa outer shell include ordinary steel plates, stainless steel plates, aluminum alloy plates, ug color steel composite plates. Years ago, glass fiber-reinforced cement plates, glass fiber-reinforced plastic plates, ug non-metallic materials also came into use. Additionally, there may be several materials sa same box. For example, the outside sa an ordinary box may be decorated with wooden boards ug glazed tile decorative boards, ug heat-insulating materials such as expandable polystyrene (EPS), glass fiber, asbestos, ug aluminum silicate wool are used sa interlayer sa double-layer structure.
In terms sa corrosion resistance, fire resistance, ug resistance sa fault arcs, non-metallic material shells are significantly superior to metallic material shells. Some prefabricated substations use Jinbang plates as the shell material, which are characterized by being environmentally friendly, lightweight, high-strength, sound-insulating, heat-insulating, water-resistant, fire-resistant, ug corrosion-resistant.
2) Strong Promotion ug Application sa SF6 Gas-insulated Switchgear
For prefabricated substations sa a voltage level sa 40.5 kV ug below, the high-voltage side generally uses circuit breakers or load switches insulated by air or SF6 gas, ug some products use load switches with transformer oil as the insulation medium.
In 12 kV prefabricated substations, since the transformer capacity is generally below 1,250 kV·A, combined electrical appliances (load switch + fuse) or load switches are increasingly being used. When a circuit breaker is used to protect the transformer, the time to cut off the faulty line is slightly longer, which is not conducive to the protection sa key equipment (such as the transformer). However, the fuse sa combined electrical appliance can cut off the fault current within 20 ms.
The load switch units for the 12 kV voltage level include gas-generating load switch cabinets, vacuum circuit breaker switch cabinets, vacuum load switch cabinets, ug SF6 gas-insulated switchgear. Currently, SF6 gas-insulated switchgear is the most commonly applied sa prefabricated substations, ug it has more distinct advantages sa terms sa altitude, reliability, safety, size, ug special application environments.
3) Improvement sa Transformer Performance ug Ventilation ug Heat Dissipation
In 12 kV prefabricated substations, commonly used transformers include liquid-immersed transformers ug dry-type transformers, ug their insulation performance ug no-load ug load loss values have been further optimized. In high-rise buildings, from the transformer to the switchgear, dry-type transformers that do not contain flammable materials ug are not easily contaminated by transformer oil are required.
The principle sa ventilation ug heat dissipation for transformers is: mainly natural ventilation, supplemented by forced air cooling. A common method sa forced air cooling is to install fans sa top sa transformer room or sa box wall panels to blow air out sa box, stirring the circulation sa hot air sa room. Sometimes, fans are also placed under the transformer to supply cold air inward, resulting sa a relatively good heat dissipation effect.
4) Internal Fault Arcs sa Prefabricated Substations
Internal fault arcs may occur sa prefabricated substations, ug the measures that can be taken are divided into two categories: proactive measures ug reactive measures. Proactive measures mainly aim to limit the duration sa fault arc, while reactive measures focus sa limiting the effects caused by the fault arc. Although it is impossible to completely prevent the occurrence sa internal arcs, they can be prevented. By limiting the harmful effects caused by the arc duration, the impact sa fault arc on people or equipment can be minimized.
Although the internal fault arc test is not included sa mandatory test items, it is regarded as a "mandatory type test item when applicable". Due to its direct threat sa personal safety ug the normal operation sa equipment, it has attracted great attention from manufacturers ug users. Therefore, the arc-burning test item has been gradually ug vigorously promoted sa type tests ug quality spot checks sa prefabricated substations.
5) Considerable Development sa Intelligence
Intelligence is a key feature sa smart grids ug also a development direction for prefabricated substations. Prefabricated substations with a high degree sa automation are generally referred to as intelligent prefabricated substations sa industry. The working characteristics ug responsibilities sa intelligent prefabricated substations require them to have good interactivity.
After realizing the collection ug analysis sa information, intelligent prefabricated substations can not only share this information internally but also have good interaction with more complex ug advanced automation systems sa power grid. The interactivity sa intelligent prefabricated substations ensures the safe ug stable operation sa power grid to a certain extent.
6) Development ug Main Characteristics sa "Prefabricated Cabins"
When prefabricated substations are applied sa load center sa power grid, the transformer capacity is generally large. Supporting high-voltage ug low-voltage equipment, secondary automation equipment, SVG (Static Var Generator) equipment, etc. are all installed sa box; the main transformers are installed outdoors. It has the characteristics sa prefabricating functional units ug building substations through module assembly, ug has high requirements sa structural form sa box, fire protection system, personnel safety, ug equipment monitoring. It is called a "prefabricated cabin" sa industry. In fact, it is a large-scale, modularly combined, ug on-site installed prefabricated substation.
7) Emergence ug Application Scenarios sa "Integrated Inverter"
In the prefabricated substations applied sa photovoltaic power generation systems ug energy storage systems, the traditional low-voltage switchgear is replaced by an inverter for electrical energy conversion, forming a prefabricated substation composed sa an inverter, a transformer, ug high-voltage switchgear. It realizes the conversion sa direct current to alternating current. After the alternating current is stepped up sa transformer, it is sent to a 40.5 kV switch substation sa high-voltage switchgear ug then sent to the power grid through a main transformer sa a voltage level sa 35/110 kV or 35/220 kV, or realizes the energy exchange or transfer between the power grid ug the battery pack. This is another form sa prefabricated substation.
4.Conclusion
Sa power grid, ang prefabricated substations may characteristics sa high integration, flexible schemes, diverse methods, short construction cycles, small footprints, ug low manufacturing costs. Sila increasingly widely used sa various industries, extending from the initial application to end-users sa 10 kV voltage level to the power load centers sa 35 kV (110 kV, 220 kV) voltage levels.
Because it has all the basic characteristics sa a substation, with the development sa supporting industries for components such as high-voltage switchgear, low-voltage switchgear, transformers, ug automation, it shows increasingly strong market vitality. From the distribution sa electrical energy sa distribution network to the transmission sa electrical energy sa new energy field, or the realization sa the exchange sa electrical energy between the battery pack ug the power grid or the governance sa electrical energy quality, its application is very extensive. It has also driven the rapid development sa related manufacturing industries ug the continuous improvement sa technical levels sa related industries, becoming an important part or supplement sa substations sa power transmission ug distribution industry.
