[application of outdoor box substation in urban power distribution system]: 1. Introduction box substation (referred to as box substation) is not unified at home and abroad.
In November 1995, IEC 1330 (November 1995) "high and low voltage prefabrication...
One, the introduction
The name of box substation (box substation for short) is not unified at home and abroad.
In November 1995, IEC 1330 (November 1995) formally promulgated the standard of "high and low voltage prefabricated substation".
Box substation is different from the conventional civil substation, its main characteristics are:
1. Completed the design, manufacture and installation of the substation in the manufacturing plant, and completed the internal electrical wiring.
2. The substation has passed the prescribed type test.
3. The substation has been verified by the factory test.
Box is a kind of the high voltage switch equipment, distribution transformers and low voltage power distribution equipment according to certain wiring schemes in the integration of factory prefabrication of indoor, outdoor compact type distribution equipment, has a complete set of sex strong, small volume, covers an area of less, can deep into load centers, improve the quality of power supply, reducing wear and tear, the location of the power cycle is short, flexible, strong adaptability to the environment, easy installation and use, safe and reliable operation and less investment, quick effect and a series of advantages.
The boxes can be changed into urban areas, which can be installed beside sidewalks, green areas, road intersections, living quarters, production sites, high-rise buildings and other places.
The area occupied by the same capacity box change is only 1/5 ~ 1/10 of the area occupied by the civil engineering station, which greatly reduces the amount of engineering design and construction. In addition, the box change can exempt users from declaring infrastructure projects, reduce the approval procedures, and achieve less investment and quick results.
This kind of substation has been widely used in Europe and the United States, and is also accepted and favored by more and more users in China.
Ii. Overall structure of box-type station
The overall structure of the box-type station refers to the layout of the three main parts of the box-type station -- high-voltage switchgear, transformer and low-voltage distribution device.
At home and abroad, the overall layout of the box station mainly has two forms: one is combined, one is integrated.
Alleged combinative type, it is to point to these 3 parts are each one room and compose "eye" font or "taste" font is decorated.
And integral type is to point to be main body with transformer, fuse and load switch are installed inside transformer casing, form integral type arrangement.
China is an active standard of IEC standards, so the box station layout in China is a combination.
In combinatorial box transformer, the room where the high voltage switchgear is located is generally called the high voltage room, the room where the transformer is located is generally called the transformer room, and the room where the low voltage distribution device is located is called the low voltage room.
These 3 rooms can have two kinds of arrangement in station of box type, namely "eye" font is decorated and "taste" font is decorated.
The box material of the box type transformer substation developed by Beijing beinengdelishier co., ltd. with the introduction of the technology developed by delishier co., ltd. of Germany is unique. The material is composed of reinforced glass fiber polyester material with a variety of hard float bubbles.
(1) high mechanical strength, light weight, surface resistance to knock and scratch, and can prevent the invasion of harmful substances and pests.
(2) good resistance to ultraviolet radiation, good resistance to exposure, internal combustion of special materials, the heat conductivity of the shell is equivalent to about 24cm thick brick masonry heat conductivity.
The temperature inside the box can be increased due to the external temperature.
(3) this material achieves the optimal insulation value by means of embedded hard foam, and the noise reduction value reaches 379 db at 2500Hz.
(4) easy to form, good shape-variability, strong decorative, adaptability and coordination to the environment, the surface can be decorated into imitation fur surface, small gravel surface and other forms according to the user's choice, the environment has decorative effect.
(5) moisture-proof, flame retardant, corrosion resistant, able to adapt to various climatic conditions, the shell will not produce condensation due to alternating heat and cold.
(6) simple and convenient assembly, suitable for the requirements of various structures.
After the continuous market development of norincon dreischel company, at present, this kind of box station has been widely used in the urban network transformation of many cities in China, such as Beijing power supply bureau, pingdingshan power supply bureau, etc.
Because of its excellent technical performance and perfect quality and won the praise of many users.
Iii. Medium-voltage open inside the box transformer [application of outdoor box transformer substation in urban power distribution system]:
In November 1995, IEC 1330 (November 1995) "high and low voltage prefabrication...
Close the equipment
Box station, if the terminal wiring, the use of load switch - fuse combination: if the ring network wiring, the ring network power supply unit.
The power supply unit of ring network is generally equipped with load switch, which consists of two load switch cabinets as the inlet and outlet lines and a transformer circuit cabinet (load switch + fuse).
In order to reduce the interruption of power supply, it is expected that the power supply unit of ring network will have a great development.
Germany dreischer company has adopted SF6 insulated medium voltage switching equipment, which is the pioneer of SF6 insulated medium voltage switching equipment.
SF6 ring network power supply unit is characterized by greatly improved personal safety, easy installation, less maintenance, provincial, significant economic benefits.
The power supply unit of ring network is composed of intervals, generally at least three intervals, namely, two cable inlet and outlet intervals and one transformer loop interval.
Figure 1 shows the basic wiring diagram of the power supply unit of the ring network.
In the figure, switch A and B can timely restore the continuous power supply of the loop when isolating the fault line segment.
Fuse F connected to switch C provides protection in the event of internal failure of medium/low voltage transformers.
Switch C also grounding the fuse and transformer.
Ring cable is generally used in urban network. Where overhead line is used, overhead line can be led to the power supply unit of ring network, and then introduced and drawn out by cable.
In general, busbar and switch closed within the shell filled with SF6, inflation pressure is commonly 2 ~ 0 0 5 bar gauge pressure.
Because the shell is closed, so it is not affected by the external environment, improve the reliability of the equipment, and because of SF6 insulation, so it can achieve small volume, but also because of the low inflating pressure, sealing and other problems are easy to solve.
Shell of SF6 ring network power supply units generally designed for first class equipment, that is to say shell by 2 5 ~ 3 mm thick steel plate or stainless steel welded, during the life of a seal.
The shell is welded without sealing to ensure maximum gas sealing.
In order to prevent the explosion of the shell caused by internal fault, a unique fault arc limiter is used, that is, when there is an internal fault, the pressure rises and the shell bulging belly, the deformation of the mechanical connecting rod and the grounding knife immediately grounding, can eliminate the fault arc.
4. Characteristics of KSP outdoor box substation
(1) rated voltage of outdoor box substation: 12, 175, 24KV.
(2) capacity level: 250, 630, 1250KVA.
(3) the shell wall plate is composed of reinforced glass fiber polyester material with a variety of hard floating bubbles, and the surface is protected by a layer of resin that is resistant to atmospheric corrosion, ultraviolet light and engraving.
The substation is equipped with special materials that are difficult to ignite, and the heat inside the substation is transferred to the outside more slowly, thus avoiding the formation of condensation.
(4) the shell by the screw of anti-corrosion of aluminum bracket and polyester wall, a multilayer noise can be reduced in 37 9 decibels.
(5) aluminum door strip with stainless steel bolt and guide shaft liner is guaranteed to be free from maintenance, and tightened door strip is sealed to effectively prevent theft.
(6) the sales of box-type stations are equipped with a manual emergency door bolt, which can be opened from the inside if the door pin is closed.
(7) the top cover of the box is single and can be lifted. It is composed of reinforced fiberglass polyester shell filled with hard foam. The shell, wall plate and door plate meet the requirements of high insulation.
(8) movable ventilation Windows for transformer heat dissipation can be closed automatically when pressure waves may appear inside.
In the maintenable box transformer, there are waterproof multi-layer wood composite floors, and the different intervals are separated by reliable iron plates.
(9) outdoor box-type variable in structure adopted measures with the spring tension between head and body, under normal circumstances the lid closed, failure occurs when the arc, arc fault resulted from the tremendous power of the internal pressure of box body is rapidly rising, at this point, by the spring tension of raise a few centimeters to release pressure quickly, avoid explosion accidents.
(10) box-type transformer with fault arc limiter can effectively prevent radiation in case of failure in the box transformer, and the safe operation of equipment can be ensured by installing medium-voltage distribution equipment with integrated fault arc limiter.
(11) it has many functions such as rain and snow, wind and dust, moisture, small animals, explosion proof, electric shock, and misoperation.
V. conclusion
Box-type station has been widely used in foreign countries, has arisen in China.
In China, more and more box station manufacturers, the use of more and more.
In this regard must be familiar with the provisions of the international standards in this respect, especially for internal arc fault test method and test criterion, draw lessons from foreign internal arc fault in defense on a variety of measures, improve the ability of box-type stand defense internal arc fault, had better not happened, once happened, also can minimize the impact.
Combined with the reality of our country, improve the functions of box station, with excellent performance, innovative structure, quality service, meet the challenge from domestic counterparts.
