Box-type substation structure composition

1. Box structure:

The box body of the European-style substation is composed of three parts: the base, the shell and the top cover.

The base is generally made of channel steel, angle steel, flat steel, steel plate, etc., and is welded or connected with bolts to form a fixed shape; in order to meet the needs of ventilation, heat dissipation and wire access, strip holes and moderately sized circles should be opened at the corresponding positions.形孔。 Shaped hole. The box shell, roof channel steel, angle steel, steel plate, aluminum alloy plate, color steel plate, cement board, etc. are bent, assembled or connected by screws, hinges or related special accessories.

Regardless of the material of the box-transformer shell, it must have the following five prevention functions: sun, rain, dust, rust, and small animals (such as snakes). In order to prevent the strong solar radiation in the hot summer, the shell of European-style substation is generally equipped with insulation material with low thermal conductivity as filler. Commonly used fillers are: rock wool board, polystyrene foam and so on.

In the traditional "combined substation" of unified design, the shell is usually filled with insulating filler. This method is no longer adopted by most designers. This is because the insulating filler can prevent strong sunlight in the hot summer. Radiation also hinders the dissipation of a large amount of heat generated during the operation of the transformer. Therefore, in addition to the method of piercing the blind holes on the shell, the designers also adopted the method of increasing the heat dissipation area and strengthening the air convection to reduce the heat dissipation. manufacturing cost.

The surface of the European-style box change: There are many methods for the surface of the European-style box change. In northern China, most of the traditional methods such as painting, baking and spraying are used for treatment; in the economically developed areas of southern China, in addition to the above methods, Paste colored tiles on the outer shell of the cement board structure, or paste veneers and other methods for surface treatment, especially the appearance of the box change in the residential area, which is more coordinated and unified with the style of the local buildings.

2. Structure of high voltage power distribution device:

European-style box substation high-voltage power distribution devices can be divided into two types from the way of entering: terminal type and return type; from the direction of incoming line, it can be divided into: overhead entering from the top of the box (traditional box transformer uses this method to Many) and the use of high-voltage cable trenches to enter and exit lines from underground, which is a more common method of modern design.

At present, there are many SF6 series load switches that use SF6 gas as the arc extinguishing medium, and their cost is higher than the FN-10 series high-voltage load switches. This kind of switch structure has fuse, no fuse, grounding switch, etc., but it is generally equipped with a live display; the operating mechanism is generally manual, but also electric. With a fuse, when the circuit has a short circuit fault, it can automatically cut off the switch to protect the circuit, transformers, switches and other equipment.

There are also vacuum switches that use vacuum as the arc extinguishing medium. This type of switch can be used alone or with a fuse, and can also be used in series with SF6 series load switches, but this will increase the cost, if the user has no special This is not required to be used.

High-voltage metering: In high-voltage power distribution devices, if users have high-voltage metering requirements, a high-voltage metering cabinet must be installed.

Power supply departments across China have no unified requirements for high-voltage or low-voltage measurement. The power supply regulations in Northwest China stipulate that when the transformer capacity is greater than 160KVA, high-voltage metering must be adopted; the switch of the high-voltage metering cabinet must be controlled by the power supply department. The power supply departments in North China such as Beijing and Tianjin believe that the low-voltage side should be used for the measurement of box-type substations. In this way, the reliability of power supply can be improved, the unstable factors caused by high-voltage measurement can be reduced, and the loss of the transformer itself can be converted into electricity bills. , Borne by the user.

The structure of the high-voltage metering cabinet of the box-type substation is generally composed of CT, PT, meter, remote control, and telemetering devices.

3. Transformer room structure:

European-style box substations are equipped with independent transformer rooms, which are mainly composed of transformers, automatic temperature control systems, lighting and safety fences.

When the transformer is running, a large amount of heat will be generated in the box transformer and dissipated to the transformer room. Therefore, the heat dissipation and ventilation of the transformer room are the key issues that should be considered in the design of the European box transformer. When the transformer is running, a large amount of heat is continuously generated. Make the temperature of the transformer room continue to rise, especially when the ambient temperature is high, the temperature rises faster, so only relying on natural ventilation to dissipate heat often cannot guarantee the reliable and safe operation of the transformer; in the design of the European-style box change, except for the box with a smaller transformer capacity In addition to the use of natural ventilation, temperature measurement protection is generally designed, which is solved by forced exhaust measures. The system mainly consists of a measuring device that can measure the room temperature and oil temperature of the transformer. Then, through manual and automatic control circuits, whether the exhaust fan needs to be put into operation is set and controlled according to the setting range of the transformer's reliable and safe operating temperature.

In the European box substation, the transformer can be either an oil-immersed transformer or a dry-type transformer. However, since the price of dry-type transformers is relatively high, oil-immersed transformers should be preferred to reduce the manufacturing cost if the user has no special requirements. cost. The transformer capacity is generally 100-1250KVA, and the maximum should not exceed 1600KVA.

4. Structural design of low-voltage chamber:

The low-voltage chamber of the European-style box-type substation should be different in design structure according to the use occasions of industrial and mining enterprises or residential communities. Generally, for the European box transformers used by industrial and mining enterprises, power supply and lighting power supply should be designed separately. When using low-voltage metering, under normal circumstances, the Power Supply Bureau requires separate metering of lighting electricity. This is mainly because the unit price of lighting electricity is generally higher than power electricity. The structural design of substations used in residential quarters does not need to consider the issue of power consumption.