The box-type substation is a kind of new complete equipment which can penetrate into the load center as the electricity and distribution. Its application in China has just begun, it adapts to power system transmission and transformation equipment to oil-free, miniaturization, low loss, low noise, complete set, non-polluting, maintenance-free direction of development, it occupies less land, the installation of rapid and convenient, Box Type Transformer Substation reliable operation, mobile convenience, less investment and other advantages, more and more users trust and affirmation, is widely used.
Structure and performance of box-type substation
The box-type substation is composed of high voltage switchgear, transformers, Low-voltage switchgear and power compensation devices, which form a compact and variable distribution unit in one or several boxes. It is mainly used in replacing traditional civil substation and realizing the function of changing power distribution. At present, it is mainly used in 3-35kv distribution system users. High-voltage Line into the box-type substation, after the high-voltage switch, from the transformer into low pressure, and then through the low-voltage main switch and branch switch to the final electrical equipment. Box Type Transformer Substation Box variable specifications are more, specific can be categorized as:
1 from the wiring scheme: can be divided into single end loop, double end loop, loop network loop three kinds of schemes.
2 According to the use of conditions: can be divided into indoor and outdoor two forms.
3 According to the structure: can be divided into one style and split. One-piece is mainly used for outdoor, the split is mainly used in indoor.
4 from the enclosure: can be divided into steel plate shell, composite plate shell, Box Type Transformer Substation aluminum alloy shell and so on.
Third, the Characteristics of box-type substation
Box-type substation is a combination of products, it has the following characteristics compared with conventional equipment:
1) compact structure, investment province, small footprint. Because the box change is the distribution of several large parts in a closed box, through optimal design, reasonable combination, Box Type Transformer Substation the insulation distance between the components greatly reduced. It compresses the footprint and occupies space. The box becomes about 6-10m2, can be placed directly on the green belt. The design data show that compared with the traditional civil substation, the use of box can reduce the footprint of about 80%, and eliminate land acquisition and housing costs about 60%.
2 Easy installation and quick construction. The main components of the box change and two times wiring are assembled in the factory and shipped to the site after commissioning and passing the test. The installation of the crane in the construction of the base to be fixed, one day can be loaded into operation, Box Type Transformer Substation installation greatly simplified, the workload greatly reduced, speed up the construction progress, shorten the installation period, save the construction costs, has significant economic value.
3 High reliability and safety. General conventional substation electrical equipment, due to the long-term outdoor, its insulation and conductor susceptible to atmospheric pollution and deterioration. The box changes due to the characteristics of structural design, the conductor, internal insulation, contact parts, such as completely enclosed in the box, the protection of the shell can generally be Ip2x and Ip3x or higher, Box Type Transformer Substation not easily affected by external pollution, not easy due to dust, rain, salt, fog, animals and external damage caused by accidents, high reliability. The box is not exposed to the outside of the box, and will not cause short circuit and electric shock hazard. High-pressure side has a complete five prevention measures, equipped with mechanical and electrical chain, high security.
4 The general interchangeability is strong. Box variable high-low pressure scheme is complete, high and low voltage between the line scheme can be any combination, high-low pressure equipment and components can choose a variety of famous or imported products; transformer can choose dry or oil-immersed transformers, Box Type Transformer Substation electrical components versatility, interchangeability strong.
5) easy to operate and maintain. Each room has an automatic lighting device, transformer room has track and transformer car, easy to install and replace the transformer, open the box door can be high and low pressure room maintenance.
6 flexible in and out of the cable. High-voltage introduction of the use of cable or overhead line, low voltage leads to the use of cable, introduction, Box Type Transformer Substation the cable can be buried directly or ditch road to high-voltage power supply and users, can also be led to the pole.
IV. Equipment SELECTION
1 High Voltage Switchgear cabinet
There are two ways to configure high voltage switchgear in box changing: One is circuit breaker, the other is load switch and fuse. Because the circuit breaker volume is big, the price is expensive, and the maintenance workload is big and so on reason, general design, recommends chooses the second method. The first approach is used only at higher requirements. High-voltage switchgear cabinet can be made of domestic switches or imported switchgear.
Transformers can be used oil-immersed transformers or dry-type transformers. Dry type transformer is recommended. Dry-type transformer with low loss, low noise, no oil and other characteristics, can avoid the traditional oil leaching products leakage, explosion to the environment pollution, no fire hazard, has good environmental value. When choosing the transformer, it is suggested that the transformer belt Wen Xian, temperature control, Box Type Transformer Substation fan and 0 sequence protection equipments.
3 Low voltage switch
Low-voltage switch variety, users can be selected according to need, recommended low voltage switch belt tripping coil and leakage protection.
The protected configuration can be configured according to the needs of the user, and the recommended box changes with the following monitoring, alerting, control and protection methods:
High-voltage equipment set high voltage current-limiting fuse protection, single-phase short-circuit protection, overload protection and five-guard security.
The transformer is provided with high temperature start-up fan and tripping protection (high voltage switch tripping) and 0 sequence protection.
Low-voltage equipment installation Main switch has over-current tripping, shunt tripping, Box Type Transformer Substation bypass switch over-current tripping and leakage protection.
The box is changed to set emergency tripping button and incident sound and light alarm. Sound and light alarm signal is taken from transformer short-circuit, 0 sequence, temperature protection, HV circuit breaker fault protection, low voltage main switch overcurrent protection, bypass switch overcurrent and leakage protection.
Because the box-type substation has the small footprint, the installment is quick and convenient, the electrical performance and the mechanical performance is good, the appearance is neat beautiful, the investment is few and so on merit, can in depth the load center, may use in the urban public construction, the concentrated residential area, the factory, the mine, the It is expected that there will be a wider application in the near future.