150kv Hydro Electric Power Plant Switchyard

Hydro Electric Power Plant Switchyard
HEPP switchyard accepts and distributes electric energy from water turbine generator, and transmission to place of high-voltage distribution device in grid or load point. The switchyard is composed by transformer, switch device, disconnecting switch, current transformer, voltage transformer, arrester, bus device and related structure. The electric energy will raise to required voltage after passing through main transformer, then the long-distance transmission from switchyard will be start.

Transformer yard
It is the place where transformer installed, and there are two arrange methods.
- 1. Outdoor type
It will be different according to structure of powerhouse of HEPP, capacity of HEPP and the arrangement of the whole plant, that it can be placed between powerhouse and dam, on the draft platform, on the one side of main power house or top side, and some also place on the hill near main powerhouse.
- 2. Indoor type
For the powerhouse underground or inside the dam, it was trend to place in the underground house or sideway inside the dam which was parallel with main powerhouse. And the transformer yard should be separated from switchyard by wall if the switchyard also placed inside the underground house.
Generally, the transformer yard for HEPP should close to main powerhouse as much as possible to short voltage bus from generator and reduce losses of electric energy as well. Beside that, the following items should be taken fully consideration as blame-proof, explosion-proof, lightening-proof, moisture-proof, air cooling, transportation and maintenance.

Switchyard
It can be divided into indoor and outdoor distribution device according to the place where electric apparatus are placed.

Outdoor distribution apparatus
It can be divided into low type, middle type, mid-high type and high type according to the height of electric apparatus and bus.- 2. Middle type, all electric apparatus installed on a support with required height to make sure necessary height between charging parts and ground, and the bus arranged higher than the level of electric apparatus. This type has been widely applied around the world because of huge experience has been accumulated.
- 3. Mid-high and high type, the electric apparatus and bus were installed in the level of different height separately and overlap. The mid-high type is overlap arrangement of bus and circuit breaker, current transformer and so on. And high type is overlap one set of bus and its disconnecting switch with other set of bus and related disconnecting switch. Disadvantage of high type is large amount of steel structure required, difficult in operation and maintenance, and the same for mid-high type.
However, the high type also has its own advantage of less land required, generally half of middle type, along with problem solving during operation and maintenance as well as its properties of suitable for the power plant located at steep place, it has been applied by many HEPP step by step.
And the ladder type arrangement can also be applied according to the special site condition to reduce land requirements and earth excavation amount further.

Indoor distribution apparatus
Place electric apparatus of 110kV and 220kV inside according to the arrangement of HEPP, the distance among each device is less than the outside one, so, the land requirements is lower and the influence from serious outside environment can be avoid. However, it will need more cost for civil construction and more time needed as well. Sometimes, partial equipments can be placed outside to reduce construction cost.

SF6 full closed combined electric apparatus distribution device
It is of new type high voltage device composed by SF6 full closed combined electric apparatus, where SF6 gas was used as material for insulation and arc extinguishing, quality resin epoxy insulator as support. Such equipments as bus, disconnecting switch, grounding switch, transformer, arrester, cable terminal and so on can be make to standard separate structure of different wiring, that can be used for distribution device of different wiring.
The advantage is much less area needed as well as more safety, reliability, long maintenance period, lower noise and more suitable for the large HEPP in the high mountain.

What we can do to facilitate your work on the construction of HEPP switchyard?
- Design the switchyard according to the specification of the power plant as well as the unit inside.
- Work out single line drawing accordingly.
- List all the equipment needed in the switchyard and technical requirements for them.
- Procurement of all of these equipments from quality factory with reasonable price.
- Arrange manufacture, package, delivery and shipment of these equipment according to fixed schedule.
- Send our engineer to supervise the installation and commission of the switchyard.
- Help client to do related test and get final approval on the switchyard from government public department.

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