Switchyards

TPP Brestanica has 3 main switchyards:

1. 110 kV GIS switchyard,
2. 10,5 kV GIS switchyard,
3. 0,4 kV switchyard.

Since the beginning of the millennium, many studies have pointed towards the need to replace the old 110 kV open-air switchyard. Grid development and new production units on our site have increased the short–circuit power, which surpassed the capabilities of the open-air switchyard that was in operation at the time.
Elektro Slovenija (ELES), Elektro Celje (EC) and TE Brestanica (TPP Brestanica) joined forces and in 2006 started the project to build a new switchyard. GIS type was the best possible solution to insure reliable operation and fit into the limited space available.
Areva’s B65 type GIS with SF6 insulation gas won the primary equipment tender, control and protection went to ABB. Construction was completed in 2009.
The new switchyard has a double bus bar system with 17 bays. It houses enough space to fit additional 4 bays if needed.
Main features in the GIS switchyard are:

• Local command centre
• Own consumption distribution
• Rectifiers and inverters
• DC batteries
• Diesel generator
• IT room

TPP Brestanica is an independent offsite auxiliary power supply for nuclear power plant Krško, therefore it must be able perform a black start. To achieve this, several fast manipulations must be carried out in the GIS switchyard. For this reason, "emergency operation mode" was implemented. It enables the TPP Brestanica operating personnel to gain full control over RTP Brestanica.
In the annex of the building, Elektro Celje built a new 20 kV switchyard, which replaced the old 20 kV one, located on TPP Brestanica site. Two new 110 / 20 kV transformers were implemented at the same time.
The deconstruction of the old, open-air switchyard had a positive effect on the environment and the surrounding town. Overhead cables, wires and pillars were taken down, thus the appearance and the feeling in the town improved.


10 kV switchyard with 110/10 kV transformation was the main connection to the power grid through the history of TPP Brestanica. But with the erection of PB4 and PB5 it only serves as a system to provide own consumption.
With new GT units PB4 and PB5, additional auxiliary systems needed to be powered. Two new 10/0,4 kV transformers were introduced, but the old 10 kV switchyard was not suitable to simply connect them. In the year 2000 a new 10 kV GIS nitrogen insulated, double bus bar switchyard was built to service our needs. This modern, flexible, remote controlled switchyard enabled other big projects in TPP Brestanica to go underway.
Today, very important electrical equipment is connected to the 10 kV GIS switchyard:

• 110/10,5 kV transformer
• Four 10,5/0,4 kV transformers
• 20/10,5 kV transformer
• 10,5 kV cable connection the water pumping station

Each bay has a control and protection module, connected to the MicroSCADA control system.
As mentioned before, new production units PB4 and PB5 also brought new consumption in the 0,4 kV grid. For the lack of space and fire safety, a new location for the 0,4 kV switchyard was chosen. It is now situated next to the 10 kV GIS. The 0,4 kV switchyard has 4 separate segments, powered by 4 separate 10,5/0,4 kV transformers. Segments can be easily connected with each other by simple switch manipulations. This gives it great flexibility and reliability even during maintenance of certain parts of the switchyard.