St. Nikola
The project includes 52 turbines, connected to the wind farm substation with an underground cable network, and through an overhead line the generated electricity is being transmitted to the national electricity grid of Republic of Bulgaria.
The project includes construction of:
- 52 turbines Vestas V90 3.0 MW
- 60 km of 33kV underground cable network
- 33/110 kV substation
- 5.2 km 110 kV overhead line
The Turbines
The turbines in Saint Nikola Wind Farm are a product of Vestas – a world leader in the development of modern power engineering from renewable sources. The company has installed more than 39,000 turbines in 63 countries and still is in business – every four hours somewhere in the world a new turbine is being installed. Vestas V90 3.0 MW turbines are the latest and most advanced technology of the producer. They have modern design comprising cylindrical towers and three rotor blades fixed on a nacelle containing the generator, gear box and other operating installations. These are the highest wind turbines in Bulgaria so far – the hub height of Vestas V90 3.0 MW is 105 m. Each turbine has three rotor blades, each with a length of 44 m, weight of 6,700 kg, and rotor diameter of 90 m.
Underground cable network
The turbines have been grouped in 8 branches and connected through an underground cable network consisting of 60 km cable trenches. The cables are laid at 1.5 m depth and the cable trenches are situated within the limits of the existing agricultural roads. In regard to achieving the project standards and minimizing the transmission losses, the network has been designed at 33 kV, and the cable cross-section varies according to the number of the turbines attached.
Substation
The generated electric power collected from the inner cable network will be delivered to the 33/110kV Saint Nikola substation. The substation is fully automated and meets the highest operational standards. The equipment is supplied by ABB. Two transformers, 100MVA each, product of Hyundai Bulgaria, are installed in the substation.
The equipment installed is in compliance with the European and Bulgarian quality requirements.
110kV Overhead Line
After the voltage has been increased to 110kV at the Saint Nikola substation, the produced electricity is then transmitted through an overhead line to the point of interconnection of the wind farm to the national electricity grid of the Republic of Bulgaria. The length of the overhead line is 5.2 km and includes the installation of 34 pillars.
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