A number of wind turbines were granted planning permission near Edinburgh, Enercon required these wind turbines to be connected to the local 11kV distribution network. The nearest electrical 11kV connection point however was located 2.8 km and the land in between both the wind turbine and 11kV connection point was not owned by the client, this meant that it proved difficult to obtain wayleaves to install a new 11kV cable across the privately owned land. An alternative solution was to install a new 11kV cable at the side of an existing public road with a total route length of 4.8 km.
Using the electrical power software DigSILENT Engineering Power Solutions conducted a load flow and short circuit study to assess the impact of what the new wind turbines would have on the voltage and assess the magnitude of the additional short circuit current at the 11kV point of connection. SP Energy Networks accepted the load flow and short circuit study report and granted connection to the 11kV distribution network.
Engineering Power Solutions proceeded with the design and was requested to produce a detailed design for an 11kV switch station and an 11kV substation at both ends of the new 11kV cable. To enable the electrical contractors to quote for the work the EPS electrical design workpack included:
The wind turbines were successfully installed and connected to the 11kV distribution system to produce a maximum of 2.4 MW electrical power (an average of 21,024,000 kWhrs per annum). This is the equivalent of supplying 840 homes.
Peter Rawson - Operations Director