Aurora was appointed by Windcare to undertake a series of power system studies for a new 4.5MW windfarm, connected at 33kV at the Keith Hill site near Edinburgh. Unusually for a project such as this, the 33kV busbar was classed as a transmission system, so as well as the usual studies required by the DNO, Aurora had to undertake a number of additional studies to meet the National Grid connection requirements.

Aurora was responsible for carrying out all the key power system studies for the site, in order to obtain approval of the DNO and National Grid. The studies undertaken included a P28 transformer energisation study with PSCAD, a G5/4 Stage 3 harmonics study, a fault ride through study, a reactive power flow study with ETAP and an earthing design study using CDEGS.

Liaising directly with the Client, the DNO, National Grid and the equipment manufacturer, Aurora was able to develop a detailed power system model of the network. Various simulation studies were then undertaken to demonstrate compliance with the standards. At the same time Aurora also built a model in Digsilent to compare the performance of the two simulation packages, to begin the roll out of DigSilent across Aurora’s future T&D projects.

As part of the earthing design study, Aurora subcontracted a soil resistivity analysis to a local company. Aurora then used CDEGS to develop a detailed model of the soil layers, fault current return paths and the earth grid, allowing Aurora to perform a series of detailed touch and step voltage calculations for the site.