Energization of step-up transformers for wind-farms: Modeling and its validation by tests performed on a 10 MW site

The voltage quality of the energy delivered is a major issue for wind-farms owners and also for the Distribution networks operators. The no-load energization of step-up transformers of wind-farms from the distribution network may lead to high inrush currents which may affect this power quality and, in certain cases, lead to high overvoltages and high inrush currents. Those phenomena involved are described in the case of a 2.05 MVA 20 kV/960 V transformer, with a detailed description of the modeling of the network. A comparison between simulations and on site tests is firstly presented in the case of the energization of one transformer alone, secondly in the case where three others transformers are already connected, showing a good agreement between simulations and measurements.