Examination of grid connection requirements of electrically coupled wind farms using Neplan software

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Prikler László
Department of Electric Power Engineering

My task consisted of making the simulation modell of a twin-wind farm with the NEPLAN power system planning and information system software for electrical transmission, distribution and industrial networks. This tool is commonly used nowadays in Hungary for sizing the middle voltage cable network of wind farms not only to fit the international and Hungarian regulations but also to get the most favourable economical solution. “Twin” as an attribute here describes the fact that two wind farms are electrically and geographically close to each other. In this work I present the network model of a Hungarian wind farm currently in design stage. Both farms with nominal rating of 20 MW would be connected to the MV busbar of a transformer station with 132/22 kV nominal voltage and 25 MVA transformers. The task was exciting and complex because I have used the NEPLAN software during my previous works but the job never required this in depth knowledge of the software before. Learning of other modules was necessary beside of making simple LoadFlows studies in order to execute the thesis tasks properly and in accordance with the Hungarian practice. I needed to learn to use the short circuit, the contingency analysis and the profiled LoadFlow modules.

For sizing the cable network I used a probabilistic mathematical approach to estimate the wind speed distribution at rotor height from the existing wind speed measurement data at 10 m height. While comparing these data I concluded that the most accurate results could be obtained by carrying out the measurements at the height of turbines for several years in advance. Further, making these data accessible for companies responsible for the internal cabling design of a wind farm would be also useful because the current calculations based on average wind speed give significantly different results. As a result of the carried out simulations I came to a conclusion that establishing the wind farm at the planned site does not need further network reinforcement. The planned park with the proposed configuration does not have unfavourable impact to the nearby HV and MV distribution grid and fulfils the regulations of the Hungarian DSOs.


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