Evaluation of Energy Losses in a Wind Farm

Abstract: In recent years, the power production from wind power and other renewable energy sources has increased significantly. Arguably, this is due to the greenhouse effect and the economic benefit of generating power from the wind. Wind power has the potential to replace other non-renewable power sources. Thus, it is of interest to maximize the efficiency of the wind farms, to produce the most power to the grid. This implies that the power losses within the wind farms needs to be minimized. Evidently, there are expected and unavoidable power losses within the wind farm. However, when there are unexpected power losses or the power losses exceed what is expected, the question arises as to what the reason for this is and if it is possible to avoid or decrease these power losses. In this thesis, a case study is conducted in collaboration with Skellefteå Kraft. An existing wind farm is studied, as the case company noted inconsistencies in power losses. One section has a larger share of power losses than the other section in the wind farm. Thus, it is of interest to the case company to find out why this is, to find the source to these power losses, as unnecessary power losses mean a loss of profit as well as loss of useful power produced from renewable energy sources. This suggests that if the sources of the power losses are identified and the power losses are deemed unnecessary for the operation of the wind farm, the case company can take actions accordingly. Hence, this thesis aims to identify the sources of the power losses and to create basis to whether these power losses are justified and necessary for the operation of the existing wind farm or not. To study the power losses in the existing wind farm, a model is developed utilizing load flow analysis. The load flow analysis is based on real hour power production data of the year of 2019. Thus, several load flow calculations are carried out to modify the system parameters to optimize the accuracy, and to verify the model. The model is then used to estimate and evaluate the power losses within the wind farm, and for identification of the sources of the power losses. The results of the case study prove that a rather accurate model was successfully developed. The model indicates that, for the year of 2019, the difference in power losses between the two sections of the wind farm was primarily due to the de-icing systems. The de-icing system of one section constituted for a significantly larger share of the power losses in that section than what the de-icing system of the other section constituted for the power losses in the other section. This suggests that the de-icing system needs to be evaluated further. Due to the design of the wind farm, there is an additional transformer in one of the sections. Through utilizing the model, the power losses of the additional transformer were estimated. For the year of 2019, the model indicated that the power losses of the additional transformer contributed rather insignificantly to the difference in power losses between the two sections.