Determining and analysing production losses due to ice on wind turbines using SCADA data

Abstract: Wind turbines are becoming a more common sight and a more important part in the power grid. The benefits are mainly that wind energy is a renewable energy source and a single wind turbine can produce enough electricity to cover several households’ annual electricity need and not producing carbon dioxide as a rest product. Drawbacks are fluctuation in wind speed, which makes it difficult to regulate. The turbines need to be placed far from cities which cause losses in transmission in the national power grid.  In cold areas with long winters there is a risk of high energy losses due to iced blades. If there is ice accretion on the wind turbine blades it can cause a production loss and in extension economical losses by not selling the electricity. Finding those events is of high interest and there are methods to prevent and remove ice. However, there are occasions when there is ice on the blades, but no sensors signal this, and the production loss is a fact. There is a presumed production loss of 5-25 % annually due to icing on wind turbines in Sweden, depending on where the site is located. There is no general method for detecting ice in the industry but there are several methods available developed by different parties.  In this master’s thesis, a software has been developed in cooperation with Siemens Gamesa Renewable Energy to identify production losses on wind turbines due to icing using historical SCADA data. The software filters the raw data to construct a reference curve, to which data during cold weather is compared. It was found that low temperature causes ice losses, and the risk of an ice loss increases as temperature decreases. The annual losses at investigated wind farms were 4-10 % of the expected annual production.