How to ensure that the power electronics in a wind turbine are maintained in time and on a scheduled basis? This is the question occupying researchers at the University of Bremen’s Institute for Electrical Drives, Power Electronics and Devices (IALB). To find the answer, they have enlisted the help of three medium-sized enterprises in the North of Germany to work together in a joint project financed by the Federal Government.
The participating enterprises are Windrad Engineering GmbH in Bad Doberan, WindGuard Certification GmbH in Varel, and FREQCON GmbH in Walsrode. The project is being funded over a three-year period in an amount of 1.1 million euros by the German Ministry for the Economy and Energy. It bears the title “Retrofitting and Assessment of the Remaining Life-Cycle of the Power Electronics of Wind Turbines with Dual Feed Induction Generators – Independent of Manufacturer”, or “WEA-Retrofit” for short,
Strongly deviating stresses and loads
The life cycle of the power electronics incorporated in wind turbines is determined by the actual stresses and loads the electronics are subjected to during their rough everyday operation. They have to stand up to the stresses caused by the wind, interactions between the various power electronic systems among each other, as well as those issuing from the grid. These stresses and loads can vary greatly, even among units located on the same wind farm. It is therefore not possible to predict what kind of stresses and loads each individual power electronics will actually be subjected to over a given period of time. It follows, therefore, that it is also not possible to plan maintenance repairs or the availability of specialist engineers and spare parts in advance.
Project sequence and partners
In an initial step, by means of high-resolution measurements the researchers will investigate the causes of outages of the power electronics in wind turbines. The project partner WindGuard Certification GmbH will support the researchers at the University of Bremen with their know-how in the area of mapping grid characteristics. As a member of the University of Bremen’s Center for Wind Energy Research (ForWind), the Institute for Electrical Drives, Power Electronics and Devices (IALB) is working with Windrad Engineering GmbH on the development of special measuring systems. ForWind is joint research center supported by the universities of Bremen, Hanover and Oldenburg. The project partner FREQCON GmbH will then integrate the newly developed online models for assessing the life cycles of power electronics in the control system of a compensation inverter as a prototype. It should be possible to retrofit over ten-year-old wind turbines without the need for a new certification procedure. The measuring data and evaluation results obtained during the project will be made available to researchers at the Fraunhofer Institute for Wind Energy and Energy Systems Engineering (IWES) in Bremerhaven. This is the first time a project to create a data pool of high-resolution measuring data on wind turbines has been undertaken in Germany.
You can find more information on the project partners under www.ialb.uni-bremen.de; www.windrad-online.de; www.windguard-certification.de and www.freqcon.com
