Optimized Wind Turbine Lay-out

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Jens Molly Consult, Germany

mail@jens-molly.de

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ABSTRACT:

 

Wind turbines in the past have been designed mostly with a specific power installation of around 400 Watts or more per square meter rotor disk area. This value can be seen as a historical value, based on the lay-out of Danish stall controlled wind turbines designed in the early eighties of the last century. From the nineties on the pitch controlled wind turbines entered the market step by step, but for competition reasons their lay-out concerning the power installation was kept at the similar level of around 400 W/m2 as for the stall controlled turbines. But for pitch controlled wind turbines the specific power installation can be chosen in a way that the price for the generated energy is as low as possible. With the need to reduce the energy production cost at the low wind speed sites in Southern Germany the industry used the advantages pitch control offers and designed wind turbines with specific power installations much lower than before and offered them with 200 W/m² to 300 W/m² to achieve a more economic operation of wind farms in the low wind regions. Another trend could be observed with the upcoming offshore wind farm installations. First wind turbines installed offshore had specific power installations of 500 W/m² and more.  New installations today have 300 W/m² to 350 W/m², in other words, very nearby to the low wind speed design but applied in the strong offshore winds. The question is now, which are the reasons for this design change?

The choice of the specific power installations of wind turbines should depend on the application goal to achieve the best economic lay-out. Some of these goals could be:

• Economic profit optimization for the wind farm investor/operator

• Profit optimization for the manufacturer of the wind turbine

• Cost optimization of the electric energy transportation and distribution grid

• Energy cost optimization of a wind turbine/storage system

• Increase the supply reliability for an energy generating system using different energy sources

• Best fulfillment of a long term nationwide energy supply plan, e.g. a successful Energiewende (Energy Transition) in Germany

• Best lay-out to achieve the lowest energy costs for the consumer

All these optimization reasons will lead to different specific power lay-outs of wind turbines. Only reasons like the first two can be achieved by market forces but all the others are not of real interest for the wind farm operator or the manufacturer. If we look at the first two reasons the question is if a turbine optimized to fulfill the profit expectations of the manufacturer will be the best also for the wind farmer?

The paper will answer these and other questions in detail and explains how to find the ideal specific power lay-out of wind turbines which lead to the lowest energy production costs and at the same time can be manufactured at lower costs. These wind turbines are sold today successfully because their correct lay-out is a win-win situation for both, manufacturer and wind farm operator.

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BIOGRAPHIE:

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Jens Peter Molly made his engineering degree (Dipl.-Ing.) in Aero and Space Technology at the University of Stuttgart in 1972. After finishing the University, he worked as a Scientific Assistant for Prof. Hütter at the Institute for Airplane Design and Construction at the same University. Because Prof. Dr. Hütter was the well-known global wind energy expert at that time he had his first contact with wind energy in 1973 when writing an important part of a study about “New Energy Sources for the Future” on behalf of the German Ministry for Research and Technology.

 

In 1976 he moved from the University of Stuttgart to the German Aerospace Research Establishment (DFVLR, today DLR) and became the leader of the Department for Wind Turbines. His wind energy group designed two wind turbines, one with 10 kW and one with 100 kW power installation. In 1985 he founded together with two friends the company WISA-Energiesysteme GmbH (Wind and Solar Systems) and continued with wind energy research studies funded by the German government and the European Commission.

 

In January 1990, he became the founding managing director of the DEWI GmbH, a wind energy research company founded by the German federal state of Lower Saxony. This position he held until end of 2016. DEWI finally became a wind energy service provider with branches in seven countries and with DEWI-OCC, founded in 2003, the second largest certifier of wind turbines world-wide.

 

In 1993 he initiated two research projects for the harmonization of wind energy related measurement procedures together with other European institutions. This activity finally resulted in the foundation of the world-wide known MEASNET group of institutes (Measurement Network of Wind Energy Institutes) which apply jointly developed, harmonized measurement procedures of high quality. From the foundation of this organization in 1997 until 2010 he was the Executive Chairmen of MEASNET.

 

In 1979 and 1990 he published two wind energy books.

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