Insulating Systems for Wind Turbine Generators

Rudolf Bruetsch, Von Roll Isola, Switzerland

The use of renewable energy sources has increased considerably in the past due to the strong demand for a sustainable protection of our environment. Amongst these renewable energies the use of wind power has shown the fastest growth. During the last twenty years the installed wind power capacity has increased globally with a rate of about 30 % per annum. Europe is the leading continent in using wind energy for power generation with an installed capacity of about 28’000 MW which corresponds to 75 % of the global wind power capacity.

In parallel to this fast growth, the technology of wind turbine generators has changed remarkably since its beginnings. The production cost of one kilowatt hour of wind power has fallen by 20 % over the past five years alone. Today the commercial size range of wind generators covers machines from 50 kW up to 3 MW. Generator types are:

• Asynchronous and synchronous
• Low and high voltage
• Air and water-cooling
• Single speed, two-speed or semi-variable speed operation and full variable speed drives
• Permanent magnet synchronous generators

Wind turbine generators have to be designed to withstand severe environmental conditions. Once installed, generators must be very reliable because they are not easily accessible for maintenance and repair. They have to be designed and manufactured to operate with a minimum of maintenance. Furthermore electrical performance has to be optimized for varying wind conditions.

A critical component for both requirements – low maintenance/long lifetime and high electrical performance – is the insulating system of the generator. Von Roll Isola has a long experience in developing insulating systems for wind generators and is the only supplier worldwide to manufacture all materials of the insulating system including the processing equipment. Benefits for the customer are that all materials come from one source and are proven to be compatible. Both materials and systems are tested by Von Roll Isola. These materials are:

• Conductor and conductor insulation
• Stack consolidation materials

§         Main wall insulation

§         Anti-corona products

§         Finishing and sealing tapes

§         Slot insulation and wedging

§         Bracing materials

§         Finishing coatings

The paper gives a detailed description of the insulating systems recommended for the different types of wind turbine generators, test results and an overview on the processing equipment including indications on manufacturing cost reductions which can be achieved.

rudolf.bruetsch@vonroll-isola.com

Tel. +41-61-785 53 27

Fax +41-61-785 51 85