As the market for large offshore wind turbines increases, the requirement to reduce the cost of energy becomes more important. The installed base of offshore wind turbines is expected to rise by up to 5 GW per year through to 2020.
The Compact High Efficiency Generator (CHEG) project aims to advance the state of the art in wind turbine generator technology by reducing the cost of the turbine and increasing the efficiency of the generator to reduce cost of energy. The generator and gear box are major turbine components and constitute a major part of the cost, complexity and failure modes of wind turbines. The use of the innovative pseudo direct drive (PDD) generator within wind turbines will reduce the capital cost of such installations and subsequent decommissioning, and have a positive impact on operation and maintenance costs.
CHEG will deliver a pseudo direct drive (PDD) machine based around Magnomatics innovative magnetic gear technology which brings significant advantages in efficiency and reduced costs of maintenance due to its method of transmitting torque through the magnetic gear without the physical contact and subsequent requirement for lubrication required by traditional mechanical gearing.
Preliminary overall Levelised Cost of Energy (LCoE) modelling shows significant advantages from the PDD system when compared to other current machine topologies, with notable advantages in increased efficiency, reducing cost by 2% taking worst case scenarios, high relative annual energy output, reduced mass and reduced maintenance costs.
The consortium believes that the technology being developed, whilst potentially groundbreaking in reducing cost of energy, must be affordable to potential end users once serial manufacturing volumes are achieved. It is estimated that the proposed technology with be within 2.5% of the cost of the current state of the art technology when manufactured in similar volumes for a similar output turbine.
The PDD technology has been successfully developed to prototype level for such applications as traction motors for electric vehicles, actuators for aircraft control surfaces and propulsion motors for small marine vessels. The efficiencies and compactness of the machines when compared to best-in-class machines from competing technologies indicate that significant reductions in mass, size and cost could be achieved when using the PDD technology as a generator in wind and tidal generation applications.
Experimental data has confirmed theoretical efficiencies on small PDD machines built under laboratory conditions of more than 95% and similar theoretical efficiencies for larger machines are over 98%; volume some 40% less and mass 35% less than best in class permanent magnet machines that are currently considered to be the state of the art.
The objectives of the CHEG are:
- Increase European wind turbine supply chain opportunities by developing innovative generator technology that gives significant advantage in LCoE to end users by minimising capital cost, reducing operation and maintenance costs and increasing generator efficiency.
- Demonstrate the feasibility of multi-megawatt PDD generator systems through design, manufacture and test of a scaled 500 kW demonstrator appropriate for demonstration to the market under the guidance of an end user.
- Verify the design tools used in the 500 kW demonstrator by verification of actual versus design characteristics and evaluate the relevance of the design tools to multi-megawatt scale machines.
- Develop the supply chain for the various components of the generator, aiming for capability for supply up to multi-megawatt scale variants.
- Develop and employ manufacturing techniques for unique components (the pole piece rotor (PPR)) aiming for capability of supply up to multi-megawatt scale variants.
- Develop manufacturing techniques to assemble the unique features of the PDD generator – namely the additional magnetic components that form part of the stator and for the assembly of the PPR and high speed rotor (HSR) – aiming for techniques scalable to multi-megawatt machines.
- Predict relative LCoE in comparison to current state of the art (Dual Feed Induction Generator and direct drive techniques) and emerging technologies such as high temperature superconducting.
- Establish a technology roadmap detailing supply chain, technology and process route developments needed to enable large scale PDD generators to be successfully manufactured to meet market demand.