Fully Superconducting Electrical Machines for Renewable Energy
This project provides a proof of concept of a novel electrical machine topology (dual armature) that enables the optimal use of magnetic field flux within the machine by incorporating a secondary coaxial armature that links the flux lines from the field structure to the machine's shaft. In conventional machines, only the flux lines oriented towards the stator coils can effectively generate induced voltage. This enables the design and construction of generators or synchronous condensers of substantially higher power density (power output per unit mass), which is particularly critical in contemporary machine applications where weight is critical, such as wind turbine generators and electric vehicles.
In the field of wind power generation, the proposed machine provides several substantial improvements, namely:
the proposed architecture can be used as a low-speed direct drive machine, avoiding the need of an external gear reduction. This represents a substantial advantage in applications such as wind generators and synchronous condensers.
the elimination of gear reduction represents a significant contribution to wind power generation, because gear boxes for wind generators are a significant component of the total mass and cost, besides other reliability and maintenance costs.
A novel hybrid modeling and simulation technique is being developed that will enable the coupled simulation of transient dynamic effects in the proposed machine using geometry-dependent parameters (such as self inductance and coenergy) obtained from finite element analysis. Computation of geometry dependent parameters in electrical machines is very computationally intensive, in particular when 3D models are used. Several machine parameters are therefore calculated off-line in a static sense using finite element software. On the other hand, dynamic simulators that predict transient response are forced to assume several such parameters as constant or as a sinusoidal with a certain offset. The proposed methodology uses finite element look-up tables, of machine electrical parameters obtained off-line, to produce higher fidelity simulations of dynamic machine performance with low computational cost. The proposed approach can be used to model motors, generators and synchronous condensers.
A future and promising application of the dual armature topology is for the implementation of synchronous condensers, either normal conducting for power levels in the medium range (hundreds of kW) or superconducting in the high power range (several MW). Synchronous condensers are power conditioning units that can be connected to the power grid to provide improved power factor when a high number of reactive loads affect the quality of the power delivered by the network.