Computationally-Efficient Electro-Thermal Modeling of Wave Energy Conversion Systems via Pseudo Steady-State PMSM Model

Ocean wave energy is a widely available and largely unexploited renewable energy source. Generation equipment needs to operate reliably and withstand rough seas, so power shedding in high sea states is as important as maximum power extraction in low sea states for minimum levelized cost of energy. Wave resources fluctuate and are represented by statistical distributions, so both sizing of the powertrain components and power maximising control need to be optimized over multiple simulations. Computationally efficient models are required include the wave frequency dynamics with a period of a few seconds, over a run duration of an hour. This paper develops a new pseudo-steady-state model of the permanent magnet synchronous machine (PMSM) for system codesign and real-time platform control. For use under load-shedding control, the model needs to include field-weakening operation and winding temperature estimation and losses. Dynamic equations for the generator and current control are replaced by an analytical solution giving a factor of 15-40 times speed up in solution time.