Nonlinear harmonic balance modelling for wave energy converter array layout assessment

Abstract

Wave energy converters (WECs) are most likely to be deployed in large arrays to reduce their cost of energy. However, the energy production of such arrays can be both positively and negatively affected by hydrodynamic interactions. Therefore, array layouts need to be carefully optimised. Such optimisation is usually carried out via hydrodynamic models that neglect more complex descriptions of WECs (e.g. nonlinear and non-ideal effects in the hydrodynamics and power take-off system) and the impact of advanced control. However, the articulation of these effects is crucial, since they can strongly impact on the array performance, questioning the conclusions drawn from simplistic linear assessments. This paper suggests the harmonic balance (HB) method to assess the behaviour of WEC arrays, which can efficiently articulate nonlinearities. Results from the HB approach are identical to the steady-state solution of a traditional (nonlinear) time-domain simulation, while highlighting the potential for a significant computational cost reduction.