Direct drive surge wave energy converter with grid integration functionality

This paper addresses the design and simulation validation of a direct drive surge wave energy converter (DDSWEC) as an efficient device for harnessing marine wave energy in near-shore locations. The proposed DDSWEC is composed of a rigid rectangular plate producing linear motions in response to surge forces of ocean waves. A translator is devised to transfer the wave energy to a linear permanent magnet synchronous generator, which all together form the power take-off (PTO) system. In the proposed scheme, the mechanical simplicity of PTO system is a superior feature in reducing power losses in the wave-electric power conversion chain. Additionally, suitable mechanical degrees of freedom lead to an impressive increase in the power conversion efficiency. Besides, mathematical modeling of the mechanical and electrical systems governing DDSWEC is interrogated in depth. In addition, through a comprehensive frequency contents analysis, the capture width of DDSWEC and the device efficiency are scrutinized to validate its well performance. Because the stochastic behavior of waves induces voltages with variable frequency and magnitude, which are undesirable features for grid integration, a full-scale back-to-back converter with both generator and grid-side controls is accordingly implemented. To validate the overall performance of the proposed DDSWEC, a test system is designed in Matlab/Simulink platform by which several time-domain simulations for both the monochromatic and irregular waves are conducted. Copyright (C) 2015 John Wiley & Sons, Ltd.