A Multi-Filter Based Dynamic Power Sharing Control for a Hybrid Energy Storage System Integrated to a Wave Energy Converter for Output Power Smoothing

The output power fluctuations from the wave energy converters (WECs) with a high peak-to-average ratio need to be smoothed out before supplying power to electric loads or power grids. Usually, short-term energy storage is used to smooth out the output power fluctuations of WECs. In this article, a novel multi-filter-based dynamic power-sharing control is devised for a hybrid energy storage system (HESS) integrated with a grid-connected WEC. An advanced model of HESS-integrated WEC consisting of a direct-drive permanent magnet linear generator, a supercapacitor, and a battery system is developed to test the proposed multi-filter-based dynamic control strategy under realistic conditions. The distinguishing features of this study are as follows; 1) the power-sharing strategy is based on a dynamic filter that is designed to change its corner frequency depending upon the incoming ocean wave, 2) the low and the high-frequency power components are allocated based on ocean wave conditions, 3) the proposed strategy is suitable for the real-time control of the proposed HESS integrated with the WEC, and 4) a detailed model of the WEC is used instead of using a pre-saved power profile. The results suggest that with the implementation of the proposed multi-filter-based dynamic power-sharing scheme in the HESS integrated WECs, the output power can be effectively smoothed out before supplying the power to the grid.