Principle and control strategy of a novel wave-to-wire system embedded ocean energy storage optimization

Abstract

Fluctuation and unpredictability of wave power output affect the safe operation of the power grid, which greatly restricts the development of wave power generation. This paper firstly introduces the principle and control strategy of wave to wire (W2W) model, whose input is from wave energy conversion (WEC) system and output to the electrical power injected into grid for stable power. Then, an adapted particle swarm optimization (APSO) algorithm-based maximum power point tracking technology (APSO-MPPT) considering adaptive inertia weighting variables is presented for quick dynamic reaction. Comparisons are made with the traditional constant voltage method, INC method, P&Q method, and PSO algorithm, the APSO-MPPT method can reduce the tracking time by 9.3% less than the quickest traditional. Secondly, a K–SOC curve algorithm-based hybrid energy storage system (KSC-HESS) optimization is conducted for smoothing the wave power output, with real time control performance. Simulations under output power fluctuation, load pulsation and load unbalancing situations are occupied for demonstrating high performance for the characteristics of the proposed KSC-HESS, in both reducing high-frequency burden for super-capacitors and protecting batteries from over voltage. Furthermore, results of prototype experiment verified the effectiveness with better efficiency by adapting the proposed APSO-MPPT and KSC-HESS for the proposed W2W system. Analysis shows the proposed W2W approach has comparative advantages of control complexity and high reliability for renewable power output.