Micro/small wind turbine power control for electrolysis applications

Abstract

This paper compares the efficiency of three power converter and maximum power point tracking (MPPT) systems for connecting a micro/small wind turbine to an electrolyser stack: a conventional DC–DC voltage converter with hill-climb search (HCS); a novel variable electrolyser cell load controller where the number of series cells varies to allow MPPT; a novel hybrid DC–DC voltage converter integrated with direct-connect circuitry, variable cell control and lookup-based MPPT. The variable cell and hybrid converters demonstrated superior performance, averaging efficiencies 2–4% higher than the conventional converter, reaching near ideal at a wind speed of 7.7 ms−1 due to direct connection. MPPT function measured electrolyser current as a power reference. HCS performed MPPT at approx. 98% of ideal but requiring very advanced function including variable step size and intelligent perturbation to achieve this during dynamic conditions. The variable cell and hybrid converters produced superior MPPT (based on lookup data) to HCS. This demonstrates alternative novel power control and MPPT approaches for low-cost and efficient hydrogen production from micro/small wind-electrolysis systems.