Adaptive Step Size Based Hill-Climb Search Algorithm for MPPT Control of DFIG-WECS With Reduced Power Fluctuation and Improved Tracking Performance

Abstract

One of the major challenges in harnessing wind energy is to extract maximum power from intermittent generation of wind farms as wind power generation strongly depends on wind speed variation. Among different maximum power point tracking (MPPT) algorithms, traditionally, hill climb search (HCS) method is widely used because of its simple implementation and turbine parameter-independence. However, the conventional HCS algorithm has some drawbacks such as power fluctuation and speed-efficiency tradeoff. Similarly constant tip-speed ratio (TSR) MPPT control method requires precise knowledge of optimal TSR of the turbine. Therefore, in this paper a new adaptive step size based HCS controller is proposed to mitigate the deficiencies of other techniques by incorporating wind speed measurement. The function-based adaptive control scheme evaluates the step size by the variation of the wind speed and extracted power range. The proposed variable step size based HCS-MPPT system is simulated at variable wind speed. A prototype system is also built with a low-power doubly-fed induction generator (DFIG). It is found from the results that the proposed controller reduces the steady-state power fluctuation of the DFIG based wind energy conversion system significantly compared to the conventional HCS-MPPT controller and constant TSR based MPPT controller at variable wind speeds.