Optimal operation of fuel cell/wind turbine hybrid power system under turbulent wind and variable load

Abstract

In this paper is proposed a new Extremum Seeking Control (ESC) algorithm for optimal operation of Wind Turbine (WT) under turbulent wind. In this proposal the dithers’ amplitude is WT system dependent, not constant or decreasing exponentially as in the classic ESC schemes. So, instead of one, the proposed ESC scheme has two loops: (1) the classic ESC loop controlled by the loop gain (k1) to accurately find the Maximum Power Point (MPP); (2) the anticipative ESC loop controlled by the dither gain (k2) to speed-up the localization of the current MPP under turbulent wind. The obtained results for a 100 Hz dither highlight the performance of the ESC-based MPP tracking algorithm proposed: about 99.9% tracking accuracy and a searching time less than 120 ms. This performance assures a tracking efficiency higher than 99% even for gusts of wind that may occur. The Fuel Cell is proposed as backup energy source for WT Hybrid Power System to sustain the load demand and reduce the size of the Energy Storage System (ESS), even for a high variability of the WT power. In comparison with Static Feed-Forward (sFF) strategy, a fuel economy of 5 lpm can be obtained using the ESC-based Real-Time Optimization (RTO) strategies proposed here, which means about 10% from the nominal fuel consumption.