Robust Small-Signal Stability of a Wind Turbine-Battery System in an Isolated Microgrid for Offshore Hydrogen Production

This paper focuses on an islanded wind turbine-battery microgrid that supplies an electrolyzer load for offshore hydrogen production. Small-signal stability is assessed while accounting for operating point changes due to wind variability as well as battery aging. To this end, a polynomial parameter varying descriptor model of the microgrid is determined and it is validated by comparison with a PSCAD microgrid simulation. Robust stability of the descriptor model is analyzed by checking sufficient linear matrix inequality conditions accounting for the time variation of the parameters. The benefit of the approach is discussed with regard to the classical root locus method. This stability analysis also results in the determination of the minimal battery rated power ensuring robust stability.