LPV-based active power control of wind turbines covering the complete wind speed range

Abstract

This paper focuses on the active power control of wind turbines. Modern grid codes increasingly demand active power control in order to guarantee utility grid stability under high wind energy penetration. Active power control provides capabilities to regulate wind power below rated, to maintain a power reserve, to indirectly regulate the grid frequency, etc. New controllers are necessary to tackle the extended operating modes and new objectives. This paper addresses the control problem using LPV techniques, since they are particularly suited to cope with the nonlinearities that arise along the extended operating region. The proposed controller was evaluated on a 5 MW wind turbine benchmark. For that purpose, very demanding and realistic testing scenarios were built using the FAST aeroelastic wind turbine simulator as well as standardized wind speed profiles. The proposed controller was compared with the gain scheduled PI traditionally used for wind turbine control and also with a gain scheduled ℋ∞ controller. Finally, a comparative load analysis is presented with the aim of showing that the softer and lower pitch activity of the proposed controller decreases the extreme load events.