Improved control strategy of DFIG-based wind turbines using direct torque and direct power control techniques

This paper presents different control strategies for a variable-speed wind energy conversion system (WECS), based on a doubly fed induction generator. Direct Torque Control (DTC) with Space-Vector Modulation is used on the rotor side converter. This control method is known to reduce the fluctuations of the torque and flux at low speeds in contrast to the classical DTC, where the frequency of switching is uncontrollable. The reference for torque is obtained from the maximum power point tracking technique of the wind turbine. For the grid-side converter, a fuzzy direct power control is proposed for the control of the instantaneous active and reactive power. Simulation results of the WECS are presented to compare the performance of the proposed and classical control approaches.Peer reviewedFinal Accepted Versio

Board gender diversity and corporate environmental performance: the moderating role of family and dual class majority ownership structures

While prior work has investigated the impact of (a) ownership structure and (b) board gender diversity separately on corporate environmental performance, researchers have not studied the potentially important relationship between ownership control and female board diversity in influencing corporate environmental performance jointly. We do so in the context of majority ownership in family controlled and dual class firms whose motives and influence are theoretically different from that of the firm’s minority shareholders. Drawing on resource dependency, socio-emotional wealth theory, and secondary agency theory, we hypothesize that majority family owners and dual class owners likely choose women directors to help advance their personal preferences for environmental CSR. Our empirical tests utilizing 2755 US firmyears over the 2010-2015 show that, as hypothesized, these two majority ownership types interact with board gender diversity to positively influence corporate environmental performance