A Robust H∞ Control Based on LMI for PMSG-based Grid-connected Wind Energy System

Enhancing the integration of renewable energy sources into electrical grids via grid-connected converters requires robust control schemes to ensure the stable behavior of these converters during disturbances on the grid side. In this paper, a robust control strategy for a grid-connected Permanent Magnet Synchronous Generator (PMSG) is designed for variable-speed wind applications. The controlled variables include the electromagnetic power generated by the machine, dc-link voltage, and reactive power that is injected to the grid side. This paper proposes a robust H-infinity control scheme enhanced by the D-stability technique using a Linear Matrix Inequality (LMI) approach, which takes into account the detailed model of the back-to-back converter system to which the PMSG is connected. The control scheme is validated on an OPAL-RT-based real-time simulator and the results indicate that, in different conditions, the robust H-infinity control scheme provides a superior response during shortcircuit faults and PMSG speed variations, compared to those of the standard PI vector control scheme. This control scheme shall be extended to implement the decentralized control method for each of the generating units of the Dynamic Virtual Power Plant, a concept introduced in the H2020 POSYTYF project.