Active Damping of Grid-Forming Voltage-Source Converter Using Fractional-Order Regulators

For a reliable integration of power-electronic-based generation in the future energy system, the grid-forming (GFM) converter has been extensively considered as a potential solution. However, while operating as a voltage source that is synchronized via active power regulation, the GFM converter exhibits insufficient damping, particularly when synthetic inertia is incorporated for frequency support. To address this concern, this article has developed active-damping control schemes using fractional-order regulators. Differing from the existing control approaches, which may significantly alter the inertial response quantified using an inertia constant, the proposed controls are developed to introduce adequate damping for both power set-point tracking and external disturbances, while maintaining the original explicit relationship between the GFM converter's inertial response and the inertia constant. In this context, a preferable inertial response, precisely defined by the inertia constant as specified by certain grid codes, along with adequate damping, is achieved simultaneously. The effectiveness of the proposed controls has been validated though both theoretical analyses and experimental results.