Zhejiang dianli (Aug 2024)
Research on a small-signal stability criterion for MMC controller
Abstract
High voltage direct current (HVDC) transmission based on modular multilevel converter (MMC) is widely used in large-scale renewable energy delivery. However, the lagged inertia of MMC controllers may undermine the small-signal stability. Firstly, the mechanical inertia of synchronous generators is analyzed, and a second-order unified expression of inertia applicable to MMC controller is proposed. Secondly, based on the dynamic and inertial delay of MMC closed-loop controller, a small-signal stability criterion for MMC controller connected to weak power grid is presented. Finally, through simulation analysis of a double-side MMC grid-connected system, the correctness of the proposed stability criterion is validated.
Keywords