Distributed Damping Evaluation Method of the Power Systems Integrated with Wind Farms During the Sub-Synchronous Control Interaction

This paper proposes a distributed damping evaluation method (DDEM) to assess the damping distribution0 in doubly-fed induction generator (DFIG)-based wind farms during sub-synchronous control interactions (SSCI). The proposed DDEM identifies sensitive control parameters of the DFIG wind turbines at oscillatory frequencies through the explicit expression of the system's damping loss factor (DLF). It also evaluates the damping contribution by calculating the distributed damping loss factor (DDLF) for each element or subsystem in real-time. Initially, this paper presents the DLF concept for basic vibration systems and extends it to oscillatory power systems. Subsequently, an analytical expression of the DLF in DFIG-based wind farms is derived by calculating the dissipated energy and the maximum transient energy at the sub-synchronous frequencies. The DLF is then decomposed into DDLFs according to the physical structure of the oscillatory system, facilitating the development of the DDEM to evaluate the damping contributions. The efficacy of the DDEM is demonstrated through two case studies: the modified IEEE first benchmark model on sub-synchronous resonance (SSR) and the Guyuan wind power system model in North China.