Dynamic-Tracking Damping Controller for DFIG-Based Wind Farms to Mitigate Sub-Synchronous Control Interactions

This article proposes a dynamic-tracking damping controller (DTDC) and designs an implementation scheme to alleviate the subsynchronous control interactions in series-compensated networks integrated with doubly-fed induction generator (DFIG) based wind farms. The DTDC can track subsynchronous oscillatory current components under various operating conditions, providing high damping performance for DFIG wind turbines at a broader range of subsynchronous frequencies. This is accomplished by designing an extra extended state observer based compensated loop for the rotor-side converter of DFIG, which enables the extraction and compensation of oscillatory current components at the subsynchronous frequencies. In addition, the implementation scheme for the damping controller is designed based on the dissipated energy criterion, which can identify the weak damping wind farm and determine the number of wind turbines required to be installed. The proposed DTDC's effectiveness and implementation scheme are validated using the modified IEEE first benchmark model and a wind farm model in North China, respectively. The control hardware-in-loop experiments results demonstrate that the DTDC outperforms traditional approaches with superior damping and robustness under varying wind speeds, compensation levels, and the number of online wind turbines.