Energy-Shaping Controller for DFIG-Based Wind Farm to Mitigate Subsynchronous Control Interaction

Increasing use of series compensation in doubly-fed induction generator (DFIG)-based wind farms has led to subsynchronous control interaction (SSCI) incidents. The irregular exchange of energy between the network side and generator side is considered responsible for SSCI. Therefore, an energy-shaping controller (ESC) is proposed in this paper to mitigate SSCI from the energy perspective. Firstly, based on energy relationship and physical nature, Hamiltonian model is established to describe the system structure. Secondly, the controller is obtained by solving the energy equation. Damping is then injected into the controller dynamics and it is back-propagated to the system, ensuring the global asymptotical stability. Thirdly, the controller is further improved to make gamma-dissipation inequality hold, thereby enhancing the robustness. Time-domain simulation and impedance model (IM)-based stability analysis are conducted to evaluate the damping performance of ESC. Simulation results demonstrate the effectiveness of ESC under a wide range of operating conditions. Moreover, ESC also improves system robustness against external disturbance and parameter uncertainty.