An Additional Resonance Damping Control for Grey-Box D-PMSG Wind Farm Integrated Weak Grid

Considerable efforts have been made to address the resonance issue of the Direct-drive Permanent Magnet Synchronous Generator (D-PMSG) wind farm integrated power systems. However, the D-PMSG controller structure and parameters are concealed because of commercial secrecy, thus the target system exhibits grey-box characteristics. The existing resonance damping methods are either unavailable for grey-box systems or economically infeasible, which makes resonance damping of grey-box systems extremely challenging. To address this issue, this paper proposes an Additional Resonance Damping Control (ARDC) specifically for the grey-box D-PMSG system. This strategy is achieved by incorporating an additional control loop outside the D-PMSG controller. Firstly, the external impedance characteristics are obtained by the frequency sweeping technique offline and then the key parameter of the additional control loop is determined by the Bode-diagram-based method under the worst stability scenario. Once the resonance occurs, the external impedance of the black-box D-PMSG is reshaped online to increase the magnitude stability margin of the system, thus providing effective resonance damping. The ARDC's effectiveness is finally verified in the simulation and controller-hardware-in-the-loop experiment under various operating conditions.