A physically-inspired method for robust configuration of control parameters of PLL-based VSC to enhance transient stability

This paper proposes a physically-inspired robust configuration method to tune the power and current control loop parameters of a grid-connected voltage source converter (VSC) that utilizes the phase-locked loop (PLL), with the goal of improving the transient stability of the closed-loop system. To be specific, by modeling the PLL dynamics as a second-order motion system, the VSC’s control parameters are optimized to enhance the beneficial restoring force that essentially pulls the PLL back to the steady state when a large disturbance occurs. Particularly, the configuration process employs the linearized model of the system, making the optimization analytical and easily implemented. Moreover, the robustness of the tuned parameters with respect to the operating point drift of the VSC is also considered during the parameter optimization. Comparative simulations show the superiority of the proposed method in enhancing the transient stability of the VSC as well as in the robustness of control performance. • The power and current control loops of the VSC are taken into consideration. • The PLL is modeled as a controlled “position-speed” second-order dynamical system. • The PI parameter configuration method is transient stability oriented. • The linear prediction of the restoring force satisfies the accuracy requirement. • The proposed method is proved to be effective as the operating point shifts.