Perturbation Stability Margin Investigation on the Fixed PMSG Controller in Wave Energy Application

The robustness and stability of the permanent magnet synchronous generator (PMSG) closed-loop system in wave energy application is analyzed with uncertainty in the form of the additive perturbation and the coprime factorization respectively. The difference between them is also investigated. A proper method to solve the perturbation stability margin by the coprime factorization is proposed when the controller is fixed. The perturbation stability margin is researched when the perturbation plant and the fixed controller are coprime simultaneously. Further, this margin calculation method can be reduced into 3 steps while the Bezout equation is satisfied. This method can solve the problem of perturbation stability margin when the controller is fixed and provided a quantitative index for the robust analysis of the perturbation plant. The simulation has proved its effectiveness and shown the good potential in wave energy application.