Optimal controller design of a doubly-fed induction generator wind turbine system for small signal stability enhancement

Multi-objective optimal controller design of a doubly-fed induction generator (DFIG) wind turbine system using differential evolution (DE) is presented. A detailed mathematical model of DFIG wind turbine with a closed-loop vector control system is developed. Based on this, objective functions addressing the steady-state stability and dynamic performance at different operating conditions are implemented to optimise the controller parameters of both the rotor and grid-side converters. A superior ε-constraint method and method of adaptive penalties are applied to handle the multi-objective problem and the constraint with DE, respectively. Eigenvalue analysis and time-domain simulations are performed on a single machine infinite bus system as well as a nine-bus multi-machine system with two DFIG wind turbines to illustrate the control performance of the DFIG wind turbine with the optimised controller parameters. The electric energy productions of the studied DFIG wind turbine system with and without optimised controller parameters under turbulent wind speed are also demonstrated.