A novel inertial control strategy for full-capacity wind turbine with PLL by optimizing internal potential response

This paper proposes a new inertial control strategy for full-capacity wind turbine (FCWT) synchronized with grid via phase locked loop (PLL) technique. It is worth noting that there is no need to measure the grid frequency and obtain the frequency differential as the fairly common practice does. The control strategy is essentially realized by optimizing the response characteristic of the internal potential, which is actually the rotating space vector of the FCWT's output voltage produced by the grid-side converter. In order to obtain the expected response characteristic of the internal potential, control bandwidths of both PLL and DC-link voltage loop are optimized. It is exactly based on that the FCWT can fast response and participate in stabilizing the grid frequency firstly relying on the stored energy in DC-link capacitor when disturbance occurs in grid. In the meantime, the variation of DC-link voltage during the response process is used to fine-tune the speed reference value to obtain the large kinetic energy in the mechanical system. Simulation model was built in MATLAB/Simulink and simulated results demonstrate the feasibility and correctness of the presented control strategy.