Constant power control of wind turbines during unbalanced faults

Control of PMSG-based wind turbines in weak grids during unbalanced faults

“…Clearly, if a reasonably constant active power is to be delivered to the grid, the calculated current reference (9) needs to be imposed. As i αβ gref might contain reasonably large harmonics, the current control loop should be able to provide zero steady state error for multiple harmonic references.…”

“…On the other hand, sliding-mode control or predictive control can be used to effectively impose the desired stationary frame current references. The design of such controllers is relatively straight forward for the considered first order plant (9).…”

“…Therefore, the wind turbine front-end current can be calculated to inject constant active and reactive power to the acnetwork [7], [8], [9]. However, large wind turbine converters have commutation frequency and voltage restrictions that might affect such a constant power delivery during transients.…”

“…The presented work considers stationary frame of reference current control based on a constant power reference. Previous work by the authors assumed the connection to an infinite power bus [9]. The presented work considers the effects of increasing line impedance, relatively slow switching frequency and dc-link voltage limitations on overall performance have been studied, considering both the electric and mechanical subsystems of the wind turbine.…”