Research On Control Strategy For Ride-through Operation Of Double-fed Wind Power Generation Systems During Grid Fault

In recent years，with the rapidly increase of wind power generation capacity, its influenceon grid is becoming more and more important, how to realize the ride-through operation ofdouble-fed wind power generation systems during grid fault becomes a focus in the study ofdomestic and foreign scholars. Based on double-fed wind power generation as the researchobject, the paper encloses the research on control strategy for the ride-through operation ofdouble-fed wind power generation systems during grid fault.Firstly, the double-fed wind power generation system mathematical model in the idealcondition is established. And the grid-said converter and rotor-said converter of double-fed windpower generator unified mathematical models in three-phase stationary reference frame andtwo-phase rotational reference frame is established respectively. Based on the models thedissertation proposes a typical dual loops control structure of PWM converters in thesynchronous rotational reference frame. This will provide the fundamental basis for studyingcontrol systems for grid-said converter and rotor-said converter further. And each part of thesimulation model is established. Based on this, the transient process of double-fed wind powergeneration during grid voltage dip is analyzed, and the dynamic responses of double-fed wingpower generation during two typical kinds of grid voltage dip are compared through simulation.Aiming at the above situation combined with the stator-rotor current and dc bus voltagerise caused by the grid voltage dip and it’s harmful effect, On the one hand, a PI-based improvedvector control strategy controller, which introduces the rotor rotating component negativefeedback to the rotor current and introduces the current feedback compensation to the dc busvoltage improves the ability of the ride through operation of double-fed wind power generationsystems during grid fault, is adopted. On the other hand, a novel proportional resonant (PR)controller is adopted. Because the traditional vector control system based on the PI controllerneeds complex rotating frame transformation and exists decoupling item and feedback compensation term. Moreover, the traditional control system will be more complex if lowharmonic is needed compensation. But PR controller can archive zero steady state error, andneedn’t the complex rotating frame transformation and the couple or feedback voltage. Sothrough the grid-said and rotor-said convertor’s mathematical model, the inner control systembased on the PR controller combined with the outer ring control based on the PI is proposed. Itcan make the system structure greatly simplified.