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Wind shear is among the important sources of torque fluctuation on mechanical side and output power fluctuation on electromagnetic side and grid connection point, which frequency are triple turbine rotation frequency. With the increase in wind turbine single capacity and wind power integration scale, the power fluctuation caused by wind shear canno...
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Citations
... Compared with the harmonic suppression methods from motor structure optimization, the optimization methods from a control algorithm can suppress harmonics without changing the existing hardware conditions. In [15], a synchronous frequency rotation filter was used to directly extract the fundamental back-EMF, which can simplify the control algorithm. However, the existence of a low-pass filter will lead to the degradation of the dynamic performance of the motor drive system. ...
Due to the characteristics of inductance parameter mismatch and back electromotive force harmonics caused by novel leakage flux branches and other non-ideal factors for the variable-leakage-flux permanent magnet (VLF-PM) motor, its control system suffers from a deteriorated performance of the rotor position estimation. To overcome the problems mentioned above, an adaptive tracking estimator of the rotor position is proposed in this paper for the VLF-PM motor control system. First, the proposed method simplifies the VLF-PM motor mathematical model and reduces the effect of inductance parameter variations according to the active flux concept. Then, robust and gradient descent algorithms are utilized to maintain the robustness of inductance parameter variations and eliminate the specific order harmonics owing to the novel leakage flux branches. Meanwhile, the accuracy and stability are enhanced. Furthermore, the position compensation based on the current adaptive tracking strategy is proposed to compensate the rotor position error caused by other non-ideal factors. Finally, the feasibility of the proposed estimated system is verified.
With the increasing size and scale of wind turbines, the ripple caused by wind shear may have negative effects for wind turbines, such as decreasing grid-connected power quality and increasing mechanical loss. To address this issue, a virtual dual-ripple suppression strategy is proposed to suppress the ripple caused by wind shear without additional cost and sacrificing system efficiency. Firstly, in this paper, a three-bladed double fed wind turbine is taken as the research object with the analysis of its transmission mechanism and form of ripple. Secondly, an online artificial neural network (ANN) ripple detection method is proposed to detect the time-varying low frequency ripple with high accuracy. In addition, a virtual dual-ripple suppression strategy composed of two ANN-based filters is utilized to suppress electromagnetic torque ripple and grid-connected power ripple simultaneously. Finally, the accuracy of presented ANN ripple detection method and suppression strategy are verified by MATLAB simulation. The results show that the virtual dual-ripple suppression strategy can effectively suppress the transmission of ripple while increasing the conversion efficiency of wind energy without additional hardware circuit and equipment.
