Review of Torque Ripple Suppression Methods for Doubly Fed Induction Generator under Non-Ideal Operating Conditions
Liu Yi1,2, Zhang Maoxin1, Xu Wei1,2, Ge Jian1, Chen Yahong1, Li Mingxian3, Dong Yipeng3
1. State Key Laboratory of Advanced Electromagnetic Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan 430074 China; 2. Research Institute of Huazhong University of Science and Technology in Shenzhen Shenzhen 518052 China; 3. Zibo Jingke Electric Co. Ltd Zibo 255000 China
Abstract:Under non-sinusoidal and unbalanced operating conditions, the doubly fed induction generator (DFIG) encounters significant torque ripple issues, which can severely damage the gearbox and drive shaft and threaten the safety and stable operation of the system. In recent years, numerous solutions have been proposed. This paper classifies and summarizes the existing technical solutions, enabling scholars in related fields to quickly understand the research status and development trends, thereby promoting the further development of torque ripple suppression technology for DFIG. Existing technical solutions can be divided into hardware structure improvement and control strategy improvement methods. The hardware structure improvement method mainly includes using multi-pulse rectifiers, adding passive filters, and using voltage source converters. This method can effectively suppress torque ripple but requires changing the machine structure or adding additional equipment. As a result, the system cost is high, so the hardware structure improvement method is often used in the system design stage. The control strategy improvement method is the most commonly used, including the torque closed-loop control method, the torque open-loop control method, the non-ideal component elimination method, and the multi-objective predictive control method. The torque closed-loop control method can achieve high-precision torque control and has good system stability but its target extensibility is low, which is often used in applications requiring high torque quality. The torque open-loop control method has strong target extensibility and is often employed in systems with multiple control targets. However, the torque open-loop control method highly depends on machine parameters, and the parameter perturbation seriously affects the torque ripple suppression performance. The non-ideal component elimination method is relatively simple to control. However, it cannot simultaneously eliminate non-ideal components of voltage and current, and the effect of torque ripple suppression is unsatisfactory. This method is usually adopted in applications requiring high voltage or current quality. The multi-objective predictive control method can achieve multi-target collaborative optimization. However, no general method exists to optimize the weight factors for multiple control targets. In the future, the DFIG power generation system should adopt a collaborative suppression method combining hardware structure and control strategy improvement methods to restrain torque ripple more economically and effectively. Additionally, the control strategy improvement method should include parameter identification, parameter-free control, and harmonic loss suppression to improve the machine parameter robustness and efficiency of the control system. Furthermore, the torque ripple suppression method under the fault state of the DFIG system needs to be further explored to improve the system’s fault-crossing ability.
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