Coordinated Control Strategy of Series and Parallel Grid Side Converters for DFIG System under Unbalanced Grid Voltage
Kang Yilong1,2, Zheng Tingting3, Miao Shihong1,2, Liu Ziwen1,2, Liu Yuliang1,2
1. State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan 430074 China; 2. Hubei Electric Power Security and High Efficiency Key Laboratory Huazhong University of Science and Technology Wuhan 430074 China; 3. State Grid East Inner Mongolia Electric Power Company Limited Electric Power Research Institute Hohhot 010020 China
Abstract:Under unbalanced grid voltage, the stator and rotor currents of a doubly fed induction generator (DFIG) are unbalanced, which influences the safe and stable operation of the machine, and double frequency ripples will appear in the output power of the doubly fed wind power generation system. In order to improve the operational performance and output quality of the system significantly, the operation mechanism of the doubly fed wind power generation system with a series grid side converter (SGSC) is analyzed in this paper, and the control strategy for the SGSC aiming at maintaining the stator voltage balance is proposed, which ensures the balance of stator and rotor three-phase currents. On the basis of the system with a SGSC, the mathematical model of the parallel grid side converters (PGSC) under unbalanced grid voltage is analyzed, and the double frequency power control equation is established. Combined with the double frequency ripples generated by the SGSC, a control strategy based on a reduced-order resonant power compensator for the PGSC is proposed, the goal of simultaneously suppressing the double frequency ripples of the output active and reactive power of the system is achieved. The proposed strategy which is proved to be correct and effective by the simulations of a doubly fed wind power generation system model in PSCAD/EMTDC.
康祎龙, 郑婷婷, 苗世洪, 刘子文, 刘昱良. 不平衡电网电压下双馈感应发电机系统串联和并联网侧变换器协调控制策略[J]. 电工技术学报, 2018, 33(zk1): 193-204.
Kang Yilong, Zheng Tingting, Miao Shihong, Liu Ziwen, Liu Yuliang. Coordinated Control Strategy of Series and Parallel Grid Side Converters for DFIG System under Unbalanced Grid Voltage. Transactions of China Electrotechnical Society, 2018, 33(zk1): 193-204.
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