Circulating current control strategy for parallel full-scale wind power converters

Jing Lyu; Jianwen Zhang; Xu Cai; Haisong Wang; Jinshui Dai

Circulating current control strategy for parallel full-scale wind power converters

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Author(s): Jing Lyu ¹ ; Jianwen Zhang ^{1, 2} ; Xu Cai ^{1, 2} ; Haisong Wang ¹ ; Jinshui Dai ¹
- Affiliations: 1: Wind Power Research Centre, Department of Electrical Engineering, Shanghai Jiao Tong University, Shanghai 200240, People's Republic of China ;
  2: State Key Laboratory of Ocean Engineering, School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiao Tong University, Shanghai 200240, People's Republic of China
Source: Volume 9, Issue 4, 30 March 2016, p. 639 – 647
DOI: 10.1049/iet-pel.2014.0926 , Print ISSN 1755-4535, Online ISSN 1755-4543

Received 02/12/2014, Accepted 14/08/2015, Revised 08/04/2015, Published 30/03/2016

Converter parallel techniques can increase the power rating, but there is a circulating current problem. Therefore, this study focuses on the circulating current problem in parallel full-scale wind power converter systems. The general definition of circulating currents is first introduced. The concept of circulating current percentage is then defined to quantitatively analyse the relatively serious situation of circulating currents for parallel converter systems. Then, the generation mechanisms of circulating currents are analysed based on the mathematical model of circulating currents. Actually, circulating currents can be regarded as a kind of disturbance to the load currents of a parallel system. Thereby, a novel control strategy, based on circulating current feed-forward compensation for parallel converter systems, is proposed and a feed-forward controller is designed. Finally, simulations based on MATLAB/Simulink and hardware-in-loop experiments based on RT-LAB are carried out. Both simulation and experimental results validate the proposed circulating current control method.

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