Affiliation of Author(s):计算机科学与技术学院/人工智能学院/软件学院
Journal:PROCEEDINGS OF THE 2017 12TH IEEE CONFERENCE ON INDUSTRIAL ELECTRONICS AND APPLICATIONS (ICIEA)
Key Words:STATCOM Negative-sequence currents current THD Unbalanced
Abstract:The unbalanced grid voltages can generate negative-sequence currents for the cascaded H-bridge STATCOM. To limit the negative-sequence currents, the negative-sequence currents control loop and negative-sequence grid voltage feedforward are usually employed. However, these methods would result in asymmetric three-phase dc-link ripples and low modulation index, which will deteriorate the current THD. To improve the currents quality, this paper proposes a new negative-sequence current limiting method by varying three clustered de voltages. To counteract the negative sequence grid voltage, the relationship between the negative-sequence voltage and clustered de voltage is established. This relationship reveals that the differences between three clustered dc voltages and their average voltage can generate negative-sequence voltages, which can achieve symmetric modulation waves to balance three-phase dc-link ripples, and limit the third harmonic currents. Moreover, to achieve fixed and high modulation index, a modulation index control is employed by regulating the average voltage of three clustered voltages. The advantages of proposed method are verified in a 380V/7kVar cascaded STATCOM prototype.
ISSN No.:2156-2318
Translation or Not:no
Date of Publication:2017-01-01
Co-author:wang,sen,Lu, Daorong,Yao, Jianhui,Sun, Yongheng,Wang, Jiangfeng,xy,hhb
Correspondence Author:王森章
Date of Publication:2017-01-01