Control of Electronic Power Transformer with Star Configuration under Unbalanced Load Conditions |
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Authors: | Jie Tian Chengxiong Mao Jiawei Yang Dan Wang Jiming Lu Jun Qiu |
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Affiliation: | 1. State Key Laboratory of Advanced Electromagnetic Engineering and Technology , Huazhong University of Science and Technology , Wuhan , China;2. School of Electrical and Electronic Engineering , Huazhong University of Science and Technology , Wuhan , China;3. Wuhan Iron and Steel (Group) Corp., Wuhan , China |
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Abstract: | The electronic power transformer has many advantages, such as reactive power compensation, voltage regulation, harmonic suppression, and power factor correction. When a three-phase electronic power transformer with a star configuration is applied in the distribution network, three-phase load unbalance will cause three-phase DC voltage unbalance if the electronic power transformer controller generates improper asymmetric voltage signals, which may trigger over-voltage protection. The effects of three-phase load unbalance to the work condition of the electronic power transformer are analyzed, and a control algorithm is proposed to balance three-phase DC voltages in this article. Meanwhile, input stage control, isolation stage control, output stage control, and individual DC voltage balancing control are presented. Simulation and lab experimental results show that the electronic power transformer still works properly even under serious unbalanced load conditions. |
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Keywords: | electronic power transformer solid-state transformer three-phase load unbalance cascaded multilevel converter |
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