# A Cascaded D-STATCOM Integrated with a Distribution Transformer for Medium-voltage Reactive Power Compensation

• Lei, Ertao (School of Electrical and Electronic Engineering, Huazhong University of Science and Technology) ;
• Yin, Xianggen (School of Electrical and Electronic Engineering, Huazhong University of Science and Technology) ;
• Chen, Yu (School of Electrical and Electronic Engineering, Huazhong University of Science and Technology) ;
• Lai, Jinmu (School of Electrical and Electronic Engineering, Huazhong University of Science and Technology)
• Accepted : 2016.12.03
• Published : 2017.03.20

#### Abstract

This paper presents a novel integrated structure for a cascaded distribution static compensator (D-STATCOM) and distribution transformer for medium-voltage reactive power compensation. The cascaded multilevel converter is connected to a system via a group of special designed taps on the primary windings of the Dyn11 connection distribution transformer. The three-phase winding taps are symmetrically arranged and the connection point voltage can be decreased to half of the line-to-line voltage at most. Thus, the voltage stress for the D-STATCOM is reduced and a compromise between the voltage rating and the current rating can be achieved. The spare capacity of the distribution transformer can also be fully used. The working mechanism is explained in detail and a modified control strategy is proposed for reactive power compensation. Finally, both simulation and scaled-down prototype experimental results are provided to verify the feasibility and effectiveness of the proposed connection structure and control strategy.

#### Acknowledgement

Supported by : National Natural Science of China

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