Reduction of Three-Phase Voltage Unbalance Subject to Special Winding Connections of Two Single-Phase Distribution Transformers of a Microgrid System Using a Designed D-STATCOM Controller

• Published in: IEEE transactions on industry applications Vol. 54; no. 3; pp. 2002 - 2011
• Main Authors: Wang, Li, Liu, Wei-Sheng, Yeh, Chuan-Chieh, Yu, Chien-Hsiang, Lu, Xiu-Yu, Kuan, Bing-Lin, Wu, Hong-Yi, Prokhorov, Anton Victorovich
• Format: Journal Article
• Language: English
• Published: IEEE 01.05.2018
• Subjects: Automatic voltage control; Distribution static synchronous compensator; distribution transformer; Electrical engineering; Generators; Mathematical model; microgrid system; Microgrids; U-V/V-V winding connections; voltage unbalance; Windings
• ISSN: 0093-9994; 1939-9367
• DOI: 10.1109/TIA.2017.2786707

The U-V or V-V winding connections of two single-phase distribution transformers are widely utilized in distribution systems to deliver power to various three-phase and/or single-phase loads. Such special winding connections of distribution transformers can cause three-phase voltage unbalance in distributions systems, which could also lead to unexpected trip of ground relay, extra power losses on distribution-system lines, reduced operating efficiency of induction-motor loads, etc. This paper proposes a distribution static synchronous compensator (D-STATCOM) to effectively improve the voltage unbalance of a distribution system connected with a microgrid system. The studied microgrid system contains various renewable-energy resources, a diesel-engine generator, and three distribution transformers with U-V and/or V-V winding connections. The simulation results show that the proposed D-STATCOM with the designed controller can effectively reduce voltage unbalance of the distribution system connected with the studied microgrid system when the distribution transformers have U-V and/or V-V winding connections.