A T, Star-Delta and Zigzag Connected Transformer Connections of 5-Level and 7-Level VSC Based DSTATCOM for Power Quality Improvement

Abstract: In this paper, a new three-phase four-wire Distribution Static Compensator (DSTATCOM) based on a T- connected transformer and a three-leg Voltage Source Converter (VSC) is proposed for power quality improvement. The T-connected transformer connection mitigates the neutral current and the three-leg VSC compensates harmonic current, reactive power, and balances the load. Two single-phase transformers are connected in T-configuration for interfacing to a three-phase four-wire power distribution system and the required rating of the VSC is reduced. The Insulated Gate Bipolar Transistor (IGBT) based VSC is supported by a capacitor and is controlled for the required compensation of the load current. The DC bus voltage of the VSC is regulated during varying load conditions. The DSTATCOM is tested for power factor correction and voltage regulation along with neutral current compensation, harmonic elimination, and balancing of linear loads as well as nonlinear loads. The performance of the three-phase four-wire DSTATCOM is validated using MATLAB software with its Simulink and power system block set toolboxes.

Keywords: D-STATCOM, Harmonics, Inverter Transformer, Power Quality.