Power quality enhancement of a T-connected autotransformer based on 72-pulse AC–DC converter with rated power reduction

Abstract

In this paper, a thorough analysis is carried out in order to achieve an optimal design of a T-connected autotransformer based on 72-pulse AC–DC converter. Accordingly, the main purpose of the paper is focused on the power KVA rating reduction for power quality applications. The first merit is that the T-connected autotransformer configuration requires two single-phase transformers, which is more economical (in weight and volume) as compared with other topologies using three single-phase transformers. The second one is that the application of the pulse doubling technique with a low power rating (0.6% of the load power rating) results in a simpler and more economical configuration of the whole system and increased number of pulses. It provides a more economical solution to achieve harmonic mitigation in electric power systems as compared with other 72-pulse AC–DC converters. The simulation and experimental results show that the input current THD is less than 3% using the proposed topology. The results indicate a significant reduction in the total cost and volume of the proposed 72-pulse configuration in comparison with similar configurations. Also, it is shown that the proposed converter rating is about 43.61% of the DC load power.