Minimizing Harmonics and Transformer Derating in Low Voltage Distribution Networks by DC Distribution

摘要

The widespread use of power electronic loads which are nonlinear in nature has led to the injection of current and voltage harmonics in low voltage distribution system. As the distribution transformers have to meet the harmonic losses caused due to the nonlinear loads, their power handling capacity is decreased leading to the derating of transformers. This paper investigates the feasibility of reducing harmonic distortion and derating of transformers by employing a hybrid ac-dc distribution system, in which the dc loads are powered by dc supply through a three phase diode bridge rectifier. For this, an in-depth analysis of the harmonic distortions in the power supply of different domestic buildings is performed by real time measurement and the impact of these harmonics on the derating of transformer in a conventional distribution system is evaluated by simulation. The improvement in power quality by dc distribution is demonstrated by simulation and experimental validation.