Harmonic Analysis of a Third Rail Systems: A Case Study in Malaysia

Abstract

Harmonic distortion is one of the most important power quality issues in third rail electrification systems. The use of rectifiers and inverters in the third rail system can inject a significant amount of harmonic distortion to the electrical network. This paper aims to investigate the harmonic distortions for a DC urban third rail system at various operating conditions. The electrical network of Mass Rapid Transit Line 2 (MRT 2) Malaysia is modelled using ETAP software. The model had considered the effect of the inter-phase transformer in the 12-pulse rectifier. The current injection method is used to measure harmonic distortion at Point of Common Coupling (PCC) at the 132 kV and 33 kV buses. A normal and degraded operating conditions of power supply are investigated. From the simulation results, it is found that the 11th and 13th order harmonics have exceeded the statutory limit at 33 kV network for the normal operating condition. For the degraded operating condition, only the 11th harmonic order has exceeded the statutory limit. Keywords: Harmonic Distortion; DC Urban Rail; Various Operating Conditions