A Power supply reliability assessment model for the Colombo suburban railway network

Abstract

An electrified railway network is one of the solutions for Colombo traffic congestion due to high population density and high daily passenger flow into the city from the suburbs. Although the initial cost of a railway electrification project is higher compared with other alternatives such as improvements to bus transport, energy, maintenance and operational costs can be lower if the system is designed, maintained effectively and used efficiently. System failures or, delays in system operations should be minimized to reduce the time wasted in traveling. Reliability and punctuality are the major factors to attract more passengers to use public electrified transport facilities for their daily travel. Power supply is a critical factor to maintain a higher reliability in an electrified railway system. Designs to upgrade the 230 km long Colombo suburban railway network commenced in 2017 and currently in progress in four stages. Different options for the power supply configuration and the back-up power systems have been identified, qualitatively evaluated and then recommended for implementation. A quantified reliability assessment has not been reported in the design. A standardized procedure and a reliability assessment model would be required to evaluate the reliability of each optional configuration to supply power and backup power. In this research, optional configurations to supply power to the future electrified railway system of the Colombo Suburban Railway Project area were developed. Reliability assessment was conducted for each optional configuration using the models developed and simulated using Monte Carlo simulation technique. Reliability worth analysis was done to weigh the costs and benefits of configurations with higher reliability. The model developed can be used for reliability assessment of the power supply to any suburban electrified railway system in Sri Lanka.