The structure of railway electrification system is a single-phase line, it uses power electronics devices and has a time varying load characteristic. This is a cause of considerable current unbalance, harmonics and variable reactive power consumption. This usually leads to power quality problems affecting the proper operation of the equipment. Because of the train's unique operation and electrification characteristics, power quality has been a major problem in railway networks. Throughout the history of railway electrification, many research were dedicated to power quality studies. A variety of power conditioning devices have been explored and deployed to traction systems. In this paper, a power quality problem investigation is done by evaluating and measuring major power quality parameters to confirm the mentioned problems on the Ethio-Djibouti railway line. The power quality quantities are measured using Chauvin Arnoux CA 8335 device and relevant data for power quality analysis are extracted using POWER log 5.8 software. Moreover, the power reliability is also evaluated for the same railway network by considering two substations, respectively the Hurso and Adigala substation. The power reliability studies are carried out by considering the recorded outage data due to Overvoltages for a period of one year. The measured data indicates a low power factor which even amounts 0.2, a maximum current unbalance values of 70% and harmonic distortion of 50%. The longest power outage due to over-voltage was 202 hours in January at Adigala substation with a power supply availability of 0.70 p.u in the 2020 years.

This paper uses Newton–Raphson method for DC power flow analysis of the Addis Ababa light Rail Transit (AALRT). The study focuses onthe line section from Menilik II square station up to Lideta station. First the tractive effort required by the trains for different scenarios such as train movement in a straight line, a curved line, and a line with gradient is computed as the chosen line section contains all these scenarios. Then the total input power will be calculated using computed tractive effort obtained for each scenario and using other input parameters obtained from AALRT, and different papers. The input power for the different loads is computed, and the input power is used to analyse the bus voltage for different loads and train positions. Newton Raphson Method is used to solve the DC Power bus problem assuming that the train requires constant power while moving between two feeding stations. Even if using the rail as the return conductor for DC traction systems has economic advantages, it has some limitations like the rail potential and stray current. A rail potential study is carried out and conclusions are drawn. The result shows that the maximum voltage drop was 0.1 p.u and the train power consumption increases by 136.73 kW as the train takes a gradient of 3.92% and keep increasing again by 29.17kw with a curve resistance (100 meters). The Rail potential moves from 6.0139V to 29.85V proportionally with the variation of the total ground resistance.