Addis Ababa, the capital of Ethiopia, inaugurated the first electrified light rail transitsystem 4 years ago in September 2015, which makes it the first of its kind in sub-Saharan and eastern African countries. The railway line has a total length of 34.25 km with 39 passenger stations and 19 traction substations. Currently, the performance of the traction power supply system degraded severely due to the existence of harmonics in the traction network. Realizing the above problem, the harmonic analysis of Addis Ababa light rail transit electrified power supply system is presented. The analysis is performed on one of the substations called 'Lideta' rectifier substation. To this end, mathematical modelling and analysis of the traction main components such as the catenary, the traction transformer, the traction rectifier and the load have been done. Finally, MATLAB simulation has been performed, and the result comes with a significant reduction in harmonic distortion, which is far below the 5% limits of IEEE standard.This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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Renewable energy sources, such as photovoltaic, fuel cell and wind energy are becoming a sustainable alternative to non-renewable sources like fossil fuel. However, to integrate these energies into the grid, power electronic converters plays major role due to their power conditioning capability, reliability and effectiveness. In this paper, design, modeling and analysis of a DC-DC boost converter with robust controlling technique, fuzzy sliding mode controlling strategy has been developed and a brief comparison has been performed with a sliding mode controller and a clasical PID controller which employed both current and a voltage control loop. The system is designed to achieve a fast dynamic response, zero steady-state error, and satisfactory stability. To realize that a detailed mathematical derivation of sliding mode fuzzy logic controller and a linearized small signal model of the power electronic converter around its DC steady state operating point is performed. Finally, in order to evaluate the designed system, a software simulation based on MATLAB/ Simulink environment is developed and results of the simulation shows the effectiveness of the proposed techniques.

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Cities all around the globe are ramping up efforts to transform their infrastructure in order to achieve a carbon-neutral and sustainable future, resulting in fast electrification of transportation networks. The need for power in this industry is rising, notably in light rail transit. Application of train rooftops wind energy conversion has the potential to power light rail transits with renewable energy. This research paper presents a way to generate electrical energy by utilizing strong wind pressure from light rail trains that channels the induced wind towards the turbine. The current invention's main aim is to establish a method and system for producing energy utilizing winds that can be conveniently available in the operation of trains. Here the wind energy is independent of the variations in the direction and speeds in which seasonal winds move, which do not have the appropriate wind force or force at all times or places for operating the wind turbines. Vertical axis wind turbines are selected due to their advantage for the application under consideration. SOLIDWORKS and MATLAB simulation software were used for the design of the Train Roof-Tops Wind Energy Conversion System (TRT-WECS). The former was used to perform computational fluid dynamics (CFD) on the both normal train as well as the train having a turbine installed on the top, and a comparison has been made in terms of various parameters that affect the performance of the newly designed TRT-WECS. A mathematical model comprising mechanical and electric components has been developed by using MATLAB. Finally, the study found out that this special TRT-WECS design installed in each train provides an annual energy output of 4.9 MWh.