Assessment and Mitigation of Voltage Drops on Traction Lines: Case Study of Sebeta-Adama Line

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Addis Ababa University


The transmission line in an electrified railway system must provide power transmission within the voltage limit at safe and quality conditions. Therefore, system analysis within the traction power system is vital to the design and operation of an electrified railway. Loads in traction power system are often characterized by their mobility, wide range of power variations, regeneration and service dependence. One of the main problems in the railway supply stations are the voltage drops due to the changes of the load. Voltage drop in electrified railway have an influence on the location of traction substation (reduces distance between traction transformer and section post length) and operating railway transport in a such condition disturbs transportation system, as a result the reactive power compensator should be installed to have a better voltage at receiving end. Ethiopian railway cooperation is constructing national railway transport from Sebeta to Meiso with seven feeding traction substation from Sebeta to Adama. In this thesis traction network voltage drop analysis is undertaken for various feeding condition. Taking sample section from Sebeta substation to Indode substation analyses of the traction network voltage drop over the feeding condition has been conducted for different loading cases. The modeling and simulation of the system is done by MATLAB/SIMULINK software. The systems without Static Synchronous Compensator (STATCOM) have been simulated to investigate the voltage drop for different operating cases. Accordingly, the voltage drop for normal operation case is 5.922kV which is 27.55% voltage regulation. The voltage at the end point of the section is 21.56kV and is within the standard limit (TB10009-2005). However, the voltage drop for over zone (two consecutive sections without section post) is increased to 49.89% and the voltage at end point of the section becomes 18.346kV which is beyond the standard limit. With the STATCOM, for normal operation case the voltage regulation becomes almost zero and for the over zone operation it is reduced to 0.07%. This result clearly indicate that STATCOM application improve the voltage profile and performance of the railway systems.



Voltage Drops, FACTS Devices, STATCOM, Compensator, Voltage Fluctuation