Performance Testing and Power Quality of DC Semi-Fast Chargers of Electric Vehicles (EVs) for Public Transportation: a Case Study

Abstract

This paper contains the analysis of the impact, performance, and effect on power quality of the semi-fast charging cycle of electric vehicles (EVs) within the electrical grid. The results allowed to obtain an electric model of the EV charging cycle. The procedures and results of tests on the DC semi-fast charging cycle of EVs used for the public transportation in Bogota D.C. are presented. Some tests to the EV charging cycle were applied in steady state in order to evaluate the performance and the power quality of EVs. The fact that the charging system has a total harmonic current distortion (THDi) of 7% and a total harmonic voltage distortion (THDv) that satisfactorily comply with local and international regulations is highlighted. Tests were performed in transient state of the charger and their analysis was done by using Continuous Wavelet Transform (CWT). Results in transient state of the beginning of the DC charging cycle of EVs reveal that the harmonics of greater impact are 3°, 4°, and 5°. Finally, based on the analysis of the presented results, a simulation profile of the charging system was designed using the Matlab Sim Power Systems tool. The obtained model shows an error of 2% compared to measurements in steady state. This model will be useful in decision-making on the processes of system planning in case that EVs will be massified within the public transportation in Colombia.