| In recent years,the issue of energy and environment has become increasingly serious.Electric vehicle,which replaces gasoline with electricity,has the characteristics of zero pollution,low noise,and high efficiency.It is widely promoted in countries all over the world nowadays.Constructing charging stations on a large scale is needed for the development of electric vehicle,however,a lot of harmonics are generated by charging stations when they operate,which bring great harm to the power grid if not controlled.Thus,it is necessary to study and control the harmonics of charging stations.Firstly,the structure and the harmonic characteristics of the charger,and the influence of harmonic on power factor are analyzed.The Monte Carlo algorithm is introduced to approximately solve the harmonic content of charger station.The simulation model of charger and charging station is established.The harmonic characteristics under the operaiton of multi chargers,the influence to harmonic caused by voltage classes,harmonic characteristics of charges under different powers,the configuration scheme and harmonic characteristics of different power chargers installed in charging station are analyzed.And the voltage and current characteristics of harmonic in charging station are analyzed to determine whether the harmonic generated during charging process exceeds the national standard,so that appropriate harmonic control measures can be adopted.Finally,based on the analysis of harmonic current characteristics,a hybrid active power filter for harmonic control of charging station is designed.And the simulation model of harmonic control is established in MATLAB/Simulink.By comparative analysis,the results show that the hybrid active power filter can effectively reduce the total distortion rate of harmonic current generated by charging station.This thesis analyzes the harmonic characteristics and laws under single charge and multi charges,the control scheme is proposed according to the harmonic characteristics,which provides the basis for the construction of charging stations and harmonic control. |
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