Utilization of Hybrid Filter to Eliminate Harmonics of 25 kV AC Electric Railway

Electric trains inject a large amount of harmonics to the power network and consume high reactive power which makes them one of the worst loads kinds to be used in the power systems. These loads have non-linear characteristics and cause harmonic distortion. Filtering is one of the common ways utilized to eliminate harmonics and compensate reactive power. Filters are categorized in three types: passive, active and hybrid. Both passive and active filters have their own deficiencies while hybrid filters benefit from advantages of both former filters while overcoming their deficiencies. In this paper, active, passive and hybrid filters are discussed and then a suitable hybrid structure is introduced. Thereupon a harmonic model of an intercity electric train is presented and application of the proposed hybrid filter structure to the train is simulated using MATLAB/SIMULINK. The obtained results demonstrate the effectiveness of utilization of such hybrid filter structure in elimination of harmonic components and reactive power compensation.

Keywords:

Nonlinear loads , Harmonic elimination , Reactive power compensation , Hybrid filters , Power quality improvement