Limitations of LCL filter for three-phase shunt active power filters in active traction substations

摘要

The main goal of this paper is to underline the limitations of LCL interface filter used in three-phase shunt active power filter for active traction substations. Starting from the two main functions that should be fulfilled by the interface filter, i.e. let them unchanged the current harmonics that must be compensated and stop harmonics due to inverter switching, it is shown that they can not be met and that the only viable solution is to achieve a compromise between the two. The analysis carried out is based on the transfer functions of currents and creates the premises to elaborate the design algorithm to achieve the most appropriate compromise between the two requirements.