Theoretical and experimental evaluation of the indirect current control in active filtering and regeneration systems

Abstract

The active filtering and regeneration systems used in active DC traction substations must allow the natural transition from filtering to regeneration mode and vice versa. In the both operation modes, active filtering and regeneration, the grid current must be sinusoidal. Consequently, the magnitude of the fundamental network current is necessary in the control part, in order to generate the reference current. The reference current must be permanently estimated, because it is determined by the load which can be variable. In filtering mode operation, the magnitude of the fundamental grid current can be determined using the load current, but in regeneration mode it can't be estimated directly. In this paper, the indirect current control method is used to estimate the reference current in the both operation modes, active filtering and regeneration. First, the indirect current control method is substantiated, from theoretical point of view, in the case of regeneration mode operation. Next, the analysis based on a specific Simulink model and experimental tests prove the validity and very good performances of the investigated method.