A DC model for transient analysis of a series active filter integrated with a double-series diode rectifier

This paper proposes a DC model of a series active filter integrated with a double-series diode rectifier. The model is developed with the help of the d-q coordinates transformation. It can be used to accurately and simply analyze transient characteristics of the integrated system around the fundamental frequency, instead of analyzing a complex AC-DC system taking into account the behavior of switching devices. The analysis makes the following assumptions: the system is balanced, and the three-phase supply currents are continuous; supply current harmonics in the integrated system are not so large as to affect the transient characteristics; and the DC load is resistive. The analysis using the DC model tells us that either increasing the active filter gain or decreasing the cut-off frequency of the harmonic detector results in a slow response, and causes a large and long transient of the DC voltage. Simulation results using the EMTDC software package verify the validity of the proposed DC model.