DC System Resonance Analysis

DC filters and dc smoothing reactors are primarily designed to meet performance requirements with regard to telephone interference levels and commutation failure frequency. Other factors, however, place constraints on the size of the dc filter capacitance and the smoothing reactor inductance. The principal constraint is the avoidance of resonance conditions on the dc side at a low order harmonic of the commutating voltage. This paper discusses the factors which must be considered when analyzing dc side resonance. Specific considerations for the Intermountain Power Project are given.