Title :
Effect of DC ripple and commutation on the line harmonics of current-controlled AC/DC converters
Author :
Grötzbach, Manfred ; Draxler, Bertram
Author_Institution :
Dept. of Electr. Eng., Univ. of Federal Defence Munich, Neubiberg, Germany
Abstract :
Line harmonics are usually predetermined under the simplified assumption that the DC current is sufficiently smoothed. But in practical operation of controlled converters, e.g., feeding medium-sized DC drives, DC ripple often cannot be neglected. For the predetermination of line harmonics, this means that the operating point is specified by the EMF and the mean value of the DC current, i.e., the associated control and commutation angles are unknown. The consideration of the basic effects of commutation and DC ripple leads to line current harmonics that are separated into positive and negative sequence systems. Selected results of systematic evaluations show the amplitude and phase as functions of DC reactance as well as of the EMF and mean DC current in the range of usual low- and medium-voltage supply networks. In comparison with the conventional precalculations assuming sufficient DC smoothing, significant deviations occur in the case of higher DC ripple
Keywords :
commutation; electric current control; power convertors; power system harmonics; DC reactance; DC ripple; DC smoothing; EMF; commutation; current-controlled AC/DC converters; line harmonics; low-voltage supply networks; medium-voltage supply networks; Analog-digital conversion; Bridge circuits; Control systems; DC-DC power converters; Industrial power systems; Medium voltage; Power harmonic filters; Power system harmonics; Power system planning; Smoothing methods;
Journal_Title :
Industry Applications, IEEE Transactions on