Design and development of controllable filter banks for harmonic current suppression on the AC side of the converters of DC transmission lines

Elimination of current harmonics on the ac side of converter bridges of dc transmission system has been investigated and reported. This includes characteristic current harmonics at ideally stipulated normal conditions and also the uncharacteristic ones at abnormal conditions particular ly with weak ac system. Suppression of uncharacteristic harmonics is achieved with the use of phase locked oscillator or by firing angle modulation. Furtber elimination is affected via active and or passive filters. Design, control of these and the performance evaluation under changing system conditions and requirements are presented.