C-type filter design based on power-factor correction for 12-pulse HVDC converters

The use of conventional (single-tuned and high-pass) filters for HVDC systems can be difficult due to the likelihood of resonance caused by single-tuned filters, and considerable power losses in high-pass filters. This paper presents the C-type filter as an alternative to the conventional filtering in HVDC systems, to improve both the power quality and the power factor, and to reduce the power losses. The merits and limitations of the C-type filter compared to the conventional filters are studied in this paper, and a design method is presented based on power factor correction over a wide range of frequencies. The performance of the designed filters and their superior performance is evaluated for a 12-pulse HVDC converter system, based on simulation studies conducted in the MATLAB software environment.