Influence of Converter Bus Serious Harmonic Distortion on HVDC Transmission System

Possibility of serious harmonic distortion (SHD) increases as multi-infeed direct current (MIDC) transmission develops rapidly in recent years. In this paper, the mechanism of high voltage direct current (HVDC) controller working against SHD is proposed for theoretical derivation of phase locked loop (PLL) output and valve commutation process. To reduce static error of constant extinction angle (CEA) controller and enhance active power transmission, the insertion of current error (CE) controller into CEA is minified. A calculation of inverter operating point is proposed in the end. The correctness of mechanism and algorithm is verified through power systems computer aided design (PSCAD) simulation.