Analysis of harmonic transmission characteristics in HVDC system

Harmonic is an important factor threatening the safe and stable operation of HVDC system. This paper firstly analyzes the mechanism of harmonics caused by converter transformer. Then., the whole process that harmonics transfer back and forth between the AC system and DC system through the converter is studied by switching function method., which shows the frequency of harmonics is changed systematic after commutation. The analysis method of Harmonic Multi-infeed Interaction Factor for harmonic transmission characteristics in multi HVDC(DC/DC) system is proposed in this paper. Research shows the induced harmonic magnitude from remote DC converters are relative to the electrical distance. PSCAD simulations verify the methods and conclusions.