On May 29

2017

a commutation failure occurred in Yongfu DC project in China due to out-of-zone AC system short circuit fault. During this course

a large number of harmonics were excited and sustained for a long time

resulting in tripping of multiple groups of filters and DC power limiting. In this paper

the harmonic characteristics and recovery characteristics of the incident are analyzed based on the on-site recording and sequences of event. It is proposed that harmonic oscillation of DC connected to AC network via full series compensated lines is the direct cause of generating a large number of harmonics. The relationship between harmonic attenuation characteristics and the number of filter groups is qualitatively analyzed. Combined with EMTDC simulation analysis

the relationship between harmonic characteristics and series compensation

DC power and high reactance is verified. On this basis

DC operation control scheme is proposed and automatic bypass series compensation control measures are implemented. Finally

field tests verify the effectiveness of DC control measures.