Research on harmonic transfer between HVDC transmission and AC grid

Abstract

Due to the reverse distribution of China's economy and resources, HVDC transmission with great advantages in long-distance and large-capacity transmission has been greatly developed. At the same time, the diversity of harmonic sources in the AC power grid is increasing, such as new energy power generation, electrified railways, and electric vehicle charging piles. These all have led to the extensive use of high-power power electronic equipment. In addition, the interaction of harmonics between AC and DC systems may cause Harmonic amplification, harmonic cross-modulation, harmonic resonance and harmonic instability. These all threaten the stability of power grid. This paper first analyzes the harmonic characteristics of HVDC transmission, establishes the harmonic model of HVDC transmission, and analyzes the harmonic characteristics of various harmonic sources in AC system. On the basis of this, the transmission characteristics of the DC side harmonics to the AC side and the transmission characteristics of the AC side harmonics to the DC side are theoretically derived and analyzed, and derive the DC voltage characteristics corresponding to the AC positive sequence, negative sequence and zero sequence voltage. Then the harmonic transfer model of the AC and DC side is obtained.