Abstract:  Increasing the proportion of cable lines will change the harmonic transfer characteristics of the transmission power grid at HVDC receiving-end. In this paper, the concept of cable rate is proposed firstly, and the harmonic model of distribution parameters of transmission line that accurately considers the cable rate is derived. Then, the model of harmonic voltage transfer coefficient for AC and DC system harmonics transmitted through the outgoing line of HVDC inverter station is established, which considers the cable rate. Finally, taking Yihua HVDC project in Shanghai as an example, the influence of cable rate on harmonic interactive transfer characteristics of transmission power grid at HVDC receiving-end under different modes of outgoing line is analyzed in detail. The results show that the harmonic transfer characteristics between HVDC system and AC transmission power grid at receiving-end are constrained by modes of outgoing line at HVDC inverter station, parameters of outgoing line, cable rate and harmonic frequency；the increase of cable rate will cause the resonance frequency to shift to the left, and the offset in the high frequency is more serious. The derived model can quantitatively analyze the degree of harmonic amplification according to actual line parameters and cable rate, which is a significant basis for cable line planning and construction of receiving-end transmission grid in the future.

Key words: transmission power grid at receiving-end, cable line, HVDC transmission, cable rate, harmonic model of transmission line, harmonic voltage transfer coefficient