Study on transient characteristics of secondary arc of AC/DC hybrid transmission lines on the same tower

The AC/DC hybrid transmission line is affected by electromagnetic coupling. After the line is failed, the secondary arc is difficult to extinguish, which posed a serious threat to the stable and reliable operation of the line. Taking a 500 kV AC double-circuit and ± 800 kV Yun-Guang UHV DC transmission line on the same tower as an example, this paper is built an AC/DC hybrid transmission line model through PSCAD, studied the influence of coupling section length and fault point location on the transient characteristics of the secondary arc, and analyzed the suppression effect of the DC line coupling operation mode on the secondary arc. According to the findings, the secondary arc current of AC and DC lines is greatly influenced by the length and location of the coupling section. The AC line fault is located at the midpoint of the coupling section. When the length of the coupling section is 400 m, the amplitude of the secondary arc current has reached the minimum value. When the DC line fault is located at the midpoint of the coupling section, the amplitude of the secondary arc current has reached the maximum value. In addition, the bipolar coupling operation mode of DC lines can effectively limit the amplitude of secondary arc current and recovery voltage of AC and DC lines, and the suppressive effect of secondary arc is obvioused.