Influence of harmonics of DC ice melting device on MOA leakage current

In recent years, extreme weather such as low temperature freezing rain and snow has caused great threat to the safe and stable operation of the power grid. The DC ice melting device is a key technical means to cope with extreme weather and can effectively improve the ability of the power grid to resist freezing disasters. In 2019, the Kunming Power Supply Bureau 500kV Qidian substation installed DC ice melting device. Since the rectifier unit of the DC ice melting device uses traditional half-controlled power electronic components, a large amount of harmonics will be generated on the AC/DC side. The zero-power debugging of the DC ice-melting device and the line melting test show that the harmonic will not only affect the system protection action, but also affect the measurement of the leakage current of the metal oxide arrester, thus affecting the judgment of the insulation characteristics of the system equipment. In this paper, the DC melting device in Qidian substation and its harmonic characteristics are studied, and the influence of harmonics generated by DC ice melting device on the leakage current measurement of metal oxide arrester in the system is studied. The theoretical derivation and analysis of this process are given. In order to further guide the operation of the DC ice-melting device and the elimination of harmonics, the theoretical basis for the influence of the leakage current monitoring of the metal oxide arrester is provided.