Corona performance of a conductor bundle for bipolar HDVC transmission at plusminus 750 kV

As part of an overall study on the corona performance of bipolar HVDC transmission lines between ± 600 kV and ± 1200 kV, the corona performance of a 4 × 1.6 in. conductor bundle has been studied on an outdoor test line at a nominal voltage of ± 750 kV. The conductor bundle has been tested over a period of about six months covering summer, fall and winter conditions. The study included long-term measurements at ± 750 kV as well as periodic measurements at varying voltages between ± 600 kV and ± 900 kV and at monopolar voltages of + 750 kV and - 750 kV. The principal parameters measured are radio interference (RI), corona losses (CL) and audible noise (AN). Some measurements of ion current density at ground level have also been made. An analysis of the test results is presented in this paper showing the statistical corona performance of the conductor bundle on an annual basis, the generating quantities of RI, CL and AN as functions of the maximum bundle conductor gradient^*, frequency spectra and lateral profiles of RI and AN.