Bipolar HVDC transmission-system study between +- 600 kV and +- 1200 kV: corona studies, Phase II

The results of a comprehensive study on the corona performance characteristics of bipolar high-voltage direct-current (hvdc) transmission systems operating at a nominal voltage of +- 900 kV are presented. Results are also presented of bipolar and monopolar cage tests on 19 conductor bundle configurations at voltages corresponding to maximum conductor bundle gradients varying between 20 kV/cm and 30 kV/cm. The test line using 6 x 4.06 cm conductor bundles was operated over a period of more than 12 months, covering all possible variations in weather conditions. The voltages varied from +- 750 kV to +- 1050 kV, with most of the tests carried out at +- 900 kV. The results obtained from the bipolar test line include (1) statistical evaluation of the radio interference (RI); (2) audible noise (AN) and corona loss (CL) performance of the 6 x 4.06 cm bundle at nominal voltages; (3) influence of the line voltage on the RI, AN, and CL performance of the bundle; and (4) data on the frequency spectra of AN as well as on the lateral profiles of RI, AN, ion current density, and electric field at ground level. Moreover, tests were performed to study the psychoacoustic effects of dc coronamore » noise as well as a subjective RI from a dc transmission line. In addition, an aboveground electric field and ion current probe was developed for purposes. The study also included an evaluation of the corona performance characteristics of such parameters as the number and size of conductors in the bundle. Finally, a number of special tests were also carried out on the electric field and ion induction effects on people and objects. The results presented in this report provide the basic technical information required for the design of hvdc transmission systems at a nominal voltage of +- 900 kV from the point of view of corona performance.« less