Investigation of Corona and Field Effects of AC/DC Hybrid Transmission Lines

This paper describes laboratory and analytical studies that have been conducted by The Bonneville Power Administration to determine corona and electric field effects of a proposed ac/dc hybrid transmnission line. The proposed hybrid line would consist of a 500 kV ac circuit operating on the same structure as a ±500 kV dc circuit. Generally, the laboratory studies show that, with some modifications, equations used at BPA for calculating corona phenomenon can be used for a hybrid line. The paper also describes a technique for estimating dc electric field parameters which are enhanced by the presence of ions