SUMMARY

The conversion of an existing AC circuit into DC operation is an attractive option to increase the capacity of existing power transmission corridors. If one of several AC circuits on a tower is converted, the result is also called hybrid AC/DC configuration. For dimensioning of such system a number of electrical effects, for example, overlapping of the electromagnetic field and the corona characteristics have to be considered. A key difference is that under the influence of DC fields, corona generated ions drift into the inter-electrode region towards nearby conductors as well as towards ground. The focus of this paper is on the DC ion current injection into nearby grounded conductors (as a preliminary step towards estimating the DC current component in AC conductors). To the present day several approaches have been developed to predict the ion flow in the environment of DC and hybrid AC/DC transmission systems. A shortcoming of existing validation measurements is that only ground-level ion currents and electric fields have been compared. To the authors ’ knowledge, at the time of writing, there exists no comparison between simulated and measured DC ion currents suspended in parallel conductors, which are based on full-scale, outdoor arrangements. Accurate predictions of these quantities, however, are indispensable for assessing the DC current components in nearby A