Investigation of the influence of bundled conductor capacitance on power loses associated with corona discharge

Abstract

The determining factor for the presence of a corona is the value of the charge of the wire, which determines the intensity of the electric field. Quantitative characteristics of the charge value of the line phase depend on the capacity and voltage. If the influence of voltage on corona losses has been studied by many authors, the influence of capacity is practically not studied. This is primarily due to the fact that the constructive implementation of the split phase of the overhead line was very carefully determined by regulatory documents. In our opinion, today there are all possibilities for changing the designs of phases and, accordingly, their capacities. This became possible thanks to a change in approaches to the design of the structure of the phase wire on the substation. Determination of the electric capacity of the overhead line with bundled conductors is quite often performed using equivalent parameters, such as equivalent suspension height and equivalent radius. This approach makes it possible to obtain average values of the phase capacity of the overhead line. For a detailed analysis of the effect of capacity on corona losses, it is necessary to determine more reliable values of capacities and use them in calculations of corona losses. The capacity of the phase is determined by the geometric dimensions of the split phase. The obtained results indicate a very strong dependence of corona losses on the capacity of the split phase. When approaching a grounded object, the phase capacity can significantly increase. A vivid example of such an increase is the approach of bundled conductors to the elements of overhead line supports. The distances to the ground in this case will be smaller than the equivalent height of the suspension, which is used in the calculations of the specific losses per crown to determine the capacity of the phases of the overhead line. It is necessary to take into account possible changes in the capacity of the split phase at the stage of designing the overhead line. Another result of the calculations was a much greater influence of the capacity of the middle phase on the amount of losses per corona. This makes it possible to reduce corona losses due to the appropriate design of the middle phase of the overhead line, for example, by changing its splitting radius.