An approach for comprehensive condition assessment of equipment in electrical distribution grids based on the theory of evidence for managing grid expansion measures in the best conceivable way

Abstract:
In order to obtain valid decisions on the replacement or reinforcement of equipment in the electrical distribution grids, the knowledge of the actual condition of the related equipment is crucial. At point objects, such as gas-insulated switch-gears as well as secondary substations, numerous evaluation criteria can be examined within the scope of visual inspections since these are installed in an easily accessible manner. This also applies to medium-voltage overhead lines. Line objects such as medium-voltage cables are buried and require the use of diagnostic measurement methods to obtain condition information. The approach presented is intended to make condition assessments of point and line objects comparable. This is achieved by an allocation rule of evaluation results in mass figures in the frame of the theory of evidence. The worst/best case algorithm is used to combine the condition indications, which minimizes uncertainties but maintains a critical view of the results. The aggregation of intermediate valuations takes place bottom-up, from the subcomponent to the asset level. This provides an opportunity for the asset management of distribution system operators to include comprehensive considerations instead of performing exclusively asset-dedicated evaluations.