Economical and practicable condition assessment of MV- and LV-distribution grids

This study describes a procedure of condition assessment for distribution grids, which is applicable in an economical, non-intrusive and practical way. The assessment procedure is based on periodic visual inspections. It is additionally supplemented by suitable and simple measurement methods which can be used without any disconnection of the components and thus without much additional effort during an inspection. Therefore, suitable non-intrusive measurement methods for medium-voltage substations and switchgears as well as low-voltage distribution cabinets will be presented in relation to an integrated condition assessment of distribution grids. However, significance of these non-intrusive measurement methods is limited. Using the example of acoustic partial discharge detection measurement uncertainties will be determined by intensive laboratory tests and numerous field tests realised with several German distribution system operators. These values will be combined with condition information of visual inspections by using theory of evidence to express the uncertainty. Since measurements and visual inspections detect different kinds of deficiencies of electrical equipment, a combination of both is crucial to achieve a high significance of condition assessment as shown in this study.