Evaluation of substation configurations and distribution automation with the aid of reliability calculations

This paper shows the significance of combining optimal HV/MV substation configuration, restructuring distribution network and incorporating remote controlled switching on improving system reliability. A case study is used for the reliability assessment. Stedin decided to install new MV switchgear in HV/MV substations in two redundant sections placed in separate rooms. This decision leads to restructuring of the studied distribution grid, mostly by optimizing the feeding infrastructure of the MV distribution grid. Different substation configurations are assessed, resulting in comparable reliability indices for both the two-sections double busbar and the two-sections single busbar configuration, making the single busbar configuration favorable because this configuration is less expensive. Incorporating these adjustments increases total system reliability and makes distribution grid design more straightforward. Restructuring the MV distribution grid has the largest contribution in increasing system reliability. Final step is including remote controlled switching in the distribution network at the open-points, inside new-build satellite switching stations and at strategic points halfway each feeder. All these improvements reduce system average interruption duration with more than 55% per year for the considered case study.