Substation digitalization and fault isolation : A study of the influence of degree of digitalization to regulatory indicators in the power grid

Sammanfattning: With changes in the energy sector, more demand is set on the power grid as electricity consumption is seen to increase and more decentralized renewable energy production is connecting to the grid. Svenska Kraftnät, electric system transmission operator in Sweden, describes the importance a more secure operation of the power system. This is accomplished with more monitoring of the power grid or a secure grid with less power interruption. Monitoring of the power system is also of importance for supervisory authority of Energimarknadsinspektion (The Energy Market Inspectorate) for the purpose to the regulate the monopolistic activity of the energy market.  Substation digitalization involves implementation of modern IT-system for better monitoring and secure grid through preventive or corrective maintenance. This report focuses on corrective maintenance and how it improves indicators that are regulated by Energimarknadsinspektionen. This report is based on Energiforsk (Lexholm 2016) report for implementation of remote control and monitoring of switch gear will dramatically reduce interruption time of a line. The report describes the investment solution on substations and how it fully influences a distribution line. This report looks closer at a representation of how a line is changed with implementation of digitalization for different number of digital substations at different levels of either remote monitoring or remote control and monitoring. The representation is based on how digitalization influences steps to perform switchover process, a process to act on MV cable fault in distribution grid. Interviews where performed OMEXOM workers, which are responsible of maintenance for grid owner’s substation of Ellevio. How switchover takes is place is modeled based on interviews. Digitalization solution is modeled for a line and it’s influence on switchover. This report provides a method based on interviews to simulate for the KPIs based on interviews performed. Changes in the process are modeled in KPIs of regulatory indicators of customer cost and SAIDI. KPIs of need of fault isolation and fault fixing time are modeled to preview dependance on maintenance group. The simulation method can be used to assess the solution explained in Energiforsk (Lexholm 2016) and provide suggestion for implementing digital substations to the grid. This report shows how remote control and monitoring shows to highly benefit KPIs with SAIDI a regulatory indicator is reduced to 7.58% and it is benefit by applying to all number of substations. 33.3% SAIDI is reached with applying to recommended middle and sectionizer substation. These can be considered as more prioritized substations and more recommended to be digitalized. Remote monitoring shows to decrease SAIDI to 89% and the steps to perform switchover process becomes no longer dependant on information remote recieved from indicators.