Assessing the temporal and spatial impact of renewable energy integration on medium voltage transformer failures

The increasing integration of renewable energy sources (RES) in distribution networks causes a change in the operation of the grid, particularly in loading patterns, which potentially affects the failure rate of medium voltage distribution transformers. Two complementary methods are assessed to review the impact of RES on transformer failure rates. Both methods are applied on the service area of the Dutch distribution system operator Stedin. The temporal analysis reveals significant hourly correlations between failure rates and renewable generation profiles, although no seasonal trends are observed. The spatial analysis highlights localised effects, with moderate correlations in specific areas, particularly where photovoltaic generation is oriented east-west. Despite the lack of a trend indicating increased failure rates due to increasing RES penetration, the findings suggest localised stress on assets and show the need for further research into long-term ageing effects.