Coordinated Operation and Flexibility Management of Medium and Low Voltage Grids

The connection of distributed energy resources in distribution system have been increasing significantly, requiring new approaches as market-based flexibility solutions. This paper proposes the coordinated operation of on-load tap changer and flexibility services traded in a local market for voltage regulation in medium and low voltage grid. The wider action of on-load tap changer is used to restore voltages at the medium voltage feeder based on sensitivity coefficients. If voltage violations persist, flexibilities are traded in a local energy market with a cost-effective approach, where flexibility costs are minimized, and are activated according to their effectiveness indicated by sensitivity coefficients. Sensitivity coefficients are obtained in the medium voltage using an analytical approach that can be applied to multi-phase unbalanced systems, and in the low voltage using a data-driven approach due to their limited observability. Results show the proposed approach can be an effective solution to regulate voltages, combining the wider action of on-load tap changer with local flexibility, avoiding unnecessary tap changes and requesting a small volume of flexibility services.