Active distribution networks or microgrids? Optimal design of resilient and flexible distribution grids with energy service provision

Abstract Ensuring the continuity of service in electricity distribution grids at minimum costs is a key challenge in many countries, as extreme weather events and fluctuating renewable energy increase. New grid concepts such as active distribution networks with distributed energy resources, or microgrids that can operate in islanded mode, offer opportunities to improve the reliability and resilience of distribution grids. This paper presents an active distribution network design optimization with the option to transition into a microgrid, quantifying reliability and resilience improvements, and considering faults within the network as well as unexpected islanding events, which require fast-ramping distributed energy resources. Flexibility, both of loads and distributed energy resources, is used to provide energy services to the surrounding grid with a detailed and general model. Solving the resulting mixed-integer linear program with Column and Constraint Generation and Surrogate Absolute Value Lagrangian Relaxation decreases the computational time significantly. Case studies and sensitivity analyses provide general results for the reliability and resilience targets entailing the optimum transition to microgrids, and quantify the contribution of energy service provision to reduce overall costs.