Distribution networks are suffering a transformation process with the insertion of distributed energy resources, changing from a passive part of the power grid into an active system. Aiming to reduce the challenges for the distribution system operators to keep the power grid operating inside of the quality levels it is possible to propose some ancillary services. Optimum Power flow is an optimization method used to plan the distribution grid operation. Additionally, the distributed energy resources can be modeled on it and ancillary services provisioning can be considered, as proposed in this work. In this way, the objective of the present work is to formulate a Multiperiod Optimum Power Flow (MPOPF) with the insertion of distributed generation, energy storage systems, microgrids, and electric vehicles at the distribution grid. This MPOPF considers the provisioning of ancillary services by the inverters associated with the equipment connected to the main grid. In the formulation, the entire grid is modeled, considering the placement of classic equipment as a voltage regulator and capacitor banks, in addition to modern technologies as DFACTS (Distribution - Flexible AC Transmission System) and four-quadrant inverters. The MPOPF was simulated for several scenarios considering a 90-bus test feeder and a real distribution grid from Curitiba - Brazil. From the results, the MPOPF proved to be highly robust, being able to simulate the grid with all the equipment connected simultaneously, performing the optimal dispatch of active and reactive power, as well as allowing the operation of ancillary services such as voltage support, peak-shaving, and demand-side management.

Distribution networks have undergone a series of changes, with the insertion of distributed energy resources, such as distributed generation, energy storage systems, and demand response, allowing the consumers to produce energy and have an active role in distribution systems. Thus, it is possible to form microgrids. From the active grid’s point of view, it is necessary to plan the operation considering the distributed resources and the microgrids connected to it, aiming to ensure the maintenance of grid economy and operational safety. So, this paper presents the proposition of a hierarchical model for planning the daily operation of active distribution grids with microgrids. In this case, the entire grid operation is optimized considering the results from the microgrid optimization itself. If none of the technical constraints, for example voltage levels, are reached, the grid is optimized, however, if there are some violations in the constraints feedback is sent to the internal microgrid optimization to be run again. Several scenarios are evaluated to verify the iteration among the controls in a coordinated way allowing the optimization of the operation of microgrids, as well as of the distribution network. A coordinated and hierarchical operation of active distribution networks with microgrids, specifically when they have distributed energy resources allocated and operated in an optimized way, results in a reduction in operating costs, losses, and greater flexibility and security of the whole system.

Multi-microgrids and distributed energy resources in active distribution networks (ADNs).