The widespread use of distributed generation (DG) relies on methods and techniques aimed at facilitating the network integration of DG. In this context a methodology for the evaluation of the quality and relative merits of these methods and techniques is missing. CIGRE Task Force C6.04.02, which is affiliated with CIGRE Study Committee C6, has addressed this problem by proposing a set of resource and network benchmarks. In the present paper, the benchmark for integrating DG in medium voltage distribution networks is described. The proposed benchmark is representative of a real network while it is also designed for ease of use.The application of the benchmark is described through several case studies that show the impact of DG on power flow and voltage profiles at the medium voltage level.

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The increase in the amount of generators based on renewable energy sources (RES) in the power system is leading to many changes in its operation. Since the RES depends on weather conditions, coordinating the operation of the entire power system has become a more complex issue. New challenges need to be faced in order to supply the electric energy to the customers at the appropriate quality level. In this paper the concept and architecture of a complex Virtual Power Plant (VPP) will be introduced and discussed. The focus will be paid to the optimization of the structure of the VPP as well as to its optimal operation. The result of the optimization have been presented and discussed in the paper taking into account different operation scenarios.Index Terms -Virtual Power Plant, power flow monitoring and control, renewable energy sources, synchronized measurements, system observability.

The feasible operating region (FOR) indicates the operation points that an active distribution network can achieve at the interconnection point with the transmission grid when operating flexible assets within it; without disturbing the stability of the grid itself. Even though the concept is not new, many novel methods to compute the FOR efficiently have been proposed in recent years, resulting in two main schools of thought: random sampling (RS) and optimal power flow (OPF) methods. Both approaches have their merits, yet no wide‐ranging analysis regarding scenarios in which each method could be best applied has been done so far. This paper focuses on performing such a comparison; however, capability charts of flexibility providing units and grids are usually modelled as irregular convex polygons, requiring some adaptation of the RS‐methods to allow for a proper comparison of the resulting feasible operating region. Correspondingly, new methods to adapt the extraction of random samples from generic capability charts are proposed in the paper. Using models of two radial distribution grids, both OPF‐ and RS‐based methods are compared and validated. Results show that RS methods are adequate for assessing small grids, especially with the proposed improvements, while OPF‐based methods excel in larger grids.

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