A general framework for Active Distribution Network planning

The “Copernican revolution” from the current passive distribution system to the future Smart Grid paradigm aims at applying at distribution level techniques and solutions that have been used for decades in the transmission system. The future availability at this level of an integrated system for its operation is changing the planning objectives that will be mostly oriented to the maximum exploitation of existing assets and infrastructures, by working them much closer to their physical limits than in the past. The future distribution network planning will be defined with less network investments since operation’s issues can be fixed with the so called “no-network” solutions, like generator dispatch, demand side integration, control of transformer taps, reactive power management, and system reconfiguration. For these reasons, it is crucial that modern planning tools for the Active Distribution Networks integrate network operation practices in the set of feasible planning alternatives, in order to identify the best technical and economic balance between the innovative active management (that tends to maximize the utilization of existing assets in distribution network) and the traditional network expansion. The representation of load and generators cannot be based yet on unique yearly values as assumed until now by the traditional distribution planning tools, but there is the need of adopting time- series (or time dependent) models, in order to capture the operational aspects that can affect the planning stage. Obviously, for an accurate comparison of the planning options, the costs of the active management implementation should be defined, taking into account the dependency on the ICT and on the Regulatory environment (policy for refunding investments, obligation to serve or remuneration of the ancillary services). However, this evolution of the distribution network planning tools is not an easy task and many challenges arise that have to be faced. The paper presents the results of the activity conducted by the “Method for Active Network Planning” Task Force, part of the C6.19 working group, on this topic and proposes a general framework to be used as reference scheme for Active Distribution Network planning. Specifically, it is emphasised the need to apply probabilistic network calculations and risk assessments, to consider no-network solutions among the planning alternatives and to adopt Multi-Objective approaches.