Impact of MV Connected Microgrids on MV Distribution Planning

The planning and development of distribution networks with a substantial penetration of microgrids connected to the medium voltage (MV) network form the main themes of this paper. The impact of microgrids is assessed in terms of their effect on optimal network topology, losses, reliability, reserve connections, network upgrade and expansion savings. The earning base of the distribution system operator also comes under scrutiny. A suburban MV cable network is planned using a network planning algorithm developed by the authors, first with optimal routing for demand-only nodes and then with a 33% penetration of randomly located microgrids. The network is then expanded to meet the requirements of a future planning horizon, in order to compare the expanded and upgraded optimum MV network topology with and without microgrids. Apart from visually depicting the topological differences, the savings such microgrids can give to the long term distribution network investment and running costs are quantified in terms of the investment costs, loss costs and interruption costs. When networks are planned with optimal rather than full backup, the introduction of microgrids is shown to have a considerable saving impact on all cost components except the cost per unit power transfer in the distribution network.