Optimal design policy and strategic investment in distribution networks with distributed generation

The operation of microgeneration connected to the distribution network can cause statutory voltage limits, recommended voltage unbalance levels and switchgear fault ratings to be exceeded. However, there are a range of distribution network designs and operating practices and thus the impact will vary accordingly. Relating losses, voltages, currents and load unbalanced ratio leads to conclusions about the way to operate an existing network or optimise a new one with small-scale distributed generation. The aim was to investigate and develop methodology for evaluation of the long-term loss-inclusive optimal network design strategies and to determine the effect of the penetration of microgeneration such as CHP and PV in realistic distribution networks. The overall conclusion is that to accommodate microgeneration penetration into existing networks, no major capital investment is required. The need for reinforcement of the network components will depend on the level of generation and on the extent to which reverse power flows happens. In most parts of the network, microgeneration exports will not be sufficient to result in any need for network investment. However, if the network was to be planned accounting with DG, the optimal design policy adopted for distribution networks would change when compared to networks with no microgeneration.