Analysis of Strategies limiting the Reactive Power Flow between Power Distribution and Transmission Networks

The substantial increase in installed capacity of distributed generation in electrical distribution networks leads to an increasing replacement of conventional power plants in the transmission network, which causes a lack of system service provided to the transmission network. This paper discusses alternative solutions for cost-efficient provision of reactive power considering reactive power control concepts including distribution networks. It focusses on strategies limiting the reactive power flow between networks of different voltage levels and compares economic and technical characteristics with other strategies like no limitations for the reactive power exchange between voltage levels or, on the opposite, usecase-dependent reactive power target values given by the overlaid networks. The strategies are investigated with the help of a metaheuristic optimization approach. Based on these investigations it is possible to derive basic recommendations for the organization of the future reactive power exchange at the interface between distribution and transmission networks and the contents of corresponding contracts.