Derivation of Recommendations for the Future Reactive Power Exchange at the Interface between Distribution and Transmission Grid

Conventional power plants in the transmission network are increasingly replaced by distributed generation in power distribution networks. This leads to a lack of reactive power provision in the transmission network. At an ever increasing dimension, cost-intensive measures are taken, such as the installation of compensation elements. This paper aims to present and discuss alternative solutions for cost-efficient provision of reactive power considering reactive power control concepts including distribution networks. A methodology is derived which allows to calculate the potential of reactive power available from the distribution system and to calculate the use-case-dependent need of reactive power in the transmission network. A metaheuristic optimization approach has been developed to consider different comprehensive reactive power strategies. With the help of 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.