DC coupled Distribution System Groups enable lowering Provision of Ancillary Services

Since a significant number of renewable energy plants (RES) are connected to the distribution grid level, the ratio of feed-in to load in the distribution grids is very different. Today's centralized distribution system groups mean that balancing between systems is usually carried out via the transmission system, leading to additional bottlenecks and even to the shutdown of RES installations. This contribution presents a new approach to power balancing at the distribution system level. By means of DC couplings, controllable power transits between high-feed and high-load system groups are enabled, with the result that transmission losses and ancillary services to be provided can be reduced. The evaluation is carried out on basis of a generic medium-term model and shows that the concept idea enables a relief of the transmission system within the scope of power-frequency control as well as saving reserve power for power system restoration.