This is also called one-way power direction. The massive increase in the number of wind turbines and local CHP plants in Denmark means that today power often flows opposite to the power direction for which the electricity grid was designed. When energy from, for example wind turbines, cannot be used locally, the power therefore flows from low-voltage levels towards high-voltage levels in the electricity grid.

This represents a major challenge for power system operation since small production units cannot be controlled to the same extent as the large production units. The number of local production units has grown considerably and is expected to increase even further. It is therefore necessary to introduce new technology into the power system so that voltage quality and security of supply for consumers are safeguarded also in the future.