Within this contribution, optimal operating strategies for a reliable electrical energy supply system with complete integration of the generation from renewable energies will be presented. The approaches to be compared are vertical and horizontal network operation as well as network management using virtual power plants. In this connection, aspects of the energy market are combined with those of the transmission and distribution grid. The objective of all approaches is to maximize the use of renewable energies while respecting the grid restrictions to be observed. The advantages and drawbacks are compared by grid related performance indicators.