The growing share of electricity generation from intermittent renewable energy sources as well as increasing market-based cross border flows and related physical flows are leading to rising uncertainties in transmission network operation. In the mainland central Europe synchronous area due to large installations of renewable energy generation such as wind and photovoltaic, the difference between actual physical flows and the market exchanges can be very substantial. Remedial actions were identified by previous smart grid studies within the 6th European framework program in operational risk assessment, flow control and operational flexibility measures for this area. At the same time an efficient and sustainable electricity system requires an efficient usage of existing and future transmission capacities to provide a maximum of transportation possibilities. New interconnections and devices for load flow control will be integrated in future transmission networks and will offer new operational options. Further developments of coordinated grid security tools are one of the major challenges TSOs will face in future. The methods to be applied have to take into account all technological measures to enhance flexibility of power system operations. The zonal structure of the European energy market along with the legal responsibilities of TSOs for different system areas will continue to pose increasingly complex requirements to the system operators concerning the quality and accuracy of cooperation. The proposed UMBRELLA research and demonstration project is designed for coping with these challenging issues and boundary conditions. The toolbox to be developed will enable TSOs to ensure secure grid operation also in future electricity networks with high penetration of intermittent renewables. It enables TSOs to act in a coordinated European target system where regional strategies converge to ensure the best possible use of the European electricity infrastructure.