A main challenge in transmission system operation is to ensure optimal utilisation of the existing power grid. Available transmission capacity is to a large extent determined from transfer limits on critical power transmission corridors.
These transfer limits are usually determined from operational security considerations, taking into account critical contingencies and the risk of thermal overloads and stability problems. In the end the transfer limits can be seen as a compromise between market demands and the security of supply (congestion costs versus expected interruption costs).

SINTEF Energy Research has developed prototype computer tools for probabilistic security assessment to be applied by transmission system operators in daily operation planning. Increased utilisation of the transmission system is also a main objective in other important areas of research, which include power system modelling, stability analysis and control design.

New measurement devices and information systems have become available for use in transmission system operation. Based on this technology, improved on-line monitoring, control and protection systems are being developed that can increase security of operation and therefore contribute to raise transmission limits.

SINTEF is involved in research and demonstration projects to develop and test new applications for on-line monitoring and control of network operation based on the use of phasor measurement units (PMU ) and the voltage instability predicor (VIP ).