Simulative analyses of dynamical behaviour of steam-powered turbo generators during power system incidents with a higher rate of change of frequency

The national goal in the Republic of Ireland and Northern Ireland is to cover 40 % of electricity demand by renewable generating plants in 2020. This leads to less inertia in the power system and higher rates of change of frequency (ROCOF) after grid faults. This publication focuses on the dynamic behaviour of electrical generators of five different turbo generators during transients of mains frequency with a higher ROCOF. The results show that different turbo generators react in diverse ways to the frequency excursions used for the studies. The electrical torque leads according to a first estimation to torsional moments and fatigue of material of the shaft line in a tolerable range for single events. An adjustment of controllers optimized for higher ROCOF could reduce occurring oscillations. At least one investigated CCGT could trip due to protection system settings, which urges further studies.