When changing the generation mix to a larger share of converter connected generation, the important grid support from synchronous generation as inertia and short circuit power is reduced. The study shows that the reduction of inertia in the system implies a larger frequency derivative and thereby also larger frequency deviations.
From the nuclear power plant, it can be concluded that a change in the generation mix will result in a risk of larger variations in the frequency and lower short circuit current resulting in a weaker grid. Further, there is also an increased risk for oscillations in the grid following the fast control required for converters to support with fast frequency control, synthetic inertial and fault current. The nuclear power plant is an important part of the grid providing both inertia and short circuit current to the system. Therefore, it is important for the nuclear power plant to stay connected during and after disturbances.
