Trade-off analysis of virtual inertia and fast primary frequency control during frequency transients in a converter dominated network

Traditionally the electricity generation is based on rotating synchronous machines which provide inertia to the power system. The increasing share of converter connected energy sources reduces the available rotational inertia in the power system leading to faster frequency dynamics, which may cause more critical frequency excursions. Both, virtual inertia and fast primary control could serve as a solution to improve frequency stability, however, their respective impacts on the system have different consequences, so that the trade-off is not straightforward. This study presents a comparative analysis of virtual inertia and a fast primary control algorithms with respect to rate of change of frequency (ROCOF), frequency nadir and steady state value considering the effect of the dead time which is carried out by a sensitivity analysis. The investigation shows that the virtual inertia controller is effective in reducing the ROCOF compared to fast primary control. However, it is worsening frequency nadir and steady state value. Moreover, the sensitivity analysis shows the very limited effect of the two controllers on the voltage magnitude.