Time delay effects in the control of synchronous electricity grids


The expansion of inverter connected generation facilities (i.e. wind and pho-tovoltaics) and the removal of conventional power plants is necessary to mitigate the impacts of climate change.
Whereas conventional generation with large rotating generator masses provides stabilizing inertia, inverter connected generation does not. Since the underlying power system and the control mechanisms that keep it close to a desired refer-ence state, were not designed for such a low inertia system, this might make the system vulnerable to disturbances.
We investigate whether the currently used control mechanisms are able to keep a low inertia system stable and how this is affected by the time delay of control. To this end, we integrate the control mechanisms used in continental Europe into a model of coupled oscillators which resembles the second order Kuramoto model. This model is then used to investigate how the interplay of network topology, delayed control and remaining system parameters effect the stability of the interconnected power system. To identify regions in parameter space that make stable grid operation possible, the linearized system is analyzed to create the system’s stability chart. We show that lower and distributed inertia could have a beneficial effect on the stability of the desired synchronous state.