The increasing penetration of new renewable sources of energy in today's
power grids is accompanied by a decrease in available electromechanical
inertia. This leads to a reduced dynamical stability. To counterbalance this
effect, virtual synchronous generators have been proposed to emulate
conventional generators and provide inertia to power systems. The high
flexibility of these devices makes it possible to control the synthetic inertia
they provide and to have them operate even more efficiently than the
electromechanical inertia they replace. Here, we propose a novel control scheme
for virtual synchronous generators, where the amount of inertia provided is
large at short times - thereby absorbing local faults and disturbances as
efficiently as conventional generators - but decreases over a tunable time
interval to prevent long-time coherent oscillations from setting in. This new
model is used to investigate the effect of adaptive inertia on large-scale
power grids. Our model outperforms conventional constant inertia in all
scenarios and for all performance measures considered. We show how an optimized
geographical distribution of adaptive inertia devices not only effectively
absorbs local faults, but also significantly improves the damping of inter-area
oscillations.Comment: 6 pages, 5 figure