  With Denmark dedicated to maintaining its leading position in the integration
of massive shares of wind energy, the construction of new offshore energy
islands has been recently approved by the Danish government. These new islands
will be zero-inertia systems, meaning that no synchronous generation will be
installed in the island and that power imbalances will be shared only among
converters. To this end, this paper proposes a methodology to calculate and
update the frequency droops gains of the offshore converters in compliance with
the N-1 security criterion in case of converter outage. The frequency droop
gains are calculated solving an optimization problem which takes into
consideration the power limitations of the converters as well as the stability
of the system. As a consequence, the proposed controller ensures safe operation
of off-shore systems in the event of any power imbalance and allows for greater
loadability at pre-fault state, as confirmed by the simulation results.
