Can you in your simulator get solution that generator detects lost of mains or islanding with balance of active power P = 0 and AR- automatic recloseing happens on network breaker with open time pause 300 ms?
I have tought on case when the islanding operation of generator is forbiden if it is RES. You can use frequency deviation or ROCOF protection to disconnect generator and fast close the turbine (simulation) how islanding can be detected in time less the AR pause time of 300 ms. It is situation in our country.
All DG .generators need to satisfied this conditions in experiment when Pg-Pl=0, zero balanse of active power.