The objective of this paper is to describe the various measures investigated to secure the behaviour of Oman-UAE interconnected power system when facing large disturbances. When occurring, the activation of the defence plan maintains or restores the stability of the interconnected system but also to limit the spreading of the disturbance or the instability phenomena to large portions of the power system. The main defence plan and emergency actions of concern are:

A large number of severe contingencies have been simulated to locate the coherent group of generators following a loss of synchronism. These have been achieved by the simulation of 3-phase faults cleared in backup time close to 220 kV substations leading to the loss of two circuits or one 220 kV circuit and one transformer. The cases leading to the loss of synchronism of a set of generators have been detected. These cases should be addressed with adequately located and tuned out of step protections. In some situations the system splits into two or more coherent groups of generators. Simulations of faults cleared in backup time have shown that in very unlikely Oman exporting situations, the transmission system or part of it may lose synchronism with respect to the UAE system.