System conditions for and probability of out-of-phase

Investigation of the probability of power system separation with its consequences for related power plant, protection/control and circuit breaker requirements. The influence of non-synchronous power plants has been studied. Transmission system operators’ policies with respect to power swings and grid code requirements have been included in the investigations. Recommendations for future studies are in more adequate models to simulate the behaviour of power systems in distress with special attention to type testing protection relays and to support decision makers, system designers/ planners, and the operational staff in control centers.