Two-terminal out-of-step protection for multi-machine grids using synchronised measurements

To prevent critical power system conditions dedicated out-of-step protection schemes are used in high-voltage networks, otherwise referred to as asynchronous operation protection automation. Structure of out-of-step automation is proposed in this paper addressing angular instability between multiple areas of the grid. Two strategically located substations are equipped with a protection scheme performing synchronized measurement of the local voltage phasors. In addition it calculates four remote phasors in real time and exchanges measurement/simulation results via communication channels. A location for the controllable grid splitting is decided in a flexible manner inclusively addressing influence of highly variable portion of the renewable production. Power utilities currently having limited PMU coverage would benefit from application of the proposed scheme as well as transmission corridors between systems with different PMU usage practices in regards to out-of-step protection.