Defense plan against loss of synchronism in interconnected power systems

This paper presents a new approach for an out-of-step protection system for transmission corridors in interconnected power systems. The novelty of this approach is its interdependence on having a complete observability of the system. A defense plan analyzes voltage phasors measured at different network locations to determine the security state of the transmission corridor. If a disturbed state is detected, the protection system separates the network parts connected by the corridor to avoid synchronous machines falling out of step due to the divagation of the voltage phasors. Exemplary simulations are shown to compare the defense plan with conventional protection systems based on distance protection relays. A presumed interconnection of the UCTE system with the IPS/UPS system is used as simulation scenario.