PMU and DSA based wide area control system: Concept and application in large longitudinal system

In the last ten years PMUs (Phasor Measurement Units) play a more and more important role for the on-line monitoring and analysis of the state of the electrical systems. The reasons for this development are dynamic loading of transmission systems, demand on flexibility of generation, high penetration of renewable generation and decentralized load and generation centers. PMUs today allow measuring current and voltage phasors and execute functions such as power swing recognition and island detection. Indices can be created on basis of measurements, which can be used for alarming, protection and control. A combination of measurements and indices allow for creating an overall PMU index which describes the online state of the system and consequently the change of state (tendency) of the system. The information is created in the phasor data processor (PDP) which can exchange data with a dynamic security assessment (DSA) system or/and SCADA system in order to monitor local and global system states for stability, continuous steady state analysis, short term / forecast stability analysis and remedial actions. Finally, combining PDP, DSA and SCADA enables to enact a wide area protection and control arming and disarming pre-calculated system integrity schemes.