Case studies: Synchrophasors for wide-area monitoring, protection, and control

Worldwide power systems operated for maximum economy potentially sacrifice traditional stability margins. Long lines between generators and loads, changes in the generation mix, and an increase in interconnections have complicated the use of older tools for system analysis. System disturbances and blackouts at locations throughout the world have demonstrated the need to simplify how system operators obtain the situational awareness necessary to maintain stability and optimize economy. Synchronized phasor measurements (synchrophasors) provide a new method for improved visualization of system conditions and even wide-area-based control. The availability of streaming data in a standard format improves supervisory control and data acquisition (SCADA) data quality and provides automatic checks of state estimation calculations. This paper discusses some of the methods that are being used at electricity providers from locations around the world to visualize, analyze, and control power systems using synchrophasor technology. Simple values, such as voltage angles, line flows, and breaker statuses, can be viewed in real time rather than delayed by scan rates and calculations. Advanced quantities, such as oscillatory modes, damping ratios, and local time errors, can be calculated and displayed for use by operators. This paper provides examples of how these values are collected, correlated, and calculated.