See It Fast to Keep Calm: Real-Time Voltage Control Under Stressed Conditions

AS THE ELECTRICAL UTILITY INDUSTRY ADDRESSES ENERGY AND environmental needs through greater use of renewable energy, storage, and other technologies, power systems are becoming more complex and stressed. Increased dynamic changes that require improvements in real-time monitoring, protection, and control increase the complexity of managing modern grids. In an effort to ensure the secure operation of power systems, more attention is being given to voltage management. Voltage management includes addressing voltage stability and fault-induced delayed voltage recovery (FIDVR) phenomena. Deployment of phasor measurement unit (PMU)
technology, in combination with recently developed methodologies for tracking voltage
behavior, has resulted in improved real-time voltage monitoring, protection, and control.
This article describes simple and accurate methodologies based on real-time measurement—
and independent of the system model—designed for tracking both slowdeveloping
and transient voltage stability conditions under various and changing system
configurations. Tests with real-time supervisory control and data acquisition (SCADA) and PMU data, as well as data from comprehensive simulation studies, from the Bonneville Power
Administration (BPA) and Southern California Edison (SCE) systems show very accurate detection
as the system is approaching voltage instability. The calculated reactive power margin and other
indices are easily visualized for operator awareness. For quickly developing disturbances, they allow the initiation of fast control and protection actions. This methodology also discriminates well
between FIDVR and short-term voltage instability. Finally, a tool for properly modeling the
complex voltage phenomena is described.