Real-time estimation of security from voltage collapse using synchronized phasor measurements

We present a case study for estimating security from voltage collapse utilizing synchronized phasor measurements. Phasor measurement units (PMUs) provide the GPS time-synchronized voltage and current phasors that are transmitted to a central location where the system's voltage security status is determined by a decision tree type algorithm. The decision tree architecture is designed using wide area measurements generated from off-line continuation power flow simulations. Accompanying system studies revealed that bus voltage angle differences and transmission line reactive flows constitute the best measurement attributes for determining voltage security. Decision trees allow update of voltage security with speed as fast as phasors are received at the central location.