IEEE Power & Energy Magazine - September/October 2015 - 22

PMU Measurements

0.72 Hz

1.1 Hz

(a)

Simulation Results

0.72 Hz

1.1 Hz

(b)

figure 4. Model validation: comparison modes between PMU data and simulation data.

Figure 4 is another example of an offline analysis tool
used for model validation and shows (a) oscillatory modes
during a disturbance compared with (b) transient stability
model. the (b) measurement chart shows the PmU measurements (P-class data at 120 measurements in the solid line,
and the 60 frames/s interpolated data in the dashed line).
the transient stability simulation plot is an offline analysis
tool. both PmU measured and simulated plots contain 0.72
and 1.10 hz oscillatory modes. notice the negative damping
ratio on the simulated data.

Engineering Tools for
Real-Time Operations
applications in production and demonstration include
✔ situational awareness, visualization, and alarming
(angles and voltages, overloads and oscillations)
✔ voltage stability management
✔ oscillation detection
✔ enhanced emss
* adding synchrophasor measurements to the existing
state estimator
* tracking dynamic changes and contingency analysis
* distributed and linear state estimation
✔ system restoration
✔ post-disturbance event analysis, including fault location
✔ operator and engineering training with PmU-based
dispatch training simulator
✔ fault location.
22

ieee power & energy magazine

Visualization, Situational
Awareness, and Restoration
Figure 5 is a geospatial wide-area view of a transmission
system with some voltage violation view. the geospatial
view allows for the immediate identification of problem
spots, and the colors reflect the nature of the transmission
corridor. Figure 5(a) shows the predisturbance, normal voltage conditions, and (b) is the post-disturbance voltage violation regions. red and yellow denote low voltages, and blue
is high voltage. the figure is a simulated environment for
training purposes, demonstrating real-time voltage violations
with the area monitored by the PmUs and focusing on an
immediate need for reactive voltage support.
an important area of interest is voltage stability and the
detection of reactive margins under stressed system conditions.
the integration of a model- and measurement-based (or
model-free) method offers specific benefits, reflecting a particular aspect of the system operation, various manifestations of voltage instability, and measurement configurations.
a measurement-based real-time voltage instability indicator
is significantly faster than ems-based methods for voltage
instability and reactive margin detection. the model-based
voltage instability methods require an accurate system model
and, when integrated into the contingency analysis, provide
measures for enhanced real-time operation. recent developments show potential to offer fast, predictive capabilities as
well. Figure 6 shows real-time reactive bus and corridor status
monitoring for a portion of a transmission system presented
september/october 2015

Table of Contents for the Digital Edition of IEEE Power & Energy Magazine - September/October 2015