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Tom Overbye Fox Family Professor of ECE University of Illinois at Urbana-Champaign Jim Gronquist Bonneville Power Administration (BPA). Validation and Accreditation of Transient Stability (TS) Results. Overview.
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Fox Family Professor of ECE
University of Illinois at Urbana-Champaign
Bonneville Power Administration (BPA)
In May 2010, as the projectwas just beginning, we wereable to do comparisons for a full WECC case (provided by BPA)between PSLF, TSAT andPowerWorld Simulator.
The plot on the right showsthe variation in a bus frequency following thedouble Palo Verde generatortrip contingency for the three packages
We moved forward with both a top-down(full system) and bottom-up (individualmodel) approach
Within a week or two we were able to determine that abug in how the frequencydeviations for the inductionmotor loads were beinghandled by PowerWorldwas causing some of thefrequency variation. Thenew run is shown on the right. The oscillation in thePowerWorld frequencies weretracked down to a model error.
Model error was associated with a generator line dropcompensation; fixed by auto-correction
Graph shows a comparison of thefield voltage at generator
for a fault on thetwo bus equivalent system betweenPSSE, and two versions of PowerWorld Simulator
PowerWorld includes an option to automatically modify the limits to provide a “flat” solution
With the IEEEG1 governor, PowerWorld “auto-corrects” high K1to K8 values. Gens 56503, 57503 and 58503 have K1=20.4, whichcauses very high Pmech outputs in the PSLF results
Graph compares the Pmech between PSLF and PowerWorld with K1=20.4 or auto-corrected. Note the turbine rating is 71.2 MVA. Behavior is similar at 57503 and 58503.
Graph compares the Pmech between PSLF and PowerWorld for G1 at 40559 (Ice Harbor). Unit is modeled with an IEEEG3 Governor. Turbine rating is 103 MVA.
PowerWorldcannotcompensatefor thisdifference.To some extent itoffsets theK1 issue.
Note whether the K1 issue is corrected has a large impact on the resultant frequency. The two PowerWorld results mostly bracket the PSLF results. The 40559 issue also has a significant impact.
Again the two PowerWorld solutions mostly bound the PSLFresults
Results are similar for a bus in Southern California. Again the PowerWorld results (with the K1 issue either high or fixed) bracket the PSLF results.
Note changing Ta slightly has little impact on the PowerWorld results but gives a significantly fast PSLF response. The ratefeedback should limit the change in Efd.
Graphs compares the field voltage for the generator at 15914. This generator uses an EXAC1 exciter. The limit on Ve should prevent a negative field voltage. The PSLF results show negative values, with PowerWorld clamping the value at zero.