Software Patches

April 12, 2018

Features and Improvements

  • Transient Stability: Added result storage of Area ACE value
  • Transient Stability: Modified the LHFRT model so that when obtaining the frequency measurement at the bus, if the voltage is below the "Minimum PU voltage for relay frequency measurement", then the frequency is treated as at nominal
  • Transient Stability: Added a new Gen object field called "TSGovMWCap" which returns the MW Base of the active dynamic governor model if available. If either no governer is active or the active governor does not have a MW Base parameter, then this field will appear as blank.
  • Bug Fixes

    • Auxiliary Files (SCRIPT and DATA Sections): When using the RenumberMSLineDummyBuses script command, no dummy buses would be renumbered unless the optional parameter for the Delimiter was specified. This has been fixed. If no delimiter is specified, either a space or a comma will work as a delimiter.
    • Power Flow Solution: In the pre-processing step of the overall power flow solution, an estimate of generation changes is done if using island AGC control. This estimate is meant to prevent excessive MW change from going to the island slack, which could cause a power flow failure. When loading a PWB file, we were assuming that the case was solved which meant that this estimate of generation changes was not done and could lead to a power flow failure. At the end of each successful power flow solution, a loss percent value is stored for each island that will be used for subsequent power flow solutions. This loss percent value is used for the next power flow solution during the pre-processing step to estimate generation changes required to meet load MW, loss MW, shunt MW, and dc line interchange. This loss percent value will now be stored in PWB files so that if a case for which no power flow solution is attempted is saved to a file and re-loaded, the same loss percent value will be used when trying to solve the power flow solution after re-loading.
    • Power Flow Solution: Fixed another issue with the svc smsmo2 to prevent oscillations. Now it will move the shunt only if it improves the voltage or the voltage movement is greater than a tolerance and greater than the current voltage difference from the target voltage value. Also it checks that the voltage difference between new B value voltage and the target and the difference between old B value voltage and the target is greater than a tolerance. This prevents oscillations from cases in which the solution was already close enough.
    • Transient Stability: There was an error in the GGOV1 model when a non-zero value of dB was specified and a non-zero value of R was specified. This was been fixed.
    • Transient Stability: Modified to allow closing in generators in transient stability if they did not have a machine model specified. They will be modeled as a constant current injection.