Note: In order to upgrade a current license to the newest version of Simulator, please contact us at sales@powerworld.com. PowerWorld Corporation highly recommends to users who have not upgraded their licenses to Simulator 8.0 to do so. Many improvement and enhancements have been made in Simulator 8.0. See the What's New in Simulator 8.0 page for more details.

PowerWorld Simulator 6.0 Patch addresses problems that were detected in the program after its release and introduces some new functionality. These modifications are listed here. The patch was last modified in November 2000. Minor Updates made to this patch are noted below along with a date and explanation. If no date is specified, the change was made in the first patch on November 11, 1999.

If you are ready to download this patch, click here to go to the patch download page.

Area Control

• A problem with calculating the economic dispatch for some units having cubic cost curves has been rectified.
• Generation changes are no longer estimated before solving the case when area control is disabled.

Contingency Analysis

• There was an error in the processing of worst-case overload information that was caused by improperly deleting a previous contingency list. This has been corrected.
• (December 6, 1999) Fixed a problem that sometimes would occur when running Simulator on Windows 95 machines that caused a "row index out of bounds" error when the user attempted to run just a single contingency rather than the entire contingency list.
• (December 14, 1999) Fixed a problem with monitoring transmission line limit violations by Zone. Monitoring only specific Areas was working properly, but filtering by Zone was not. This is now fixed.

Contouring

• Attempts to contour quantities in MVA failed because the contours would actually be displayed in per unit. This has been fixed.
• The Ignore Above/Below option is no longer being ignored.
• Performance has been improved so that the contours are rendered more quickly.

Graphical User Interface

• When building a case from scratch and switching to run mode for the first time, the accessibility of the pause and play buttons and certain menu options was not being properly set. This has been fixed.
• A few minor problems associated with the insertion of Super Area objects on the one-line diagram have been fixed.
• The Difference Flows Dialog was not being closed when switching between edit and run modes, but now it is.
• vThe bus information dialog now allows the user to redefine the system slack.
• The ability to define fixed columns in the case information displays has been added.
• A few modifications were made to accomodate the use of black as the background color.
• A new printing option has been added to facilitate printing a one-line across multiple pages.
• Case Information Displays now accept CTRL-F as a shortcut for finding a particular record.
• The Bus View one-line now allows you to view up to two tiers of buses away from the center bus.
• (December 6, 1999) The AutoXF field for line/transformer records is now both toggleable and enterable rather than simply toggleable. This means that the small, draggable box will appear in the bottom right corner of the AutoXF fields, allowing you to apply the value of one cell to neighboring cells by dragging.
• (December 6, 1999) The automatic control options on the edit-mode version of the transmission line / transformer information dialog are now invisible if the line either is not a transformer or does not have the ability to regulate itself.
• (December 20, 1999) Fixed a possible bug of an incorrect sign on Interface Flow Fields.
• (December 20, 1999) When you try to open a second one-line diagram when a one-line is already open and maximized, both one-lines would appear un-maximized, and the close/maximize/minimize buttons for the second one-line diagram would be missing. Simulator has been modified to open the second one-line in maximized state whenever another one-line is open and maximized.
• (January 26, 2000) Added ability to show the Island Number for a Bus in the case information display for buses.
• (March 20, 2000) Upon hitting "Reset", one-lines now refresh themselves to reflect the new state of the system.
• (March 20, 2000) Enhancements made to one-line diagrams to handle Interface related drawing objects with long names.
• (March 21, 2000) Enabled the modification of Injection Group participation factors from the grid display.
• (April 18, 2000) Made several fields in the case information displays editable: Transformer Correction Table Number, LTC Regulated Bus Number, and Generator Regulated Bus Number.
• (April 27, 2000) An error was made for the fix on March 20, 2000. Diagrams which have interface pie charts were not being saved correctly.

Input/Output

• When reading a case from a PTI raw file, any transformer for which the regulating range is less than or equal to 1.0 pu will be treated as a voltage-regulating transformer. If the regulating range exceeds 1.0 unit, the transformer will be treated as regulating reactive flow. Prior to this modification, Simulator identified as voltage-controlling only those transformers whose regulating range was strictly less than, not equal to, 1.0 pu. This change was required to increase compatibility with PTI format.
• When a case was saved to a different directory, any open one-line diagrams were being saved to their original directories. This has been modified so that one-line diagrams are now saved automatically in the same directory as the case.
• A problem associated with identifying a case's main one-line when no one-line diagrams are initially open has been fixed.
• Auxiliary files containing load variation schedules were not being read properly. This problem has been rectified.
• (December 6, 1999) Simulator now no longer attempts to read transaction data from PTI Version 23 files, which have no transaction data.
• (December 14, 1999) User can now write out PTI Version 26 files. Also fixed minor problems with reading area, zone, and transformer data in PTI Version 26 files.
• (December 20, 1999) Fixed a bug that caused v.24 files to be written when v.26 file type was selected (this bug only existed for a week).
• (December 14, 1999) The wrong file extension was being assigned to a file when choosing Save As if the file was not being saved in the PWB format. This has been fixed.
• (March 23, 2000) Added the ability to read in NERC Flowgate data from an Excel Spreadsheet directly.
• (April 3, 2000) Reading of transformer controls in IEEE CF was corrected.
• (April 3, 2000) Reading TRANSFORMER events from a script file was corrected.
• (April 18, 2000) Reading of a bus renumbering list from a file was modified.

Miscellaneous

• Performance of the ownership information displays has been significantly improved.
• When using the Auto Insert Lines feature, the program now correctly checks equality with the minimum KV level, if it is specified.
• (December 6, 1999) Fixed a memory management problem that sometimes surfaced when reading Project (*.pwp) files under Windows NT.
• (December 22, 1999) The script file command WRCASE was not working properly when trying to write out the PFLIST to a file. This has been fixed.
• (March 20, 2000) The script file commands for changing GEN AGC and GEN AVR were not working correctly. This has been fixed.

Multisection Lines

• A memory problem associated with freeing memory corresponding to deleted multisection lines has been fixed.

PTDFs and TLRs

• The effect of a transaction on losses is now properly measured.
• A bug associated with calculating the PTDF for a transaction when one of the transacting parties includes the system slack has been corrected.
• (June 21, 2000) Added the ability to calculate TLR sensitivities for transacting to or from a Superarea.

Scaling and Equivalencing

• The Scale Gen to Keep ACE Constant option in the Scale Case function has been corrected to scale generation by same MW total as the load, rather than by the same factor.
• A possible divide-by-zero error was eliminated from the system reduction function.
• Performance improvements have been made to the scaling and equivalencing dialogs to help them update their data more quickly.
• (April 3, 2000) An error was fixed that used to occur in some instances when equivalencing cases with interfaces.

Transformer Tap Control

• A shortcut employed to calculate transformer tap sensitivities more quickly is now no longer used for transformers that are in parallel with other transformers.
• Some remotely regulating voltage-control transformers were effectively being taken off control when they reached their minimum or maximum tap ratios. This has been fixed.
• A bug that caused some phase-shifting transformers to change taps in the wrong direction under certain conditions has been eliminated.
• December 20, 1999) Under certain circumstances, even though you start from a solved case, transformers whose taps were at their operating limits would shift at the beginning of a new solution attempt. This has been fixed.
• (January 26, 2000) Some problems with phase-shifting transformers have been fixed.
• (May 3, 2000) Phase shifting transformer were previously modeled as discrete controllers. We have changed this so that they are modeled as continuous controllers (meaning they can have any value within their operating range).

Voltage Stability (PVQV edition only)

• When the user would try to adjust area contributions for a case that has only a single area (an unlikely scenario), a run-time error would occur. This has been fixed.
• The user is now prompted to save option settings when he closes the form if those settings have not already been saved.
• When the user changes display filters, all grids on the PV curve form will now be updated automatically to reflect the new filter settings.
• (December 20, 1999) QV Curve analysis: Saving results to a file and browsing for an output file were not working. These problems have been fixed.
• (December 20, 1999) QV Curve analysis: QV curve plots now feature a local menu allowing you to save and print the plots.
• (December 20, 1999) PV Curve analysis: A bug has been fixed in the enforcement of generator MW ramp limits that would most frequently arise in simulation involving an import to decreasing generation.
• (December 22, 1999) QV Curve drawing. The stop tolerance was sometimes too low causing the QV Curve analysis to run indefinitely waiting for the user to intercede and choose Stop. This has been fixed.
• (March 20, 2000) No longer reset plot title and axis labels every time a new plot is made.

Optimal Power Flow (OPF edition only)

• (May 3, 2000) Improved the OPF convergence when generator are operating exactly at a breakpoint in their cost functions.
• (May 3, 2000) Improved the enforcement of generator limits.
• (July 25, 2000) Fixed error caused when several generators connected to the same bus where attempting to enforce their limits
• (July 25, 2000) Fixed error caused when a generators MW limits differed from the range defined by the generators linear cost curve.

Voltage Regulation

• The lead generator of a remote regulation group must have a nonzero remote regulation percentage.
• When determining whether a unit can back off a var limit, the algorithm now checks the VQ sensitivity of the unit.
• (January 26, 2000) In exceptional cases when the power flow solution is close to the fractal boundary between two different solutions, a generate can oscillate around its var limit because the sign of the VQ sensitivity changes suddenly. Some new heuristics have been added to prevent this.
• (March 20, 2000) Reactive Capability Curve Checking improperly performed in some instances. This was corrected.
• (April 18, 2000) Fixed a problem with a generator controlling a the voltage at a bus that was connected to other buses through zero-impedance branches.

Web Publishing

• The text area on the html editor now accepts editing shortcuts such as CTRL-C for copy, CTRL-V for paste, CTRL-X for cut, and the delete key.
• When you try to test a document before publishing it, your web browser will now appear on top of Simulator, rather than hidden behind it.