PV Curves: Limit Violations

 

The Limit violations tab is found on the PV Curves dialog and allows the definition of what should be considered a violation of a monitored voltage. It also provides specification of parameters that will force the PV process to stop if voltages become inadequate. When choosing to report limit violations in the PV Curve Tool, if no limit violations are found then the minimum voltage is reported instead.

 

Identify bus voltages with...

These options will store monitored bus voltages that violate either their high or low voltage limit as of the last successful solution for each scenario. Only those buses that are set to be monitored based on the Limit Monitoring Settings will be monitored, and the low and high voltage limits for each bus are also determined by the limit monitoring settings.

Low Voltage Violations - check this box to store the buses that have low voltage violations

Always Report Lowest Voltage - check this box to always store the lowest voltage even if it is not a violation

High Voltage Violations - check this box to store the buses that have high voltage violations

Limit Group Definitions - click this button to open the Limiting Monitoring Settings dialog

When choosing to identify limit violations, the Overview table on the PV Results tab will contain information about the number of violations (#Viol), worst voltage violation (Worst V Viol), and bus at which the worst voltage violation occurs (Worst V Bus). Also, for any scenario in which a violation occurs, the Show Violations option is enabled on the local right-click menu of the Overview table. Choosing this option will open a table detailing all of the violations.

Inadequate voltage level

Stop when voltage becomes inadequate

Checking this box will stop the PV process for a scenario when any monitored bus voltage falls below the inadequate voltage threshold. The Limit Monitoring Settings dictate which buses are monitored.

Store inadequate voltages

Checking this box will store all inadequate bus voltages encountered for each scenario. The Limit Monitoring Settings dictate which buses are monitored. A list of inadequate voltages for each scenario at each transfer level will then be available for viewing as one of the local menu options obtained by right-clicking on the Overview table (PV Curve records > Show Inadequate Voltages). Inadequate voltages will also be stored in the SUBDATA section of the PWPVResultListContainer DATA section when storing PV results to an auxiliary file.

Interpolate inadequate voltages- If checked add the ability to estimate at what transfer level a voltage becomes inadequate by linearly interpolating between the two transfer levels where it goes from adequate to inadequate. It also will interpolate if an inadequate voltage occurs at the zero transfer level to determine the negative transfer at which the voltage becomes inadequate.

There are several fields available on the Overview table that provide summary information about the inadequate voltages:

Inadequate Voltage Nominal Shift- nominal transfer level at which the first inadequate voltage is recorded

Inadequate Voltage Worst Voltage- minimum voltage of all buses that have inadequate voltages at the Inadequate Voltage Nominal Shift transfer level

Inadequate Voltage Worst Voltage Bus- bus with the minimum voltage of all buses that have inadequate voltages at the Inadequate Voltage Nominal Shift transfer level

Inadequate Voltage ATC Mon- if any ATC Extra Monitors are being tracked during the analysis, this will list of the flow on the given extra monitor at the Inadequate Voltage Nominal Shift transfer level

If choosing to Stop when voltage becomes inadequate, no inadequate voltages will be stored even if this option is selected. When a scenario becomes critical because of inadequate voltages, the results that are given in the Overview table are from the last transfer level at which all voltages were adequate. The inadequate voltage reported in the results is the voltage that would be inadequate if we went beyond the reported transfer level. Because of how the reporting works to report the last non-critical results, it makes sense that there would not be any inadequate voltages stored.

 

The inadequate voltage threshold when either of the options above is checked is determined by the following options:

Specify voltage for all buses in pu - specify a single inadequate voltage threshold to be used for all monitored buses

Use Low Voltage Violation Limits for each bus - use the limit monitoring settings

Use a specified Low Voltage Limit Set - select a limit set to specify the limit from the drop-down. Up to four (A-D) specific limit sets can be specified for a bus. When using this option, all monitored buses should have the selected limit set specified. If not, the default low voltage limit will be -1.

Do not consider radial buses to have inadequate voltage (including buses that become radial due to a contingency) - check this box to exclude monitoring buses that are radial regardless of whether they are radial because they are connected to the system by a single line or because they are radial because they are connected to the system via a single in-service line (i.e. they could have more connections but all but one of the connections is open).

This option works somewhat in conjunction with a similar option found on the Limit Monitoring Settings dialog. The option Do not monitor radial lines and buses found on the Limit Monitoring Settings dialog will exclude any bus from monitoring if it is radial in the base case. This limit monitoring settings option considers buses to be radial if they are connected by a single branch and only a single branch. When the limit monitoring settings option is selected, radial buses by that definition will be excluded from the PV monitoring. When the PV option is selected, buses that are connected by only a single in-service branch after the application of any scenario contingency, or in the base case if there is no contingency, are considered radial and will be excluded from the monitoring. The PV option is enforced regardless of whether or not the option with the limit monitoring settings is selected.

Stop when dV/dQ sensitivities become negative

Checking this box will treat negative dV/dQ bus sensitivities as a critical scenario. If this option is used and there are negative dV/dQ sensitivities, the critical transfer level will be determined by backing of the transfer to the point at which no dV/dQ sensitivities are negative.

Buses that are monitored for negative dV/dQ sensitivities are the buses that are set to have their dV/dQ sensitivities tracked with the Quantities to Track setup.