See Also
The Transient Limit Monitors page is found on the Transient Stability Analysis dialog.
When running a transient stability simulation, the actual numerical results and plotting is useful, but sometimes what you really want to know is if and when any particular Operating Standards were violated. For example, tn the Western United States there are particular standards for voltage dips and frequency deviations referred to as WECC Category B and WECC Category C standards. You can add these standards by right clicking on the table and going to the Transient Limit Monitor records. Also the WECC 2016 Fault Clearing and No Fault Standard Monitors can be added in the same manner.
You can think of this similarly to how Limit Monitoring works in traditional power flow based contingency analysis. In traditional contingency analysis we do not report the voltage at every bus and the flow on every line during each contingency. Instead we only report violations of limits, which greatly reduces the amount of output data created by the tool.
In order to provide the ability to flag violations of these standards, PowerWorld has created an object called a Transient Limit Monitor which provides a great deal of flexibility for allowing the simulation to automatically monitor for these types of standards without requiring us to store the entire trace of each monitored quantity. When creating a transient stability monitor, you choose a field for a particular type of object and then build a description of what is considered a limit violation.
Defining Transient Limit Monitors Tab
To define Transient Limit Monitors, look on the Transient Stability dialog under Transient Limit Monitors and choose the Transient Limit Monitors option. When choosing this a case information display listing the transient limit monitors will be shown. For more information see Transient Stability : Defining Transient Limit Monitors. The Re-evaluate to Get Limit Monitor Violations button is use to re-evaluate the results stored to get the transient limit monitor violations. First it will look at the results stored in RAM and then, if no results are found, look into the Hard Drive *.tsr file. If the button is press under Multiple Contingencies mode the it will re-evaluate all the contingencies results.
Viewing Transient Limit Monitor Violations Tab
While running a transient stability simulation, violations of the transient limit monitors defined will be recorded and listed under the Transient Limit Monitors\Monitor Violations table on the Transient Stability Analysis Dialog. Monitor Violations will be designated by which transient contingency caused them so that when running multiple transient contingencies you will be able to see which contingency caused the violation. It may be feasible for you to abandon storing all the transient stability numerical results and instead only store the violations of the limit monitors. If violations are found you can then revisit the run and store appropriate results. For more information on monitor violations seeTransient Stability : Transient Limit Monitors Violations.
Limit Logic Tab
An object to combine Transient Limit Monitors in a logic expression. The object will provide a Logic Variable identifier with a Transient Limit Monitor to include that monitor in an expression. A limit Logic object is created with a Logic expression that is a combination of Logic Variables AND, OR, and NOT that are supported with appropriate parentheses. A Logic Variable need to be assign to a Transient Limit Monitor at the Logic Variable column in the Transient Limit Monitors Tab, then in the Limit Tab under the Logic column write the wanted Logic expression.
The Limit Logic violations will report objects that meet the Logic expression at any point during the transient stability run. There is no time component to the logic. The Limit Logic expression should only include Transient Limit Monitors of the same object type.