Fault Analysis Example

PowerWorld Simulator’s Fault Analysis tool calculates the effects of a fault throughout a system. Faults can be simulated to occur at a bus or in a line, and can be one of four types: 

• Single Line-to-Ground
• Line-to-Line
• 3 Phase Balanced or
• Double Line-to-Ground

You can specify the location on the line for an in-line fault to occur, and mutual impedance data can be imported from other PowerWorld cases or in PTI format.  

There are four ways to initiate a fault analysis study:

1. Select Tools >> Fault Analysis from the main menu.

2. Click the Fault button on the Run Mode toolbar.

3. Right click on a bus and choose Fault… from the local menu to perform a fault analysis at that bus

4. Right click on a line and choose Fault… from the local menu to perform a fault analysis at that point on the line

Any of these actions opens the Fault Analysis dialog. If you open the dialog by right-clicking on a bus or line, the fault information on that bus or line will already be filled in.  If you selected the Fault Analysis… option from the Tools menu or the Fault button, the information about the location of the fault will need to be specified.

To get you started using Simulator’s Fault Analysis tool, let’s consider an example in a simple, lossless three-bus system.  You can download the PowerWorld case and diagram files to try this example yourself: 

• Case: B3.pwb
• Diagram: B3.pwd

 

Suppose we want to calculate the fault currents (in Amps) on lines 1-2 and 2-3 when a zero-impedance, double line-to-ground fault occurs 50% along line 1-3. Follow the following steps:

• Make sure Simulator in Run Mode by clicking on the Run Mode button in the Program toolbar, or selecting File >> Switch to Run Mode from the main menu.

• Open the Fault Analysis dialog.

• Select In-Line Fault for Fault Location and Double Line-to-Ground for Fault Type. Select Bus 1 for the Near Bus and Bus 3 for the Far Bus, and enter 50 for the Location %. To see the results in amps select Amps for the Current Units. The Fault Analysis dialog should now look like the one below:

• Enter the fault impedance.  Go to the Options tab in the Fault Analysis dialog, and enter the R and X values at the top.  Since our fault has zero-impedance, we will leave these at their default of zero.

• To enter mutual impedance values, right-click on the Zero Sequence Mutual Impedances table (located at the bottom of thee Options tab in the Fault Analysis dialog) and select Insert from the resulting local menu. The Mutual Impedance Record will appear.  Enter the data as shown below.  

• Click OK to close the Mutual Impedance Record dialog.  

Note: 
- Mutual impedance values can be loaded from PowerWorld auxiliary files or in PTI format by clicking the Load Data button.
- The data may be saved in PowerWorld auxiliary format by clicking the Save Data button.

• Return to the Fault Data tab of the Fault Analysis dialog then the Calculate button in the lower left corner.
• The results that we are interested in are the currents in lines 1-2 and 2-3. Click on the Lines tab to see this data. Since this is a lossless system, the From and To currents are equal for each line. These are the results as displayed at the bottom of the Fault Data tab: