Power System Simulation for Engineers (PSS/E version versi on 30): Stability Analysis The following provides some step-by-step instructions for using the PSS/E software. Note that these instructions are meant to assist you as a guide, but one should not expect that they are perfect nor will they alleviate you from having to think. Rather, expect to apply good judgment when using the programs. When you come to a point that appears unclear to you, assess the situation as best as you can, make a decision, note your thinking on a pad of paper, and move on. Also, you should have access to the manuals as a resource to clarify any problem you come across. The manuals can be found at Start>All Programs>PSSE 30.1>Documentation (pdf files), then click on “Programs Operation Manual,” and then “Volume I.” You may find some material of particular benefit in these manuals in chapters 5 and 7, particularly chapter 7. Also, “Volume II” of the “Programs Operation Manual” shows the data formats that were used to create the Dynamic Data sheet used for this project. To perform stability analysis in PSS/E one will w ill need two data files: EX2_Stability.sav: EX2_Stability.sav: This is the saved case that was used in the first parts of the project (fault analysis); however it has been slightly modified to directly represent the step-up transformers that follow follow a generator. In this more more realistic case all three generators, still attached to buses 1, 2, and and 3, produce power at 13.8 kV. The voltage is stepped-up to 161kV by a transformer. The high sides sides of the transformers are then attached to new new buses 101, 102, and 103 respectively. It is these buses that now go out to the network. There is no line between bus 1 and bus 101, so you can “basically” think of them as the same.
457project2.dyr: 457project2.dyr: This a dynamic data file that has machine data for all machines in the system. Each machine has H = 3 and and speed damping = 2.
1. Preparing for a stability run: Several actions need to be performed before the case is ready for a stability run. (EX2_Stabiliy.sav). One can access specific instructions instructions for a. Open the new saved case (EX2_Stabiliy.sav). launching PSS/E by viewing the “PSSE_Fault_Intro_Instructions.doc” “PSSE_ Fault_Intro_Instructions.doc” file. b. With the file open, click on the Machines tab. Under the column labeled X Source t hree generators (use same value for each). (pu) input the Xd’ value for each of the thre c. Next, input the same negative and zero sequence values that you used in your fault analysis case (specifically Z-Zero on the Branches page). d. Next, in order to perform stability analysis you need to convert the generators to Norton equivalents (constant current injections) injections) and assign load characteristics to the loads. To
do this, on the top menu go Powerflow>Convert Loads and Generators. following dialog box will be displayed:
The
Click the same options as done above. e. Perform ORDR (Powerflow>Solution>Order Network for Matrix Operations). This re-orders the buses for sparsity (required because we converted the swing bus to a type PV bus). f. Perform FACT (Powerflow>Solution>Factorize Admittance Matrix). This factorizes the A-matrix. g. Perform TYSL (Powerflow>Solution>Solution for Switching Studies). This performs what you might think of as an simplified load flow calculation (basically just an I=YV). h. Perform Save/Show on your converted case. Give this converted case a different name than the saved case used in the first part of the project! Now that you have this saved you shouldn’t need to perform this first set of instructions again. i. Close out of PSS/E (this will make sense in a second). 2. Performing a base case stability run: a. To perform a stability run one must access the time-domain simulator environment using pssds4. This is a completely different PSS/E program. To open pssds4 go Start>All Programs>PSSE 30.1>Dyanmics30 CUSTOM (pssds4) b. We now need to open the converted saved case that was made earlier. To do this, click the LOLF menu button. Then open the case via File>Open>(your case.sav). c. Now to go into dynamics mode (where we’ll perform stability analysis) click the FACT/RTRN menu button. d. Read in the dynamic data sheet: File>Input>Read Dynamics Model Data (DYRE). Under the DYRE heading click the Select button and locate the 457project.dyr file. Leave the 2 other heading blank and leave all the numbers to the right at 1. e. Enter DYCH into the Command line input. Perform the consistency check (#1), it should say “Consistency Check OK,” if not your .dyr file is incorrect. Exit the activity.
f.
We next need to tell PSS/E which data to record. Click the CHAN menu button. The program responds with a number of options. 1. Choose Angle 2. Program responds with “Enter bus number, mach ID (used if there are more than 1 generators at a bus (not our case)), identifier.” In the bus number type 1, in the machine ID type 1, and leave the identifier blank. Perform this same task for buses 2 and 3. When finished click No More. 3. Repeat the above steps for output categories Pelect, Eterm, and Speed. g. Click the STRT menu button. This will perform the initial condition calculation. Program responds with “Enter channel output filename.” Enter a filename with a “.out” suffix. Program responds with “Enter snapshot filename.” Enter a filename. h. Click the RUN menu button. Program responds with a menu with user inputs for Run to, Print Every, Write Every, Plot Every. Enter 1,0,1,0 respectively. This will run the simulation from 0 to 1 second, writing nothing to screen and writing every time step to the plotting file. This is now your base case simulation. Plotting instructions are at the bottom. i. Enter STOP in the CLI to exit PSS/E 3. Performing a stability run: For stability analysis the general approach is as follows: Apply a fault o o RUN the simulation from time = 0 until t = breakers open Clear the fault and remove a line o RUN the simulation from t = breakers o pen until t = 10 seconds o a. Open pssds4 again and perform steps 2-a through 2-g. DO NOT RUN it yet! b. Enter ALTR in the command line input (CLI). This is the command to make network changes. The step we are taking here is to apply the fault. Here is the suggested sequence: 1. After entering “ALTR,” program responds with “Enter change code.” Enter 0 for no more changes. 2. Program responds with “Network data changes?” Enter 1 for yes. 3. Program responds with “Pick up new saved case.” Enter 0 for no. 4. Program responds with “Enter change code.” Enter 1 for bus data. 5. Program responds with “Enter bus number.” Enter 103. 6. Program responds with “Change it?” Enter Y. 7. Program responds with “Enter code, G, B.” Enter 1, 0, 99999999. This put s a fault with a very large susceptance at the bus (effectively, putting a short-circuit at the bus). 8. Program responds with “Change it?” Enter carriage return. 9. Program responds with “Enter load ID.” Enter -1. 10. Program responds with “Enter bus number.” Enter 0. 11. Program responds with “Enter change code.” Enter 0 to exit. c. Enter RUN in CLI. Program responds with “Enter Tpause, NPRT, NPLT, CRTPLT.” Enter , 0, 1, 0 d. Enter ALTR. (Now you need to clear the fault and remove the line.) 1. Program responds with “Enter change code.” Enter 0.
2. Program res ponds with “Network data changes.” Enter 1 3. Program responds with “Pickup saved case.” Enter 0. 4. Program responds with “Enter change code. ” Enter 1 for bus data. 5. Program responds with “Enter bus number.” Enter 103. 6. Program responds with “Change it?” Enter Y. 7. Program responds with “Enter change code, G, B.” Enter 1, 0, 0. 8. Program responds with “Change it?” Enter carriage return. 9. Program responds with “Enter load ID.” Enter -1. 10. Program responds with “Enter bus number.” Enter 0. 11. Program responds with “Enter change code.” Enter -3 for branch data. 12. Program responds with “Enter from bus, to bus, circuit ID.” Enter 103, 15 (This is if you want to remove the circuit from Parrot to Crow.) 13. Program responds by giving the data for the indicated branch and then asking “Change it?” Enter Y. 14. Program responds by querying for new data. Enter 0 to toggle status from “in” to “out.” 15. Program responds by giving the shunt data for the branch and then asking “Change it?” Enter N. 16. Program responds by asking to reverse the metered ends. Enter carriage return. 17. Program responds with “Enter from bus, to bus, circuit ID.” E nter -1. e. Enter RUN. Program responds with “Enter Tpause, NPRT, NPLT, CRTPLT.” Enter 10, 0, 1, 0 (this will simulate the s ystem response for 10 seconds). f. Enter STOP. 4. Plotting: To plot your results found above you need to use yet another PSS/E program called PSSPLT. One can access this program by: Start>All Programs>PSSE 30.1>pssplt. This program just takes a bit of playing around with to get your results to be displayed in the way you want. Your plot data will be in the .out file that you named above. I suggest using the menu commands. The basic ones are as follows: CHNF: Selects the .out file SLCT: Selects the channels you want plotted PLOT: Self Explanatory
To plot relative angles, after you select the .out file, but before you select the channels go Edit>FUNC. This will open up another list of bulleted items. Select User Defined Arithmetic Function and click ok. Next, you’ll get a window prompting you to Enter Arithmetic Function. Enter A-B. Now when you select the channels the interface will be slightly different. Now you’ll be able to take one channel (A) and subtract from it another channel (B).
