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Project 3

Step-by-step Restoration

Due: Wednesday, October 24, 1997

The objective of this project is to evaluate step-by-step restoration. All the programs you need are in a zip file restore.zip. A user's manual for the programs is also available.

Consider a distribution system with 1 transformer and 4 feeders. Each feeder has 2 sectionalizing switches. Thus the total number of sections is 12. The sections are connected in the following order; Feeder 1: 1 - 2 - 3; Feeder 2: 4 - 5 - 6; Feeder 3: 7 - 8 - 9; Feeder 4: 10 - 11 - 12. The data for these feeders are given in a table.

  1. With a transformer of 25 MVA rated load, load time constant of 120 min, and any starting sequence run APIM to minimize a) total restoration time, b) customer interruption duration. Check if the two results are the same. Try at least five more starting sequences. After a few runs you will be able to identify the starting sequence which gives you the best results. Use that starting sequence for all the later runs.
  2. Change the transformer size to 30 MVA and repeat the work to minimize the two objective functions.
  3. Put tie switches between sections 2 and 5, 6 and 9, and 8 and 11. Run two cases of your choice to see if tie switches make any difference.
  4. Plot the top-oil and the hottest-spot temperature for one of the above two cases. Are any limits violated? Also report the loss of transformer life for this case.

The program is quite user friendly. Some instructions are given in the user's manual. Also, note that you will have to go through several iterations manually to determine the right loading of the transformer. For example, the 25 MVA transformer can be loaded up to 50 MVA. You can start with 37.5 MVA to find the restoration sequence. In the next step you will use a MATHEMATICA program to find temperatures and loss of life of the transformer for the given sequence. If none of the limits are violated, increase the loading otherwise reduce the loading. After a few iterations you will get the right result. Although this project does not have teams, I would like to encourage you to discuss it with other students.