ECE 562 - Spring 2020

Final Project - Due May 8 at 2:00 PM

You may use any power flow software you wish. However, if you don't use MATPOWER, then make a note on your project report describing the software that you used (e.g., PTI's PSS/E version xx, attached C code, attached Excel spreadsheet). You will use the same data as Project 4: secure (no overload) ESCA 64 Bus Model.

You will study the Available Transfer Capability (ATC) of an interface by increasing Pgen at three non-swing generators in your Area and increasing both Pload, Qload in Area 2. The load increase should be uniform (i.e., all PQ loads increase by the same percentage). Therefore, the PQ loads in Area 2 will be uniformly scaled by the same "load scaling factor" to mimic peak loading conditions. In addition, the load growth should maintain the original power factor.

The list of "monitored" branches will include all of your internal branches above 100 kV, plus your tie-lines. A branch will be considered above 100 kV if both buses (from/to) have a base kV above 100 kV. For Area 1, there are 8 branches (5 internal, 3 tie-lines). Note: only one of the tie-lines between bus 1 and bus 20 will be considered for monitoring and for contingency selection in this project, since the two tie-lines between 1 and 20 have the same impedances. In Area 3, we will not consider the 345 kV loop with buses 60, 61, and 62. Therefore, there are 8 branches to monitor for Area 3 (5 internal, 3 tie-lines).

The list of contingencies will include each of the "monitored" branches, as well as each of the generators that participates in the transfer. Therefore, there are twelve cases to consider: one normal case (all equipment in service) and eleven contingency cases.

Available Transfer Capability (ATC) based on base case dispatch [Case 1]

  1. For the normal case and each contingency case, calculate the ATC (ignore generator Pmax limits).
    1. Calculate the new Participation Factors for the "monitored" branches via the PTDFs and the LODFs. Make sure to pickup all the lost generator MW's with your remaining two participating generators in proportion to their base case output.
    2. Calculate the new ALC's for the "monitored" branches, since they may change due to the outage.
    3. Calculate the new ATC's for the "monitored" branches.
    4. Calculate the system ATC and the critical element for the normal or contingency case based on the distribution factors.
  2. Solve a power flow for the worst case with the PQ load and Pgen values that you found from the distribution factors. If the system ATC is positive, then your PQ load and Pgen values will be larger than the base case. If the system ATC is negative, then your PQ load and Pgen values will be smaller than the base case, effectively shedding load.
  3. Compare the "monitored" branch MW flows from the distribution factors with the actual MVA branch flows (at the "from bus" end of the branch) from power flow.

Available Transfer Capability (ATC) with a re-dispatch counterflow from Area 2 [Case 2]

  1. Create a re-dispatch counterflow, based on PTDFs, from Area 2 (generators 36 and 52; use proportionality factors based on initial Pgen; ignore Pmax) to one of your Area's non-participating generators (it's ok if your non-participating generator's Pgen becomes negative) at the level of max {100, 100-ATC} such that your new ATC will have at least an additional 100 MW. For example, if your Case 1 ATC is 200 MW, then you would modify the base case by including a 100 MW counterflow. However, if your Case 1 ATC is -150 MW, then you would modify the base case by including a 250 MW counterflow. This effectively changes the initial flows on the transmission system and gives you a new "base case" on which to base your Case 2 ATC calculations.
  2. Recalculate a single ATC (not 12 ATCs) with the counterflow under the same worst case conditions as in Case 1 to show how the re-dispatch affects the worst case ATC from Case 1.
  3. Repeat the power flow calculation and the comparison from Case 1 for the re-dispatch under the same worst case conditions identified with Case 1. Note the "worst case scenario" is determined by your Case 1 results, not by your Case 2 results. Therefore, you simply repeat the analysis for the single "worst case scenario", typically a contingency scenario, that was identified with Case 1.

Deliverables

  1. Briefly describe the project.
  2. Submit formulas for the branch MW flow estimates. Include the dependence on the PTDFs and LODFs.
  3. Submit a brief description of each PTDF-based ATC study under the Case 1 dispatch (e.g., ATC (MW), transfer direction, branch contingency, generator contingency, critical element, etc.). There are twelve studies for the Case 1 dispatch (1 normal case, plus 11 contingency cases).
  4. Submit two sets (one for Case 1, the other for Case 2) of the following tables for the "worst case scenario" that you identified in Case 1. Note the "worst case scenario" is determined by your Case 1 results, not by your Case 2 results. The tables should be based on the top 10 branches chosen from the entire list of 78 branches. The following fields should be included: from bus, to bus, base case MW flow, MVA limit, ParFac, estimated MW flow at the limit point, actual MW and MVAR flows (at the "from bus" end of the branch), actual MVA flows (at the "from bus" end of the branch), and a "loading percentage error" defined by either "MW estimate"/rating - "actual MW"/rating (for MW prediction errors) or "|MW estimate|"/rating - "actual MVA"/rating (for MVA prediction errors).
    1. Top 10 MVA percentage loaded branches (rank all 78, then select top 10)
    2. Top 10 MW prediction errors (rank all 78, then select top 10)
    3. Top 10 MVA prediction errors (rank all 78, then select top 10)
    4. Any other ranking that illustrates an important point
  5. Analyze the accuracy of your ATC values with respect to the actual MVA flows. Did the distribution factors underestimate the ATC? Did they overestimate the ATC? What changes could be made to your branch loading estimates to improve accuracy?
  6. Discuss the advantages/disadvantages of using distribution factors for ATC calculations.
  7. Compare the results from the two different dispatches. What are the similarities? What are the differences?
  8. Briefly summarize the project.
  9. All students must submit the code (MATLAB, C, Excel spreadsheet, etc.) they used to calculate the ATC values as an appendix in the report. Also, be sure to include a script file that runs your entire project and generates the results for easy comparison. If your code does not run using your script file, then you will not receive any credit. Your final project report file (with code appendix) must be submitted via SafeAssignment on Blackboard.

Updated 5 Feb 2020