Load PowerWorld Simulator case Problem 6_72. This case models a slightly modified, lossless version of the 37-bus case from Example 6.13 with generator cost information, but also with the transformer between buses PEAR138 and PEAR69 open. When the case is loaded, the "Total Cost" field shows the economic dispatch solution, which results in an overload on several lines. Before solving the case, select Add-Ons, OPF Case Info, OPF Buses to view the bus LMPs, noting that they are all identical. Then Select Add-Ons, Primal LP to solve the case using the OPF, and again view the bus LMPs. Verify the LMP at the PECAN69 bus by manually changing the load at the bus by one MW, and then noting the change in the Total Cost field. Repeat for the LOCUST69 bus. Because of solution convergence tolerances, the manually calculated results may not exactly match the OFP calculated bus LMPs.

Example 6.13

To see a power flow example of a larger system, open PowerWorld Simulator case Example 6_13 (see Figure 6.6). This case models a 37-bus, 9-generator power system containing three different voltage levels \((345 \mathrm{kV}, 138 \mathrm{kV}\), and \(69 \mathrm{kV})\) with 57 transmission lines or transformers. The oneline can be panned by pressing the arrow keys, and it can be zoomed by pressing the \(<\) ctrl \(>\) with the up arrow key to zoom in or with the down arrow key to zoom out. Use Tools, Play to animate the oneline and Tools, Pause to stop the animation.

Determine the lowest per-unit voltage and the maximum line/transformer loading both for the initial case and for the case with the line from bus OAK69 to WALNUT69 out of service.