See Also
In this section we introduce an example of using the SCOPF. Consider the seven bus, three area system contained in the file B7SCOPF (included with the PowerWorld Simulator). This case is the same case used in the OPF example, except that the line from bus 2 to 3 has now a 100MVA rating, lines 1 to 2, 1 to 3 and 2 to 5 have a 120MVA rating, and all three areas are initially on OPF control. To initially solve the case using the optimal power flow, select Primal LP in the OPF ribbon group on the Add Ons ribbon tab. The solution obtained is shown below. The total case hourly cost is $16,011 / hr.
B7SCOPF Case Solved using OPF
We are interested in determining an optimal solution that meets security constraints under contingency conditions. In order to show that the current OPF solution does not enforce contingency violations, take line 1 to 2 out of service by clicking in a circuit breaker. Then solve the power flow by pressing the Solve Power Flowbutton. The result indicates that line 1 to 2 is overloaded 32%. The SCOPF algorithm will attempt to move the operating solution such that no contingency violation occurs in the system. Close line 1 to 2 back in service.
B7SCOPF Power Flow Solution with line 1-2 open
The next step is to specify the contingency conditions that the system should withstand. In order to do that, we access the Contingency Analysis dialog under Tools. Note that we can also access this dialog from the SCOPF control dialog by selecting Add Ons > Security Constrained OPF and pressing the View Contingency Analysis Form button on the Options page. The B7SCOPF case does not have contingencies associated with it. Insert single line contingencies in the contingency list by pressing the Auto Insertbutton located at the bottom left of the Contingency Analysis dialog. in the Auto Insert Dialog select the option for Single Transmission Line or Transformerand select Numbers under the Identify buses by field. Select Do Insert Contingencies. This will prompt to insert 11 single line contingencies corresponding to all the lines in the system. Select Yes. You can now close the Contingency Analysis dialog.
Return to the Security Constrained Optimal Power Flow Form. You can set the SCOPF to use the OPF solution as the base by selecting Solve base case using optimal power flow.
You can now solve the SCOPF by pressing the Run Full Security Constrained OPF. This will process the contingency violations and iteratively solve the LP program and the power flow equations to minimize the objective function and enforce equality and inequality constraints. The solution is shown below. The total operating cost is now $16,048 /hr. The increase in operating cost is due to enforcing security constraints. If a new contingency analysis is performed using the optimal solution as the reference, it will be found that no contingency violations occur for the contingencies in the list, i.e., branch flows are less than (or equal to) 100% in the post contingency condition. Thus, the system meets all the specified constraints. You can analyze the SCOPF results by browsing the information in the SCOPF tabs. Note that the CTG Constraints dialog does not show unenforceable constraints, but the branch violation of line 2 to 5 due to the contingency 5 to 7 is now binding.
B7SCOPF Case Solved using SCOPF: The system now meets the contingency constraints.