The optimal power flow (OPF) algorithm has the purpose of minimizing an objective function (usually total operation cost) by changing different system controls while meeting power balance constraints and enforcing base case operating limits. Normally however, the secure operation of a power system requires that there be no unmanageable contingency violations. Thus, the minimization of the objective function requires considering contingencies. This is achieved using a security constrained optimal power flow (SCOPF) algorithm.
While the optimal power flow (OPF) algorithm determines the optimal state of the system by iterating between solving a power flow and solving a linear program that changes the system controls, during the SCOPF solution process in addition to solving the base case power flow, all contingencies must also be solved. The linear program which then runs changes the system controls to remove contingency violations as well as base case operating violations.
The SCOPF algorithm makes control adjustments to the base case (pre-contingency condition) to prevent violations in the post-contingency conditions. If enough controls are available in the system, the solution minimizes the objective function and the system enforces contingency violations. If the system does not have enough controls, then some violations may be persistent under certain contingencies. Those represent unenforceable constraints, which result in high bus marginal costs.
The commands and options for the SCOPF are accessed by selecting the SCOPF option from the OPF ribbon group on the Add Ons ribbon tab. The SCOPF function uses the OPF options defined in the OPF Options and Results dialog and the contingency settings specified in the contingency analysis dialog. Please read through the OPF and the contingency analysis help for more information about these settings. We encourage you to become familiar with Simulator OPF and the contingency analysis tool before running SCOPF simulations. Other commands in the SCOPF dialog are used to specify the base case solution process and for accessing the SCOPF results.