| Scope and method of study. Operating an electric power system in the most optimal way has been the subject of ongoing optimal power flow (OPF) research. The objective of the OPF problem is to find an electric power system operating point that is optimal with respect to some objective. Minimizing real power losses, minimizing system operating costs, and maximizing social welfare are examples of OPF objectives. This optimization problem is constrained, however, since the operating point we choose must satisfy the Kirchhoff's law equations that describe power flow throughout the power system transmission grid, and there are operating limits. In this thesis, we add important operating limits on power system small-signal stability to the power system optimization problem to ensure that when small disturbances occur within the system, oscillations that occur in state variables such as generator rotor speed will decay quickly, returning the system to a normal operating point. Additionally, we consider power system security so that when a transmission line outage occurs, generation can be redispatched and load can be dropped for customers who have agreed to be interruptible in return for compensation. These expected costs are included in the optimization problem objective function, and we give the title of this problem the expected-security-cost optimal power flow (ESCOPF).; Findings and conclusions. Software was written in Matlab to solve the ESCOPF with small-signal stability constraints, and the software was used to find the optimal operating point of a 9-bus system. Eigenvalues of the linearized system state matrix were successfully constrained to obtain an acceptable stability margin while maximizing expected social welfare. |
