Risk-constrained AC OPF with risk limits on individual system states

Risk-based security indexes can be used as a constraint in OPF to determine the most economic generation dispatch while ensuring that the risk of power system operation stays below a given value. Existing approaches only limit the total risk, which can result in some system states having significantly higher values of risk compared to others. In this paper, a risk-constrained AC OPF that limits the individual risk of each considered system state is proposed. The resulting optimization problem is solved by a centralized method and iterative algorithm based on locational security impact factors, which quantify the impact of a change of a generator output on the risk of a certain system state. The comparison of these methods in terms of the simulation time and solution accuracy as well as the analysis of limiting the total versus individual risk is presented for the IEEE Reliability Test System.