What is optimal power flow (OPF) and how does it differ from load flow?

OPF extends load flow by optimizing an objective (minimize cost, losses, or emissions) while satisfying power balance equations and operating constraints. Unlike load flow which solves for a specified operating point, OPF determines the best operating point. Decision variables include generator outputs, voltage setpoints, and transformer taps. Constraints include generation limits, line flow limits, and voltage bounds. Solution methods include gradient-based, interior point, and genetic algorithms. Security-constrained OPF incorporates N-1 constraints.