Reactive power control for real power-loss minimization

An accurate and fast technique for real-time control of system voltage and reactive power of large-scale power systems is presented. The one-bus-away method has been modified to obtain accurate results with moderate computer requirements for online application to large-scale power networks. The approach was used to obtain a constrained minimum of the objective function for each subsystem in a deterministic number of steps, in most cases using the special geometric features of the problem. For the few cases where the optimal solution was not obtained from direct steps, good initial starting conditions for the iterative nonlinear optimal technique were obtained. The technique used was the flexible tolerance method, which works directly on objective functions and on inequality constraints without evaluating derivatives or gradients. It was selected because of its robustness, ease of implementation, and fast convergence properties for a wide range of nonlinear small-size problems. The required CPU time was small enough for significant online applications.<>