Application of Newton´s optimal power flow in voltage/reactive power control

An application of Newton´s optimal power flow methods to secondary voltage/reactive power control in transmission networks is considered. An efficient computer program based on sparse matrix/vector techniques has been developed for this purpose. It is characterized by good robustness, accuracy and speed. A combined objective function appropriate for various system load levels with suitable constraints, for treatment of the power system´s security and economy, is also proposed. For real-time voltage/reactive power control, a suboptimal power flow procedure has been derived by using a reduced set of control variables. This procedure is based on sensitivity theory applied to the determination of zones for the secondary voltage/reactive power control and the corresponding reduced set of regulating sources, whose reactive outputs represent control variables in the optimal power flow program. As a result, the optimal power flow program output becomes a schedule to be used by operators in process of real-time voltage/reactive power control in both normal and emergency operating states.