Embodiments of the present invention produce and define a relationship between local voltage and power measurements at a node of an electrical network and system conditions on a remote branch of the network. These local measurements are used to determine an optimal voltage set point at the node that, if realized by a reactive power resource, would affect the flow of reactive power or line current at one or more particular remote branches of the power system in a manner captured by the derived relationship. The change in reactive power required to obtain this voltage set point is also calculated based on local measurements.