This paper presents a power system Secondary Voltage Regulation (SVC) strategy which aims to find the optimal position of shunt capacitors and shunt reactors available within a control area to lead the bus voltages to a predefined profile. An influence-based partitioning method is proposed, the buses are grouped according to their voltage sensitivity to the reactive power injected by controllable devices, a hierarchical clustering method is used for this purpose. The resulting optimization problem of each area is accelerated using a state independent linearization of the power flow equations. The proposed methodologies are applied to the Colombian-Ecuadorian power systems achieving a reduction of voltage deviation of one of the resulting areas after a disturbance.