CONDITIONS FOR LOCALIZED RESPONSE IN DECOUPLED VOLTAGE-VAR NETWORKS

The assumption of localized response of the decoupled reactive power problem for a lossless electric power system is examined. An “echelon” structure is defined for the linearized equations describing the incremental voltage magnitudes in terms of the incremental reactive injections. The first echelon is taken as the P-V buses, the second as P-Q buses directly connected to P-V buses, etc. By including the capacitive shunts, it is shown that there are a class of “uniform” perturbations (uniform voltage changes in an echelon) that are attenuated in the direction of the P-V buses but which are amplified in the direction away from the P-V buses. Under modest assumptions concerning the strength of the ties to the P-V buses, it is shown that disturbances that are limited to echelon 2 spread in the tierwise manner previously established for the active power problem. The results are demonstrated on the EPRI scenario A system.