Identification of capacitor switching relative location using the S-transform

This paper proposes an algorithm based on the use of the S-transform for time-frequency analysis of the capacitor-switching transients. With no prior knowledge about system parameters, the time-frequency analysis of the voltage and current transient signals due to switched capacitor banks are used to simply but accurately estimate the relative location of the switched capacitor whether it is upstream or downstream. The phase-angle difference between the transient voltage and current signals at the power quality (PQ) monitoring location determines the transient energy flow direction. A general model of radial distribution system is used to simulate both an isolated and back-to-back capacitor switching. The electromagnetic transient program (EMTP) are used as a simulation tool and measurement provider. The simulation results of the transient phase-angle difference illustrate the capability of the proposed algorithm to relatively locate the switched capacitors.