A Cost Effective PI Network Filter for Elimination of Stiff Transmission Crosstalk in Zero Sequence Propogated Distribution Power Line Carrier Signals

A cost effective method for elimination of intersubstation crosstalk problem in distribution power line carrier communications systems is presented. A shunt three-phase wye-configured capacitor bank is connected between a substation transformer and any source of zero-sequence power line carrier commu nication signals being transmitted on the substation distribution network to partially alleviate unbalance conditions in the communication signals. When balan ced, these signals are not passed by a three-phase delta-wye grounded substation transformer to the main transmission line. The signal is further attenuated by connecting the common wye-point of the capacitor bank through an inductance to neutral. This forms a shunt element of either an L or pi attentuation circuit with the series inductance of the substation transformer and the transmission line inductance. The transformer series inductance and the transmission line form the serial elements of the L or pi circuit. A further shunt element at another substation distribution network completes the attenuation circuit for the pi configuration. The method was verified in an actual field application. The cost of this method is shown to be only one-fifth that of the conventional approach.