The analysis of voltage and current unbalance by application of active and reactive power in the fundamental frequency negative-sequence components

The behaviour of the fundamental frequency negative-sequence power components in unbalanced power networks is evaluated for possible information on the relative contribution by the supply and loading network. Previous studies indicated that the direction of the negative-sequence active power in the fundamental frequency do not consistently commensurate with the location of a single source of unbalance in a power system when multiple sources of unbalance are located all over the network. This paper analyse the usefulness of all negative-sequence power components in the fundamental frequency, as information on the location and the degree of contribution to the voltage unbalance at the Point of Common Coupling (PCC) of a single source of unbalance in practical power systems. The results obtained confirmed that the direction of the fundamental frequency negative-sequence active power is not consistent with the source of unbalance but that the direction of the fundamental frequency negative-sequence reactive power is informative on the dominating source of unbalance.