Sensitivity of Network Wide Voltage Unbalance Levels to Variations in Unbalanced Installations

Abstract

Voltage unbalance (VU) emission assessment is a challenging task due to the complex interactions between the sources of voltage unbalance. Consequently, to account for transferred voltage unbalance from neighbouring busbars, IEC/TR 61000-3-13 has introduced influence and transfer coefficients in the VU allocation and emission assessment process. However, no generalised practical approaches exist to evaluate these coefficients where as IEC guidelines suggest some approximations based on simulations and field measurements. As an alternative, this paper proposes a sensitivity analysis of network VU to unbalanced installations that can be employed in VU emission assessment. The proposed methodology uses readily available inputs and utilises a linearised approach to determine the network wide sensitivity of VU to unbalanced installations which makes it feasible for practical implementation.