Loss Induced Maximum Power Transfer in Distribution Networks

TL;DR

This paper analytically characterizes maximum power transfer limits in distribution networks considering thermal and voltage constraints, introducing a new loss-based limit and validating it with IEEE test feeders.

Contribution

It introduces the marginal loss-induced maximum power transfer limit, providing a more rigorous analysis than traditional methods, and explores reactive power's role in power transfer.

Findings

The new limit aligns well with test feeder results.

Reactive power's impact varies with network impedance ratios.

The analysis informs optimal distributed generation sizing.

Abstract

In this paper, the power flow solution of the two bus network is used to analytically characterise maximum power transfer limits of distribution networks, when subject to both thermal and voltage constraints. Traditional analytic methods are shown to reach contradictory conclusions on the suitability of reactive power for increasing power transfer. Therefore, a more rigorous analysis is undertaken, yielding two solutions, both fully characterised by losses. The first is the well-known thermal limit. The second we define as the `marginal loss-induced maximum power transfer limit'. This is a point at which the marginal increases in losses are greater than increases in generated power. The solution is parametrised in terms of the ratio of resistive to reactive impedance, and yields the reactive power required. The accuracy and existence of these solutions are investigated using the IEEE 34 bus distribution test feeder, and show good agreement with the two bus approximation. The work has implications for the analysis of reactive power interventions in distribution networks, and for the optimal sizing of distributed generation.