Analysis of the impact of renewable energy sources on energy losses in distribution networks

Abstract

Relevance: the rapid penetration of solar photovoltaic and wind generation into distribution networks is changing the conventional unidirectional structure of power flows. At low-to-moderate penetration, local generation can reduce upstream power transfer, feeder current and I²R losses. At high penetration, however, reverse power flow, voltage rise and reactive-power exchange can cause losses to increase again in some feeder sections. The effect of renewable energy sources on network losses should therefore be evaluated together with operating conditions, generation siting and available control resources.

Aim: to identify the mechanisms through which renewable energy sources affect energy losses in distribution networks, compare verified quantitative results reported in recent international studies, and analyze the relationship among hosting capacity, voltage profile and demand response.

Methods: to quantify the effect of renewable energy sources on distribution-network energy losses, results reported for IEEE 33- and 123-bus test systems and real low-voltage networks were compared. Active-power losses were evaluated using I²R and branch-flow relationships. RES penetration, hosting capacity, voltage deviation, and demand-response participation were used as the principal comparison indicators. Published numerical tables were used to reconstruct the voltage profile, the hosting-capacity-loss relationship, and the sensitivity of network losses to demand-response participation.

Results: the analysis shows that the effect of renewable energy sources on energy losses is nonlinear and operating-regime dependent. Meng et al. reported a 3.88% reduction in network losses under coordinated voltage control. In the results of Loji et al., demand response reduced losses in case C6 from 1471.68 to 1248.63 kWh, while the minimum voltage at bus 18 improved from 0.9141 to 0.9327 p.u. Increasing demand-response participation from 0 to 30% reduced losses from 1489.95 to 1273 kWh. These results indicate that increasing renewable generation alone is insufficient at high penetration levels; coordinated voltage and flexibility control is required.