Assessing the effects of load models on MV network losses

Network losses are often a key metric in evaluating the performance of planning and/or operational strategies. However, their assessment is traditionally carried out assuming a constant power load model that does not reflect the actual voltage-demand dependency, thus leading to inaccurate results. This work quantifies, in a real UK medium voltage (MV) network, the impact of three classic load models (constant power, current and impedance) on the quantification of energy and power network losses. A time-varying ZIP model designed for the UK residential demand is used as benchmark. Results indicate that the constant power load model, although underestimates the network losses throughout the year, outperforms the other models during summer (maximum error of 3% on power and 1.5% in energy). However, during winter the constant current model showed the best performance. The constant impedance model led to the highest errors and, consequently, should be in general avoided.