Computation of subtransmission losses based on statistical optimization approach with network constraints

The simulation of technical losses in subtransmission systems is one of the greatest challenges for utilities from technical and economical viewpoint. This paper proposes a model for technical losses estimation in subtransmission system based on an optimization and statistical model which disaggregate the power from transmission to subtransmission system. After that, the losses are estimated by an approximation using DC power flow equation with the branch-bus sensitivity matrix. The IEEE 24 bus system was used for the case study, considering one-year historic data with one-hour intervals. In this case, the 230 kV level power grid was considered as the transmission and the 138 kV level as the subtransmission network. In order to assess the proposed model, a purely statistical model was implemented to be used as a benchmark. The results indicated that the network constraints, which simulates the power injection/extraction control of some buses, would be valuable to estimate and simulate losses.