Ordinal Optimization Technique for Three-Phase Distribution Network State Estimation Including Discrete Variables

This paper has discussed transformer tap position estimation with continuous and discrete variables in the context of three-phase distribution state estimation (SE). Ordinal optimization (OO) technique has been applied to estimate the transformer tap position for the first time in an unbalanced three-phase distribution network model. The results on 129 bus system model have demonstrated that the OO method can generate a reliable estimate for transformer exact tap position with discrete variables in distribution system SE and also in short period of time. In this paper, the node voltages and power losses are calculated for 129 bus network. It is also demonstrated that OO is much faster than other accurate methods such hybrid particle swarm optimization. The losses obtained with OO are much accurate. In view of this, OO performs better than weighted least square as it provides higher accuracy of the loss calculation. In a distribution network where about 5-6% of electricity generated is lost, accurate estimation of this loss has significant technical and commercial value. The authors believe the technique proposed will help realize those benefits.