A historical distribution network state estimator using smart distribution transformer meters

The measurements given by Supervisory Control And Data Acquisition (SCADA) systems are generally insufficient for Distribution network State Estimation (DSE). The accuracy of DSE seriously relies on the pseudo measurements, which are generally inaccurate. In historical scene, measurements given by smart distribution transformer meter (SDTM) can be used to enrich the measurements for DSE. The hybrid measurements of SCADA and SDTM can satisfy the observability of DSE with certain redundancy. By using rectangular coordination and introducing intermediate variables and quadratic equalities, the SCADA/SDTM hybrid DSE is modeled as quadratic constrained quadratic estimation (QCQE) problem, which can be solved by traditional state estimation methods with sparse techniques efficiently and conveniently. Simulations on the IEEE 33-bus system show the accuracy of the hybrid DSE. The proposed DSE has been implemented in distribution networks in Zhejiang and shows good efficiency and accuracy.