Interval State Estimation with Measurement and Network Parameter Uncertainty in Unbalanced Distribution Systems

The purpose of state estimators (SEs) in power systems is to reduce the effect of measurement errors by utilizing the redundancy available in the measurement system. This paper proposes an interval state estimation (ISE) model to simultaneously formulate the uncertainties of network parameters and measurements in unbalanced distribution systems by interval arithmetic. A modified Krawczyk-operator algorithm in interval arithmetic is adopted to solve the proposed ISE model. The solutions provide the upper and lower bounds of each state variable where the true state variables must lie, under the joint effects of these uncertainties. Comparison results with existing algorithms in the unbalanced IEEE 13-bus system illustrate that the proposed method used to solve this model is many orders of magnitude faster without sacrificing the estimation accuracy.