PMU-Based Short Circuit Capacity Estimation using System and Load Impedance Variation Ratio

This paper presents a new method for the estimation of short-circuit capacity using PMU (Phasor Measurement Units) measurements of voltage and current phasors. The proposed method has two functions: the improvement of the estimation accuracy by selecting only PMU measurements which are suitable for the estimation, and the determination of whether the estimation values are erroneous or not. The proposed method focuses on variations in system side Thevenin equivalent (TE) impedance and load impedance, which affect the estimation accuracy. First, it analyses how the changes in each component of TE or load impedance affect the short-circuit estimation. Based on these results, the proposed method is developed. Then, the proposed method is validated by numerical simulations, and it is confirmed that the proposed method can properly distinguish between the correct and incorrect estimates and obtain more accurate estimation values of short-circuit capacity than other existing methods.