Biblio

The parameters of transmission line vary with environmental and operating conditions, thus the paper proposes a digital twin-based transmission line model. Based on synchrophasor measurements from phasor measurement units, the proposed model can use the maximum likelihood estimation (MLE) to reduce uncertainty between the digital twin and its physical counterpart. A case study has been conducted in the paper to present the influence of the uncertainty in the measurements on the digital twin for the transmission line and analyze the effectiveness of the MLE method. The results show that the proposed digital twin-based model is effective in reducing the influence of the uncertainty in the measurements and improving the fault location accuracy.

Influence of remanent flux on hysteresis curve of the transformer core is addressed in this paper. In addition, its significant negative effect on transformer diagnostic tests is quantified based on experimental studies. Furthermore, a novel approach is proposed to efficiently and quickly eliminate the remanent flux. This approach is evaluated based on simulation studies on a 230/63-kV power transformer. Meanwhile, experimental studies are performed on both 0.2/0.2 and 20/0.4 kV transformers. These studies reveal that the approach not only is well able to eliminate the remanent flux, but also it has various advantages over the commonly used method. In addition, this approach is equally applicable for various power, distribution, and instrument transformer types.