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Influence of electromagnetic transient physical models considering characterization characteristics on capacitive voltage transformers

Geng Jie, Yang Haiyong, Yi Li, Zhang Xiao, Wang Yihang

Archives of Electrical Engineering

2024

Vol. 73, nr 2

467--480

The equivalent circuit of traditional capacitive voltage transformers often faces the problem of complex data calculation and difficulty in grasping the internal nonlinear characteristics of transformers when constructing broadband models, resulting in poor power accuracy and stability. Therefore, with the help of electromagnetic transient physical models, the admittance sub model and nonlinear model are established by considering the frequency and saturation characteristics of the transformer. Based on the characteristics of capacitive voltage transformers, the model is processed in parallel to obtain a broadband coupling transformer model. The results showed that the error between the simulated current peak amplitude and voltage results of the model and the measured values was less than 2% and 1%, respectively. In the fault results, the harmonic error of the load voltage of the improved transformer was relatively small, far less than the error result of 2.73% of the traditional transformer. The proposed transformer model can better characterize its characteristics and has good transient response ability, providing reference tools and value for the operation and state detection of power systems.

Assessing the maximum limit of SAR-OSL dating using quartz of different grain sizes

Anechitei-Deacu V., Timar-Gabor A., Constantin D., Trandafir-Antohi O., Del Valle L., Fornós J. J., Gómez-pujol L., Wintle A. G.

Geochronometria

2018

Vol. 45, no. 1

146--159

SAR-OSL dating studies of Romanian, Serbian and Chinese loess using fine and coarse quartz have previously resulted in a series of controversial issues. We extend here the investigations using fine (4–11 μm) and different coarse quartz (>63 μm) grains extracted from aeolianites from a site on Eivissa Island (southwestern Mediterranean). Aeolianites were chosen since they contain quartz from a different geological context and have significantly lower environmental dose rates. The dose response curves of the OSL signals for fine and coarse quartz are similar to those for loess and are also represented by the sum of two saturating exponential functions. For doses up to ~200 Gy, the dose response curves of fine and coarse grains from aeolianites can be superimposed and the ages obtained for the different grain sizes are in agreement up to ~250 ka, increasing our confidence in the accuracy of the ages obtained for samples with such doses, irrespective of the magnitude of the environmental dose rate. Particularly for the fine quartz fraction, a mismatch between the SAR dose response curve and the dose response curve obtained when doses are added to the natural is reported, indicating that the application of the SAR protocol in the high dose range is problematic. This dose dependent deviation is much less pronounced for coarse grains. Thus, it seems reasonable to infer that the dose response curves for the coarse grains, although saturating earlier can be regarded as more reliable for equivalent dose calculation than those for the fine grains.