scholarly journals Lightning Performance Evaluation of Italian 150 kV Sub-Transmission Lines

Energies ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2142
Author(s):  
Fabio Massimo Gatta ◽  
Alberto Geri ◽  
Stefano Lauria ◽  
Marco Maccioni ◽  
Francesco Palone
Keyword(s):  
Monte Carlo ◽  
Performance Evaluation ◽  
Transmission Lines ◽  
Computational Cost ◽  
Lightning Strikes ◽  
Grounding System ◽  
Monte Carlo Procedure ◽  
Overhead Transmission Lines ◽  
Realistic Assessment ◽  
Low Computational Cost

A significant majority of overhead transmission lines’ (OHLs) outages is due to backflashovers caused by direct lightning strikes: the realistic assessment of the lightning performance is thus an important task. The paper presents the analysis of the lightning performance of an existing 150 kV Italian OHL, namely, its backflashover rate (BFOR), carried out by means of an ATP-EMTP-based Monte Carlo procedure. Among other features, the procedure makes use of a simplified pi-circuit for line towers’ grounding system, allowing a very accurate reproduction of transient behaviours at a very low computational cost. Tower grounding design modifications, aimed at improving the OHL lightning performance, are also proposed and discussed.

scholarly journals Modeling of different tower grounding systems using hybrid continuous circuit-trapezoidal integration method

2021 ◽  
Vol 18 (2) ◽  
pp. 225-236
Author(s):  
Mohammadbagher Asadpourahmadchali ◽  
Mohsen Niasati ◽  
Yousef Alinejad-Beromi
Keyword(s):  
Transmission Lines ◽  
Rise Time ◽  
Integration Method ◽  
Geographic Location ◽  
Soil Resistivity ◽  
Lightning Strikes ◽  
Grounding System ◽  
Current Rise Time ◽  
Current Rise ◽  
Lightning Current

In order to protect the transmission lines against lightning strikes, it is important to investigate the tower grounding system. In this paper, a recent method called hybrid continuous circuit-trapezoidal integration method is used to calculate the impulse impedance of the grounding system. Moreover, conventional structures of the grounding systems have been simulated and the results show that, with the same wire length, the square with additional wire system has the least impulse impedance as compared to counterpoise, square and crow?s foot. Moreover, the effects of soil resistivity and lightning current rise-time on the impulse impedance of these grounding systems are investigated. It is concluded that the design of the grounding system depends on the geographic location of the site in terms of soil resistivity and isotropic characteristics of the area in terms of lightning current rise-time.

scholarly journals Computing Expectiles Using k-Nearest Neighbours Approach

Symmetry ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 645
Author(s):  
Muhammad Farooq ◽  
Sehrish Sarfraz ◽  
Christophe Chesneau ◽  
Mahmood Ul Hassan ◽  
Muhammad Ali Raza ◽  
...  
Keyword(s):  
Computational Cost ◽  
Real Life ◽  
Distance Measures ◽  
Computational Time ◽  
High Dimensional ◽  
Test Error ◽  
Nearest Neighbours ◽  
Comparable Performance ◽  
Asymmetric Least Squares ◽  
Low Computational Cost

Expectiles have gained considerable attention in recent years due to wide applications in many areas. In this study, the k-nearest neighbours approach, together with the asymmetric least squares loss function, called ex-kNN, is proposed for computing expectiles. Firstly, the effect of various distance measures on ex-kNN in terms of test error and computational time is evaluated. It is found that Canberra, Lorentzian, and Soergel distance measures lead to minimum test error, whereas Euclidean, Canberra, and Average of (L1,L∞) lead to a low computational cost. Secondly, the performance of ex-kNN is compared with existing packages er-boost and ex-svm for computing expectiles that are based on nine real life examples. Depending on the nature of data, the ex-kNN showed two to 10 times better performance than er-boost and comparable performance with ex-svm regarding test error. Computationally, the ex-kNN is found two to five times faster than ex-svm and much faster than er-boost, particularly, in the case of high dimensional data.

Modeling of overhead transmission lines for trapped charge discharge rate studies

2021 ◽  
Vol 198 ◽  
pp. 107343
Author(s):  
J. Morales ◽  
J. Mahseredjian ◽  
I. Kocar ◽  
H. Xue ◽  
A. Daneshpooy
Keyword(s):  
Transmission Lines ◽  
Discharge Rate ◽  
Overhead Transmission Lines ◽  
Charge Discharge ◽  
Trapped Charge
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