Rigorous calculation method for resonance frequencies in transmission line responses

The overload degree of a transmission line is represented by currents in traditional overload protection, which cannot reflect its safety condition accurately. The sudden rise in transmission line current may lead to cascading tripping under traditional protection during power flow transfer in a power system. Therefore, timely and accurate analysis of the transient temperature rise of overhead transmission lines, revealing their overload endurance capability under the premise of ensuring safety, and coordination with power system controls can effectively eliminate overloading. This paper presents a transient temperature calculation method for overhead transmission lines based on an equivalent thermal network. This method can fully consider the temperature-dependent characteristics with material properties, convective heat resistance, and radiation heat and can accurately calculate the gradient distribution and response of the conductor cross-section temperature. The validity and accuracy of the proposed calculation method are verified by a test platform. In addition, a multi-parameter thermal protection strategy is proposed on the basis of the abovementioned calculation method. The protection can adequately explore the maximum overload capability of the line, and prevent from unnecessary tripping to avoid the expansion of accidents. Finally, the validity of the proposed protection is verified by the modified 29-bus system.

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Energy Approach for Determine Frequency and Amplitude of Vibration of Piping With Closed Side Branches

Volume 4: Fluid-Structure Interaction ◽

10.1115/pvp2015-45289 ◽

2015 ◽

Author(s):

Igor Orynyak ◽

Iaroslav Dubyk ◽

Anatolii Batura

Keyword(s):

Experimental Data ◽

Boundary Conditions ◽

Calculation Method ◽

Acoustic Vibration ◽

Energy Functional ◽

Energy Approach ◽

Calculation Algorithm ◽

Local Excitation ◽

Resonance Frequencies ◽

System Energy

This article suggests calculation method for frequency and amplitude of acoustic vibration in piping with closed side branches, caused by gaseous running flow. The calculation algorithm consists of following steps: i) local excitation system is defined; ii) different combinations of boundary conditions are formed; iii) for fixed pair of boundary conditions ratio of stored in system energy and radiated from boundaries energy is written; iv) for every frequency energy functional is maximized to find boundary conditions; v) resonance frequencies are determined from plotting a curve of maximal energy ratio vs. frequency. Energy approach was further developed to analyze amplitude of vibration. For amplitude determine balance between injected energy (which depends on the Strouhal number and is defined from experimental data for laboratory geometries), and radiated from boundaries energy is written.

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Author's rebuttal to the letter of D. S. Billingsley on the paper “A rigorous calculation method for the minimum stages in multicomponent distillation”

Chemical Engineering Science ◽

10.1016/0009-2509(75)85083-4 ◽

1975 ◽

Vol 30 (11) ◽

pp. 1447-1448

Author(s):

HenryH.Y. Chien

Keyword(s):

Calculation Method ◽

Rigorous Calculation ◽

Multicomponent Distillation

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Reliability Study of Important Cross-Over Transmission Line System Based on Series System

Journal of Physics Conference Series ◽

10.1088/1742-6596/2137/1/012028 ◽

2021 ◽

Vol 2137 (1) ◽

pp. 012028

Author(s):

Dengjie Zhu ◽

Yongli Liao ◽

Hao Li ◽

Jie Tang ◽

Zenghao Huang ◽

...

Keyword(s):

Transmission Line ◽

Transmission Lines ◽

Calculation Method ◽

Reliability Index ◽

Force Transmission ◽

Line System ◽

Reliability Calculation ◽

Safety And Reliability ◽

The Cross ◽

Line Crossing

Abstract Transmission lines inevitably cross railroads, highways, and other facilities, and in order to ensure the safety and reliability of the cross-crossing section, the influence of various random factors on important cross-crossing transmission lines needs to be fully considered. In this paper, the transmission line crossing section is treated as a tandem system according to the force transmission route, and the reliability calculation method of the cross-crossing transmission line system based on the tandem system is proposed. The reliability calculation method of each component and the reliability calculation method of the tandem system are given. Finally, an example of the reliability calculation of a 220kV cross-crossing transmission line system is given, and the results show that the cross-crossing section has the highest reliability of tower FSJ404, with a reliability index of 8.61, the second highest reliability of insulators, with a reliability index of 7.22, and the lowest reliability of tower FSJ302, with a reliability index of 4.28. The failure probability of the cross-crossing section is 0.000009245, and the reliability index is 4.28.

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