scholarly journals Nonlinear Dynamic Analysis of High-Voltage Overhead Transmission Lines

2018 ◽  
Vol 2018 ◽  
pp. 1-35 ◽  
Author(s):  
Meng Zhang ◽  
Guifeng Zhao ◽  
Jie Li
Keyword(s):  
Transmission Line ◽  
Nonlinear Vibration ◽  
Transmission Lines ◽  
Internal Resonance ◽  
Nonlinear Dynamic Analysis ◽  
Primary Resonance ◽  
Vibration Energy ◽  
Overhead Transmission Lines ◽  
Out Of Plane ◽  
Plane Direction

According to a generalized Hamilton’s principle, three-dimensional (3D) nonlinear vibration equations for overhead transmission lines that consider geometric nonlinearity are established. Based on the characteristics of an actual transmission line, the 3D equations are simplified to two-dimensional equations, and the nonlinear vibration behavior of transmission lines is investigated by combining theoretical analysis with numerical simulation. The results show that transmission lines have inherently nonlinear vibration characteristics. When in free vibration, a transmission line can undergo nonlinear internal resonance, even when its initial out-of-plane energy is relatively low; as its initial out-of-plane energy increases, the coupling of in-plane and out-of-plane vibration becomes stronger. When forced to vibrate by an external excitation, due to the combined action of internal and primary resonance, the vibration energy of a transmission line transfers from the out-of-plane direction to the in-plane direction that is not directly under the excitation, resulting in an increase in the dynamic tension and the displacement amplitude of the transmission line. Increasing damping can consume the vibration energy of a transmission line but cannot prevent the occurrence of internal resonance.

scholarly journals Transient Temperature Calculation and Multi-Parameter Thermal Protection of Overhead Transmission Lines Based on an Equivalent Thermal Network

Energies ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 67 ◽  
Author(s):  
Jian Hu ◽  
Xiaofu Xiong ◽  
Jing Chen ◽  
Wei Wang ◽  
Jian Wang
Keyword(s):  
Power System ◽  
Transmission Line ◽  
Transmission Lines ◽  
Calculation Method ◽  
Thermal Protection ◽  
Transient Temperature ◽  
Accurate Analysis ◽  
Temperature Calculation ◽  
Overhead Transmission Lines ◽  
Thermal Network

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.

Vibration Performance Analysis of FR Vibration Damper Using Finite Elements Method

2010 ◽  
Vol 44-47 ◽  
pp. 1268-1272 ◽  
Author(s):  
Xiao Yu Luo ◽  
Yi Sheng Zhang ◽  
Yong Ping Zheng
Keyword(s):  
Transmission Lines ◽  
Mechanical Vibration ◽  
Vibration Energy ◽  
The Finite Element Method ◽  
Vibration Damper ◽  
Harmonic Response ◽  
Overhead Transmission Lines ◽  
Design And Manufacturing ◽  
Work Done ◽  
Vibration Performance

FR vibration damper is widely used in overhead transmission lines to prevent aerolian vibration. In this paper, the vibration characteristics of the damper are analyzed. The finite element method software ANSYS was applied to investigate the modal, harmonic response and PSD of the damper based on the theory of mechanical vibration and dynamic analysis. The results prove that the FR vibration damper performs well in consuming the vibration energy of the transmission lines. Work done in this paper provides a new way based on numerical simulation in design and manufacturing of vibration damper, and has laid a foundation for further study of vibration damper.

Multimode Interactions in Suspended Cables

2002 ◽  
Vol 8 (3) ◽  
pp. 337-387 ◽  
Author(s):  
Ali H. Nayfeh ◽  
Haider N. Arafat ◽  
Char-Ming Chin ◽  
Walter Lacarbonara
Keyword(s):  
Internal Resonance ◽  
Multiple Scales ◽  
Equations Of Motion ◽  
Primary Resonance ◽  
Internal Resonances ◽  
Out Of Plane ◽  
Space Formulation ◽  
Suspended Cables ◽  
One To One ◽  
Plane Mode

We investigate the nonlinear nonplanar responses of suspended cables to external excitations. The equations of motion governing such systems contain quadratic and cubic nonlinearities, which may result in two-to-one and one-to-one internal resonances. The sag-to-span ratio of the cable considered is such that the natural frequency of the first symmetric in-plane mode is at first crossover. Hence, the first symmetric in-plane mode is involved in a one-to-one internal resonance with the first antisymmetric in-plane and out-of-plane modes and, simultaneously, in a two-to-one internal resonance with the first symmetric out-of-plane mode. Under these resonance conditions, we analyze the response when the first symmetric in-plane mode is harmonically excited at primary resonance. First, we express the two governing equations of motion as four first-order (i.e., state-space formulation) partial-differential equations. Then, we directly apply the methods of multiple scales and reconstitution to determine a second-order uniform asymptotic expansion of the solution, including the modulation equations governing the dynamics of the phases and amplitudes of the interacting modes. Then, we investigate the behavior of the equilibrium and dynamic solutions as the forcing amplitude and resonance detunings are slowly varied and determine the bifurcations they may undergo.

Lightning Overvoltage Analysis and Calculation of 330kV Overhead Transmission Line

2014 ◽  
Vol 556-562 ◽  
pp. 1588-1591
Author(s):  
Xiu Bin Zhang ◽  
Ding Jun Wen ◽  
Ya Ming Sun ◽  
Hong Gang Chen
Keyword(s):  
Transmission Line ◽  
Equivalent Circuit ◽  
High Voltage ◽  
Transmission Lines ◽  
Equivalent Circuit Model ◽  
Voltage Level ◽  
High Voltage Transmission Line ◽  
Overhead Transmission Line ◽  
Overhead Transmission Lines ◽  
Pollution Flashover

Lighting is one of the important reasons of transmission line trip accident. For 330kV and above ultra high voltage transmission line, lighting flashover more frequently occur. To reduce tripping rate effectively and fundamentally, lightning over voltage level should be analyzed besides anti-pollution flashover. In this paper, a simplified equivalent circuit model of a 330kV overhead transmission lines is established. The lightning over voltage of the transmission is analyzed and calculated. Method to reduce the lightning overvoltage is discussed.

scholarly journals Research on the decision of state maintenance for transmission line based on set pair analysis

2021 ◽  
Vol 71 (1&2) ◽  
pp. 17
Author(s):  
Shiyang Zhu ◽  
Le Wang
Keyword(s):  
Power System ◽  
Transmission Line ◽  
Transmission Lines ◽  
Power Grids ◽  
Financial Control ◽  
Set Pair Analysis ◽  
Overhead Transmission Lines ◽  
Maintenance Work ◽  
Maintenance Decision ◽  
Pair Analysis

Overhead transmission lines are important parts of a power system; their operation state directly affects the reliability level of the entire power system. With the in-depth development of state maintenance work for power grids, correctly evaluating the reliability of overhead transmission lines is the key to successful maintenance. A maintenance decision model for transmission lines is established in this study based on set pair analysis to achieve human financial control and low maintenance efficiency. Full consideration is provided to the influence of environmental factors, and a theoretical basis for transmission line maintenance decision is established.

scholarly journals Mechanism Design and Analysis of a New Overhead Transmission Line Inspection Robot

2020 ◽  
Vol 38 (5) ◽  
pp. 1105-1111
Author(s):  
Yishuang Wang ◽  
Chao Yuan ◽  
Yongjie Zhai
Keyword(s):  
Transmission Line ◽  
Transmission Lines ◽  
Simulation Analysis ◽  
Rapid Development ◽  
Frame Structure ◽  
Three Dimensional Model ◽  
Obstacle Crossing ◽  
Inspection Robot ◽  
Overhead Transmission Lines ◽  
Inspection Robots

The requirements of power system for the safety of overhead transmission lines are increasing. With the rapid development of mobile robot technology, the inspection of overhead transmission lines by inspection robots has become a research hotspot in recent years. Aiming at the task requirements of transmission line inspection robots and the environmental characteristics of transmission lines, researchers at home and abroad have developed a variety of inspection robots. However, most of these robots have problems such as inability to cross the strain tower, low obstacle crossing efficiency and poor safety. In order to solve the above problems, this paper proposes a new four-arm inspection robot mechanism. The robot can cross the strain tower with two different sets of arms working together. The rectangular frame structure on the walking arm improves the obstacle crossing efficiency of the robot, and the closed hanging mechanism ensures that the robot does not fall from the line. In this paper, the three-dimensional model of the robot is established, and the specific structure and motion parameters are given. Three typical obstacle-crossing modes are planned, and the motion analysis and force simulation analysis of the robot's obstacle-crossing process are carried out. The simulation result shows that the mechanism can efficiently cross the strain towers and common obstacles on the transmission line.

scholarly journals Vibration Reduction for a Flexible Arm Using Magnetorheological Elastomer Vibration Absorber

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Yushu Bian ◽  
Xuefeng Liang ◽  
Zhihui Gao
Keyword(s):  
Nonlinear Vibration ◽  
Internal Resonance ◽  
Control Method ◽  
Resonance Condition ◽  
Vibration Energy ◽  
Vibration Absorber ◽  
Semiactive Control ◽  
Magnetorheological Elastomer ◽  
Flexible Arm ◽  
Transfer Channel

The application of the magnetorheological elastomer (MRE) to nonlinear vibration control for a flexible arm is investigated in this paper. A semiactive control method is suggested to reduce vibration via the internal resonance and the MRE. To establish a vibration energy transfer channel, a tuned vibration absorber based on the MRE is developed. Through adjusting the coil current, the frequency of the vibration absorber can be readily controlled by the external magnetic field, thereby maintaining the internal resonance condition with the flexible arm. By the perturbation analysis, it is proven that the internal resonance can be successfully established between the flexible arm and the MRE vibration absorber, and the vibration energy of the flexible arm can be transferred to and dissipated by the MRE vibration absorber. Through numerical simulations, virtual prototyping simulations, and experimental investigation, it is verified that the proposed method and the suggested MRE vibration absorber are effective in controlling nonlinear vibration of the flexible arm.

scholarly journals Again about reliability characteristics of electrical power grids elements

2018 ◽  
Vol 58 ◽  
pp. 01002
Author(s):  
Abdula Abdurakhmanov ◽  
Sergey Glushkin ◽  
Vladislav Plotnikov ◽  
Andrey Shuntov
Keyword(s):  
Statistical Analysis ◽  
Transmission Line ◽  
Transmission Lines ◽  
Electrical Power ◽  
Power Grids ◽  
Overhead Transmission Line ◽  
Overhead Transmission Lines ◽  
Network Layout ◽  
Reliability Characteristics ◽  
Technical Solutions

The reliability characteristics of the (auto)transformers and overhead transmission lines of the unified national electric grid are subjected to statistical analysis. It is shown that their scheduled outages for scheduled or unscheduled repairs, as well as maintenance, weaken the network layout much more than emergency repairs. At the same time, there was a noticeable deterioration in the (auto)transformers and overhead transmission line reliability indexes over the last 30 years, which requires the development and adoption of appropriate organizational and technical solutions.

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