scholarly journals A Method for Settlement Detection of the Transmission Line Tower under Wind Force

Sensors ◽  
2018 ◽  
Vol 18 (12) ◽  
pp. 4355 ◽  
Author(s):  
Xinbo Huang ◽  
Yu Zhao ◽  
Long Zhao ◽  
Luya Yang
Keyword(s):  
Temperature Correction ◽  
Vibration Response ◽  
Transmission Tower ◽  
Wind Force ◽  
Experiment Platform ◽  
Stochastic Subspace Identification ◽  
Transmission Towers ◽  
Before And After ◽  
Tower Foundation ◽  
Environment Parameters

In view of the settlement problem of transmission tower foundation, the vibration characteristics of transmission towers under wind force are measured experimentally. In this paper, the 110 kV cat head transmission tower of Xi’an Polytechnic University is measured and analyzed. Firstly, the acceleration sensor and meteorological sensor are installed on the tower to collect the vibration response and environment parameters of the tower in real time. Then, an experiment platform is built to simulate the tower settlement, and the vibration response of the tower after settlement is measured in time. Finally, the low-order modal frequencies of the transmission tower before and after settlement under wind force load are extracted by stochastic subspace identification (SSI), and the relationship between modal frequencies of different modes is analyzed via temperature correction. By comparison and analysis, it is obvious that the X-direction modal frequencies before and after settlement under natural wind load are changed, and the change rate increases with the increase of settlement displacement, which can be used as effective evidence for judging the settlement of transmission tower foundation.

scholarly journals A Kriging Surrogate Model for the Interference Reduction in the Settlement Surveillance Sensors of Steel Transmission Towers

2019 ◽  
Vol 9 (16) ◽  
pp. 3343 ◽  
Author(s):  
Jiajia Shi ◽  
Liu Chu ◽  
Eduardo Souza de Cursi
Keyword(s):  
Surrogate Model ◽  
High Efficiency ◽  
Computational Cost ◽  
Element Model ◽  
Kriging Surrogate Model ◽  
Transmission Tower ◽  
Modal Frequency ◽  
Interference Reduction ◽  
Transmission Towers ◽  
Tower Foundation

The utilization of modal frequency sensors is a feasible and effective way to monitor the settlement problem of the transmission tower foundation. However, the uncertainties and interference in the real operation environment of transmission towers highly affect the accuracy and identification of modal frequency sensors. In order to reduce the interference of modal frequency sensors for transmission towers, a Kriging surrogate model is proposed in this study. The finite element model of typical transmission towers is created and validated to provide the effective original database for the Kriging surrogate model. The prediction accuracy and convergences of the Kriging surrogate model are measured and confirmed. Besides the merits in computational cost and high-efficiency, the Kriging surrogate model is proven to have a satisfied and robust interference reduction capacity. Therefore, the Kriging surrogate model is feasible and competitive for interference filtration in the settlement surveillance sensors of steel transmission towers.

scholarly journals Active Vibration-Based Condition Monitoring of a Transmission Line

Actuators ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 309
Author(s):  
Liuhuo Wang ◽  
Chengfeng Liu ◽  
Xiaowei Zhu ◽  
Zhixian Xu ◽  
Wenwei Zhu ◽  
...  
Keyword(s):  
Natural Frequencies ◽  
Engineering Application ◽  
Vibration Response ◽  
Modal Identification ◽  
Wireless Sensor ◽  
Transmission Tower ◽  
Transmission Towers ◽  
Vibration Responses ◽  
Active Vibration ◽  
Settlement Experiment

In the power system, the transmission tower is located in a variety of terrains. Sometimes there will be displacement, inclination, settlement and other phenomena, which eventually lead to the collapse of the tower. In this paper, a method for monitoring the settlement of a transmission tower based on active vibration response is proposed, which is based on the principle of modal identification. Firstly, a device was designed, which includes three parts: a monitoring host, wireless sensor and excitation device. It can tap the transmission tower independently and regularly, and collect the vibration response of the transmission tower. Then, vibration analysis experiments were used to validate the horizontal vibration responses of transmission towers which can be obtained by striking the transmission towers from either the X direction or Y direction. It can be seen from the frequency response function that the natural frequencies obtained from these two directions are identical. Finally, the transmission tower settlement experiment was carried out. The experimental results show that the third to fifth natural frequencies decreased most obviously, even up to 2.83 Hz. Further, it was found that under different conditions, as long as the tower legs adjacent to the excitation position settle, the natural frequency will decrease more significantly, which is very helpful for engineering application.

Field measurements of typhoon effects on a transmission tower and its modal parameter identification

2020 ◽  
Vol 23 (8) ◽  
pp. 1548-1561
Author(s):  
Hong-Nan Li ◽  
Jin-Xin Wang ◽  
Xing Fu ◽  
Liang Ren ◽  
Qing Zhang
Keyword(s):  
Finite Element ◽  
Health Monitoring ◽  
Element Model ◽  
Subspace Identification ◽  
Transmission Tower ◽  
Stochastic Subspace Identification ◽  
Wind Speeds ◽  
Identification Method ◽  
Transmission Towers ◽  
Subspace Identification Method

Many transmission towers have collapsed under typhoons in recent years, mainly due to the unclear behaviors of their structural properties, introducing many deficiencies in the design process. Therefore, implementing structural health monitoring is of great importance for investigating the structural features of large-span transmission lines. This study develops a stochastic subspace identification method to identify the modal parameters of transmission towers, and a finite element model of a transmission tower-line system is established based on a case in Guangdong Province, China. Moreover, a MATLAB program is written using the stochastic subspace identification method to perform a modal analysis on the wind-induced responses of a transmission tower, and the results are compared with those of the finite element model to verify the program’s reliability. A structural health monitoring system installed on a transmission tower recorded the wind field data around the tower and its vibration responses during Typhoon Khanun. The characteristics of the typhoon wind field and the changes in the acceleration responses under different wind speeds were calculated, and the developed stochastic subspace identification method was used to identify the frequencies and damping ratios of the tower. The results show that the identified frequencies under different wind speeds in the longitudinal and transverse directions remain essentially unchanged, indicating that the monitoring tower was safe and suffered no damage during Typhoon Khanun. The damping ratios of the monitoring tower range from 1% to 4%, where the larger values may be caused by bolt slippage.

Ultrasonic unilateral double-position excitation lamb wave defect detection and quantification method for ground electrode of transmission tower

2021 ◽  
pp. 1-15
Author(s):  
Kuan Ye ◽  
Kai Zhou ◽  
Ren Zhigang ◽  
Ruizhe Zhang ◽  
Chunsheng Li ◽  
...  
Keyword(s):  
Guided Waves ◽  
Power Transmission ◽  
Geometric Model ◽  
Guided Wave ◽  
Quantization Error ◽  
Dispersion Function ◽  
Stable Operation ◽  
Transmission Tower ◽  
Ultrasonic Guided Wave ◽  
Transmission Towers

The power transmission tower’s ground electrode defect will affect its normal current dispersion function and threaten the power system’s safe and stable operation and even personal safety. Aiming at the problem that the buried grounding grid is difficult to be detected, this paper proposes a method for identifying the ground electrode defects of transmission towers based on single-side multi-point excited ultrasonic guided waves. The geometric model, ultrasonic excitation model, and physical model are established, and the feasibility of ultrasonic guided wave detection is verified through the simulation and experiment. In actual inspection, it is equally important to determine the specific location of the defect. Therefore, a multi-point excitation method is proposed to determine the defect’s actual position by combining the ultrasonic guided wave signals at different excitation positions. Besides, the precise quantification of flat steel grounding electrode defects is achieved through the feature extraction-neural network method. Field test results show that, compared with the commercial double-sided excitation transducer, the single-sided excitation transducer proposed in this paper has a lower defect quantization error in defect quantification. The average quantization error is reduced by approximately 76%.

scholarly journals A Vibration-Based Structural Health Monitoring System for Transmission Line Towers

Electronics ◽  
2019 ◽  
Vol 8 (5) ◽  
pp. 515 ◽  
Author(s):  
Long Zhao ◽  
Xinbo Huang ◽  
Ye Zhang ◽  
Yi Tian ◽  
Yu Zhao
Keyword(s):  
Structural Health Monitoring ◽  
Transmission Line ◽  
Natural Frequency ◽  
Health Monitoring ◽  
Structural Changes ◽  
Natural Frequencies ◽  
Transmission Tower ◽  
Health Monitoring System ◽  
Wind Speeds ◽  
Before And After

In this paper, we present a vibration-based transmission tower structural health monitoring system consisting of two parts that identifies structural changes in towers. An accelerometer group realizes vibration response acquisition at different positions and reduces the risk of data loss by data compression technology. A solar cell provides the power supply. An analyser receives the data from the acceleration sensor group and calculates the transmission tower natural frequencies, and the change in the structure is determined based on natural frequencies. Then, the data are sent to the monitoring center. Furthermore, analysis of the vibration signal and the calculation method of natural frequencies are proposed. The response and natural frequencies of vibration at different wind speeds are analysed by time-domain signal, power spectral density (PSD), root mean square (RMS) and short-time Fouier transform (STFT). The natural frequency identification of the overall structure by the stochastic subspace identification (SSI) method reveals that the number of natural frequencies that can be calculated at different wind speeds is different, but the 2nd, 3rd and 4th natural frequencies can be excited. Finally, the system was tested on a 110 kV experimental transmission line. After 18 h of experimentation, the natural frequency of the overall structure of the transmission tower was determined before and after the tower leg was lifted. The results show that before and after the tower leg is lifted, the natural frequencies of each order exhibit obvious changes, and the differences in the average values can be used as the basis for judging the structural changes of the tower.

scholarly journals Collapse Analysis of a Transmission Tower-Line System Induced by Ice Shedding

2021 ◽  
Vol 9 ◽  
Author(s):  
Jiaxiang Li ◽  
Biao Wang ◽  
Jian Sun ◽  
Shuhong Wang ◽  
Xiaohong Zhang ◽  
...  
Keyword(s):  
Finite Element ◽  
Transmission Lines ◽  
Progressive Collapse ◽  
Element Model ◽  
Transmission Tower ◽  
Line System ◽  
Finite Element Software ◽  
Transmission Towers ◽  
Ice Shedding ◽  
The Impact

Ice shedding causes transmission lines to vibrate violently, which induces a sharp increase in the longitudinal unbalanced tension of the lines, even resulting in the progressive collapse of transmission towers in serious cases, which is a common ice-based disaster for transmission tower-line systems. Based on the actual engineering characteristics of a 500 kV transmission line taken as the research object, a finite element model of a two-tower, three-line system is established by commercial ANSYS finite element software. In the modeling process, the uniform mode method is used to introduce the initial defects, and the collapse caused by ice shedding and its influencing parameters are systematically studied. The results show that the higher the ice-shedding height is, the greater the threat of ice shedding to the system; furthermore, the greater the span is, the shorter the insulator length and the greater the dynamic response of the line; the impact of ice shedding should be considered in the design of transmission towers.

O2 solubility in blood and temperature correction factors for Po2

1964 ◽  
Vol 19 (5) ◽  
pp. 901-906 ◽  
Author(s):  
J. Hedley-Whyte ◽  
M. B. Laver
Keyword(s):  
Aqueous Solution ◽  
Technical Assistance ◽  
Relative Increase ◽  
Temperature Correction ◽  
Effect Of Temperature ◽  
Correction Factors ◽  
Paired Samples ◽  
Before And After ◽  
Dilute Aqueous Solution ◽  
Relative Solubility

Tonometry of 100 paired samples of blood and measurement of Po2 before and after warming in a sealed syringe showed that the relative solubility of O2 (αB/αHh2O) in fully saturated blood is constant at all temperatures between 24.5 and 38 C, i.e., fully saturated blood appears to behave as a dilute aqueous solution. When Po2 is kept constant during cooling the relative increase in dissolved O2 in blood is the same as with water. Thus, when cooling from 38 to 20 C the increase in dissolved O2, if Po2 is kept constant, is 31%. Correction factors for the effect of temperature on Po2 of blood warmed to 38 C can be based on ratios of αHh2O38/αHh20T. These factors were found to give adequate correction at O2 tensions above 250 mm Hg. Inaccuracies were found when previously proposed factors were applied to blood having a Po2 of 300 mm Hg. These results were interpreted as showing that blood is essentially fully saturated at a Po2 of approximately 250 mm Hg. Note (With the Technical Assistance of A. Murphy and A. Seifen) relative solubility; agr; hypothermia; hemoglobin; dissociation; tonometry; O2 electrode; physiologic shunt Submitted on December 23, 1963

Gust Response Factor of a Transmission Tower Under Typhoon

2020 ◽  
pp. 2150001
Author(s):  
Xing Fu ◽  
Wen-Long Du ◽  
Hong-Nan Li ◽  
Wen-Ping Xie ◽  
Kai Xiao ◽  
...  
Keyword(s):  
Wind Speed ◽  
Field Measurements ◽  
Element Model ◽  
Structural Safety ◽  
Transmission Tower ◽  
Response Factors ◽  
Line System ◽  
Transmission Towers ◽  
Synoptic Wind ◽  
Gust Response

The gust response factors (GRFs) of transmission towers in current standards are reviewed for synoptic winds. The collapse of most transmission towers has occurred under the high-intensity wind (HIW) caused by events such as typhoons, hurricanes, and downbursts. Thus, this paper studies the GRF of a transmission tower under the typhoon. First, the definition of GRF and its extended form for the transmission towers are developed. Then the wind speed simulation of a typhoon event is introduced. Based on the structural health monitoring (SHM) system installed on tower #32, the measured GRFs under the super typhoon Mangkhut are calculated. Then the finite element model (FEM) of the transmission tower-line system is established to simulate the dynamic response to further calculate the GRFs, which agrees well with the field measurements. Both the field measurement and simulation results show that the GRFs under the typhoon are larger than those under the synoptic wind and that the recommended GRFs in the Chinese standard underestimate the peak responses. Finally, a parametric analysis is performed, which demonstrates that the turbulence intensity, wind speed, and power-law exponent all have great effects on the GRFs of transmission towers. In the HIW-prone areas, it is recommended that the characteristics of the HIW can be considered in improving the GRF values to guarantee the structural safety of transmission towers.

Field measurements of wind-induced transmission tower foundation loads

1998 ◽  
Vol 1 (2) ◽  
pp. 183-199 ◽  
Author(s):  
E. Savory ◽  
G.A.R. Parke ◽  
P. Disney ◽  
N. Toy ◽  
M. Zeinoddini
Keyword(s):  
Field Measurements ◽  
Transmission Tower ◽  
Tower Foundation

Geometry Optimization and Engineering Applications of Transmission Tower Foundation in the Slope

2013 ◽  
Vol 423-426 ◽  
pp. 1243-1247
Author(s):  
Bin Peng ◽  
Xing Yun Wang ◽  
Yu Wang ◽  
He Huang
Keyword(s):  
Regression Analysis ◽  
Bearing Capacity ◽  
Geometry Optimization ◽  
Ultimate Bearing Capacity ◽  
Nonlinear Regression Analysis ◽  
Transmission Tower ◽  
Engineering Applications ◽  
Practical Engineering ◽  
Tower Foundation ◽  
Pile Length

Combining with practical engineering, geometry optimization and engineering applications of transmission tower foundation in the slope is researched by using the finite-difference software FLAC3D. The variation of the pullout, vertical and horizontal ultimate bearing capacity with the diameter and length of the pile is analyzed. And optimization program of actual project is given. Research shows that when the pile length is constant, the variation of the pullout and vertical ultimate bearing capacity is increasing with the diameter increasing significantly and the horizontal ultimate bearing capacity is not significant. When the diameter is constant, the pullout, vertical and horizontal ultimate bearing capacity is increasing with the length increasing significantly. By analyzing nonlinear regression analysis of calculation data, the formula of the ultimate bearing capacity is carried out, which can consider the different pile diameters and lengths. When the gradient and distance of slopes is constant, the pullout, vertical and horizontal ultimate bearing capacity can be carried out with the formula, which can provide a reference to specification revision and engineering.

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