Stable Operation Of Transmission Line Research Articles

Transmission Line Galloping Prediction Based on GA-BP-SVM Combined Method

The paper proposes a method to construct a model for transmission line galloping prediction using machine learning algorithms to address the transmission line galloping problem, which can result in transmission line loss and pose a greater risk to the safety of electricity in society. First, to reduce sensor noise interference, a unilateral sliding time window is used for micro-meteorological data correction, and then gray correlation analysis method and the specific gravity method are used to obtain the influence weights of micro-meteorological elements. The galloping prediction models are constructed using six algorithms, with the GA-BP algorithm model and the SVM algorithm model having better prediction effects based on performance metrics. The GA-BP-SVM combined model is constructed on this basis, and all of its performance metrics are optimal. This model's prediction accuracy in both galloping and no galloping states reaches 95.5%; the probability of correct prediction when predicted as galloping reaches 95.1%; the probability that actual galloping can be predicted reaches 92.5%. The F1-score of the combined model reaches 0.938, which indicates that it has the best prediction effect. The prediction method described in the paper is accurate and practical, and operation and maintenance personnel can flexibly develop inspection strategies and anti-galloping measures based on the prediction results to ensure the safe and stable operation of transmission lines.

Characteristics of icing without icicle on insulators under natural conditions

Icing on insulators seriously threatens the safe and stable operation of transmission lines. Most of the existing research has focused on the flashover characteristics of ice-covered insulators, lacking attention to the icing process on insulators. In order to reveal the mechanism of insulator icing, and lay the foundation for further establishment of insulator ice flashover model, this paper studies the characteristics of insulator icing without icicle. The characteristics of icing processes including the collision and freezing of water droplets, the generation and flowing of water film are analysed. On this basis, a three-dimensional numerical calculation model of insulator icing without icicle is established by using boundary element method, and the expressions of the local icing weight and thickness on the insulator surface are derived through the droplet local collision efficiency and freezing efficiency. Moreover, the time-varying characteristics of icing parameters are simulated. And the related icing tests are conducted on two kinds of insulators with different structures at Xuefeng Mountain. The results show that the distribution of collided water droplets and water film on the insulator surface will change with the increasing ice weight. Under natural conditions, compared with the aerodynamic insulator LDQ-100, the insulator LXY-120 with a smaller skirt diameter and a larger inclination angle can have a faster icing rate. However, at the insulator edge, the insulator LDQ-100 with a thinner shed has a greater icing rate of thickness. Compared with the test results, the simulation error of the model in this paper is within 15%.

Research on Multi-Factor Ice Disaster Risk Evaluation Model for Transmission Line

With the development of the transmission line scale and the improvement of the voltage level, the height and span of the tower are increasing, and the ice disaster occurs frequently in some areas, which has become an important factor affecting the security and stability of the power grid. Based on the analysis of the ice and ice flashover mechanism, this paper firstly discusses ice disaster influencing factors from three main angles, such as, the potential fault of transmission line, operation and maintenance characteristics and meteorological conditions, and then uses multi factor classification method to build the ice disaster risk evaluation model for transmission line. Further, taking the 220kV and above transmission lines in a certain area of South China as a research object, this paper evaluates all the lines and towers ice disaster risk, obtains the lines or towers with high risk level using the model, and the evaluation results have been verified on site. Finally, combined with the rating of risk evaluation factors, this paper formulates a special anti-icing measure to ensure the safe and stable operation of transmission lines.

Advanced Detecting Technologies for Aging Performances of Composite Insulators

As common electrical equipment, composite insulator played an important role on the safe and stable operation of transmission lines. Hence, it was meaningful to explore effective methods to detect the service performances of operated composite insulators. In this paper, several advanced technologies were introduced to check the performances of in-serviced composite insulators. The macroscopic properties were mainly detected by means of X-ray digital imaging system, ultrasonic phased array (UPA) and hydrophobicity measurement. In addition, the microscopic properties were analysed by the way of scanning electron microscope (SEM) observation, microscopic infrared spectral imaging system and thermogravimetric (TG) analysis. It was believed that defects such as micro-cracks, gaps etc. could be earlier and quickly found by using these detection techniques, thereby avoiding power failure accidents of the transmission lines.

Fault Statistics and Analysis of 220-kV and Above Transmission Lines in a Southern Coastal Provincial Power Grid of China

Because the causes of transmission line faults are not known clearly at present, this paper proposes fault classification for transmission lines, and analyses the characteristics of different faults. Using the transmission line faults data of southern coastal provincial power grid from 2007 to 2018, this paper analyses the influence and distribution of transmission line faults affected by lightning, typhoon, wildfire, foreign object and external damage. These five faults are the main factors affecting the safe and stable operation of transmission lines in this region. According to the different fault classification and statistical rules, the design standards for important transmission lines should be improved. Considering the factors of micro-topography, micro-meteorology and engineering cost, the inspection and maintenance of existing lines should be strengthened. The statistics and analysis will be helpful to the research, development and application of new theories, new technologies and new equipment in disaster prevention and reduction from the aspects of disaster prediction and monitoring.

Research on Fault Location and Intelligent Inspection Based on Gps + Gis Transmission Line

Transmission line inspection management is to ensure the safe and reliable operation of the power grid of a basic work. Through the line inspection workers could find that the potential risk factors, the necessary maintenance. So as to ensure the safe and reliable operation of the entire power system, this article designed an intelligent inspection system. The inspection system integrates the global positioning system, geographic information system, computer network communication technology. It can minimize the leakage detection system, the wrong test, saving costs, increase business efficiency and ensure safe and stable operation of transmission lines. In addition, the system can effectively supervise and manage the inspectors to ensure that the inspection is in place record, store and position reminders of incident data such as faults, accidents and equipment defects during the inspection process, and command personnel. But it makes it easier to pay close attention to the operating staff, so that it can grasp the safety of field staff in a timely manner, when an emergency situation can quickly locate the staff, and according to the system to provide navigation guidance to give the appropriate support or organization to rescue, And effectively put the “people-oriented, safety first” concept to implement.

Buckling Analysis of Transmission Tower Considering Ice Load

Transmission lines are important lifeline projects. The stable operation of transmission lines is closely related to economic and social security and stability. Ice storm seriously affects the safety of transmission lines. The simulation analysis of ice damage of transmission tower structure has important theoretical significance and engineering value. In this paper, the finite element software ANSYS is used to analyze the buckling of the self-supporting tower based on eigenvalue buckling analysis and nonlinear buckling analysis. The effects of vertical span, uniform ice coating, uneven ice coating, and wind load were considered. The ice thickness of the tower buckling is reduced with the vertical span decreasing under uniform ice coating the transmission line. As the coefficient of unevenness increases, the thickness of the unstable ice coating of the tower drops sharply. The unstable wind speed decreases with the increase of ice thickness.

A Recognition Method of the Hydrophobicity Class of Composite Insulators Based on Features Optimization and Experimental Verification

The hydrophobicity of composite insulators is a great significance to the safe and stable operation of transmission lines. In this paper, a recognition method of the hydrophobicity class (HC) of composite insulators based on features optimization was proposed. Through the spray method, many hydrophobic images of water droplets on the insulator surface at various hydrophobicity classes (HCs) were taken. After processing of the hydrophobic images, seven features were extracted: the number n, mean eccentricity Eav and coverage rate k1 of the water droplets, and the coverage rate k2, perimeter Lmax, shape factor fc, and eccentricity Emax of the maximum water droplet. Then, the maximum value Δxmax, the minimum value Δxmin, and the average value Δxav of the change rate of each feature value between adjacent HCs, and the volatility Δs of each feature value, were used as the evaluation indexes for features optimization. After this features optimization, the five features that are most closely related to the HC were obtained. Lastly, a recognition model of the HC with the five features as input and the seven HCs as output was established. When compared with the spray method and the contact angle method, the correct rate of the proposed recognition method was 98.1% and 95.2%, respectively. The influence of subjective factors on the spray method was effectively overcome.

A novel dissipating heat structure of converter transformer RIP bushings based on 3-D electromagnetic-fluid-thermal analysis

With the increase of transmission power in China, the heating problem of converter transformer resin impregnated paper (RIP) bushings is increasingly serious. In this paper, applying the computational fluid dynamics (CFD), using a 3D electromagnetic-fluid-thermal analysis method, and considering the heat conduction, convection, and radiation effects, the temperature field distribution of the converter transformer RIP bushing has been simulated; according to the simulation results, the max-imum temperature of epoxy impregnated paper is above the heat distortion temperature 120 °C. Then, to verify the accuracy of the simulation method, temperature rising experiment has been car-ried out. Through the comparison, the temperature difference percentage between the simulation results and the experimental results is within 9 % proving the rationality of the simulation method. Finally eight optimization schemes for the 400 kV con-verter transformer RIP bushing were proposed which include the heat conductors with different diameters and numbers and the thermal conductive oil inside the inner conductor. Through the simulation of the eight optimization schemes, it can be proven that the heat conductors and the thermal conductive oil inside the inner conductor can effectively decrease the temperature distri-bution of converter transformer RIP bushings and improve the stable operation of transmission line.

Application Research on Drag Reduced Conductors for Electric Power Transmission Lines in Strong Wind Areas

The breeze vibration duration of conductors is long, the vibration amplitude is strong and the frequency range is wide for electric power transmission lines in strong wind areas, which seriously affects the safe and stable operation of transmission lines. There are two design schemes of conductors which can achieve the purpose of reducing wind-induced disaster. One is enhancing the structural strength of conductors to withstand wind load, but the investment is enormous and the effect is limited. The other is developing drag reduced conductors to reduce wind load by changing conductor structure. This paper started from application feasibility analysis of drag reduced conductors and designed four drag reduced conductors by structure optimization of the conventional aluminium conductor steel reinforced JL/G1A-630/45-45/7, denoted as DFY630/45(45°)-R3.5, DFY630/45(60°)-R3.5, DFY630/45(45°)–R3.2 and DFY630/45(60°)-R3.2, respectively. The wind tunnel test was performed and the wind resistance coefficients in unit length of five conductors were compared. Result showed that the wind resistance coefficients in unit length of four drag reduced conductors were obviously lower than that of the conventional conductor. By controlling the manufacturing process, popularization and application of drag reduced conductors for transmission lines in strong wind areas can be realized.

Application of Fiber Bragg Grating Device in Icing Monitoring System of Transmission Lines

Ice accretion has been a huge threat for the stable operation of transmission line. Icing monitoring devices used presently are active sensors with low working stability. Signals are transmitted in the electrical form, which are easily affected by the electromagnetic interference. In this paper, an online icing monitoring device of transmission line based on fiber bragg grating (FBG) sensor is designed, and is operated as a pilot unit on the 44# tower of 110kV Zhenzou line. Experimental results show that the online icing monitoring device operates stably, and the designed fiber bragg grating sensor has high linearity, good sensitivity and high accuracy.