Yang Jingbo

Numerical simulation on the HV transmission tower-line system under ice shedding

Ice shedding from conductors may easily induce electrical and mechanical accidents, which cause serious threat to the safe operation of transmission lines. In this paper, a three dimensional finite element model of tower-conductor-ground wire-insulator system for a 500kV transmission line was established in ANSYS, and the dynamic responses of ice shedding under different load cases were analyzed for the transmission tower-line system. Newmark method is applied for the solution of the nonlinear transient dynamic analysis. Three variables were considered in the ice-shedding simulating analysis, which includes tower-line coupled effect, phase combination of the ice-shedding conductors as well as thickness of the accreted ice. Influences of all the variables on the dynamic responses of jumping heights, loads at the end of insulators and the forces of transmission tower were mainly studied.

Study on the Mechanical Behavior of Butt Welded Forged Flange with Neck

With the promotion of tube tower in transmission line, to improve processing efficiency and quality, the substitute of butt welded forged flanges for traditional flange is become the trend of future development. With solid elements and contact elements of the general-purpose finite element software ANSYS, this paper analyzes the mechanical characteristics of forged flanges with neck, summarizes characteristics of stress distribution of the flange and bolt group, and contrast the bolt axial force extracted with the test data by the true scale tower test, which proved that the analysis of the flange using solid elements and contact elements is feasible. Suggestion of measurement of flange force in the test is given according to the characteristics of the bolt force.

Application of Q420 Large Size Angle Steel in Power Transmission Tower

The steel tower applying large size angel steel which limb width exceeds 200mm is characterized with good integrity of material, clear force transmission, simple node structure, saving bolts and filling plate, convenient assembly and erection etc advantages. Technical and economic advantage of Q420 large size angle steel tower has been validated in ±800kv ultra-high DC Jinping-Sunan power transmission line engineering. It has been become a tendency to use Q420 large size angle steel to substitute angle steel tower with large design carrying capacity of common combined specification (limb width is 200mm and below). This paper makes thorough analysis and summary on application condition, application characteristic, technology and economy of application, design and research of application, application principle etc of Q420 large size angle steel.

Notice of Retraction Application study on eccentric K-joint with high-neck forging flange applied in steel tube transmission tower

Minus eccentric connection for steel tube joint could diminish the size of joint board and the windward area. According to investigations in China and other countries, theres no report about study on eccentric K-joint with high-neck forging flange connecting chord member from any research institute or scholar. Consequently, two sizes of steel tubes are selected to design two kinds of K-joint, in which their chord members are controlled correspondingly by intensity and by stability. Based on joint tests and finite element analysis, conclusions are obtained as follows. (1) As to K-joint in which its chord member is loaded by pressure and controlled by intensity, chord members on the side of tension bracing member and in the middle of joint board appear local flections when overloaded 32.5%, while theres no flexion on flange or joint board. (2) As to K-joint in which its chord member is loaded by tension and controlled by intensity, chord member is stretched in length and shrunk in diameter when overloaded 45%, flange plates are distorted slightly, while theres no flexion on flange neck or bracing member. (3) As to K-joint in which its chord member is loaded by pressure and controlled by stability, chord member on the side of tension bracing member is bent in the middle when overloaded 30%, while theres no flexion on flange or joint board.(4) As to eccentric K-joint with high-neck forging flange in which its chord member is controlled by intensity, proper minus eccentricity could diminish the size of joint board and eccentricity barely affects the bearing capacity of chord member, which could be used efficiently. (5) As to eccentric K-joint with high-neck forging flange in which its chord member is controlled by stability, K-joint is mainly bent totally in chord member, while effects on flange and joint are slight. Effects of slenderness ratio and eccentricity on bearing capacity of chord member should be studied further. Study on this new joint type is greatly advanced, which provides technical support and reference for future research on new joint types of steel tube transmission tower.

Test study on high strength high-neck forging flange of UHV steel tube transmission towers

Application of high-neck flange of steel tube tower in China and other countries is investigated. Based on the theoretical and experimental research of China Electric Power Research Institute (CEPRI) about high-neck flange with strength of Q345, which corresponds to Chinese criterion, axial tension tests about Q420 and Q460 high-neck forging flanges are carried through. It is suggested that the side of small diameter tube of butt welding flange should be strengthened in design. It is also found that steel tube near the butt weld, straight neck of flange and bolts are all under eccentrically bearing states. Bearing capacities of Q460 high-neck butt welding flanges designed by flexible and rigid ideas are also compared primarily. Feasibility and security for Q420 and Q460 high strength high-neck forging flanges used in steel tube transmission towers are testified, which provides technical support for their application in UHV transmission project and for future researches.