| Flashover accidents caused by windage yaw of suspension insulator strings of high voltage transmission lines frequently happened and threatened electric power system in recent years. Analysis indicates that the shortage of the calculation method of windage yaw of suspension insulator string in the current design code, which may cause flashover accidents, is one of the main reasons. Therefore, studying on high voltage transmission lines under random wind field, and improving the calculation method of windage yaw of suspension insulator string behave important practical significance in engineering.In this thesis, the researches on windage yaw of high voltage transmission lines and numerical simulation of wind field are firstly reviewed. It indicated that the existing time-history analysis method of the windage yaw of overhead transmission lines behaves some shortcoming, in which spatial correlation effect of wind filed and the effects of various parameters, such as wind speed, height difference, length of span, and height of the line over ground, of transmission lines on windage yaw have not be investigated throughout. To overcome this drawback, the method of numerical simulation of wind field is discussed, and based on the Kaimal spectrum of wind speed fluctuation, in which the variation of wind speed with height above ground is taken into account, and the Davenport coherence function, the fluctuating wind field along the typical transmission line section is simulated by means of WAWS. The finite element models of typical 500kV high voltage overhead transmission line section consisting of bundle conductors, insulator strings and spacers is set up by means of ABAQUS/CAE software. To take into account the dynamic and random effect of wind loads, the statistical results of windage yaw of the typical line section under wind loads, obtained from the time histories of windage yaw responses determined by means of ABAQUS software, are compared with those determined by the traditional method, which reflected that former is larger than the later and this is probably one of the most important reasons causing flashover accidents. Based on the numerical results, an adjustment coefficient of wind load, which is in the range of 1.4-1.6, is suggested to be introduced into the traditional calculation formula of windage yaw of suspension insulator string. |
