Strongly Non-linear Dynamics Research For Quad Iced Bundle Conductors

The galloping of the iced transmission line is an international research topic. Manyresearchers have paid more attention to this problem which not only has importantacademic value, but also has great social and economic significance. The topic involvesmany filed and there are many complex factors in the proceeding of study, such as thatdesign theory study, computer simulation, aerodynamics parameter identification,analog simulation and file trials. So it is expensive and has a long study period.Although there are so many researchers in the world until now, the achievement aboutthe galloping is still very little and the academic monographs are hard to be funded. Inour study, the air dynamics parameters are firstly obtained through the wind tunnel testof Tianjin University. Then a new one-degree-of-freedom hysteretic nonlinear modeland a two-degree-of-freedom nonlinear model are constructed. And then base on theexperiment data, the analysis of nonlinear dynamics (bifurcation and chaos) isinvestigated via numerical simulation. The main achievements (creative ideas) are asfollows:The aerodynamics parameters of the quad iced bundle conductors are identified:the aerodynamics parameters (lift coefficient, drag coefficient and torsional coefficient)are firstly be obtained through the wind tunnel in the world. According the existingliterature, there are only two tests about the single conductor: one is aerodynamicparameters experiment by O. Nigol in Canada, and another is anti-gallopingaerodynamic experiment in Zhongshan export. But before our experiment, we can findany experiment about the quad iced bundle conductor.A new one-degree-of-freedom hysteretic nonlinear model is constructed about thequad iced bundle conductors: In our study, consider the structure characteristic of theconductor, we give a non-dimensional hysteretic nonlinear model. The bifurcationequation is obtained by applying the undetermined fundamental frequency method ofthe complex normal form. The sensitivity parameters and its range of values areobtained to analyze and to control the galloping the quad iced bundle conductor.A new two-degree-of-freedom nonlinear model is constructed about the quad icedbundle conductors: Due to that the quality of the eccentric conductor and wind attachangle are changed, there are both inertial force coupled and aerodynamics force coupled, so a new model is developed to consider this coupled force. By applying centermanifold and invertible linear transformation, the co-dimension-2bifurcation isanalyzed. The relationships of parameters between this system and the original systemare obtained to analyze and to control the galloping of the quad iced bundle conductor.The Lyapunov exponent and the Lyapunov dimension are investigated via numericalsimulation to present a rigorous proof of existence of chaos.A new criterion formula is established to distinguish which system (strongnonlinear system or weekly nonlinear system) the quad iced bundle conductors isbelong to. Based on the two-degree-of-freedom nonlinear model and the criterionformula, we find that the vibration in the vertical direction is strong nonlinear vibrationand in the torsional direction is weakly nonlinear vibration.