| With the rapid development of national economy and urban industrialization,the demand for electricity is growing,especially in middle east area which has densely population and economy is developed,construction land become increasingly scarce,how to realize the balanced development of power demand and power delivery has become urgent problems to solve.In order to effectively solve the power transmission and the shortage of transmission line corridors,the realization of economic and efficient transport,double circuit lines on the same tower,multi-circuit lines on the same tower,UHV AC transmission,AC and DC hybrid transmission,such power transmission scheme has been widely concerned and used.According to the characteristics of multi-circuit transmission lines on the same tower,500kV/220 kV four circuit on the same tower mixed level transmission line as the research object,which simulated and analyzed induced voltage and current of the maintenance line,the space distribution of electromagnetic field near the tower and the electric field strength of typical working point of live working personnel with ATP-EMTP and ANSOFT.The introduction introduces the research background and significance,domestic and foreign progress and the status quo about multi-circuit transmission lines on same tower,induced voltagd and current needed to be considered in the live working and Theory and its principle of live working surface field strength.;when built a model,full consideration is given to the actual situation of multi-circuit transmission lines on the same tower,and simulation model is established according to the actual parameters of line and tower,the live workers;Researching the influence,such as operation current,outage information,loop spacing,horizontal wire spacing and arrangement of wire-phase sequence,on the induced voltage and current in maintenance line,the influence of temporary grounding wire spacing on the current flowing through the live worker,concluding the electric field distribution of live worker in typical working position of the tower under different operation.The results showed that the operation current mainly affect electromagnetic induction component of maintenance line,almost no effect on the electrostatic induction component;the induced voltage,current of maintenance line with maximum value when same phase sequence,then negative phase sequence,different phase sequence at last;with the increasing ofhorizontal spacing and circuit vertical spacing,decreases the degree of coupling between the lines,the induced voltage and current will be reduced;when the sides temporary grounding wire is hang in both side of maintenance position,a greater induced current still flow through the body of live worker,in order to ensure security of live worker,temporary grounding line needs to be hang in maintenance point;the most important factors which influence surface electric field is the distance between the worker and charged conductors,the characteristics of the human body.When there is live wire above the workers,the electric field strength of the head with highest value,the minimum electric field strength values in the foot;for multi-circuit transmission line on the same tower,part of transmission line is maintenanced,other operate normally,electric field strength in a few work position far beyond human perception level(240kV/m),should be out of the way to live the high potential line operations,live workers should wear a full shield clothing and use insulated tools and instruments out of high potential.According to the above results,there is some significance to choose a suitable grounding switch,make methods to maintenance and work safety protection when live working. |
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