Dynamic Capacity-Increase Of Transmission Line Based On On-Line Monitoring System

With the electricity consumption increasing brought by social and economic development,how to improve the transmission capacity of transmission lines becomes an important problem of power sector.New or expanding construction of lines not only need a certain amount of period,and a greater investment.Dynamic capacitiy-increase is based on on-line monitoring system of transmission line,by real-time monitoring conductor temperature and micrometeorology.dynamically analyses the maximum carrying capacity which can be enhanced and conductor temperatrue changes caused by the jumping current,and fully excavates the current carrying capacity of transmission line.This paper uses on-line monitoring system as a platform,and carries out the study of dynamic capacity-increase of transmission line mainly from two aspects of the steady state and transient state.Its main tasks are the following three aspects:(1) On-line monitoring system of transmission lines is introduced and theory of dynamic capacity-increase is analysed;(2) Study of dynamic capacity-increase of lines based on steady-state heat balance model;(3) Analysis of current carrying capacity of lines based on transient-state heat balance model.Firstly,this paper introduces the overview of transmission and distribution equipment monitoring center including the goal of the center building,process of condition monitoring management,the overall structure and functional orientation of the condition monitoring system.And it also briefly introduces on-line monitoring system of transmission lines,which provides a basis for the following research.Then the theoretical basis of dynamic capacity-increase of transmission I i ne i s anal ysed,through the analysis we can see that changes of conductor temperature and each micrometeorology factor have different impact on carrying capacity of line. When the wind velocity is zero,the correction of Morgan simplified formula makes the results of calculation more reasonable and realistic.Secondly,dynamic capacity-increase situation of field lines based on steady-state heat balance model is analysed.And the regression analysis method and the data in actual weather condition are used to validate the dynamic capacity-increase model,the validation results demonstrate the feasibility of the model formula in the actual operation.With the field on-line monitoring data,we use the compiled dynamic capacity-increase calculation program to analyse the dynamic capacity-increase situation of the specified line.It can be seen from the analysis that the utilization of dynamic capacity-increase technology can greatly enhance the capacity of transmission lines.Finally,current carrying capacity of field lines based on transient-state heat balance model is analysed and evaluated,conductor temperature changes caused by jumping current is mainly analysed.The Runge-Kutta method which is one of the numerical solution methods is proposed in the calculation,and the Kiel format of fourth-order Runge-Kutta method is adopted.With the field monitoring data,we use the compiled dynamic capacity-increase transient calculation program to analyse the numerical example.Before the numerical example, monitoring data is used to test the validity of the model program. From the simulation results of conductor temperature changes caused by jumping current it can be seen that,the greater the jumping current.the shorter the time to reach the maximum allowable temperature of the conductor is.In addition,combined with example,the transient ampacity,the rest of the time and the safety time are analysed and evaluated.the results show that transient current carrying capacity of the transmission line has great potential for mining.