| In recent years,the installed capacity of new energy around the world continues to increase,and the large fluctuation of new energy grid connected capacity puts forward higher requirements for the current carrying capacity of the line.Dynamic line rating(DLR)solves the problem of new energy grid connection with high economy,and has been widely studied and applied all over the world.The existing DLR methods are based on climate model and temperature model,and there is a big error in principle.In order to accurately calculate the actual maximum current carrying capacity of high-voltage overhead transmission lines,this paper relies on the DTRT-1 online monitoring device jointly developed by North China Electric Power University and Guangdong Electric Power Research Institute,and makes use of the measured data of the lines accumulated since the device was put into operation in 2013 for data mining.In view of the data monitored by the device,this paper proposes a live simulation model based on the steady-state heat balance equation,a live simulation model based on the transient heat balance equation and a calculation model of the inclination temperature of the conductor.Because there are many unknown parameters in the actual operation of the device,this paper establishes the nonlinear equations with unknown parameters based on three models,and solves them respectively by using the intelligent optimization algorithm under the guidance of the nonlinear model parameter estimation theory.The results show that the average error of the two models is less than 1%,the root mean square error is less than 10%,and the stability and accuracy are very good.However,the live simulation model based on transient heat balance equation has poor accuracy in daytime,which needs to be studied in the future.By mining the data accumulated by DTRT-1 online monitoring device,this paper not only realizes the calculation of the maximum thermal line rating based on the steady-state heat balance equation,but also realizes the accurate calculation of the sag of the transmission line,so as to ensure the safety of the crossing distance between the transmission line and the ground during the dynamic capacity increase.In addition,the unknown parameter solution method proposed in this paper can effectively deal with the aging condition of line equipment due to the bad environment,and improve the working life and reliability of equipment. |
