| Transmission line icing is one of the major natural disasters that affect the safe and stable operation of the power system.Transmission line icing usually occurs during freezing rain.When snow particles or super-cooled droplets impact on the surface of transmission lines exposed to atmospheric environment,conductors will be icing.A large number of safety accidents caused by conductor icing,such as flashover,the collapse of electric pole and tower,have been widely reported in China every year.These accidents have a great impact on the people’s normal production and life.Comprehensive researches have been conducted by many scholars and experts in this field.Numerical simulation of icing process has important significance for the anti-icing and ice disaster prediction.This paper systematically studies the icing process,analyzes the effect of atmospheric environmental factors and diameter of conductor on icing process.Then numerical simulation model was established in terms of multiple icing factors.Based on the mixed programming technology of C++,the automatically numerical simulation of icing process was implemented.The icing visualization software was developed on Qt platform.The main contents of this paper are as follows:(1)The grid automatic generation method and reconstruction method for two-dimensional iced conductor fluid calculation was studied.The automatic generation of icing grid was implemented with the C++ programming technology based on advancing front method,and the program could automatically implement the local refinement of the body-fitted grid according to input meshing size parameters.The generated grid was of good quality and can be used for the calculation of the follow-up fluid mechanics solver.The standard grid file data format used for data transfer between grid and fluid mechanics solver was studied.The data transfer between grid and solver was realized by utilizing the Inp file format.(2)The numerical simulation model and automatic control method for fluid calculation of two-dimensional icing conductor were studied.The k-ε turbulence model based on RNG method was solved by the finite volume method.By using WIN32 API function CreateProcess()combined with Journal file,Fluent solver could be iteratively controlled to automatically solve the fluid field calculation of the reconstructed grid.The numerical distribution and vector of fluid field before and after icing were analyzed.The results had shown that the distribution of fluid field around the conductor will be changed as the ice shape changed,which will further affect the process of ice coating growth.The calculation method of water droplet collision characteristics were studied and the droplet trajectories and the local collision rate were calculated based on the Lagrange method.The results indicated that the collision characteristics of water droplets will change as the ice shape changed.(3)The numerical simulation method of ice-coating growth process for two-dimensional iced conductor were studied.The growth mechanism of ice was studied,and the ice growth process was divided into multiple micro-time-step icing process.The effect of different time step ts on the ice shape and ice mass was studied.By comparing with the results of the literature,we drew the conclusion that the value of ts will affect the accuracy of ice prediction,and the reasonable selection of ts value was essential for the accuracy of simulation.Besides,the time step ts which directly affects the time cost and accuracy of simulation was taken into account,and the optimal time step model of icing simulation was established.The automatic numerical simulation of the icing process was realized.The effect of different atmospheric environment parameters and conductor diameter on conductor ice mass and ice shape was analyzed,and the effects of various parameters on icing were obtained.In order to validate the icing simulation model in this paper,the natural icing experiment was carried out in Natural Icing Test Station of Chongqing University at Xuefeng Mountain.The ice mass and ice shape in 30 minutes were consistent with the predicted results in this paper,which proved that the simulation model was accurate and effective.(4)Data visualization method of two-dimensional conductor icing process were studied.Based on the C++ mixed programming technology and Qt(A cross platform C++ graphical user interface application development framework)platform,using the dynamic link library technology,several core modules of icing simulation process were regarded as the class library of visual simulation system.A visual simulation software for two dimensional conductor icing process was developed by integrating all modules. |
