Research On Ice Thickness Measurement For Power Lines And De-icing Method

With the development of electric power industry and increasingly complicated structure of power grid, it is important to maintain safe operation of electric power for social stability and economic development. Icing of electric transmission lines is one of serious natural disasters which would cause substantial damage to power system and thus bring instability and unsafety. Therefore, the de-icing method of adjusting operation mode and changing power flow distribution is researched in this thesis.Firstly, the traditional calculation of icing parameters is introduced. A novel method of ice thickness measurement for transmission lines based on traveling wave transmission time difference is presented. Formulas of ice thickness calculation are theoretically derived, The arriving intervals of the traveling wave is recorded by GPS location system. Results are compared with field measured data in some certain power grid and show that this method is suitable to calculate the average ice thickness of transmission line.Based on the heat equilibrium of the conductor's icing process, the thermal balance equation is established and the formulas of calculating the minimum current and time of de-icing are derived. Theoretical simulation and engineering practice results have shown that the de-icing time decreases with an increase of current. The de-icing method of conductors is studied when operation mode and power flow distribution are changed. The operation mode is changed using open-loop strategy according to the loop networks and the mathematical optimization model is established to analyse each scheme. The simulation is conducted for WSCC-9 and EPRI-36 nodes system and results show that the de-icing method is theoritically feasible based on operation mode adjustment and can be applied without consideration of the transmission capacity.