Study On Dynamic Response Of Zippered Deicing Of Transmission Line Considering Wind Load

In the process of transmitting electric energy,the transmission line inevitably needs to cross many areas with bad weather.Under certain conditions,the water in the air will form ice on the transmission line.The falling off of the ice will bring impact effect to the whole transmission line,resulting in wire breakage,tower toppling and other accidents,which seriously threatens the reliability of power grid.At present,the research on transmission line deicing is mostly based on the premise that the icing falls off at the same time.In fact,the deicing is a zippered process,and the transmission line is often accompanied by wind load during operation.The combined action of deicing load and wind load will make the stress situation of transmission line extremely complex.The research on the dynamic response of zippered deicing of transmission line under wind load is closer to the actual situation.It is of great significance to the design and daily operation and maintenance of transmission line.The main contents of this paper are as follows:（1）Considering the geometric nonlinearity of the transmission line,the finite element model of the transmission line is established in ANSYS,and the shape finding and modal analysis are carried out on the model.The errors between the sag of each point of transmission line and the frequency of each order of transmission line obtained from the shape finding analysis and the theoretical calculation results of catenary and suspension vibration are within 1%,which proves the correctness of transmission line model.The concentrated load method is used to simulate the transmission line icing and deicing,and the numerical simulation is carried out according to the existing test.The time history curve of the vertical displacement of the transmission line midpoint and the time history curve of the transmission line tension are basically consistent with the test results,which proves the applicability of the icing and deicing simulation method.（2）The insulator-line model with five consecutive gears is established to simulate the deicing of transmission line under different icing thickness,deicing speed and initial deicing position,and study the dynamic response of zippered deicing of transmission line without wind load.The research shows that the ice thickness has the greatest impact on the unbalanced tension between adjacent gears,followed by the vertical displacement of the transmission line midpoint,and has the least impact on the transmission line tension.Under different deicing speeds,the maximum unbalanced tension between adjacent gears,the maximum vertical displacement of the transmission line midpoint and the maximum transmission line tension corresponding to the ice thickness of 15 mm are 2.79-3.96 times,2.36-2.85 times and 1.44-1.55 times respectively when the ice thickness is 5mm.When the deicing speed is greater than or equal to 200m/s,the maximum value of vertical displacement and tension at the midpoint of the conductor will not change with the change of deicing speed.When the deicing speed is greater than or equal to 100m/s,the maximum value of unbalanced tension between adjacent gears will not change with the change of deicing speed.When the deicing speed is not within the above range,the maximum values of vertical displacement at the midpoint of transmission line,transmission line tension and unbalanced tension between adjacent gears decrease with the decrease of the deicing speed,and the vertical displacement of the midpoint of the transmission line is most affected by the deicing speed.The severity of transmission line vibration after deicing is related to the initial deicing position,which gradually decreases as the initial deicing position moves from the midpoint of transmission line to the end of transmission line.（3）Based on the characteristics of average wind and fluctuating wind,the time history of fluctuating wind speed is simulated by harmonic superposition according to Davenport spectrum,and the wind load on transmission line is calculated according to the specifications.Considering the sudden change of wind load caused by the change of aerodynamic shape of transmission line at the moment of de icing,the deicing of transmission line under different wind speed and deicing speed is simulated,and the dynamic response of zippered deicing of transmission line under the action of average wind and fluctuating wind is studied.The results show that the pulsating wind can amplify the dynamic response of transmission line after deicing,and the amplification of fluctuating wind increases with the decrease of deicing speed.Under the action of average wind,the lateral swing of transmission line after deicing decreases with the decrease of deicing speed.Under the action of pulsating wind,the lateral swing of transmission line after deicing is basically not affected by deicing speed.