| Overhead transmission line is an important part of power network as well as significant to the construction of ultra-high voltage transmission projects in China.As the main power equipment of overhead transmission line,the transmission tower is crucial to the safety,reliability and economic significance of the power system.Overhead transmission lines are often built in the wild,which makes them vulnerable facing various complex environmental factors.In particular,transmission towers are prone to bend or even collapse due to extreme meteorological disasters such as typhoon.In recent years,typhoons frequently hit the southeast coastal areas of China,causing damage to some transmission towers usually with long operating life and serious rust,which seriously threatens the safety of the power grid.Transmission tower is a typical wind-sensitive structures.Under extreme wind load such as typhoon,vibration and deformation happen inevitably to transmission tower.Therefore,it is of great value to carry out the research on the on-line status monitoring device of transmission tower in order to evaluate the performance and risk of transmission tower.The main research content of this article is as follows:(1)This paper proposes a system for the on-line monitoring system of transmission tower.The system includes sensors,micrometeorological stations,communication terminals,monitoring platforms and cloud servers,which can monitor dynamic responses of the tower such as vibration acceleration and inclination during typhoons.An online monitoring and communication network based on 4G-WIFI routing is built.A power optimization system,including the maximum power tracking module of photovoltaic solar panel and the power monitoring and control module are designed.The corresponding sensor optimization arrangement scheme is formulated based on the theory of structural mechanics modal analysis.The system realizes the on-line monitoring,analysis of the dynamic response of the transmission tower,which can reflect the structural deformation and load condition under the effect of high wind or typhoon.(2)The dynamic response of 110 k V tower under the influence of typhoon was obtained and studied by using the on-line monitoring sensors.By analyzing the excitation and the response parameters of each monitoring node,extracting its fluctuation characteristic parameters,using SOM neural network to divide the fluctuating processes respectively,the relationship between wind field characteristics and the mechanical response of the transmission tower was obtained.Finally,the method of converting the mechanical response of the tower into the displacement constraint of the tower's FEM model was studied.The results show that the fluctuation characteristics of the mechanical response of the tower structure can better "identify" the state of the tower in the strong wind field,and provide a reference for evaluating the structural risk of transmission tower.(3)A finite element simulation model of a 110 k V transmission tower was built and its wind load simulation was studied.Based on the principle of finite element,ANSYS was used to constructed an accurate transmission tower model.Based on the mechanical response of the tower node obtained by the online monitoring devices,the static response of the tower in different wind field was analyzed using ANSYS.The equivalent stress of main material was analyzed and the vulnerable ones were stressed.(4)The equivalent stress of the main materials of transmission tower was used as the evaluation index which were empowered according to the CRITIC method(Criteria Importance Through Intercriteria Correlation),and the risk assessment of transmission tower were obtained.In this way,a wind-related risk assessment system of transmission tower based on the online monitoring was determined,which was applied to a 110 k V tower during a typhoon.(5)A wind tunnel test was carried out to examine the purposed risk assessment method by building an equivalent scale model of a transmission tower and studying the process of its destruction under the wind load.The mechanical response characteristics of the model was analyzed,so did the stress of the model's materials.The state of the model under different wind speeds was evaluated correctly,which proved the validity and feasibility of the wind-related risk assessment method proposed in this paper in extreme situation. |
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