| It has become a very serious problem more and more that overhead electric transmission lines forced out-of-service caused by goaf earth surface subsidence degrades the safety and stabilization operation of power grid. Therefore, to investigate the influence of goaf earth surface subsidence on the overhead electric transmission lines and to renovate it by proper and high efficiency and economic method have very important significance for the secure and steady and economic operation of power system. In this paper, we attempt to solve the above problem in three aspcets as follow:1. The influence of earth surface subsidence on the overhead transmission lines is investigated systemically. The action and influence on the overhead transmission line’s tower, which locates in static earth surface subsidence basin’s different zones, is analysed. Then, the qualitative and quantitative methods are used to study there primary factors, which impact the earth surface subsidence basin forming, i.e. traveling angle and start distance and roof. The course of earth surface subsidence basin forming drawn above is verified by the field data.2. The renovation scheme of overhead transmission line inclined caused by goaf earth surface subsidence is presented roundly. The influence of tangent tower and dead-end tower inclined is discussed. Then, the scheme of overhead transmission line sag adjustment is presented. Theoretics and field experience show that it is the first choice to release the tension of overhead transmission line or oraerial ground electrode when the tower inclines in the early stage.3. The countermeasure and comprehensive treatment of goaf earth surface subsidence is presented. The countermeasure by ameliorating tower foundation is studied, and a whole foundation of tower is proposed to prevent and cure the goaf earth surface subsidence, which has been verified in an actual engineering. |
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