Field Strain Testing of Transmission Tower Under Wind Load

Abstract

Detailed accident analysis of a tower failure in Henan was got in this paper. A strain test system was established, location of measuring point was determined at the same time. Long-term monitoring test of the strain value of the 3# experimental tower in the test base of transmission line in electric power of Henan was accomplished. Analysis of the test data under wind-induced vibration lays the data foundation for preventing the damage of wind and disaster in Henan power system. Introduction The safety and stable operation of the power system are affected by inclement weather and natural disasters, which becoming important contributing factors to the power grid failure. According to statistics, 1299 times line dancing occur on 1035 lines involving 35kV-1000kV voltage levels as of 2010, including 707 line dancing trip, causing power outages, leading to direct economic losses about 50 billion and indirect economic losses about 100 billion. Changing dynamic tension is produced when power line vibrating under the effect of fluctuating wind, and a complex dynamic coupling system is formed among power line and tower. However, due to the lack of more precise analysis methods to guide the design of tower preventing wind, tower damage often occurs in a particular area, resulting tower down accident under strong wind. At present, the transmission towerdynamic analysis model to calculate the power line system, the wind load model and wind-induced response analysis and the wind tunnel test have been studied by domestic and foreign scholars, but long-term studies on the transmission tower site monitoring carried out less. In this paper, the stress concentration of transmission tower under wind-induced vibration is determined by modeling and analysis on finite element software, related strain measurement and analysis on the key positions of tower III in Jianshan real Transmission Line testing base located in Henan. Strain situation of the transmission tower critical nodes are obtained under wind-induced vibration, important data support are provided to the transmission structure design and the implementation of warning systems monitoring wind speed, Contributing to the safe operation of the Henan power grid. [5] Accident investigation of a transmission tower down in Henan The evening of July 27, 2007, Henan Kaifeng was hited by thunderstorms, tornadoes, severe convective weather, 21:18, a 500kV line tower VI crashed. A 500kV line tripped, phase selection A, RECLOSURE unsuccessful, Forced power transmission unsuccessful. A 500kV line # 119# 124 straight six base tower dumping under strong convective weather was discovered by line patrol. Figure 1 shows the tower dumping cases: N122 (ZLM-36) tower destruction: bottom sliding bolt of the main tower column was pulled off, tower overall dumping, the 2 Pull disc on the right side of the tower were pulled out to 20m outside, no damage to the main column; N123 (ZLM-36) tower destruction: bolt connecting the bottom of main tower column was pulled off, tower overall shift to the left and reverse 8m, tower dumping, no damage to the foundation;N124 (ZB3-45) tower destruction: tower head felled to the ground, Middle of the tower twisted and dumped, no damage to the foundation, line broken. International Conference on Applied Science and Engineering Innovation (ASEI 2015) © 2015. The authors Published by Atlantis Press 1154