| Southeast Shanxi-Nanyang-Jingmen UHV AC transmission lines into commercial operation since 2009,Nanyang-Jingmen I line segments in the process of operation found that the line more than hard jumper wire shield ring connection plate and the support b ar appear fracture accident.Currently,the main design for shield ring from electrical performance considerations,the relevant standards of grading ring mechanics performance requirements are put forward to meet only 2000 N,the mechanical strength of different voltage grade is not difference.In the process of inspection and because of the UHV shield ring does not belong to standard hardware,no spare parts,the scene can only adopt the method of weld reinforcement to emergency handling,so in the past,t he service life of the shield ring is more short,the serious influence the stability of the UHV line running.According to the analysis of fracture mechanism of UHV shielding ring,the fracture type will be studied first in this paper for the verification of that if the UHV shielding ring is damaged by intensive force or not through the fluctuating wind vibration(turbulence),on the one hand,the pulse equivalent wind load as static load and the static performance analysis according to the working conditio n of common,on the other hand Davenport spectrum model is adopted and combined with the harmonic synthesis method for simulating fluctuating wind spectrum,and then using fluctuating wind spectrum analysis was used.Select fault point location near Laohekou every 10 years and 50 years of basic wind pressure and based on the characteristics of UHV shield ring to ultimate bearing capacity analysis,found only in the support bar would occur because of fluctuating wind strength destruction,but recent years ma intenance in the actual situation of shield ring fracture,eliminate fracture reason is caused by the mechanical strength is not enough or pulsating wind.And then because involves the dynamic performance analysis,dynamic characteristics should be carried out for structure analysis to understand the vibration of the shield ring state variable,and the modal analysis,finite element method)is not entirely realistic,therefore put forward a kind of non-contact and suitable for UHV line image recognition method for vibration recognition,two methods of mutual authentication,determine the UHV shield ring is consistent with the first order modal vibration state.Thirdly,the thesis will from the aspects of vortex-induced resonance(laminar flow)to study the UHV shield ring is belong to fatigue failure of fracture types,combined with the vortex-induced resonance principle and characteristics of UHV shield ring,to determine the UHV shielding incentive range ring vortex-induced resonance wind speed and wind pressure time history functions(vortex-induced vibration load spectrum),thus the vortex-induced resonance analysis.The results show that the resonant characteristics of the ultra-high voltage shield ring vortexes correspond to the actual fracture conditions.For further clear fracture reasons,according to the result of vortex-induced vibration fatigue calculation,the introduction of probability statistics theory and combining the vortex-induced resonance condition to from the aspects of the probability of wind speed and direction of UHV shield ring fatigue life forecast of 0.87 years,completely fit the actual situation.Finally,a new type of shielding ring is designed with the idea of energy dissipation and vibration reduction,and the mechanical propert ies and electrical properties of the new shielding ring are verified from the simulation and test angle.The innovation and characteristics of this thesis are:(1)A method for image identification of vibration frequency of shield ring structure is developed.Compared with the traditional sensor monitoring method,this method has the greatest advantage that it can realize non-contact measurement and complete the vibration frequency test of the shielding ring without power failure.(2)Based on the theory of structural dynamics and fatigue damage,a method for calculating the vibration of shield ring structures considering the probability of wind speed and direction is established.Compared with the traditional method of fatigue analysis of gold,the results of structural dynamics analysis are more consistent with the actual working conditions,and the analysis is more reliable.(3)A new type of ultra-high pressure hard jump wire shield ring is designed for the first time to reduce vibration energy consumption. |
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