输电线路共振舞动机理试验研究

EXPERIMENTAL STUDY ON RESONANCE GALLOPING MECHANISM OF TRANSMISSION LINE

该文开展了输电线路共振舞动机理试验研究,以湖南省某220 kV输电线路工程为原型,基于动力相似原理,设计制作了塔线体系试验模型。为最大限度保有输电线路本身的动力特性,设计研发了一套非接触式电磁激励系统。采用单相面内激励、三相面内激励以及三相面外激励等不同的激励工况,对输电线路的强迫振动特性进行了测试和分析。结果表明:系统共振是引发输电线大幅舞动的主要机理,输电线路发生大幅舞动的激励频率均趋近于系统的各阶固有频率且振型一致。塔-线之间、相-相之间存在显著的耦合振动现象,非激励相也会发生大幅舞动,其幅值有时甚至超过激励相,相与相之间存在明显的动力吸振现象。三相输电线路在共振状态下的振动形式非常复杂,从时程上看,相间存在同步、反向同步和延迟同步等振动形式,且相间常常发生同周期拍振或异周期拍振现象,异周期拍振时,振幅此消彼长,能量在相间往复传递。从轨迹上看,有直线形、椭圆形、新月形、“8”字形、甚至混沌运动等,且由于随机干扰的影响,轨迹会发生漂移现象。

Experimental study of transmission line was carried out in order to clarify the resonance galloping mechanism.To this end,a 220 kV three-phase transmission line project in Hunan province was taken as a prototype,and then the test model of tower-line system was designed on the basis of dynamic similarity principle.Besides,a non-contact electromagnetic excitation system was developed in order to retain the dynamic characteristics of transmission line to the maximum.Under various excitation conditions(single-phase excitation in-plane,three-phase excitation in-plane and three-phase excitation out-of-plane),the forced vibration characteristics of transmission line were analyzed.The results show that the system resonance is the main mechanism resulting in the galloping of transmission line.The excitation frequencies inducing galloping are all close to the natural frequencies of each order of the system,and the vibration modes are consistent.Also,there are obvious coupled vibrations between tower-lines and phase-phase.However,the non-excitation phase may also result in a large galloping,and the amplitude sometimes even exceeds the excitation phase.And there is an obvious dynamic vibration absorption phenomenon between phases.Obviously,the vibration form of the threephase transmission line in resonance state is very complicated.From the time history perspective,there are synchronous,reverse synchronous and delayed synchronous vibrations between phases,and the same-period beat vibration or different-period beat vibration often occurs.When different-period beat vibration occurs,the amplitude changes one after another,and energy is transferred back and forth between phases.From the trajectory perspective,there are straight,elliptic,crescent shaped,figure-eight shaped and chaotic movements,and the trajectory shows a drifting phenomenon because of the random disturbance.