A new electrical method of conductive carbon-film(with waterproof and anticorrosion ability)was proposed to continuously measure crack propagation rate of brittle rock under THMC coupling condition.A self-designed cou...A new electrical method of conductive carbon-film(with waterproof and anticorrosion ability)was proposed to continuously measure crack propagation rate of brittle rock under THMC coupling condition.A self-designed coupling testing system was used to conduct THMC coupling fracture tests of the pre-cracked red sandstone specimens(where the temperature is only changed)by this new electrical method of conductive carbon-film.Calculation results obtained by the energy method coincide well with the test results.And the higher the temperature is,the earlier the crack is initiated and the larger the crack propagation rate and accelerated velocity are,which can prove the validity of the new electrical method.This new electrical method has advantages of continuously measuring crack propagation rate over the conventional electrical,optical and acoustic methods,and can provide important basis for safety assessment and cracking-arrest design of deep rock mass engineering.展开更多
户外冲击放电试验导致附近建筑内通话中断、网络重启等问题时有发生,近年来带有智能组件的变压器进行冲击耐压试验时智能组件故障率高达50%,迫切需要开展冲击试验过程的电磁骚扰研究。为此进行了冲击试验的骚扰源特性分析,分析结果表明...户外冲击放电试验导致附近建筑内通话中断、网络重启等问题时有发生,近年来带有智能组件的变压器进行冲击耐压试验时智能组件故障率高达50%,迫切需要开展冲击试验过程的电磁骚扰研究。为此进行了冲击试验的骚扰源特性分析,分析结果表明冲击电流幅值可超过10 k A,频率主要在10 MHz以下。基于骚扰耦合路径分析,提出了将电缆屏蔽层与接地网导体联合建模的直接耦合法,该方法可以同时考虑电缆屏蔽层的散射效应和电缆内部瞬态的波动效应,误差分析表明该方法比国际大电网会议(CIGRE)推荐的解耦法计算结果更加精确。在武汉特高压交流试验基地开展的典型冲击放电试验表明:直接耦合法计算结果与测量结果基本一致,验证了直接耦合法的准确性;冲击试验情况下电缆屏蔽层双端接地比单端接地降低骚扰电压水平效果更好。展开更多
The harmonics and resonance of traction power supply systems(TPSSs)aggravate the electromagnetic interference(EMI)to adjacent metallic pipelines(MPs),which has aroused widespread concern.In this paper,an evaluation me...The harmonics and resonance of traction power supply systems(TPSSs)aggravate the electromagnetic interference(EMI)to adjacent metallic pipelines(MPs),which has aroused widespread concern.In this paper,an evaluation method on pipeline interference voltage under harmonic induction is presented.The results show that the Carson integral formula is more accurate in calculating the mutual impedance at higher frequencies.Then,an integrated train-network-pipeline model is established to estimate the influences of harmonic distortion and resonance on an MP.It is revealed that the higher the harmonic cur-rent distortion rate of the traction load,the larger the interference voltage on an MP.Particularly,the interference voltage is amplified up to 7 times when the TPSS resonates,which is worthy of attention.In addition,the parameters that affect the variation and sensitivity of the interference voltage are studied,namely,the pipeline coating material,locomotive position,and soil resistivity,indicating that soil resistivity and 3PE(3-layer polyethylene)anticorrosive coating are more sensitive to harmonic induction.Field test results show that the harmonic distortion can make the interference voltage more serious,and the protective measures are optimized.展开更多
基金Projects(51474251,51874351) supported by the National Natural Science Foundation of China
文摘A new electrical method of conductive carbon-film(with waterproof and anticorrosion ability)was proposed to continuously measure crack propagation rate of brittle rock under THMC coupling condition.A self-designed coupling testing system was used to conduct THMC coupling fracture tests of the pre-cracked red sandstone specimens(where the temperature is only changed)by this new electrical method of conductive carbon-film.Calculation results obtained by the energy method coincide well with the test results.And the higher the temperature is,the earlier the crack is initiated and the larger the crack propagation rate and accelerated velocity are,which can prove the validity of the new electrical method.This new electrical method has advantages of continuously measuring crack propagation rate over the conventional electrical,optical and acoustic methods,and can provide important basis for safety assessment and cracking-arrest design of deep rock mass engineering.
文摘户外冲击放电试验导致附近建筑内通话中断、网络重启等问题时有发生,近年来带有智能组件的变压器进行冲击耐压试验时智能组件故障率高达50%,迫切需要开展冲击试验过程的电磁骚扰研究。为此进行了冲击试验的骚扰源特性分析,分析结果表明冲击电流幅值可超过10 k A,频率主要在10 MHz以下。基于骚扰耦合路径分析,提出了将电缆屏蔽层与接地网导体联合建模的直接耦合法,该方法可以同时考虑电缆屏蔽层的散射效应和电缆内部瞬态的波动效应,误差分析表明该方法比国际大电网会议(CIGRE)推荐的解耦法计算结果更加精确。在武汉特高压交流试验基地开展的典型冲击放电试验表明:直接耦合法计算结果与测量结果基本一致,验证了直接耦合法的准确性;冲击试验情况下电缆屏蔽层双端接地比单端接地降低骚扰电压水平效果更好。
基金This work was supported by the National Natural Science Foundation of China(No.51877182).
文摘The harmonics and resonance of traction power supply systems(TPSSs)aggravate the electromagnetic interference(EMI)to adjacent metallic pipelines(MPs),which has aroused widespread concern.In this paper,an evaluation method on pipeline interference voltage under harmonic induction is presented.The results show that the Carson integral formula is more accurate in calculating the mutual impedance at higher frequencies.Then,an integrated train-network-pipeline model is established to estimate the influences of harmonic distortion and resonance on an MP.It is revealed that the higher the harmonic cur-rent distortion rate of the traction load,the larger the interference voltage on an MP.Particularly,the interference voltage is amplified up to 7 times when the TPSS resonates,which is worthy of attention.In addition,the parameters that affect the variation and sensitivity of the interference voltage are studied,namely,the pipeline coating material,locomotive position,and soil resistivity,indicating that soil resistivity and 3PE(3-layer polyethylene)anticorrosive coating are more sensitive to harmonic induction.Field test results show that the harmonic distortion can make the interference voltage more serious,and the protective measures are optimized.
