基于波形衰减因子的电缆接头绝缘早期故障状态监测

Condition Monitoring for Incipient Faults of Cable Joint Insulation Based on Waveform Attenuation Factor

电缆状态监测对于预防非计划停电、保障供电可靠性有重要意义。实测数据表明,电缆接头在永久性故障前可能重复发生多次早期故障扰动,基于对早期故障扰动波形特征的定量分析,可实现对电缆接头早期故障状态的监测。该文首先分析了电缆早期故障发展物理过程,建立了计及电弧击穿通道碳化累积效应的早期故障等效物理模型;结合小电流接地系统单相接地故障模型,分析了通道碳化累积效应对早期故障暂态波形特征影响;提出基于暂态波形衰减因子刻画电缆接头早期故障发展状态,并基于Prony算法提取衰减因子实现对电缆接头早期故障状态监测。基于仿真模型和物理实验证明了暂态信号衰减因子与电缆接头早期故障严重程度呈负相关,即故障越严重衰减因子越小,验证了该文模型和思路的正确性。

Cable condition monitoring is significant for preventing unplanned outage and ensuring power supply reliability.Measured data indicate that recurring incipient faults may appear in the cable joint before the permanent fault.The quantitative analysis towards incipient fault disturbance waveform characteristics may be adopted to monitor the cable joint incipient fault condition.First,the physical evolution process of the cable incipient fault is analyzed in this paper.Subsequently,the equivalent physical model of the incipient fault is established considering the accumulative effect of path carbonization caused by arcs.The accumulative effect of path carbonization on transient waveform characteristics of incipient faults is analyzed by combining the single-phase grounding fault model of small current neutral grounding system.The attenuation factor of transient waveforms is proposed to characterize cable joint incipient fault evolution conditions.The incipient fault condition monitoring of the cable joint is realized through attenuation factors extracted by the Prony algorithm.Through the simulation and physical experiments,it is verified that the attenuation factors of transient signals are inversely related to cable joint incipient fault severity.Namely,the more severe the fault is,the smaller the attenuation factor is,which testifies the accuracy of the proposed model and thinking.