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In order to locate short circuit fault in power cable systems accurately and in a timely manner, this paper proposes a novel traveling-wave-based fault location method improved by unsupervised learning. There are two main steps of the method: a) record the traveling-wave data and build a sheath current matrix; b) cluster the data and identify the arrival time by the characteristic cluster. The improvement mainly lies in that the high-dimensional data can be directly used for clustering. A PSCAD (Power System Computer Aided Design) simulation has been carried out for a selected HV (high voltage) cable circuit. Results indicate that the hierarchical structure of condensed cluster tree just corresponds to the positional relationship between the fault point and monitoring points. The clustering results can be used for the identification of the arrival time of the traveling wave. The potential problems of the method lie in the “noise” identification. Ordinary samples can be labeled as “noise” by HDBSCAN. The combined use of DBSCAN and HDBSCAN maybe a solution for the “noise” problem.

this paper discusses research and trial application of mobile sensing and interactive diagnostic technology for power cable lines. The comprehensive construction of intelligent operation and maintenance system combined with the modern information technology, intelligent technology and the traditional technique is an urgent demand. The mobile sensing and interactive diagnostic technology for power cable lines integrates technique of conventional statue detecting, on-line monitoring, tunnel monitoring and patrol robot, supported by the internet of things technology and combined with RFID technology, individual mobile terminal technology, multiple states sensing technology, patrol robot technology, the distributed diagnosis technology and data interactive technology. The whole system makes operation staffs conveniently acquire operation indicators and preliminary analysis of power cables lines and tunnels in the process of patrol and maintenance, master and update real-time operational information of power cables lines and tunnels, such as operating state, fault prediction, risk level and maintenance recommendation by communicating with control center platform. Further application of the technology will innovate maintenance mode and promote intelligent level, efficiency and effects of operating management and maintenance of power cable lines comprehensively.

In recent years, SGCC accelerate the establishment of distribution power networks. The quality management of distribution cables devices directly affects the reliability of power grid operation. This paper proposes a new system about the quality evaluation and management of distribution network cables and accessories based on life-cycle quality evaluation model, which includes access quality quantitative evaluation, operating performance quantitative evaluation and interact overall process quantitative evaluation. It aims to establish the quality evaluation and control platform based on data fusion analysis of life-cycle operation and maintenance data to provide solution of the interact operational process quality evaluation and control of distribution cables and accessories and improve the reliability of power grid operation.

Tangent delta (TD) measurements using very low frequency (VLF) sinusoidal waveform in aged cable system have been proved sensitive to water tree degradation and insulation aging. Whereas, the application of VLF in acceptance tests on new cable systems of medium voltage is still on research and development. This paper presents an experimental study of the capability of the main VLF testing methods for newly installed 10kV XLPE cable systems in acceptance tests. Compared with oscillation wave excitation, the different waveforms including sinusoidal (Sinus) and cosine-rectangular (CR) of VLF voltage were employed to stress the nine samples of artificial defects of different types. Various characteristics of TD measurement and partial discharge (PD) measurement were analyzed. The results showed that VLF-Sinus voltage has a distinctive ability of detection for a wet or lossy accessory through TD or PD measurements. It is recommended to employ a combination of the monitored VLF-Sinus withstand with TD measurement and the PD measurement under damped alternative current (DAC) or VLF-CR as field diagnostic tools in acceptance test for newly installed cables.

The relative permittivity and conductivity of the semi-conductive layer and semi-conducting resistance water layer of the high voltage cable were measured by the broadband dielectric spectrometer in the frequency range of 1–100MHz. Based on the measured results, the transmission characteristics of the partial discharge signal of the high voltage XLPE cable were simulated and calculated and finally the theoretical models were obtained. Besides, sinusoidal signal measurement experiment was done on cables of 110kV and 220kV with different lengths and types. It is found that attenuation degree of signal propagation becomes serious with the increase of cable's length and signal frequency, which verifies the effectiveness of high-voltage cable partial discharge propagation model. It is the semi-conducting layer that has serious attenuation characteristic to high frequency signal.