Online Monitoring and Diagnosis of HV Cable Faults by Sheath System Currents

Abstract

Cross-bonded metal sheath connection is applied in sectioned single-core power cables to reduce or eliminate the voltages which are induced in the sheath over long distances. However, cross-bonded cables present an opportunity as well as a challenge for on-line measurement and diagnosis of cable conditions. In this paper, a methodology to identify cable faults through analysis of the sheath system currents in a cross-bonded cable system is presented. Firstly, a numerical model is established to simulate the sheath currents in cross-bonded cable systems. Secondly, analyses of several faults, which happen frequently with serious consequences, are presented on the basis of current measurement at the link cable. Simulations of normal and fault conditions are given to determine the feasibility of fault diagnosis. A case study using field data from a cable tunnel in China considering the normal condition is presented to verify the numerical model. Results in normal condition show good consistency with field data with error less than 5%. Simulation results of fault conditions show that analysis of readings from 6 current sensors can distinguish different fault types and fault positions using the method proposed. Based on the analyses, criteria are established for sheath loop fault type diagnosis.

Analysis of Cable Screen Currents for Diagnostics Purposes

“…Analysis of cable screen currents gives a possibility to distinguish the type of line (cable or overhead) affected by an earth fault [20]. Furthermore, cable screen current measurements can be used for the detection of problems in cross bonded lines, e.g., short-circuited cable screens during flooding or insulation breakdown in cable joints [21][22][23]. Furthermore, the wrong order of cable screen connections in parallel connected cables can be detected.…”

Detection and Localization of Defects in Cable Sheath of Cross-Bonding Configuration by Sheath Currents

“…For utilities, the main advantage of performing on-line measurements for the assessment of the cable sheath condition is that the interruption of the power supply is not required, while in off-line measurements a planned shutdown is needed [1][2][3][4].…”

“…Different criteria (depending on the type of the defect) were developed by Xiang Dong et al [1] to detect defects in cable sheaths by measuring sheath currents when CB configurations without transposition in flat formation are adopted. Although this study is very efficient to detect the defects in cable sheaths, the influence of the load current and the unbalance of the lengths of the minor sections have not been studied on the criteria proposed.…”

Cable joint fault detection for the ring main unit based on an adaptive TNPE algorithm

“…Zigang, Wei, Sun, and Sun ()) presented a power system's dynamic‐state‐updating method, which can deal with the delay under a related measurement, and used it to realize the accurate estimation of the dynamic state for the power system. Dong, Yang, Zhou, and Hepburn () proposed an online monitoring and diagnosis method for high‐voltage cable faults based on a sheath current analysis. Some machine learning algorithms enhance the model's ability of generalization, such as accurate online revised support vector machine regression (Rodil & Fuente, ), stochastic configuration networks (D. Wang & Li, ), and another algorithm (J. Tang, Yu, Chai, & Zhao, ) can adapt to the training sample and parameters or structure of the fault detection models.…”