High-voltage cable bonding to prevent cable termination faults based on zero-sequence current

Abstract

Zero-sequence current (ZC) occurs due to harmonics and unbalanced loading current. ZC increases the sheath voltage (SV) and cable temperature, so cable faults occur on cable terminations in high-voltage underground cable lines (HVUCL). In literature, bonding methods are used to prevent ZC effects, but these methods are not adequate to prevent ZC effects for long HVUCL under high harmonic distortion because ZC is not considered when these methods are designed. In this study, the modified sectional solid bonding (MSSB) is suggested for long HVUCL that works under high harmonic distortion rate and unbalanced loading conditions. Namely, ZC is considered when MSSB is designed. MSSB parameters should be determined before HVUCL is installed for the most economical and practical bonding. SV of HVUCL should be known to determine MSSB parameters, so SV of HVUCL is forecasted by using adaptive network-based fuzzy inference system (ANFIS), artificial neural networks (ANN), and hybrid ANN. Training and forecasting errors of hybrid ANN are less than ANFIS and ANN methods, so hybrid ANN methods are suggested to forecast SV of HVUCL. Also, MSSB parameters should be optimized, so optimization methods are used for optimization of MSSB. When MSSB method is used for bonding of long HVUCL, harmonic distortion rate and SV in cable terminations are not exceeded the determined limits to prevent cable faults.