An Investigation of Electromagnetic Transients for a Mixed Transmission System With Overhead Lines and Buried Cables

Abstract

An electromagnetic transient study has been performed based on a practical 500 kV mixed transmission system. The system has overhead lines, submarine cables and underground cables. An exact expression of earth-return impedance for submarine cable has been developed. A new equivalent homogeneous earth method (EHEM) is also proposed based on the exact formula. The influences of air, seawater, seabed, wired armor structure and multi-layer seabed on series impedance and modal propagation constants of submarine cable are investigated. A novel modeling procedure on parametrical side of mixed transmission system is proposed in this paper. Moreover, the input sequence impedances of mixed transmission system are studied based on traditional Line / Cable Constant routines and the new method. Transient simulations are also performed using classical and new methods. The results are further validated with recently proposed MoM-SO technique.

Analysis of Cross-Bonded Cables Using Accurate Model Parameters

“…The new LCD is capable of accounting for overhead lines, underground cables, mutual couplings between overhead and underground conductors together with a consideration of multilayer earth, stranded conductors, proximity effect, high frequency transient and complete expression of earth-return parameters, etc. Recent research [28], [39] shows that the abnormal characteristics of input impedance and propagation constant produced by CPC method may cause passivity violation in numerical fitting of the WB model, and it could further lead to simulation instability. The LCD avoids such problems and provides a new tool to researchers and engineers for accurate simulation of cables and lines in power grids.…”