A Novel Lightning Overvoltage Protection Scheme Using Magnetic Rings for Transmission Line Systems

Overvoltage protection technology is critical to the safe and stable operation of power electronics equipment and power systems. In this article, based on the characteristics of lightning traveling waves, a novel lightning overvoltage protection scheme was proposed using magnetic rings (MRs) for transmission line systems (TLSs). First, the dynamic inductance of the lightning protection scheme using MRs was theoretically derived by combining the ampere loop law and the infinitesimal method. The finite-element method was then used to verify the theoretical derivation of dynamic inductance (TDDI) of the lightning protection scheme. Furthermore, the TDDI was integrated into the electromagnetic transient program, and the electromagnetic transient model (ETM) of the TLS with the lightning protection scheme was established. Subsequently, the effects of MR characteristics under the influence of various factors on the protection performance of the lightning protection scheme were investigated. Finally, the MR string in the lightning overvoltage protection scheme with optimal physical structure was used for field application. The results confirmed the feasibility of the lightning overvoltage protection scheme and ETM accuracy.