Fault location in multi-terminal HVDC networks based on Electromagnetic Time Reversal with limited time reversal window

This paper aims at proving the application of the fault location method based on the Electromagnetic Time Reversal (EMTR) to multi-terminal HVDC (MTDC) networks. In particular, the paper integrates the EMTR fault location technique with the protection scheme recently proposed within the EU project TWENTIES. Further, in view of the peculiarity of the fast protection schemes required by HVDC applications, the paper discusses the performances of the EMTR-based fault location technique by using limited time-windows over which the fault-generated electromagnetic transients are time-reversed. The paper also discusses the advantage of the EMTR fault location related to the use of a single observation point to the case of MTDC grids. Indeed, such a peculiarity may represent a major advantage avoiding necessary time synchronization between the MTDC-fault recording stations and might represents, also, a backup protection system. The performances of the proposed method are validated by numerical simulations obtained using the EMTP-RV simulation environment where electromagnetic fault-transients are reproduced with reference to the MTDC benchmark network of the project TWENTIES.