Single-Ended Differential Protection in MTDC Networks Using Optical Sensors

Abstract

This paper presents a method for rapid detection of faults on VSC multi-terminal HVDC transmission networks using multi-point optical current sensing. The proposed method uses differential protection as a guiding principle, and is implemented using current measurements obtained from optical current sensors distributed along the transmission line. Performance is assessed through detailed transient simulation using Matlab/Simulink R models, integrating inductive DC-line terminations, detailed DC circuit breaker models and a network of fiber-optic current sensors. Moreover, the feasibility and required performance of optical-based measurements is validated through laboratory testing. Simulation results demonstrate that the proposed protection algorithm can effectively, and within very short period of time, discriminate between faults on the protected line (internal faults), and those occurring on adjacent lines or busbars (external faults). Hardware tests prove that the scheme can be achieved with the existing, available sensing technology.

Review and Evaluation of the State of the Art of DC Fault Detection for HVDC Grids

“…Moreover, communication incurs extra cost, whilst it also causes reliability issues. In [19], the authors achieved to reduce drastically the time delay caused by the communication link but at the expense of installation of extra sensors at various points across the lines. However, current differential can still be used as a means of bus and converter protection [20].…”

Centralised busbar differential and wavelet‐based line protection system for multi‐terminal direct current grids, with practical IEC‐61869‐compliant measurements

“…There are five modular multi-level converters (MMCs) in the network operating at ±400 kV (in symmetric monopole configuration), current-limiting inductors and hybrid circuit breakers (HbCBs). The MMC models utilised in this paper are identical to those used in [1,12,25,26] and the AC-DC network parameters are presented in Table 1. The lines have been modelled using a distributed parameter model.…”

Steady-state performance of state-of-the-art modular multilevel and alternate arm converters with DC fault-blocking capability

“…The AAC arm inductance should be sufficient to enable the arm current to be transferred between arms during overlap, while providing a degree of current filtering [23]. In MMC the arm inductance (or accumulated DC side inductance [31]) can act as a filter for the circulating currents and to prolong current rise time in the event of a DC-side fault. An AAC requires a sizeable DC filter to attenuate 6 th harmonic current and its multiples.…”