Time-Domain-Based Distance Protection for Transmission Networks: Secure and Reliable Solution for Complex Networks

Distance protection is popular in transmission networks and constitutes a large installed base across grid systems. The most widely accepted implementation of distance protection is based on voltage and current phasors. Today the electric grids are becoming increasingly complex and dynamic in nature. With power electronic converter interfaced systems such as renewables, HVDC, FACTS, etc., there is a need for fast, secure and reliable protection decisions. The phasor-based distance protection is prone to reliability issues in such networks and is inherently limited in speed. Recently, ultra-fast protection solutions based on fault induced traveling waves are commercially available. Although promising, such solutions may miss faults near voltage zero-crossing, falsely detects nonfaulty disturbances as faults and as such lack wider acceptance in contemporary transmission lines where protection security is a non-negotiable requirement. In comparison, time-domain based distance protection solutions have appeal in terms of reliability and speed. In addition, an ideal time-domain distance protection should be applicable to various networks such as series compensated lines, lines connected to renewables and long underground/sub-sea cables. In this paper, we propose a method for time-domain based distance protection to meet these requirements. The method operates based on current based operating quantity and a novel dynamic restraining quantity which is calculated for the fault zone boundary point. The proposed method inherently overcomes influence of series compensation, renewable integration and provides a fast and reliable identification of in-zone and out-of-zone faults. It is tested for various networks using laboratory experimental data and field records. Further it is implemented in an IED platform and tested with RTDS simulations in hardware-in-loop mode. The method is found to work satisfactorily and consistently over the extensive test scenarios.