Comparison of High-Speed Transient-based Pilot Directional Protection Algorithms for Distribution Grids

The protection challenges introduced by penetration of renewable-based generation in the distribution network stipulates the use of pilot directional protection schemes. The transient-based pilot directional protection techniques are widely used in high voltage and ultra-high voltage transmission networks because they offer reliable and fast operation with reasonable communication demands. However, their application in modern distribution network has not been explored so far. Ever since the advent of RALDA relay in 1978 by ASEA, relay manufacturers have investigated and developed different methods to determine fault direction based on delta quantities. These algorithms are fundamentally different in terms of their operating principle. This paper introduces the development and design principles of some of the existing methods along with some alternate pilot directional protection schemes including current-only solutions. Moreover, the performance evaluation for a 22kV modern distribution system has also been conducted. Finally, the performance of all the tested algorithms are compared and the limitations of each of the techniques are summarized.