Adaptive Third-Zone Distance Protection Scheme for Power System Critical Conditions

An adaptive third-zone distance protection scheme is necessary to distinguish between faults and system stressed conditions such as power swing, voltage instability, and load encroachment. Fast and reliable detection of third-zone three-phase fault during these conditions is still a challenging issue. To address this issue and to restrict the cascaded outages, a matrix pencil method (MPM) based supervised detection index (SDI) is developed by utilizing instantaneous current. Using MPM technique the signal is reconstructed. Next, the error between the reconstructed and the original signal is estimated and the mean of the estimated error is then calculated. The absolute maximum value of mean is considered as a detection index in the proposed work. The main objective of the proposed algorithm is to provide precise detection and discrimination of third-zone three-phase fault from stressed operating conditions through an adaptive threshold. Effectiveness of the proposed algorithm is illustrated by simulation studies carried out on the IEEE 39-bus test system and 400 kV Indian Eastern Regional Grid (IERG) using PSCAD/EMTDC software. The results demonstrate that the supervised algorithm can improve power system security during critical operating conditions.