An Adaptive Distance Protection Scheme Considering Fault Resistance,
Injected Current, and Structural Changes in the Power System
Abstract
Faults in power systems occur for various reasons, such as aging or
natural disasters. Detecting, locating, and promptly clearing these
faults is crucial for maintaining the safety and reliability of
transmission lines. Distance relays, which protect transmission lines,
detect faults, estimate their location, and send the required commands.
However, these relays may experience mis-detection due to manipulated
impedance arising from both internal and external factors. These factors
include measurement device errors, network topology changes, the
presence of fault resistance, and injected currents from remote line
terminals. To address this challenge, we propose an innovative adaptive
protection scheme that considers fault resistance, changes in network
topology, and injected current from the opposite end of the line. By
estimating the equivalent circuit impedances of the network connected to
the terminal of the transmission line, this protection scheme utilizes
impedance estimation techniques at the line terminals and offline
network information. Simulation studies (tested on the IEEE 39-bus
standard network) show that the proposed scheme accurately estimates
fault location and fault resistance with high precision. The simulation
results demonstrate its effectiveness in improving the performance of
conventional distance protection relays in both the first and second
protection zones (Z_1 and Z_2).