Calculated reactance between relay point and fault represents an accurate estimation of fault distance when the fault resistance or the R/L ratios of the equivalent impedance at line ends are very small. When these conditions are not satisfied, a large error results in locating fault distance due to back-feed effect from the remote end. A new recursive algorithm for distance protection is developed, which accurately determines the fault location by predicting the back-feed current. The prediction needs estimated values of the remote end source impedance to be passed to the relay via a communication link. Trip decision is based on checking the evaluated fault location and its variation with time. The algorithm is validated by digitally simulating transmission lines with different fault conditions taking into consideration the reduction in the generator reactance after fault inception. Simulation results show a fault detection time of about one half-cycle.
[1]
A. Wiszniewski.
Accurate fault impedance locating algorithm
,
1983
.
[2]
Charles H. Roth,et al.
A Microcomputer-Based Interactive Transmission Line Simulator
,
1983,
IEEE Transactions on Education.
[3]
M. Fikri,et al.
An accurate algorithm for high resistance earth-fault distance protection
,
1986
.
[4]
Q. S. Yang,et al.
Microprocessor-based algorithm for high-resistance earth-fault distance protection
,
1985
.
[5]
B. Jeyasurya,et al.
Design and Testing of a Microprocessor-Based Distance Relay
,
1984,
IEEE Transactions on Power Apparatus and Systems.