Design of a Distance Relay Using Adaptive Data Window Filters
Date
2001
Authors
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Degree Level
Masters
Abstract
Transmission lines are generally protected by distance relays. Most distance
protection relays presently available use microprocessor technology. They estimate
fundamental frequency phasors from the quantized values of voltage and current samples. The relays use filters that use fixed sample data windows of one cycle of the nominal frequency. Therefore, the transient response of the filter is about one cycle and the estimated impedances do not converge before this time. However, it is possible to use different lengths of data windows at different sampling instants and improve the transient response.
This thesis describes a distance relaying technique, which uses adaptive data window filters. Relay algorithms that use adaptive data window filters and fixed data window filters were also developed and their performances were compared by using data
from simulations using the electromagnetic transient program, EMTDC/PSCAD. Results
obtained from a sample power system and a part of the SaskPower transmission network
are presented. Different operating conditions of these power systems and, faults of
different types and at various locations were simulated for performance evaluation. It
was observed from the simulation results that the seen impedances obtained using the
adaptive and fixed data window techniques converged to the same values. The results
indicated that the convergence of the seen impedance was significantly faster when the
algorithm using the adaptive data window technique was used. Selected results are
presented in the thesis.
The adaptive data window technique and the fixed data window technique were
implemented to form prototype distance relays using a general-purpose relay. The
hardware and software constituents of the relay are presented in this thesis. The relays
were tested using the Real-Time Playback Simulator (RTPS) for a variety of faults
simulated on a part of the SaskPower system using the EMTDC/PSCAD program. The
procedure for testing the relay by using a playback simulator is reported.. The test results
indicated that the relays operated correctly for all the faults simulated inside the
protection zone and did not issue a trip command for the outside faults. The test results
also confirmed that the adaptive data window-based relay is able to issue trip commands
in lesser time compared to the time taken by the fixed data window-based relay, while the impedances computed by both relays converged to the same values. Selected results are included in the thesis.
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Degree
Master of Science (M.Sc.)
Department
Electrical and Computer Engineering
Program
Electrical Engineering