Design a Fast Digital Protective Relay Algorithm for High Voltage Transmission Line

Auday A.H. Mohamad, Essar Gafar Ahmed


Modeling of protective relays is economical and feasible alternative to investigate the performance of relays and protection systems. This paper presents a new approach for MHO Relay Algorithm in MATLAB based on Fast Fourier Transform Algorithm (FFT) which can estimate exact magnitude of DC offset component and completely eliminates it from operating quantities during faults and also makes use of smoothing window to filter out noise if any. The proposed Numerical Algorithm performance is tested on simulated transmission line of Merowe-Atbara 500 KV, 50 Hz, and 236.7 Km using data generated by PSCAD/EMTDC. The proposed MHO algorithm evaluated by using MATLAB to models a power system and simulates many fault conditions on a selected transmission line such as different Fault locations, resistances with various fault angles. Sample results of these studies show the comparison between the presented Algorithm and PSCAD/EMTDC in detection and tripping time.


relays and protection systems; (FFT) Algorithm; PSCAD/EMTDC; MHO.

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