Simulation of a power transformer differential protective relay

Abstract EN

The aim of this work is to simulate a differential relay, which ensures security for external fault, inrush, and overexcitation conditions and provides dependability for internal faults, to protect a single phase power transformer.

This work combines harmonic restraint and blocking methods with a waveshape recognition technique.

The harmonic based dual slope characteristic differential relay is modeled in MATLAB (version 7.3) functions.

Two approaches are used to simulate the power transformer transients modeling to evaluate the differential relay performance for different operation conditions : The first approach has modeled the power transformer transients in MATLAB functions to simulate the inrush, overexcitation and external fault conditions, the interfacing of this model with the differential relay MATLAB functions is accomplished via the sampler model which is simulated in the environment of SIMULINK.

The second approach has modeled the power transformer transients using the power system blockset to simulate the internal faults and the sinusoidal inrush current conditions, this model is set to interact with the differential relay MATLAB functions by the environment of SIMULINK.