*112634*

Simulation of induction motor protection relay

S.A Utanan, A.S. Glazyrin.

Department of Electric Power System, National Research Tomsk Polytechnic University, Tomsk, Russia

Abstract

In this paper a simulation of induction motor protection relay is presented. The technique provides a simple model construction and visualization.

Key words: induction motor, protection relay, visualization, simulation.

Introduction

To simulate the operation of relay protection is required to perform three main points. Description is of mathematical model of the protected object. Defining the principles is operation of protection relays. Finally, verification of operation the model.

Model of the induction motor

In this paper, a simplified mathematical model of two-phase induction motor in the axes α, β. The mathematical description in the form of ordinary differential equations is presented below.

(1)

The principle of protection

The scheme of the majority of the relay can be represented in the form of several basic blocks. This block of rectification, low pass filter, a comparator, and an electronic key.

Fig.1 Block diagram of the relay

Checking the operation of the model

For example, we work minimum voltage relay. The relay has two stages. The first stage has a time delay setting, and 9c voltage equal to 0.7 of nominal. The second stage is triggered when the voltage drops to 0.5 rated voltage (Un) with a time delay of 5 s.

Fig.2 The general scheme of the model

Fig.3 Block diagram of the relay

The figure shows the work of the first stage of the relay. When the voltage drops to 0.7 Un run time delay stage, then runs an electronic key (EK) to forming a team trip.

Conclusion

This method allows the simulation by means of simple visual elements to simulate the principle of majority sewn up.