impact of harmonics on the operation of different type of the relay.

1. “Impact of Harmonics on Tripping Time of
Overcurrent Relay”
Malaviya National Institute Of Technology Jaipur
Department Of Electrical Engineering
Sesion-2016-17
Submitted By
SUYASH KUMAR CHAURASIYA
(2016PES5128)
Submitted to
PROF. K. R. NIAZI

2. Content
 Introduction
 What is harmonics?
 RMS and THD of the non-sinusoidal load current.
 Experimental measurements
 Different types of devices used in experimental
circuit.
 Result’s
 Conclusion

3. Relay is a sensing
device which senses
abnormal voltage and
current condition in
power system and send
signal to circuit breaker
to remove faulty part
from rest of the power
system.
Introduction

4. • Over current
relay1
• Directional relay
2
• Distance relay
3
Types of relay
A relay that
operates or picks
up when it's
current exceeds a
predetermined
value (setting
value) is
called Over
current Relay.

5. Types of over
current relay
• Instantaneous over current relay
1
• Inverse definite minimum time
over current relay2
• Very inverse type over current
relay3
• Extremely inverse over current
relay4

6. What is harmonics?
A harmonics of a sinusoidal wave is a
component frequency of the signal that
is an integer multiple of the
fundamental frequency , i.e. if
fundamental frequency is f , the
harmonics have frequencies 2f , 3f , 4f
, … etc.
Causes of harmonics in the system
 Non linear loads
 Power electronics devices
 Saturated transformer
 capacitor bank switching

7. RMS and THD of the non-sinusoidal load current
Definition of RMS: That steady current which, when flows
through a resistor of known resistance for a given period of time
than as a result the same quantity of heat is produced by the
alternating current when flows through the same resistor for the
same period of time is called R.M.S or effective value of the
alternating current.
In other words, the R.M.S value is defined as the square root of
means of squares of instantaneous values.
The rms value of a pure sinusoidal waveform is defined as:

8. Continued..
The rms value of a non-sinusoidal current waveform is defined as:
Simplifying the above equation results in

9. What is T.H.D ?
The total harmonic distortion of load current is defined as:
THD stands for Total Harmonic Distortion and can be used to
estimate the degree to which a system is nonlinear

10. The standard characteristic of relay
A solid state over current relay type MCGG of Alstom
T&D Protection & Control Ltd is used.
Operating time characteristics of the relay are provided
by manufacturer as follow:

11. Experimental measurements
 A single-phase testing system for
measuring the effects of (individual
and/or mixed) harmonic currents on
the performance and tripping time
of protective relays has been
developed (Fig.1& Fig.2).
 A computer based waveform
generator, an amplifier and
corresponding software and
interface circuits are used to test a
solid state over-current relay of type
MCGG manufactured by Alstom
T&D Protection & Control Ltd.

12. Different types of devices used in experimental circuit
1. Waveform Generator
2. Power Amplifier
3. Resistor (10 ohm)
4. Relay(alstom 1φ o.c relay type MCGG)
5. Digital Timer(resolution of timer is 10ms)
6.Power Quality Analyzer

13. Continued…
 Using the experimental set up of Figure 2; tripping
times of the relay are measured for distorted currents with
THD levels of 10%, 20% and 30%.
 The fundamental component is varied from 1.20 to 4.4
times of the pickup current.

14. Result’s
*Note: minus sign (-) denotes that tripping time is shortened.

15. Result’s
*Note: minus sign (-) denotes that tripping time is shortened.

16. Result’s
*Note: minus sign (-) denotes that tripping time is shortened.

17. Conclusion
1. Based on test results, it can be generally concluded that the
effect of harmonic currents would lead to a shortened
operation time of the solid-state relays; relay performs
differently when THDI waveform distortion varies.
2. The higher the THDI, the greater the variation of tripping time
that can be seen. Significant deviations can occur with 20% or
greater THD in current waveform at all three (Standard
Inverse, Very Inverse and Extremely Inverse) characteristics of
relay.
3. Harmonics mostly show significant effects on tripping time at
overload current ranges (1.2 to 2 times of pickup current); in
case of fault conditions, those effects are theoretically
negligible.

18. 1. In harmonic-polluted environment as such industrial factories,
the proper coordination of relay may be violated. This may
cause nuisance problems and sometime shutdown power
supply unexpectedly.
2. Finally, impact of harmonics on the coordination of relays
should be carefully investigated because this impact depends
greatly on configuration of grid, setting time and relay’s
utilized characteristic as well.
continued..

19. References
1. IEEE paper : ‘Impact of Harmonics on Tripping Time of
Overcurrent Relays ‘by M.A.S. Masoum, SM IEEE, S.M.
Islam, SM IEEE, K. Tan, M IEEE, N.X. TUNG
2. ‘Impact of Harmonics on Tripping Time and Coordination
of Overcurrent Relay’ by TUNG .N.X , FUJITA. G ,
MASOUM. M.A.S , ISLAM .S.M