1. POWER QUALITY IMPROVEMENT IN
DC DRIVES BY SUPPRESSING
HARMONICS
Under the guidance of
Prof. K.V.DEVADAS
Head of the Department, E&E
KVGCE- Sullia.
Presented by,
ARAVIND NARAGUND
4th sem. M.Tech (CAID)
KVGCE- Sullia

2. ABSTRACT
This project presents various techniques like passive filter, shunt active
filter, sinusoidal pulse width modulation and selective harmonic elimination for
harmonic reduction. The power quality parameters such as “Total Harmonic
Distortion of voltage” (THDV) and “Total Harmonic Distortion of current”
(THDI) has determined in each case of above said techniques for different ratings
of DC motor and also extended the work to higher pulse converters (up to 96
pulse). By using MATLAB for simulation, the clear comparison of power quality
parameters has made between before and after application of above discussed
techniques.

3. 1. INTRODUCTION
Figure : Three phase bridge rectifier circuit for speed control of DC motor
 Power quality
 Current quality
 Voltage quality
 Total harmonic distortion

4. 2. POWER QUALITY IMPROVEMENT
TECHNIQUES
The following are types of the filters generally used.
(a) Passive filters (b) Active filters and (c) Hybrid filters
2.1) Passive Filters
Passive implementations of linear filters are based on combinations of
resistors(R), inductors(L) and capacitors(C). These types are collectively known
as passive filters, because they do not depend upon an external power supply
and/or they do not contain active components such as transistors.

5. 2.2) Shunt Active Filter
Figure : Basic Scheme of shunt active
filter

6. Figure: Voltage source converter topology for active
filters.
VOLTAGE SOURCE CONVERTERS

7. Multi-pulse systems result in two major accomplishments namely,
1. Reduction of ac input line current harmonics.
2. Reduction of DC output voltage ripple.
2.3) Multipulse Converters
2.3.1 12-PULSE CONVERTER

8. 2.3.2 24-PULSE CONVERTER
Two twelve pulse converters phase shifted by 15 degrees from
each other, can provide a twenty four, obviously with much lower
harmonics on ac and DC side. Its ac output voltage would have order
harmonics i.e., 23rd, 25th, 47th , 49th harmonics with magnitudes of
1/23rd , 1/25th , 1/47th ,1/49th ,…respectively, of the phase shift.
2.3.3 36, 48 AND 96-PULSE CONVERTER
Higher number of pulse converters can be implemented by
connecting appropriate number of six pulse converter either in
series or parallel with proper degree of phase shift between them.
The connection for 36, 48 and 96-pulse converter is shown in fig
3.8, 3.9 & 3.10 respectively.

9. 3. MATLAB/SIMULINK MODELS AND
RESULTS
3.1) 6 Pulse Converter

10. THDI before application of Filter = 15.32%

11. 3.2) 6 Pulse Converter with Passive Filter

12. THDI after application of Passive Filter = 4.16

13. 3.3 ) Application of Shunt Active Filter to 6 Pulse Converter.

14. After Application of Shunt Active Filter, THDV = 2.07, THDI = 0.91

15. 3.4) 6 Pulse Controlled Converter

16. Before application of PWM Signals THDV = 1.462, THDI = 0.4179

17. 3.5) After application of PWM Signals

18. After application of PWM Signals THDV = 0.60, THDI = 0.20

19. 3.6) 12 Pulse Converter

20. For 12 Pulse Converter THDV = 1.37, THDI = 1.95

21. 3.7) 24 Pulse Converter

22. For 24 Pulse Converter THDV =1.30, THDI = 1.93

23. 3.8) 36 Pulse Converter

24. For 36 Pulse Converter THDV =1.26 ,THDI = 1.94

25. 3.9) 48 Pulse Converter

26. For 48 Pulse Converter THDV =1.02,THDI =2.32

27. 3.10) 96 Pulse Converter

28. For 96 Pulse Converter THDV =1.36,THDI =2.00

29. Table 1 Comparison of THDI for Multipulse converters
Rating of
Motor in
HP
4 pulse
Converter
6 pulse
Converter
12 pulse
Converter
24 pulse
Converter
36 pulse
Converter
48 pulse
Converter
96 pulse
Converter
%THDI %THDI %THDI %THDI %THDI %THDI %THDI
5 37.16 3.11 2.46 2.40 2.31 2.47 2.38
10 7.24 3.11 2.78 2.44 2.13 2.44 2.19
20 6.42 1.67 2.22 2.20 2.03 2.38 2.04
30 5.92 2.56 2.06 2.04 1.96 1.94 1.98
40 6.26 2.41 1.95 1.93 1.92 2.35 1.98
Table 2 Comparison of THDV for Multipulse converters
Rating of
Motor in
HP
4 pulse
Converter
6 pulse
Converter
12 pulse
Converter
24 pulse
Converter
36 pulse
Converter
48 pulse
Converter
96 pulse
Converter
%THDV %THDV %THDV %THDV %THDV %THDV %THDV
5 6.35 1.51 1.30 1.15 1.03 1.07 1.11
10 6.33 1.51 2.07 1.46 1.07 1.07 1.11
20 7.21 2.79 1.50 1.37 1.14 1.07 1.16
30 6.34 1.60 1.43 1.34 1.2 1.20 1.25
40 5.11 1.53 1.37 1.30 1.24 1.04 1.34

30. Plot of %THDI vs Different Rating(in HP) of DC Motor

31. Plot of %THDV vs Different Rating(in HP) of DC Motor

32. 4. CONCLUSION
Power Quality related issues, and various harmonic suppression techniques
are discussed in detail. The reduction techniques such as passive filter, shunt active
filter and multipulse converters are simulated using Matlab/Simulink. From the
simulated results, it’s found that quality of power has improved after application of
filters. For multipulse converters with increase in number of pulses, the total
harmonic distortion has reduced and thus quality of power is improved. And it’s also
found that the power quality parameters such as THDV and THDI has reduced for
large DC motor loads.

33. REFERENCES
[1] John N. Chiasson, Leon M. Tolbert, Keith J. McKenzie, Zhong Du, A
Complete Solution to the Harmonic Elimination Problem, IEEE
Transactions on Power Electronics, vol. 19, no. 2, march 2004 (491-499).
[2] M.Izhar, C.M.Hadzer,S.Masri and S.Idris, A Study of the Fundamental
Principles to Power System Harmonic, National Power and Energy
Conference 2003 Proceedings, Bangi
Malaysia. (Page no: 225-231).
[3] Tony Hoevenaars, Kurt LeDoux, Matt Colosino, Interpreting IEEE
Std 519 and Meeting its Harmonic Limits in VFD Applications, Paper
No. PCIC-2003-15.
[4] Math H J Bollen, “Understanding Power Quality Problems; Voltage
sags and interruptions”, Wiley India, 2011.
[5] Roger C Dugan, et.al, “Electrical power Systems Quality”,3rd
Edition, TMH, 2012.

34. THANK YOU