Power quality analysis using lab view

IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
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Volume: 03 Issue: 09 | Sep-2014, Available @ http://www.ijret.org 322
POWER QUALITY ANALYSIS USING LabVIEW Swarupa N1, Vishnuvardhini C2, Poongkuzhali E3, M R Sindhu4 1Bachelor of Technology, Electrical and Electronics Engineering, Amrita Vishwa Vidyapeetham, TamilNadu, India 2Bachelor of Technology, Electrical and Electronics Engineering, Amrita Vishwa Vidyapeetham, TamilNadu, India 3Bachelor of Technology, Electrical and Electronics Engineering, Amrita Vishwa Vidyapeetham, TamilNadu, India 4Associate Professor, Electrical and Electronics Engineering, Amrita Vishwa Vidyapeetham, TamilNadu, India Abstract In the present scenario the ever increasing existence of non linear loads and the increasing number of distributed generation power systems in electrical grids modify the characteristics of voltage and current waveforms in power systems, which differ from pure sinusoidal wave. The target of this paper is to design an accurate measurement system and display the system parameters under distorted system conditions. Harmonics, Sub Harmonics, and Inter Harmonics are measured and displayed using LabVIEW. The voltage and current are sensed using sensors for various loads, which are then interfaced with the PC using DAQ (Data Acquisition) card and displayed using LabVIEW. The Hardware implementation includes setting up of test systems such as diode bridge rectifier and thyristor based converter with various loads such as resistive, inductive and DC shunt motor. Experimental results obtained for various loads and source conditions are cross verified with theoretical analysis. The response obtained in hardware and simulation proves the effectiveness of the system. Keywords: Data Acquisition, Power Quality, Harmonics, Sub harmonics and Inter harmonics
--------------------------------------------------------------------***---------------------------------------------------------------------- 1. INTRODUCTION Paragraph Over the recent years, there has been an increased emphasis and concern for the quality of power delivered. This concern for the quality of power has increased due to the considerable usage of non linear loads such as adjustable-speed drives, arc furnaces, switched mode power supplies, electronic ballasts etc. The harmonics created by these non-linear loads are non-sinusoidal in nature, which leads to poor power factor, low system efficiency and other power quality issues. Power quality is defined in the Institute of Electrical and Electronics Engineers IEEE standard terms as “the concept of powering and grounding electronic equipment in a manner that is suitable to the operation of that equipment and compatible with the premise wiring system and other connected equipment.” Most of the important international standards define power quality as the physical characteristics of the electrical supply provided under normal operating conditions that do not disrupt or disturb the customer’s processes. Therefore, power quality problem exists if any voltage, current or frequency deviation results in failure or in bad operation of customer’s equipment. Normally problems like surges, poor voltage, frequency regulations, voltage switching transients, electrical noise, power loss and Electro-Magnetic Interference effects are frequently encountered in the load side. This leads to damage of capital-intensive appliances, safety concerns of the load, loss of reliability of the power electronic devices and a huge economic loss, which affects the power quality. The main causes of the poor power quality are Power supply failures, malfunctioning of power electronic equipments, over heating on the load side, loss of reliability, increase of losses in the system. Power quality parameters include real power, reactive power, apparent power, harmonics distortion, distortion power factor, displacement power factor, Crest factor and net source power factor.
Jing Chen, Tianhao Tang [4] had proposed use of LabVIEW software platform for power quality detection and interpreted system characteristics harmonic detection, voltage, current waveforms which includes their deviations.
Shahedul Haque Laskar [2] had surveyed different existing methods of power quality monitoring which is already in use which includes all existing technologies involved in the field of power quality monitoring. H.E Wenhai[8] had developed a new noise test system which comprises the testing technology, the computer technology and the network technology based on virtual instrument technology. Using data acquired card (DAQ card) we can acquire and generate signals such as voltage, current, noise, temperature etc, so the total test system is more economical. S. K Bath, Sanjay Kumra [1] had gathered information about system parameters which is then measured and simulated using LabVIEW as distorted power waveforms to know the amount of harmonics and distortion in the system, so that appropriate actions are taken to reduce development time and harmonics and to design higher quality products. Qiu Tang, Zhaosheng Teng, Siyu Guo and Yaonan Wang [5] had designed a multifunctional Virtual monitoring system which monitors the power quality and then implemented in LabVIEW environment. The root mean square (RMS) value, the waveforms of current and voltage, current and voltage crest factor, the harmonic components, the total harmonic distortion (THD) waveforms of the voltage and current signals can be calculated and displayed in the system.

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LabVIEW is a programming language used for acquiring signal, data presentation and measurement analysis. The LabVIEW platform provides models and specific tools to solve applications ranging from signal processing algorithms to voltage measurements, targeting number of platforms interfacing desktop and embedded devices. Virtual instruments represent a traditional hardware- centered system to software centered systems that exploit connectivity capabilities of workstations and desktop computers. Computing power display and productivity LabVIEW is easy to incorporate with the new LabVIEW applications into the existing systems without losing hardware information. NI LabVIEW software has more than 600-700 built functions for frequency analysis, signal synthesis, mathematical functions, probability and statistics, interpolation, curve fitting and many more. 2. SIMULATION RESULTS Paragraph Measure and display the following system parameters under distorted system conditions (Harmonics, Sub Harmonics, and Inter Harmonics)- RMS Voltage Vrms, RMS Current Irms, Total Harmonic Distortion (THD), Real Power, Reactive Power, Apparent Power, Distortion Power, Distortion Power Factor, Displacement Power Factor, Net Source Power Factor, Voltage Crest Factor, Current Crest Factor, Ipeakand Vpeak is the objective of the work. The above system parameters are simulated using LabVIEW software under normal and distorted conditions. These parameters are simulated and cross verified analytically.
Fig -1: Harmonic Currents Consider the nonlinear system which takes source currents consisting of following harmonics Third HarmonicI2=20sin 6πft , f=150Hz,
Fifth HarmonicI3=15sin(10πft), f=250Hz,
Seventh HarmonicI4=10sin(14πft), f=350Hz,
Sub HarmonicI5=5sin(5πft), f=125Hz
Fig -2: Fundamental Current The above figure include, Fundamental Current i=10sin (ωt), Frequency = 50Hz, Samples=1000/s,No of samples=140 Time Period =20m/s
Fig -3:Total Instantaneous Current
Total instantaneous Current= i1+i2+i3+i4+i5 =100sin⁡(100πt−60°)+ 20sin 300πt + 15sin 500πt + 10sin 700πt + 5sin(250πt) Three Test Cases are taken where case (1) includes no phase difference between source current and source voltage, case (2) includes source current lags source voltage by 30 degrees and (3) source current leads source voltage by 60 degrees. For each case the results obtained for the above system parameters are cross verified mathematically. The simulated results and mathematically obtained are tabulated below for each case. Case (1):
----------- (1)

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Fig-4. Case (1) :Simulated Output- Voltage and Currents are inphase Case (2):
Fig-5. Case 2(i)- Simulated Output when Current Lags Voltage by 30 ̊
Fig-6. Case2(ii)-Simulated Output when Current Leads Voltage by 60 ̊ Case (3)
Fig-7.Case (3)-Simulated Output- Introducing Distortion in Voltage Waveforms

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Table -1: Comparison of Simulated Results with results after Theoretical Verification
System Parameters
Simulated Results
Results after Verification
RMS Voltage
229.81
229.80 V
RMS Current for Fundamental
70.7107
70.71 A
RMS Current for 3rd Harmonic
14.1421
14.14 A
RMS Current for 5th Harmonic
10.6066
10.60 A
RMS Current for 7th Harmonic
7.07107
7.07 A
RMS Current for Sub- Harmonic
3.53553
3.53 A
CASE(1) V and I in phase (=0)
THD Voltage
0 V
0 V
THD Current
0.27386A
0.27 A
Real Power
16250 W
16.249 KW
Reactive Power
0 KVAR
0 KVAR
Apparent Power
16848.4VA
16.938KVA
Distortion Power
4440.25VAD
4812 VAD
Distortion Power Factor
0.964
0.96
Displacement Power Factor
1
1
Net Source Power Factor
0.964
0.96
Voltage Crest Factor
0
0
Current Crest Factor
0.2738
0.27
Ipeak
80A
89.94A
Vpeak
229.804V
229.80V
Case (2) I lags V by 30°
THD Voltage
0V
0V
THD Current
0.2738A
0.27A
Real Power
16250W
16.072 KW
Reactive Power
8.12KVAR
8.124KVAR
Apparent Power
16848.4 VA
16.938KVA
Distortion Power
4450.125 VAD
4812 VAD
0.964
0.96
1
0.86
0.964
0.82
0
0
Current Crest
0.273
0.27
Factor
Ipeak
90.07A
89.94A
Vpeak
229.81V
229.80V
Case (2) I leads V by 60°
THD Voltage
0V
0V
THD Current
0.2738A
0.27A
Real Power
18223W
18.124 KW
Reactive Power
0KVAR
0KVAR
Apparent Power
16848.4 VA
16.938KVA
Distortion Power
4450.125 VAD
4579 VAD
0.964
0.96
0.5
0.86
0.964
0.82
0
0
0.273
0.27
Ipeak
90.07A
89.94A
Vpeak
229.81V
229.80V
Case(3)
THD Voltage
0.03V
0.034V
THD Current
0.2738A
0.27A
Real Power
16250W
16.249 KW
Reactive Power
0KVAR
0KVAR
Apparent Power
16050.3 VA
16.856KVA
Distortion Power
4487.83 VAD
4812 VAD
0.936
0.9639
1
1
0.96
0.96
0.034
0.034
0.273
0.27
Ipeak
90.07A
89.94A
Vpeak
229.81V
237.61V
2. HARDWARE IMPLEMENTATION Test System I is selected as 3, 400V, 50Hz sinusoidal supply connected to 3 diode bridge rectifier feeding
i. Resistive Load
ii. RL Load
iii. DC Shunt Motor
Test System II is selected as 3, 400V, 50Hz sinusoidal supply connected to 3 thyristor converter feeding
i. Resistive Load
ii. RL Load

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Block Diagram
Fig-8. Block Diagram for Test Cases 1 and 2

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2.1 Test System 1 The connection diagram for test System I is selected as 3, 400V, 50Hz sinusoidal supply connected to 3 diode bridge rectifier feeding various loads is shown in Fig 9.
Fig-9. Equivalent Circuit for 3 Diode Bridge Rectifier with loads
2.1.1 Simulated Result-3 Diode Bridge Rectifier Feeding
2.1.1.1 Resistive Load
Fig-10 Simulated Output- 3 Diode Bridge Rectifier feeding Resistive Load The results obtained after simulation for test system (I) for 3 diode bridge rectifier feeding resistive load is shown below in Table 2. Here a resistor value of 100ohm 5A is used which resist the RMS currents up to 5A. The THD values of voltages are found to be lesser than that of currents as no harmonics are induced in voltage waveforms. Fig 10 displays the simulated output obtained using LabVIEW.

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Table 2: Simulated Results of obtained for 3 Diode Bridge Rectifier feeding Resistive Load
System Parameters
Simulated Results
R Phase
Voltage RMS
0.3390 V
Current RMS
4.6422 A
THD Current
0.2826 A
THD Voltage
0.0345 V
Real Power
1.5739 W
Y Phase
Voltage RMS
0.330 V
Current RMS
5.1878 A
THD Current
0.3033 A
THD Voltage
0.0473 V
Real Power
1.7280 W
B Phase
Voltage RMS
0.3588 V
Current RMS
5.0037 A
THD Current
0.2484 A
THD Voltage
0.039 V
Real Power
1.7958 W
TOTAL REAL POWER
5.0977 W
2.1.1.2 RL Load
Fig-11 Simulated Output- 3 Diode Bridge Rectifier feeding RL Load
Fig 11 displays the simulated output of 3 Diode Bridge Rectifier feeding RL Load Here the values of Resistor and Inductor are selected as R=100ohm, 5A L=390mH. The results obtained after simulation for test system(I) for 3 diode bridge rectifier feeding DC shunt motor load is shown below in Table 3. Here an inductor value of 390mH is used. As charging and discharging is involved in inductor the time constant will be more for a RL load. Table 3: Simulated Results for 3 Diode Bridge Rectifier feeding RL Load
System Parameters
Simulated Results
R Phase
Voltage RMS
2.6432 V
Current RMS
10.2069 A
THD Current
0.4592 A
THD Voltage
0.032 V
Real Power
27.2168 W
Y Phase
Voltage RMS
2.6896 V
Current RMS
10.2763 A
THD Current
0.4513 A
THD Voltage
0.0367 V
Real Power
27.6398 W
B Phase
Voltage RMS
2.7422 V
Current RMS
9.9741 A
THD Current
0.3969 A
THD Voltage
0.0498 V
Real Power
27.3921 W
TOTAL REAL POWER
82.2487 W

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2.1.1.3 DC Shunt Motor
Fig-12 Simulated Output- 3 Diode Bridge Rectifier feeding DC Shunt Motor The results obtained after simulation for test system (I) for 3 diode bridge rectifier feeding DC shunt motor load is shown below in Table 4. The simulated output of 3 diode bridge rectifier feeding DC shunt motor load is displayed in Fig 12. The output of the diode bridge rectifier is connected to the armature of the DC shunt motor. The DC supply is given to the shunt motor. The speed can be controlled by armature voltage controller.
Table 4: Simulated Results 3 Diode Bridge Rectifier feeding DC Shunt Motor
System Parameters
Simulated Results
R Phase
Voltage RMS
1.6811 V
Current RMS
8.2577 A
THD Current
0.1987 A
THD Voltage
0.022 V
Real Power
13.88 W
Y Phase
Voltage RMS
1.7268 V
Current RMS
7.8426 A
THD Current
0.2586 A
THD Voltage
0.045 V
Real Power
13.5428 W
B Phase
Voltage RMS
1.8028 V
Current RMS
8.3706 A
THD Current
0.2214 A
THD Voltage
0.0326 V
Real Power
15.0911 W
TOTAL REAL POWER
42.5161 W
2.2 Test System II Connection Diagram
Fig-13 Connection Diagram- Test system II 2.2.1 Simulated Result-3 Thyristor Converter Feeding ResistiveLoad Test System II is selected as 3, 400V, 50Hz sinusoidal supply connected to 3 thyristor converter feeding Resistive Load of 230ohm, 1.7Ampere is shown in Fig.14.

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Fig-14 Simulated Output- 3 Thyristor Converter feeding Resistive Load The results obtained after simulation for test system(II) for 3φ Thyristor Converter feeding Resistive Load is shown below in Table 5. The SCR’s are triggered at α=45° and it allows the current to flow through the circuit in forward- biased condition and reversed- biased condition. The resistive load used here resists the current up to 3A.
Table 5: Simulated Results- 3 Thyristor Converter feeding Resistive Load
System Parameters
Simulated Results
R Phase
Voltage RMS
0.5566 V
Current RMS
2.5181 A
THD Current
0.5155 A
THD Voltage
0.0174 V
Real Power
1.4017 W
Y Phase
Voltage RMS
0.5552 V
Current RMS
3.061 A
THD Current
0.4899 A
THD Voltage
0.0184 V
Real Power
1.699 W
B Phase
Voltage RMS
0.5559 V
Current RMS
2.5207 A
THD Current
0.503 A
THD Voltage
0.0149 V
Real Power
1.4014 W
TOTAL REAL POWER
4.5029 W
3. CONCLUSION AND FUTURE WORK Non-linear loads introduce harmonics that has many undesirable effects such as increased losses, thermal stress and reduced lifetime of the equipment on the power system. Hence power quality analysis / monitoring should be done in any system to avoid undesirable effects due to harmonics and also avoid some of the factors such as electromagnetic compatibility, voltage sag, flickers, transients, notching and interruptions. A background study of the graphical programming tool LabVIEW on power quality analysis was done. LabVIEW program for power quality analysis is formulated and its performance is verified with non-linear loads- 3 Diode Bridge Rectifier fed R-load, 3 Diode Bridge Rectifier fed DC shunt motor and 3 Diode Bridge Rectifier fed RL-load and 3 Thyristor converter fed R Load. The obtained results were verified with theoretical calculations. ACKNOWLEDGMENTS Firstly we would like to thank our department for having provided us with an opportunity to work on this project and enhance our technical knowledge and skills. This would not been a success without the guidance of the following people. We express our sincere gratitude to our guide Dr. M.R.SINDHU, Associate Professor Department of Electrical and Electronics Engineering, for her dedication and continuous support and sincere help and encouragement given during the entire project. We are very much grateful to express our sincere thanks to Dr. T.N PADMANABHAN NAMBIAR, Professor and to Dr. A.T. DEVARAJAN, Professor Department of Electrical and Electronics Engineering, for his constant support, suggestion and encouragement throughout the progress of the project.
We also like to extend our heartfelt thanks to the lab staffs of Power Electronics Lab and Electrical Machines Lab for their constant support and opportunity to utilize the lab

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facilities. Above all we would like to extend our special thanks to LORD ALMIGHTY for giving us strength and courage, and or PARENTS for their love and moral encouragement which lead us to complete the project successfully. REFERENCES
[1] Bath, S. K.; Kumra, S., "Simulation and Measurement of Power Waveform Distortions using LabVIEW," IEEE International Power Modulators and High Voltage Conference, Proceedings of the 2008, vol., no., pp.427, 434, 27- 31 May 2008.
[2] Laskar, Shahedul Haque; Muhammad, Mohibullah, "Power Quality Monitoring by Virtual Instrumentation using LabVIEW," Universities' Power Engineering Conference (UPEC), Proceedings of 2011 46th International, vol., no., pp.1,6, 5-8 Sept. 2011.
[3] Alves, R.; Goncalves, D.; Pinto, J.G.; Batista, J.; Afonso, J.L., "Development of an Electrical Power Quality Monitor based on a PC," Industrial Electronics, 2009. IECON '09. 35th Annual Conference of IEEE , vol., no., pp.3649,3653, 3-5 Nov. 2009
[4] Jing Chen; Tianhao Tang, "Power quality analysis based on LABVIEW for current power generation system," Power Electronics, Electrical Drives, Automation and Motion (SPEEDAM), 2012 International Symposium on , vol., no., pp.865,870, 20-22 June 2012
[5] Qiu Tang; Zhaosheng Teng; Siyu Guo; Yaonan Wang, "Design of Power Quality Monitoring System Based on LabVIEW," Measuring Technology and Mechatronics Automation, 2009. ICMTMA '09. International Conference on , vol.1, no., pp.292,295, 11-12 April 2009
[6] Wakileh, George J “Power systems harmonics: fundamentals, analysis, and filter design.” Springer, Berlin ; New York, 2001.
[7] Jovitha, Jerome, “Virtual Instrumentation Using LabVIEW”, PHI Pvt. Ltd., 2010.
[8] H E Wenhai, "Design of the Noise Testing System Based on LabVIEW," Computer Sciences and Convergence Information Technology, 2009. ICCIT '09. Fourth International Conference on , vol., no., pp.95,98, 24-26 Nov. 2009

Power quality analysis using lab view

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