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Power Quality Issues _Literature Survey
This document summarizes a literature review on power quality issues in industries. It was prepared by five students under the guidance of Prof. N.R. Bhasme. The document defines power quality and discusses various power quality problems such as disturbances, imbalance, distortion, fluctuations and flicker. It describes these problems in detail and lists their possible causes. It also discusses who is affected by power quality issues and how. The document covers monitoring of power quality parameters and the benefits of monitoring. It concludes by emphasizing that power quality issues can result in significant financial losses for businesses.
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Power Quality Issues _Literature Survey
- 1. Power Quality Issuesin Industries Under the guidance of Prof. N.R. Bhasme Ajay Sahu (BE09F03F027) Ketan Bhavsar(BE09F03F034) Dhammanand Bansode(BE09F03F048) Umeshsing Maher(BE09F03F052) Mithilesh Pohnerker(BE09F03F60) ______________________________________________________________________________
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- 3. Content • WHAT IS POWER QUALITY • PQ PROBLEMS • DESCRIPTION OF PQ PROBLEMS • WAVEFORMS:PQ DEFINITIONS • SOURCES OF PQ PROBLEMS • PQ PROLEMS & POSSIBLE CAUSES • WHO GET AFFECTED • HOW THEY AFFECT • HOW TO MONITOR • BENEFITS OF PQ MONITORING • CONCLUSION • REFERENCE ______________________________________________________________________________
- 4. What is PowerQuality? The term Power quality is used to describe the extent of variation of the voltage, current and frequency on the power system. The variation of voltage and current can either be in terms of magnitude or waveform shape/distortion. What Is Power Quality Monitoring? The best way to detect and diagnose the problems in electrical power system is called Power quality monitoring ______________________________________________________________________________
- 5. Why PQ issuch a Big Problem? – The sensitivity of today’s electronic equipment makes it susceptible to power disturbances – For some devices, a momentary disturbance can cause • scrambled data • interrupted communications • a frozen mouse • system crashes and equipment failure ______________________________________________________________________________
- 6. Power Quality Problems • 1.Disturbance I. Voltage sag II. Voltage interruption III. Voltage swell IV. Transient V. Voltage notch • 2.Imbalance • 3.Distortion • 4.Voltage fluctuation • 5.Voltage flickering ______________________________________________________________________________
- 7. Description • 1.Disturbances A disturbance is defined as the temporary deviation from the steady state waveform. • Voltage Sag Reduction in voltage magnitude for a short period of time. • Voltage interruption Voltage sag with 100% reduction in amplitude. ______________________________________________________________________________
- 8. • Voltage swell Increase in RMS voltage or current at the power frequency between 1.1 to 1.9 per unit for a duration of 8milisec to 1min. • Transient Voltage disturbance shorter than sag/swell and are caused by sudden changes in power system. • Voltage notch Periodic transient occurring within each cycle. ______________________________________________________________________________
- 9. • 2.Imbalance A situation in which voltage, frequency and phase all are different. • 3. Distortion It is generally expressed in terms of harmonics which are sinusoidal voltages or currents having frequency that are integer multiple of the frequency at which the supply system is designed to operate. ______________________________________________________________________________
- 10. • 4. Voltagefluctuation The rapid change in voltage magnitude in the allowable limit I.E., 95% to 105%. • 5.Voltage flickering The color occurring when the frequency of variation of light flux lies between few hertz and fusion frequency. ______________________________________________________________________________
- 11. PQ Definitions Revisited IEEE Categories Std 1159-1995 Short Duration Typical Variations Duration Instantaneous Sag 0.5 – 30 cycles Momentary Sag 30 cycles – 3 sec Temporary Sag 3 sec – 1 min ______________________________________________________________________________
- 12. PQ Definitions Revisited IEEE Categories Std 1159-1995 Short Duration Typical Variations Duration Instantaneous Sag 0.5 – 30 cycles Momentary Sag 30 cycles – 3 sec. Temporary Sag 3 sec – 1 min. Instantaneous Swell 0.5 – 30 cycles Momentary Swell 30 cycles – 3 sec. Temporary Swell 3 sec – 1 min. ______________________________________________________________________________
- 13. PQ Definitions Revisited IEEE Categories Std 1159-1995 Short Duration Typical Variations Duration Instantaneous Sag 0.5 – 30 cycles Momentary Sag 30 cycles – 3 sec. Temporary Sag 3 sec – 1 min. Instantaneous Swell 0.5 – 30 cycles Momentary Swell 30 cycles – 3 sec. Temporary Swell 3 sec – 1 min. Momentary Interruptions 0.5 – 30 cycles Temporary Interruptions 30 cycles – 3 sec. ______________________________________________________________________________
- 14. PQ Definitions Revisited IEEE Categories Std 1159-1995 Long Duration Typical Variations Duration Sustained interruptions > 1 min Under voltages > 1 min Over voltages > 1 min ______________________________________________________________________________
- 15. PQ Definitions Revisited IEEE Categories Std 1159-1995 Long Duration Typical Variations Duration Sustained interruptions > 1 min Under voltages > 1 min Over voltages > 1 min Voltage imbalance Steady state Waveform Distortion ______________________________________________________________________________
- 16. PQ Definitions Revisited IEEE Categories Std 1159-1995 Long Duration Typical Variations Duration Sustained interruptions > 1 min Under voltages > 1 min Over voltages > 1 min Voltage imbalance Steady state Waveform Distortion DC offset Steady state Harmonics Steady state Inter harmonics Steady state For Electric Utilities Control of Voltage and Prevention of Outages is Power Quality ______________________________________________________________________________
- 17. Who is Affected? • High Cost Facilities o Semiconductor plants o Pharmaceuticals o Data centers • Medium Cost Facilities o Automotive manufacturing o Glass plants o Plastics & Chemicals o Textiles
- 18. Sources of PQProblems Internal Sources • Utility Sources – Lightning • Individual Loads –Lighting, Elevators, Coolers, HVAC – PF Correction • Uninterruptible Power Supplies Equipment • Variable Frequency Drives – Faults – Switching • Battery Chargers • Large Motors During Startup • Electronic Dimming Systems • Lighting Ballasts (esp. Electronic) • Arc Welders, and Other Arc Devices • Medical Equipment, e.g. MRIs and X-Ray Machines • Office Equipment and Computers • Wiring ______________________________________________________________________________
- 19. PQ Problems andPossible Causes Typical problems Disturbance Type Possible Causes Overheated neutral Steady-state Shared neutrals Intermittent lock-ups Improper or inadequate wiring Frequency deviations High source impedance SCR/Rectifiers and notching Harmonics ______________________________________________________________________________
- 20. PQ Problems andPossible Causes Typical problems Disturbance Type Possible Causes Overheated neutral Steady-state Shared neutrals Intermittent lock-ups Improper or inadequate wiring Frequency deviations High source impedance SCR/Rectifiers and notching Harmonics Interruption Utility faults Garbled data Inrush currents Random increase in harmonics levels Inadequate wiring ______________________________________________________________________________
- 21. PQ Problems andPossible Causes Typical problems Disturbance Type Possible Causes Overheated neutral Steady-state Shared neutrals Intermittent lock-ups Improper or inadequate wiring Frequency deviations High source impedance SCR/Rectifiers and notching Harmonics Interruption Utility faults Garbled data Inrush currents Random increase in harmonics levels Inadequate wiring Intermittent lock-ups Sags/Swell Source voltage variations Lights flicker Inrush/surge currents Garbled data Inadequate wiring ______________________________________________________________________________
- 22. PQ Problems andPossible Causes Typical problems Disturbance Type Possible Causes Overheated neutral Steady-state Shared neutrals Intermittent lock-ups Improper or inadequate wiring Frequency deviations High source impedance SCR/Rectifiers and notching Harmonics Interruption Utility faults Garbled data Inrush currents Random increase in harmonics levels Inadequate wiring Intermittent lock-ups Sags/Swell Source voltage variations Lights flicker Inrush/surge currents Garbled data Inadequate wiring Component failure Impulses Lightning Dielectric breakdown EMI/RFI Load switching Lock-ups Capacitor switching Garbled data Static discharge Wavy CRTs Hand-held radios Loose wiring/arcing ______________________________________________________________________________
- 23. PQ Problems andPossible Causes Typical problems Disturbance Type Possible Causes Overheated neutral Steady-state Shared neutrals Intermittent lock-ups Improper or inadequate wiring Frequency deviations High source impedance SCR/Rectifiers and notching Harmonics Interruption Utility faults Garbled data Inrush currents Random increase in harmonics levels Inadequate wiring Intermittent lock-ups Sags/Swell Source voltage variations Lights flicker Inrush/surge currents Garbled data Inadequate wiring Component failure Impulses Lightning Dielectric breakdown EMI/RFI Load switching Lock-ups Capacitor switching Garbled data Static discharge Wavy CRTs Hand-held radios Loose wiring/arcing Overheated transformers and motors Harmonics Electronic loads Voltage and current distortions SCR/rectifier Garbled data Lock-ups ______________________________________________________________________________
- 24. Major PQ Problems Outages, 6% Spikes, 7% Swells, Sags, 56% 31% Swells Sags (Dips) System fault conditions Associated with system faults Switching on a large capacitor bank Switching of heavy loads Switching off a large load Starting of large motors ______________________________________________________________________________
- 25. How Do TheyAffect You • Motors stall • Computers crash • Production is affected • Equipment damaged • Product spoilage • ‘The lights go out’ ______________________________________________________________________________
- 26. How To MonitorPQ Parameters? POWER QUALITY PROBLEM SOLUTION VOLTAGE SAG UPS,DVR,CVT VOLTAGE INTERRUPTION UPS VOLTAGE SWELL UPS,POWER CONDITIONER TRANSIENT SVC VOLTAGE NOTCH SNUBBER CKT IMBALANCE PROTECTION SCHEME DISTORTION SERIES & SHUNT ACTIVE FILTER VOLTAGE FLUCTUATION SVC VOLTAGE FLICKERING VOLTAGE UNBALANCED RELAY ______________________________________________________________________________
- 27. Cost of VoltageSags Textile Industry Plastics Industry Glass Industry Process Industry Semiconductors $1k $10k $100k $1M $10M Losses per Voltage Sag Event ______________________________________________________________________________
- 28. Benefits Of PowerQuality Monitoring Direct Benefits / Technical Benefits • – Energy Savings • – Release of blocked capacity • – Reduced temperature rise • – Increased reliability / Life of equipment (e.g. Transformer, Motors, capacitors...) • – Reduced mal-function of equipment (e.g. Drives, Relays, Meters) Indirect / Regulatory Benefits • – Penalty savings / Incentives (e.g. Demand charges, Pf penalty) • – Tax benefits • – Compliance to standards & Regulations ______________________________________________________________________________
- 29. PQ is aBusiness Problem • Power Quality issues cause business problems such as cost productivity, idle people and equipment – Lost orders, good will, customers and profits – Lost transactions and orders not being processed – Revenue and accounting problems – Customer and/or management dissatisfaction – Overtime required to make up for lost work time According to Electric Light and Power Magazine, 30 to 40 Percent of All Business Downtime Is Related to Power Quality Problems. ______________________________________________________________________________
- 30. PQ Problems areExpensive – Berkeley Lab Study Estimates $80 Billion Annual Cost of Power Interruptions … Research News, Berkeley Lab, February 2, 2005 – $50 billon per year in the USA is lost as a results of power quality breakdowns …. Bank of America Report – A manufacturing company lost more than $3 million one day last summer in Silicon Valley when the “lights went out.” … New York Times January 2000 – “A voltage sag in a paper mill can waste a whole day of production - $250,000 loss” … Business Week, June 17,, 1996 – Half of all computer problems and one-third of all data loss can be traced back to the power line … Contingency Planning Research, LAN Times ______________________________________________________________________________
- 31. Conclusion • Disturbances place all businesses at risk both in terms of financial losses and energy efficiency so they should be taken seriously. • Power quality monitoring is very essential to get an uninterruptable and efficient power supply. ______________________________________________________________________________
- 32. References • Understanding Power Quality Problems – Voltage Sags & Interruptions, Math H J Bollen, Ieee Press. • An Integrated Approach To Power Quality Improvement, R Venkatesh & S R Kannan, - Et Power Tech 2001. • Solutions To The Power Quality Problem, Prof. Ray Arnold, iee Power Engineering Journal, April 2001 • Power Quality Issues A Distribution Company Perspective,iee Power Engineering Journal, April 2001 • Monitoring Power For The Future, Afroz K. Khan, ______________________________________________________________________________
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Editor's Notes
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