Dr.V.V.Karthikeyan RESEARCH SEMINAR ON POWER QUALITY ISSUES 1

Presentation Overview  Introduction  Power Quality Issues  Possible Solutions for Power Quality Problems 2

Introduction  A perfect power supply, that is available within voltage and frequency tolerances, has a sinusoidal wave shape.  With proliferation of non-linear loads such as diode/thyristor rectifiers, non-sinusoidal currents degrade the power quality in power transmission/distribution systems.  The power quality, that is actually the voltage quality, is being addressed in most cases. 3

Introduction continued..  Interest in Power Quality has increased significantly over the last decade. The main reason for the awareness of the power quality problems is the load equipment which is more sensitive to power quality variations.  Modern load devices contain microprocessor based controls and power electronic devices that are sensitive to power disturbances.  The term “poor power quality” means that there is a sufficient deviation from standards that can cause equipment failure. Such deviations are due to non- linear loads in the system. 4

Power Quality Issues Sources of Harmonics Static Power Converters Arc furnaces, mine hoists loads Switched Mode Power Supplies (SMPS) PWM Drive Utility Interface with Distributed Energy Sources Problems due to Harmonics Problems on the customer side Problems on the utility side Consequences of harmonic distortion on equipments Power quality standards Possible solutions to power quality problems 5

Contents – Effects of power quality – Power Quality definitions revisited – What is needed for PQ monitoring ? – GE Multilin’s solution PQMII EPM9000 series – Summary Monitor and Analyze Power Disturbances, Disruptions & Harmonics

PQ is a Business Problem Power Quality issues cause business problems such as: – Lost 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.

Is Power Quality Such a Big Problem?

Why PQ is such 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

PQ Problems are Expensive – 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

Who is Affected? – Lost production – Scrap – Costs to restart – Labor costs – Equipment damage and repair – Other costs 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

PQ Definitions Revisited IEEE Categories Std Short Duration Variations Typical Duration Instantaneous Sag0.5 – 30 cycles Momentary Sag30 cycles – 3 sec Temporary Sag3 sec – 1 min

PQ Definitions Revisited IEEE Categories Std Short Duration Variations Typical Duration Instantaneous Sag0.5 – 30 cycles Momentary Sag30 cycles – 3 sec. Temporary Sag3 sec – 1 min. Instantaneous Swell0.5 – 30 cycles Momentary Swell30 cycles – 3 sec. Temporary Swell3 sec – 1 min.

PQ Definitions Revisited IEEE Categories Std Short Duration Variations Typical Duration Instantaneous Sag0.5 – 30 cycles Momentary Sag30 cycles – 3 sec. Temporary Sag3 sec – 1 min. Instantaneous Swell0.5 – 30 cycles Momentary Swell30 cycles – 3 sec. Temporary Swell3 sec – 1 min. Momentary Interruptions0.5 – 30 cycles Temporary Interruptions30 cycles – 3 sec.

PQ Definitions Revisited IEEE Categories Std Long Duration Variations Typical Duration Sustained interruptions> 1 min Under voltages> 1 min Over voltages> 1 min

PQ Definitions Revisited IEEE Categories Std Long Duration Variations Typical Duration Sustained interruptions> 1 min Under voltages> 1 min Over voltages> 1 min Voltage imbalanceSteady state Waveform Distortion

PQ Definitions Revisited IEEE Categories Std Long Duration Variations Typical Duration Sustained interruptions> 1 min Under voltages> 1 min Over voltages> 1 min Voltage imbalanceSteady state Waveform Distortion DC offsetSteady state HarmonicsSteady state Inter harmonicsSteady state For Electric Utilities Control of Voltage and Prevention of Outages is Power Quality

Sources of PQ Problems Utility Sources – Lightning – PF Correction Equipment – Faults – Switching Internal Sources Individual Loads –Lighting, Elevators, Coolers, HVAC Uninterruptible Power Supplies Variable Frequency Drives 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

PQ Problems and Possible Causes Typical problemsDisturbance TypePossible Causes Overheated neutral Intermittent lock-ups Frequency deviations Steady-stateShared neutrals Improper or inadequate wiring High source impedance SCR/Rectifiers and notching Harmonics

PQ Problems and Possible Causes Typical problemsDisturbance TypePossible Causes Overheated neutral Intermittent lock-ups Frequency deviations Steady-stateShared neutrals Improper or inadequate wiring High source impedance SCR/Rectifiers and notching Harmonics Interruption Garbled data Random increase in harmonics levels Utility faults Inrush currents Inadequate wiring

PQ Problems and Possible Causes Typical problemsDisturbance TypePossible Causes Overheated neutral Intermittent lock-ups Frequency deviations Steady-stateShared neutrals Improper or inadequate wiring High source impedance SCR/Rectifiers and notching Harmonics Interruption Garbled data Random increase in harmonics levels Utility faults Inrush currents Inadequate wiring Intermittent lock-ups Lights flicker Garbled data Sags/SwellSource voltage variations Inrush/surge currents Inadequate wiring

PQ Problems and Possible Causes Typical problemsDisturbance TypePossible Causes Overheated neutral Intermittent lock-ups Frequency deviations Steady-stateShared neutrals Improper or inadequate wiring High source impedance SCR/Rectifiers and notching Harmonics Interruption Garbled data Random increase in harmonics levels Utility faults Inrush currents Inadequate wiring Intermittent lock-ups Lights flicker Garbled data Sags/SwellSource voltage variations Inrush/surge currents Inadequate wiring Component failure Dielectric breakdown Lock-ups Garbled data Wavy CRTs Impulses EMI/RFI Lightning Load switching Capacitor switching Static discharge Hand-held radios Loose wiring/arcing

PQ Problems and Possible Causes Typical problemsDisturbance TypePossible Causes Overheated neutral Intermittent lock-ups Frequency deviations Steady-stateShared neutrals Improper or inadequate wiring High source impedance SCR/Rectifiers and notching Harmonics Interruption Garbled data Random increase in harmonics levels Utility faults Inrush currents Inadequate wiring Intermittent lock-ups Lights flicker Garbled data Sags/SwellSource voltage variations Inrush/surge currents Inadequate wiring Component failure Dielectric breakdown Lock-ups Garbled data Wavy CRTs Impulses EMI/RFI Lightning Load switching Capacitor switching Static discharge Hand-held radios Loose wiring/arcing Overheated transformers and motors Voltage and current distortions Garbled data Lock-ups HarmonicsElectronic loads SCR/rectifier

Major PQ Problems Source: EPRI, 1994 Spikes, 7% Sags, 56% Outages, 6% Swells, 31% Sags (Dips) Associated with system faults Switching of heavy loads Starting of large motors Swells System fault conditions Switching on a large capacitor bank Switching off a large load

Cost of Voltage Sags Textile Industry Plastics Industry Glass Industry Process Industry Semiconductors $1k$10k$100k$1M $10M Losses per Voltage Sag Event Source: EPRI “The Economics of Custom Power”, IEEE T&D Show 2003

Cost of Momentary Outages Momentary Outages create problems when computers and clocks reset, equipment stalls, and work stops.

Benefits of Continuous PQ Monitoring Continuous PQ Monitoring Detects, Records, and Leads to the Prevention of PQ Problems Power Quality monitoring provides a continuous “Health Check” of a facility’s power system … for example: o Harmonic interaction between loads and power conditioning equipment spotted o High Inrush currents from equipment startup detected o Transients from load switching are seen It provides data to see, diagnose and avert looming problems – “like squeaky brakes on a car” o Trends can be detected o JIT equipment maintenance programs can be established It acts like a “Black Box” on an airplane to tell you what, when, and where a Power Quality event occurred … to prevent it from reoccurring

What is needed for PQ Monitoring? PQ Monitors must detect and record the 7 types of PQ problems – Transients – Interruptions – Sag/Under Voltage – Swell/Over Voltage – Waveform Distortion – Voltage Fluctuations – Frequency Variations These include Flicker and Compliance to ITI(CBEMA), IEEE and ISO Standards Plus they must … Be easy to use Be Suitable for continuously monitoring indoors and outdoors Interface with standard PQ analysis Software…PQDif format Be fast enough to capture high speed events that produce equipment problems Have enough storage to save the waveforms you need Have PQ analysis tools that produce usable, actionable recommendations ITI: Information Technology Industry Council (Computer & Business Equipment Manufacturer’s Association)

Real Time Field Recorded Events Source: AGA Brazil Meter: EPM9650 Period: Jan 2005 – Dec 2005 Continuous Monitoring of the Station for PQ Problems

Finally… If You Can’t Measure it You Can’t Manage it If You Can Measure it You Can Manage it Thank you ….