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

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Dr.V.V.Karthikeyan

RESEARCH SEMINAR ON POWER QUALITY ISSUES

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Presentation Overview

Introduction Power Quality Issues Possible Solutions for Power Quality Problems

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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.

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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.

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Power Quality IssuesSources of HarmonicsStatic Power ConvertersArc furnaces, mine hoists loadsSwitched Mode Power Supplies (SMPS)PWM Drive Utility Interface with Distributed Energy SourcesProblems due to HarmonicsProblems on the customer sideProblems on the utility side Consequences of harmonic distortion on equipmentsPower quality standards Possible solutions to power quality problems

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 Facilitieso Semiconductor plantso Pharmaceuticalso Data centers

• Medium Cost FacilitiesoAutomotive manufacturingoGlass plantsoPlastics & ChemicalsoTextiles

PQ Definitions RevisitedIEEE CategoriesStd 1159-1995

Short Duration Variations

Typical Duration

Instantaneous Sag 0.5 – 30 cycles

Momentary Sag 30 cycles – 3 sec

Temporary Sag 3 sec – 1 min



Typical Duration


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.



Typical Duration


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.


Long Duration Variations

Typical Duration

Sustained interruptions

> 1 min

Under voltages > 1 min

Over voltages > 1 min



Typical Duration


> 1 min



Voltage imbalance Steady state

Waveform Distortion



Typical Duration


> 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

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 CausesTypical problems Disturbance Type Possible Causes

Overheated neutralIntermittent lock-upsFrequency deviations

Steady-state Shared neutralsImproper or inadequate wiringHigh source impedanceSCR/Rectifiers and notchingHarmonics




InterruptionGarbled dataRandom increase in harmonics levels

Utility faultsInrush currentsInadequate wiring






Intermittent lock-upsLights flickerGarbled data

Sags/Swell Source voltage variationsInrush/surge currentsInadequate wiring








Component failureDielectric breakdownLock-upsGarbled dataWavy CRTs

ImpulsesEMI/RFI

LightningLoad switchingCapacitor switchingStatic dischargeHand-held radiosLoose wiring/arcing








Component failureDielectric breakdownLock-upsGarbled dataWavy CRTs

ImpulsesEMI/RFI

LightningLoad switchingCapacitor switchingStatic dischargeHand-held radiosLoose wiring/arcing

Overheated transformers and motorsVoltage and current distortionsGarbled dataLock-ups

Harmonics Electronic loadsSCR/rectifier

Major PQ Problems

Source: EPRI, 1994

Spikes, 7%

Sags, 56%

Outages,

6%

Swells,

31%

Sags (Dips)Associated with system faults

Switching of heavy loadsStarting of large motors

SwellsSystem fault conditions

Switching on a large capacitor bankSwitching off a large load

Cost of Voltage SagsTextile 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.

Category Minimum MaximumIndustrialSemiconductor Manufacturing $20.0 $60.0Electronics $8.0 $12.0Automobile Manufacturing $5.0 $7.5Pharmaceutical $5.0 $50.0Glass $4.0 $6.0Rubber and Plastics $3.0 $4.5Petrochemical $3.0 $5.0Food Processing $3.0 $5.0Textile $2.0 $4.0Metal Fabrication $2.0 $4.0Mining $2.0 $4.0Paper $1.5 $2.5Printing(Newspapers) $1.0 $2.0

CommercialHospitals, banks, civil service $2.0 $3.0Communications, information processing $1.0 $10.0Resturants, bars, hotels $0.5 $1.0

Commercial shops $0.1 $0.5Source: EPRI “The Economics of Custom Power”, IEEE T&D 2003

Cost of Momentary Interuption($/kW Demand)

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 detectedo 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 ….

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

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