power quality fundamentals: the electric environment mark

Power Quality Fundamentals: The Electric Environment

Mark Stephens, PEManagerIndustrial Studies Electric Power Research Institute 942 Corridor Park Blvd Knoxville, Tennessee 37932 Phone 865.218.8022 [email protected]

Defining Power Quality

3© 2009 Electric Power Research Institute, Inc. All rights reserved.

Transmission Substation

Farm Service

120/240 Volts

Split Phase

Home Service

120/240 Volts

Split Phase

Commercial Service

120/208 Volts

3 Phase

Distribution Substation

Distribution Grid

7.2kV to 34.5kV

Industrial Service

2,400 Volts and

277/480 Volts

3 Phase

Sub-Transmission Grid

35kV to 138kV

Industrial Service

4,160 Volts

3 Phase

Transmission Grid

69kV to 765kV

Generation

Step-Up

Transformer

Generator Plant

20kV


IEEE-1159


Why is PQ Important?

•What happens to a manufacturing process when a power quality problem occurs?

•Who is to blame?

•How do we work together to fix the problems?


Interrelated Processes

Air Compressor

PowerSource

ProcessExhaust

PCWPump

PowerProcess

Mechanical

AutomatedProcess

InterlockedAutomated

Process

Is CompressedAir Present?

Is ProcessCooling Water

Present?

Are the ExahaustSystems Running?

Is PowerPresent?

Is InterlockedProcess Running?

Ok to RunAutomated

Process

CONTINUALLYREPEATED

StopAutomated

Process

NO

YES

NO

NO

NO

NO

YES

YES

YES

YES


What’ the Cost of Power Quality Problems?

Lets Take a Guess!Rank these from most expensive per event to

least….

• Paper• Food and Beverage• Automotive• Plastics• Semiconductor


Typical Reported Per Event Cost of PQ Disturbance

No. Process Reported

Cost Service Voltage Load 1 Semiconductor $1,500,000 69 kV 25 MW 2 Semiconductor $1,400,000 161 kV 30 MW 3 Semiconductor $ 700,000 12.5 kV 10 MW 4 Metal Casting $ 200,000 13.8 kV 16 MW 5 Chemical Plant $ 160,000 12.5 kV 5 MW 6 Pulp and Paper Mill $ 110,000 161kV 100 MW 7 Aerospace Engine Machining $ 100,000 13.8kV 10 MW 8 Food and Beverage $ 87,000 12.5 kV 5 MW 9 Chemical Plant $ 75,000 66kV 3 MW 10 Chemical Plant $ 75,000 66kV 5 MW 11 Electronic Components $ 75,000 12.5 kV 5 MW 12 Crystal Growth $ 60,000 12.5 kV 1 MW 13 Chemical Plant $ 46,175 66kV 30 MW 14 Wiring Manufacturing $ 34,000 12.5 kV 2 MW 15 Chemical Plant $ 18,000 12.5 kV 2 MW 16 Fibers Plant $ 15,000 12.5 kV 1 MW 17 Paper and Packaging $ 10,000 12.5 kV 4 MW 18 Plastic Bag Manufacturing $ 10,000 480V 4 MW 19 Plastics $ 7,500 12.5 kV 4 MW 20 Stainless Steel Manufacturing $ 5,500 12.5 kV 2 MW

Automotive Automotive Reported as high Reported as high as $700,000.as $700,000.


Power Quality Terms

• Outage (Interruption)• Momentary Interruption• Voltage Sag• Voltage Swell• Impulsive Transient• Oscillatory Transient• Steady State Voltage Variation

(over/under)• Single-Phasing• Voltage Imbalance• Voltage Harmonics

• Terms to Avoid• Blinks• Blips• Brownout• Blackout• Dips• Spikes• Dirty Power• Glitches


Understanding Dirty Power: Outage/Service Interruption

• Key Power Conditioning Technologies– UPS – Generator

• Key Outage Parameter– Duration of outage and frequency

of outage• Battery sizing• Generator Fuel Requirement


Understanding Dirty Power: Voltage Sag/Swell

• Key Power Conditioning Technologies– UPS – Capacitor Based UPS

– Dip Proofing Inverter

– Constant Voltage Transformer (CVT)– Dynamic Sag Corrector

• Key Parameter– Duration milliseconds to seconds– Voltage 10%-90% of nominal (Sag)– Voltage 110%-170% of nominal (Swell)

• Most voltage swells are 120-130% of nominal

Voltage swell Voltage sag


Voltage (%)

Yearly Sag and

Interruption Rate

FrequencyCumulativeFrequency

0 to 10 4.56 9.19% 9.19%10 to 20 0.48 1.08% 10.27%30 to 30 0.72 1.53% 11.80%30 to 40 1.56 3.08% 14.88%40 to 50 2.04 4.11% 18.99%50 to 60 3.12 6.23% 25.22%60 to 70 5.16 10.42% 35.64%70 to 80 9.6 19.39% 55.03%80 to 90 22.08 44.98% 100.00%

How Common are Sags and Interruptions?

Results of Three years Power Quality Monitoring at 277Power Distribution Sites in U.S. (EPRI DPQ Study)

Key result: For every 1 momentary interruption a customer will see 8 voltage sags


Reliability/Power Quality Myth 1

• Those annoying Sags, “brown-outs” and interruptions are due to insufficient utility capacity– especially when it occurs during peak summer

periods– perception strong in mature or rapidly developing

service areas– miss-information can add confusion


Reliability/Power Quality Reality 1

• Those annoying Sags and interruptions are most likely due to distribution faults and short circuits– interruptions (0 to 10% of nominal volts)

• momentary in duration (up to 5 minutes duration)• sustained or extended duration (> than 5 min.)

– voltage sags (10-90% of nominal volts)• resulting from fault clearing on parallel or “sister”

circuits


Targeting by Cause

Florida

Northwest US

EPRI Fault Study

Other

Construction activity

Vandalism

Ice/snow

Vehicle accident

Dig−in

Wind

Animal

Equipment failure

Tree contact

Lightning

0 5 10 15 20 25

Percent of faults by cause

0 5 10 15 20 25

FIGURE 7.1Tom Short, Electric Power Distribution Handbook, CRC Press, 2004


Effects of Voltage Sags

• Lights may or may not flicker

• Equipment shutdown or malfunction

• Can result in production downtime an/or product loss

-1

-0.5

0

0.5

1

0 1 2 3 4 5 6 7 8

Duration (4 Cycle)

Magnitude (50% of nominal)

(MagDur)


Outage or Sag ?

SagSag

OutageFault

Utility Substation

Customer ACustomer ACustomer BCustomer B

Customer CCustomer C


Voltage Sags - How Many Phases “sag”?

One Phase68%

Two Phases19%

Three Phases

13%

Source: EPRI Distribution Power Quality Study


Why Voltage Sags Occur...

• Line-to-Ground/Line-to-Line Faults Occuron the Utility System due to:

- Weather- Trees- Public Interference

• Internally induced plant events (starting of large high inrush load)

• Although the utility can reduce the number ofevents (tree trimming, root cause analysis)it is impossible to eliminate all voltage Sags.


Cause of Voltage Sags

Faults


Locations Where Animal Faults Occur

Structural failure

Unknown

Sectionalizers

Capacitors

Conductor jumping

Breakers

Switchgear

Insulator contamination

Grounded pole−top hardware

Regulators

Pole−top ground wires

Potheads at riser locations

Phase−to−phase conductor contacts

Cutouts

Surge arresters

Reclosers

Jumper wires contacts

Phase−to−neutral contacts

Transformers

0 10 20 30Percentage of utilities listing the item

as a top−five outage−frequency problem

0 10 20 30

Data source: EPRI TE-114915


Vehicle Caused Event


Storm, Lightning and Wind Caused Outages


Vandalism Caused Event


Reliability/Power Quality Myth 2

• Utility reliability is getting worse– customers claim never having as many problems in the

past– did not have these problems somewhere else– customer peer comparison may drive belief that reliability

to their site has worsened– overall belief that cost cutting, down-sizing, and other

initiatives can have a negative effect


Reliability/Power Quality Reality 2

• Electric power has been and will be into the foreseeable future an analog technology– vs. the major advantages which digital technologies have

fostered as a whole

• However at the same time, industry expectations continue to rise– automation, just in time processes, reduced manpower,

tighter margins, global economy


Voltage Sags Come In All Shapes & Sizes

• Lights may or may not flicker

• Tools shutdown or malfunction

• Can result in production downtime an/or product loss

-1

-0.5

0

0.5

1

0 1 2 3 4 5 6 7 8

Duration (4 Cycle)

Magnitude (50% of nominal)


150.0V

75.0V

0.0V105.83 ms/div0.00ns 2.12sec

RMS Sag Disturbance PQPager/3100 PQNode

Circuit Foil, USA 01/13/2003 10:18:27.00 AM

Three Phase Delta

1V2V3V


150.0V

75.0V

0.0V105.83 ms/div0.00ns 2.12sec


LEO 8032 01/03/2003 10:58:44.00 AM

Three Phase Wye

1V2V3V


150.0V

75.0V

0.0V105.83 ms/div0.00ns 2.12sec


LEO 8032 02/04/2003 10:39:28.00 AM

Three Phase Wye

1V2V3V


200.0V

100.0V

0.0V105.83 ms/div0.00ns 2.12sec


LEO 8032 04/29/2003 06:55:20.00 AM

Three Phase Wye

1V2V3V


150.0V

75.0V

0.0V105.83 ms/div0.00ns 2.12sec


LEO 8032 02/04/2003 01:25:22.00 PM

Three Phase Wye

1V2V3V


SARFI

• System Average RMS (Variation) Frequency Index

• Typically normalized to per site/per year data

T

ix N

NSARFI ∑=


Distribution Power Quality Study Part II

AggregationPeriod SARFI-70 SARFI-50 SARFI-10 SARFI-ITIC SARFI-

SEMI

60 seconds 13.69 5.74 0.91 13.91 8.29

5 minutes 13.02 5.49 0.83 13.17 7.81

1 day 9.84 4.49 0.62 9.84 5.95

DPQ II All Sites


DPQ II ResultsIEEE 1346 Contour Chart Format

½ to

1 c

yc

2 cy

c

3 cy

c

4 cy

c

5 cy

c

6 cy

c

10 c

yc

20 c

yc

30 c

yc

1 se

c

2 se

c

5 se

c

10 s

ec

30 s

ec

60 s

ec

120

sec

510152025303540455055606570758085

Sag Coordination ChartAll-Sites, One-Minute Aggregate Window

36-3834-3632-3430-3228-3026-2824-2622-2420-2218-2016-1814-1612-1410-128-106-84-62-40-2

VoltageMagnitude (%)

DurationEvents perSite per Year


Duration Voltage (%) 1 cyc 2 cyc 3 cyc 4 cyc 5 cyc 6 to 10

cyc 10 to 20

cyc 20 cyc to 0.5 sec

0.5 to 1 sec

1 to 2 sec 2 to 5 sec > 5 sec > 5 sec 10 to 30 sec

0.5 to 1 min

1 to 2 min

0 to 10 4.0% 14.9% 26.6% 36.4% 43.0% 61.0% 81.0% 86.0% 90.0% 92.8% 93.7% 96.9% 98.9% 99.2% 99.2% 100.0% 10 to 20 4.0% 14.9% 26.5% 36.3% 43.0% 60.5% 80.6% 85.8% 89.7% 92.2% 93.6% 95.6% 98.6% 99.0% 99.2% 99.3% 20 to 30 4.0% 14.9% 26.5% 36.2% 42.9% 60.0% 79.9% 85.6% 89.6% 92.0% 93.5% 95.5% 98.6% 99.0% 99.2% 99.3% 30 to 40 4.0% 14.8% 26.3% 36.1% 42.7% 59.5% 79.1% 85.4% 89.4% 91.8% 93.5% 95.5% 98.5% 99.0% 99.2% 99.3% 40 to 50 4.0% 14.7% 26.0% 35.8% 42.5% 58.7% 77.9% 85.1% 89.1% 91.6% 93.4% 95.5% 98.5% 99.0% 99.2% 99.3% 50 to 60 3.9% 14.3% 25.4% 35.3% 41.9% 57.0% 76.0% 84.5% 88.6% 91.4% 93.3% 95.3% 98.3% 99.0% 99.2% 99.3% 60 to 70 3.6% 13.3% 23.8% 34.5% 41.1% 54.8% 73.8% 83.9% 88.1% 91.2% 93.2% 95.0% 98.0% 98.9% 99.2% 99.3% 70 to 80 2.9% 10.7% 21.4% 32.9% 40.2% 52.2% 71.6% 83.4% 87.4% 90.8% 93.1% 94.5% 97.6% 98.9% 99.2% 99.3% 80 to 85 1.5% 6.6% 17.5% 29.7% 38.4% 47.3% 65.2% 82.0% 86.5% 90.4% 92.9% 94.1% 97.2% 98.9% 99.2% 99.3%

DPQ II ResultsEquipment Design Guidance

Based on DPQII data, a piece of equipment would ride through 76% of all events in one year if it could withstand a 50% for 20 cycles.

Based on DPQII data, a piece of equipment would ride through 76% of all events in one year if it could withstand a 50% for 20 cycles.


Guideline for Equipment Short Duration Interruption Immunity Requirement

0.3%

0.6%

1.6%

2.3%

2.6% 5.2

% 10.0% 15

.2% 19.4%

83.8%

92.9%

98.7% 99

.7%10

0.0%

100.0

%

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1 cyc 2 cyc 3 cyc 4 cyc 5 cyc 6 to 10cyc

10 to20 cyc

20 cycto 0.5sec

0.5 to 1sec

1 to 2sec

2 to 5sec

5 to 10sec

10 to30 sec

0.5 to 1min

1 to 2min

Short Duration Interruptions

Per

cent

(%) o

f Sho

rt D

urat

ion

Inte

rrup

tion

Eve

nts

Avo

ided

/Yea

r

Momentary Interruption Design Guideline


Plant in Industrial Park Fed from Distribution System In South

0102030405060708090

100

0 5 10 15 20 25 30 35 40 45 50 55 60

Duration (Cycles)

%Vn

omin

al

SEMI F47 ITIC %Vnom


Overlay of PQ Data with Equipment Susceptibility

0102030405060708090

100

0 5 10 15 20 25 30 35 40 45 50 55 60

Duration (Cycles)

%Vn

omin

al

%Vnom PLC with AC PS Ice Cube Relays AC Digital Inputs


Total Events: 16Events Violating ITIC Low er Curve: 11Events Violating ITIC Upper Curve: 0

0.0

0.5

1.0

1.5

2.0

2.5

0.001 0.01 0.1 1 10 100 1000

Duration (seconds)

Vol

tage

Mag

nitu

de (p

u)

ITIC Magnitude-Duration Scatter Plot

PQView®

Distribution Fed Customer with Lots of Distribution Fed Customer with Lots of Exposure (North East)Exposure (North East)


Transmission Fed Data from 15 U.S. Plants(from SEMI Task Force Work)

Disturbance DataAll Semiconductor Sites

0%10%20%30%40%50%60%70%80%90%

100%110%

1 10 100 1000Duration (cycles)

Perc

ent o

f Nom

inal

Vol

tage


Duration of Events From Transmission

Source: SEMI Power Quality and Equipment Ride-Through Task Force

InternalTask Force Report: SEMI9804


Magnitude of Events From Transmission

Source: SEMI Power Quality and Equipment Ride-Through Task Force

InternalTask Force Report: SEMI9804


Conclusions

• Perfect Power Quality is not attainable.

• The Voltage Sag is the most common power quality problem effecting industrial customers.

• The majority of these events are mostly short in duration (less than 200ms) Sagging from from 10% to 50%.

• EPRI studies show that most events are severe on a single-phase only on utility side.

• Power Quality data indicates that SEMI F47 compliant equipment will lead to fewer process upsets and equipment shutdowns.

power quality fundamentals: the electric environment mark

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