score 2003 power quality basics

8/14/2019 SCORE 2003 Power Quality Basics

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SCORE 2003Short Course On Reliability &

Energy

Power Quality Basics


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Copyright 2003 Progress Energy Short Course On Reliability & Energy 2

PQ Basics

Terms and Definitions Causes of Events

Possible Mitigation Questions


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What is Power Quality

Any power problem manifested involtages, current, or frequencydeviations that results in failure or

misoperation of customer equipment.


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-150

-100

-50

0

50

100

150

0

Power Quality Measurement

Duration (Time) Cycles (.016 seconds per cycle)

Seconds, Minutes, Hours

Magnitude (Voltage level) Transient level I.e. = 1000 volts

RMS - Voltage level i.e. = 120 volts

Waveforms Distortions


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-200

-150

-100

-50

0

50

100

150

200

0

Magnitude and Duration

60 cycles/sec = 60 Hz

Duration

Time

Magnitude

VoltageLevel

169 volts

120 Volts RMS

One Cycle

.01666 seconds


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Terms and Definitions

Transient or Surge

Sag

Swell

Interruption

Outage

Harmonics





Duration

Steady State Condition


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Transient or Surge (Impulse)

Transient or Surge (Oscillatory)

Sag

Swell

Momentary Interruption

Interruption

Outage Harmonics

Unbalance

.00000005 -- .002 sec

.000005 -- .050 sec

.008 -- 1 min

.008 -- 1 min

.008 -- 3 sec

3 sec to 1 min

Greater than 1 min Steady State Condition


Duration


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What is Power Quality & Reliability?

0

100

200

300

400

500

0.000001 0.00001 0.0001 0.001 0.01 0.1 1 10 100

Time in Seconds

Per

centofNom

inalVoltag

e

Voltage Tolerance EnvelopeApplicable to Single-Phase120- Volt Equipment SWELL Region

Outage

Long

TermE

vent

ShortTermE

vent

T

ransient

Surge

Interruptions (


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A Transient can be classified into two categories,

impulsive and oscillatoryDuration < 50 ns to 50 ms .00000005 seconds to .002 seconds

.000005 seconds to .050 seconds

What is a Transient or Surge?


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This is the category that TVSS (Transient

Voltage Surge Suppressor) SPD equipmentis designed to mitigate.

Impulsive


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Sources of Transients

Lightning

Static

Arc Welding

Switching

Contactor

Relays SCRs


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Oscillatory (Low Frequency)


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Capacitor Bank Switch

Substation Bank Line Bank


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Voltage Sags


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Momentary Interruptions

Breaker Tripped


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Outage


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Causes of Sag, Interruptions Outages


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115 kV Substation

23k

VFeeder

Transformer

480 V

Customer

Transformer

480 V

Transformer

480 V

Transformer

480 V

Customer Customer

Customer

Fuse Fuse

Fuse Fuse

Fuse

Fuse

Feeder

Breaker

Simplified Utility SystemTransmission @ 115 kV

Transformer

Distribution @ 23 kV

Regulator

23k

VFeeder

23kVFeeder

Transformer

480 V

Customer

Transformer

480 V

Transformer

480 V

Transformer

480 V

CustomerCustomer

Customer

FuseFuse

FuseFuse

Fuse

Fuse

Feeder

Breaker

23k

VFeeder


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Example


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115 kV Substation

23k

VFeeder

Transformer

480 V

Customer

Transformer

480 V

Transformer

480 V

Transformer

480 V

Customer Customer

Customer

Fuse Fuse

Fuse Fuse

Fuse

Fuse

Feeder

Breaker

Simplified Utility System

Transmission @ 115 kV

Transformer

Distribution @ 23 kV

Regulator

23k

VFeeder

23k

VFeeder

Transformer

480 V

Customer

Transformer

480 V

Transformer

480 V

Transformer

480 V

CustomerCustomer

Customer

FuseFuse

FuseFuse

Fuse

Fuse

Feeder

Breaker

23k

VFeeder

Outage

Momentary Interruption

Sag


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Waveform Distortion

Harmonics Interharmonics

Voltage Balance Overvoltage

Undervoltage


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Wave Distortion


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Harmonics


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Voltage or Current Unbalance

Maximum Deviation from Average Voltage

Average Voltage

243 Volts RMS

241 Volts RMS

233 Volts RMS

X 100 (for Percent)

239 Average Volts

6

2392.5% Voltage UnbalanceX 100 =

EXAMPLE

Measured Voltages


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Customized Solutions

0

100

200

300

400

500

0.000001 0.00001 0.0001 0.001 0.01 0.1 1 10 100

Time in Seconds

PercentofNominalVoltage

Voltage Tolerance EnvelopeApplicable to Single-Phase120- Volt Equipment

SWELL Region

Outage

LongTermE

vent

ShortTermE

vent

Tr

ansient

Surge

Interruptions

SAG RegionUndervoltage

Overvoltage


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0

100

200

300

400

500

0.000001 0.00001 0.0001 0.001 0.01 0.1 1 10 100

Time in Seconds



SWELL Region

Outage

LongTermE

vent

ShortTermE

vent

Tr

ansient

Surge

Interruptions

SAG Region

TVSS or SPD

Line Reactors

Isolation Transformers

Undervoltage

Overvoltage


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0

100

200

300

400

500

0.000001 0.00001 0.0001 0.001 0.01 0.1 1 10 100

Time in Seconds



SWELL Region

Outage

LongTermE

vent

ShortTermE

vent

Tr

ansient

Surge

Interruptions

SAG Region

TVSS or SPD

Line Reactors


Power Conditioner

orCVTUndervoltage

Overvoltage


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0

100

200

300

400

500

0.000001 0.00001 0.0001 0.001 0.01 0.1 1 10 100

Time in Seconds



SWELL Region

Outage

LongTermE

vent

ShortTermE

vent

Tr

ansient

Surge

Interruptions

SAG Region

TVSS or SPD

Line Reactors


Power Conditioner

orCVTUndervoltage

Overvoltage

UPS

UPS

&

Genset


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IEEE 1159-1995Recommended Practice For Monitoring Electric Power Quality

Table 2 Categories and typical characteristics of power system

electromagnetic phenomena

Categories Typical Spectral Typical Durat ion Typical Voltage

Content Magnitude

1.0 Transient

1.1 Impulsive

1.1.1 Nanosecond 5 ns rise < 50 ns

1.1.2 Microsecond 1 us rise 50 ns - 1 m s

1.1.3 Millisecond 0.1 m s rise >1 m s

1.2 Oscillatory

1.2.1 Low frequency < 5 k Hz 0.3 - 50 m s 0 - 4 pu

1.2.2 Medium frequency 5 - 500 k Hz 20 us 0 - 8 pu1.2.3 High frequency 0.5 - 5 M Hz 5 us 0 - 4 pu

2.0 Short duration variations

2.1 Instantaneous

2.1.1 Sag 0.5 - 30 cycles 0.1 - 0.9 pu

2.1.2 Swell 0.5 - 30 cycles 1.1 - 1.8 pu

2.2 Momentary

2.2.1 Interruption 0.5 cycles - 3 s < 0.1 pu

2.2.2 Sag 30 cycles - 3 s 0.1 - 0.9 pu2.2.2 Swell 30 cycles - 3 s 1.1 - 1.4 pu

2.3 Temporary

2.3.1 Interruption 3 s - 1 min < 0.1 pu

2.3.2 Sag 3 s - 1 min 0.1 - 0.9 pu

2.3.3 Swell 3 s - 1 min 1.1 - 1.2 pu

3.0 Long duration variation

3.1 Interruption, sustained > 1 min 0.0 pu

3.2 Undervoltage > 1 min 0.8 - 0.9 pu

3.3 Overvoltage > 1 min 1.1 - 1.2 pu

4.0 Voltage imbalance steady state 0.5 - 2%

5.0 Waveform distortion

5.1 DC offset steady state 0 - 0.1%

5.2 Harmonics 0 - 100th H steady state 0 - 20%

5.3 Interharmonics 0 - 6 k Hz steady state 0 - 2%

5.4 Notching steady state

5.5 Noise broad-band steady state 0 - 1%

6.0 Voltage fluctuations < 25 Hz intermittent 0.1 - 7%

7.0 Power frequency variations < 10 s


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PQ Events

Questions?

score 2003 power quality basics

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