Power Quality Basics - Progress Energy Inc · Power Quality Measurement O Duration (Time) Cycles X...
Transcript of Power Quality Basics - Progress Energy Inc · Power Quality Measurement O Duration (Time) Cycles X...
Power Quality Basics
Presented by
Scott Peele PE
PQ Basics
Terms and DefinitionsSurge, Sag, Swell, Momentary, etc.
MeasurementsCauses of EventsPossible MitigationPQ ToolQuestions
Power Quality Measurement
Duration (Time) Cycles (.016 seconds per cycle)
Seconds, Minutes, HoursMagnitude (Voltage level)
Transient level I.e. = 1000 voltsRMS - Voltage level i.e. = 120 voltsWaveforms
Distortions
-150
-100
-50
0
50
100
150
0
-200
-150
-100
-50
0
50
100
150
200
0
Magnitude and Duration
60 Hertz/second
DurationTime
Mag
nitu
deV
olta
ge L
evel 169 volts120 Volts RMS
One Cycle .01666 seconds
Terms and Definitions
Transient or Surge SagSwellInterruptionOutageHarmonics
Magnitude and DurationMagnitude and Duration Magnitude and DurationMagnitude and DurationDurationSteadystate Condition
Duration
Transient or Surge Impulse
Transient or Surge oscillatory
SagSwellMomentary InterruptionInterruptionOutageHarmonicsUnbalance
.00000005 -- .002 seconds
.000005 -- .050 seconds
.008 -- 60 seconds
.008 -- 60 seconds
.008 -- 3 seconds3 seconds to 1 MinuteGreater than 1 Minute Steadystate ConditionSteadystate Condition
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
Perc
ent o
f Nom
inal
Vol
tage
Voltage Tolerance EnvelopeApplicable to Single-Phase120-
Volt EquipmentSWELL Region
Outage
Long
Ter
m E
vent
Shor
t Ter
m E
vent
Tran
sien
tSu
rge
Interruptions (<10% of Nominal)
SAG Region
What is a Transient or Surge?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
Impulsive
This is the category that TVSS (Transient Voltage Surge Suppressor) SPD equipment is designed to mitigate.
Sources of Transients
LightningStaticArc Welding
SwitchingcontactorrelaysSCR’s
Oscillatory (Low Frequency)
Capacitor Bank Switch
Substation Bank Line Bank
Voltage Sags
Momentary Interruptions
Breaker Tripped
Outage
Causes of Sag, Interruptions Outages
115 kV Substation
23 k
V Fe
eder
Transformer480 V
Customer
Transformer480 V
Transformer480 V
Transformer480 V
Customer Customer
Customer
Fuse Fuse
Fuse Fuse
Fuse
Fuse
FeederBreaker
Simplified Utility SystemTransmission @ 115 kV
Transformer
Distribution @ 23 kVRegulator
23 k
V Fe
eder
23 k
V Fe
eder
Transformer480 V
Customer
Transformer480 V
Transformer480 V
Transformer480 V
CustomerCustomer
Customer
FuseFuse
FuseFuse
Fuse
Fuse
FeederBreaker
23 k
V Fe
eder
Example
115 kV Substation
23 k
V Fe
eder
Transformer480 V
Customer
Transformer480 V
Transformer480 V
Transformer480 V
Customer Customer
Customer
Fuse Fuse
Fuse Fuse
Fuse
Fuse
FeederBreaker
Simplified Utility SystemTransmission @ 115 kV
Transformer
Distribution @ 23 kVRegulator
23 k
V Fe
eder
23 k
V Fe
eder
Transformer480 V
Customer
Transformer480 V
Transformer480 V
Transformer480 V
CustomerCustomer
Customer
FuseFuse
FuseFuse
Fuse
Fuse
FeederBreaker
23 k
V Fe
eder
Outage
Momentary Interruption
Sag
Time
Quick Trip
6-12 cycles
.3 -
2.0 seconds
13 cycles 15 seconds 35 seconds
lockout
Load Current
FaultInitiated
FaultCurrent
13 cycles
13 cycles
6-12 cycles
6-12 cycles
15 seconds
15 seconds
35 seconds
35 seconds
.3 -
2.0 seconds
.3 -
2.0 seconds
Faulted Feeder
Adjacent Feeder
100%
0%
100%
0%
Voltage
Voltage
FeederBreakerOperation
Substation Voltages During a Feeder Fault
68% Cleared on FirstQuick trip
27% Cleared on Secondand Third Relay
5% Goes to Lock Out
Steadystate Condition Waveform Distortion
HarmonicsInterharmonicsVoltage BalanceOvervoltageUndervoltage
Wave Distortion
Harmonics
Voltage or Current Unbalance =
Maximum Deviation from Average Voltage
Average voltage
243 Volts RMS241 Volts RMS233 Volts RMS
X 100 (for Percent)
239 Average Volts
6239 2.5% voltage unbalanceX 100 =
EXAMPLE
MeasuredVoltages
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
Perc
ent o
f Nom
inal
Vol
tage
Voltage Tolerance EnvelopeApplicable to Single-Phase120-
Volt EquipmentSWELL Region
Outage
Long
Ter
m E
vent
Shor
t Ter
m E
vent
Tran
sien
tSu
rge
Interruptions
SAG Region
TVSS or SPDLine Reactors
Isolation TransformersPower Conditioner
or CVT
UPS
UPS & Genset
IEEE 1159-1995Recommended Practice For Monitoring Electric Power Quality
Table 2 Categories and typical characteristics of power systemelectromagnetic phenomena
Categories Typical Spectral Typical Duration Typical VoltageContent 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 pu 1.2.3 High frequency 0.5 - 5 M Hz 5 us 0 - 4 pu2.0 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 pu 2.2.2 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 pu3.0 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 pu4.0 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
Power Quality Tool
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