PTD H 1TM / Re 12-2005 1

Power Transmission and Distribution

High Voltage

The Key Question …

Power Quality Power Quality

or or LowLow--CostCostEnergy ?Energy ?

PTD H 1TM / Re 12-2005 1

PTD H 1TM / Re 12-2005 2

Power Transmission and Distribution

High Voltage

Power Quality - Terms and Definitions

Short InterruptionsVoltage SagsOvervoltages

FlickerHarmonicsUnbalances

Voltage Fluctuations

Supply Reliability

System Outagescausing Supply

Interruptions

System Faults Load DisturbancesSystem Faults

Power Quality

Voltage Quality

PTD H 1TM / Re 12-2005 3

Power Transmission and Distribution

High Voltage

Power Quality - Influencing Factors

Qualität

tatsächlicherQualitätslevel

EinflußgrößenM

anag

emen

tO

rgan

izat

ion

App

lied

Tech

nolo

gy

Prot

ectio

n C

once

pt

Mai

nten

ance

Prot

ectio

n S

ettin

gs

Syst

em P

lann

ing

Staf

f

Net

wor

k St

ruct

ure

Doc

umen

tatio

n

Erec

tion

&In

stal

latio

n

Load

For

ecas

t

Cos

t Man

agem

ent

Com

mun

icat

ion

Syst

em

Power Quality

Influencing Variables

actual Level of Quality Weak-

Point Analysis essential

PTD H 1TM / Re 12-2005 4

Power Transmission and Distribution

High Voltage

Distribution System Enhancement – High Reliabilitythrough Redundancy

No Back-up(Repair: Days)

Back-up with Switch-Over(short Interruption: ≤ 1 s)

Infeed

Circuit Breaker

Disconnector

Loads

Back-up without Transition(no Interruption)

PTD H 1TM / Re 12-2005 5

Power Transmission and Distribution

High Voltage

Example 1998 - Unavailability [min / Customer / Year] and Electricity Tariff [ Pf. / kWh]

0

50

100

150

200

250

300

350

400

S N GR GB B F IRL E D I

Una

vaila

bilit

ym

in /

Cus

tom

er /

Yea

r

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

10.0

11.0

12.0

Ele

ctric

ity T

ariff

Pf.

/ kW

h

Unavailability

Electricity Tariff

Sources:[1] ETG im VDE: Qualität

der Stromversorgung.dialog (1998) Heft 1, S.21

[2] Strohschein, H.: Liberalisierungdes Strom- und Gasmarktesaus Sicht der Industrie.FGE-Kolloquium des IAEWder RWTH Aachen, 05.02.1998

PTD H 1TM / Re 12-2005 6

Power Transmission and Distribution

High Voltage

Utility Voltage Sag Analysis

Based upon a composite of 222 monitoring Sites of the EPRI DistributionPower Quality Project (EPRI RP3098-01) during 6/93 to 6/94

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

>0.80.6 to 0.8

0.4 to 0.60.2 to 0.4

0.0 to 0.2

Duration (sec)

5

4

3

2

1

0

Magnitude (%)

Source: IEEE Industry Application Magazine Jan./Feb.96

PTD H 1TM / Re 12-2005 7

Power Transmission and Distribution

High Voltage

ITI Curve (former CBEMA)Vo

ltage

in %

Disturbance Duration

1 µs 1 ms 10 ms 100 ms 1 s 10 s 100 s

Typical Conditions,which lead to anOutage of the Facility

Causes of Voltage Sags & Interruptions• Lightning Faults• Insulator Failures• Structural Failures• Accidents• Switching Operations• Equipment Failures• System Stability Osc.• Reclosures• System Collapse

Causes of Voltage Sags & Interruptions• Lightning Faults• Insulator Failures• Structural Failures• Accidents• Switching Operations• Equipment Failures• System Stability Osc.• Reclosures• System Collapse

Source: Information Technology Industry Council, www.itic.org

PTD H 1TM / Re 12-2005 8

Power Transmission and Distribution

High Voltage

Power Quality - Acceptable Power Supply Interruptions

Source: PTD SE PT, 2000

101

102

103

104

105

106

Systems

InstantaneousReserve

Industrial Systems

AutomaticChangeover

Larger Industry,DepartmentStores,Residential Areas

Households,Farmers,Small Industry

Remote Manual Switching(with available EmergencyPower Supply)

Local ManualSwitching

10 ms 100 ms 1 sec 1 minute 1 dayTime of Interruption

1 hour

Loss

of P

ower

/kW

PTD H 1TM / Re 12-2005 9

Power Transmission and Distribution

High Voltage

Power Quality - Economic Impact on the Customers

Textile Industry

Plastic Industry

Glass Industry

Industry with specialized Processes

Semiconductor Industry

$10k$1k $100k $1M $10M

Costs/USD perVoltage Sag

Source: PTD SE PT, 2001

PTD H 1TM / Re 12-2005 10

Power Transmission and Distribution

High Voltage

Economic Losses (US$) of Supply Outages in Semiconductor Industry

Source: Anderson Consulting, 1999

$ 7 m per Year

$ 1.5 m per Day

$ 100-200 k per Hour

Average of 6 - 17 Interruptions per Year

Total Losses $ 1.6 bn – worldwide (> 200 Chip Factories)

per Plant

PTD H 1TM / Re 12-2005 11

Power Transmission and Distribution

High Voltage

Impact of System Disturbances on Power Quality

Type of Disturbance Possible Causes ConsequencesVoltage Dips Successfully cleared

FaultStart-up of large Motors

Shutdown of Equipment, particularly Electronic Devices

Overvoltages Load Rejection May harm Equipment with inadequate Design Margin

Harmonics, harmonic Distortions

Non-linear Loads

Resonances

Voltage Distortion causes additional Heating in MotorsMisoperation of Electronic Devices

Flicker, Voltage Fluctuations

Start-up of large MotorsElectric Arc Furnaces

Weakening of ComponentsMalfunctionsAnnoyance of People

Transient Overvoltages

Lightning StrikeSwitching Events

Misoperation of Electronic DevicesReduced Lifetime of EquipmentInsulation Failure

Supply Interruptions System Faults Shutdown of EquipmentMisoperation of Electronic Devices

Phase Unbalances Unbalanced Loads Risk of Disconnection of the overloaded PhaseMachine Overheating

PTD H 1TM / Re 12-2005 12

Power Transmission and Distribution

High Voltage

Consequences

An example of Flicker: Voltage Swings through Motor Drives

PTD H 1TM / Re 12-2005 13

Power Transmission and Distribution

High Voltage

Harmonic Measurements in an Office Building

Time

%of

Nom

inal

Vol

tage

PTD H 1TM / Re 12-2005 14

Power Transmission and Distribution

High Voltage

Power Quality Problems affecting the Load

Voltage Sags

Harmonics

Pre-Distortions

Voltage UnbalancesNetwork Load

PTD H 1TM / Re 12-2005 15

Power Transmission and Distribution

High Voltage

Power Quality Problems caused by the Load

Network LoadHarmonics Currents

Flicker

Reactive Power

Unbalances