power quality

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GRIDTechnical Institute

Power Quality Monitoring

> Power Quality Monitoring: Basic Principles and Application Examples2

Measure of disruptions in the power supply

Availability

Reliability

Power Quality Events recorded to an existing standard

Power System Analysis

What is Power Quality?

M571 Compact Disturbance Recorder

> Power Quality Monitoring: Basic Principles and Application Examples3

Power Quality Standards

Some existing Power Quality standards

EN 50160 Standard (Europe)

IEEE 1159 Recommended Practice (North America)

NRS-048 standards (South Africa)

also ITIC (CBEMA) curve for computer equipment

Defining the technical criteria for voltage quality

> Power Quality Monitoring: Basic Principles and Application Examples4

Power Quality definitions: Dips and Surges

Voltage dips

Amplitude and duration

0

20

40

60

80

100

120

110%

100%

90%

Time

Surge/Swell - Above 110% of Nominal value

Dip/Sag - Below 90% of Nominal Value

Short time 1min to 60min

Very Short time 1 sec to 1min duration

RMS Value calculated over 10 minute period

> Power Quality Monitoring: Basic Principles and Application Examples5

Power Quality definitions: DISDIP

Distribution of Dips Report

Tabular distribution of dip events

> Power Quality Monitoring: Basic Principles and Application Examples6

ITIC CurvePower Quality Envelope

ITIC Curve: 1996

0%

50%

100%

150%

200%

250%

300%

350%

400%

450%

500%

0 3 20 500 10000

Rating

Time mS

Voltage tolerance

ITIC (CBEMA) Curve revised 1996

Single phase IT operating parameters

Swells or Overvoltage: rating very short over 110%(towards 0ms)

Sags or Undervoltage: rating very short under 70% (500ms) Financial Costs

> Power Quality Monitoring: Basic Principles and Application Examples7

Power Quality definitions: Interruptions

Voltage interruptions

Amplitude and duration

Interruption below 1% of Nominal value EN50160

Interruption below 10% of Nominal value IEEE 1159

Time duration depends on equipment tolerance, generally more than 1 cycle

0

20

40

60

80

100

120

110%

100%

90%

10%

1%

InterruptionTime

> Power Quality Monitoring: Basic Principles and Application Examples8

Power Quality definitions: Harmonics and Signalling voltages

Voltage harmonics

Losses proportional

to Frequency 2

Total Harmonic Distortion (THD%)

Measured according IEC 61000-4-7

Measure every 200ms using FFT, 10min RMS average

Signalling voltages, 3 sec RMS average

0%

2%

4%

6%

8%

10%

12%

50HZ

63HZ

100H

Z

153H

Z

200H

Z

Limit

> Power Quality Monitoring: Basic Principles and Application Examples9

Power Quality definitions: Flicker

Voltage flicker

Severity

Time

Measured according IEC 61000-4-15, over a 2hour period (Plt) over a 10 min period (Pst)

Modulation of the RMS voltage that can be seen by the human eye ~8.8HZ

Classified by a severity index:1 = good

<1 = better

>1 = worse

0

20

40

60

80

100

120

110%

100%

90%

> Power Quality Monitoring: Basic Principles and Application Examples10

Power Quality definitions: Unbalance

Voltage unbalance

Percentage

Time

Where the voltage vectors do not add to zero

Where the voltage magnitudes are unequal

10 minute average of RMS values

0

20

40

60

80

100

120

110%

100%

90%

Time

> Power Quality Monitoring: Basic Principles and Application Examples11

Power Quality definitions: Frequency

Frequency change

Swiss- Italian Fault September 2003

EN 50160 : 50 Hz +4% / -6%

NRS048 : ±2.5% for grid network

> Power Quality Monitoring: Basic Principles and Application Examples12

Sources of poor Power Quality

Power Quality flows

Power Quality as a polluter

Sources:

Industrial sites

Domestic rural sites

Utility network

Exported to others

Imported from others

Circulate within the site

> Power Quality Monitoring: Basic Principles and Application Examples13

Cause and Effect of poor Power Quality 1

Dips / Sags

Remote fault, load switching

Trips, process control restarting, motors stalling

Surges / Swells

Lightning strikes, arcing and switching

Trips, damage to insulation and winding, destruction of sensitive devices

Interruption

Faults, equipment failure, protection operation

Production down time

Financial costs

> Power Quality Monitoring: Basic Principles and Application Examples14

Cause and Effect of poor Power Quality 2

Voltage Variation

Load variation (e.g. welding, furnaces..)

Trips, damage to insulation and winding

Harmonics and Interharmonics

Power electronics, non-linear loads; signalling voltages

Equipment mal-operation, damage to motors, generators and transformers

Flicker

Load variations at a particular frequency(e.g. arc furnaces..)

Noticable effects in the lighting

Financial costs

> Power Quality Monitoring: Basic Principles and Application Examples15

Cause and Effect of poor Power Quality 3

Voltage Unbalance

Unbalanced Load variation

Overheating in motors and generators

Frequency

Loss of generation, governors

Generator trip (extreme)

Financial costs

> Power Quality Monitoring: Basic Principles and Application Examples16

Why monitor Power Quality? 1

SUPPLIERS

Network Planning

• accurate forecast of demand

• load profiling

• optimise transformer load

• optimise PQ remedy location

Legislation (de-regulated energy markets)

Monitor Consumers

Proactively respond to complaints

Asset management and customer care

> Power Quality Monitoring: Basic Principles and Application Examples17

Why monitor Power Quality? 2

CONSUMERS

Identify source of PQ problems

Reduce Financial Costs

• Lost production

• Replacement of equipment

Reduce Operational Costs

• Interruption of services

• Working environment (Flicker)

Compliance

• With supply agreements

Asset management and customer care

> Power Quality Monitoring: Basic Principles and Application Examples18

Most prevalent Power Quality problems

0

10

20

30

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Eq

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Dat

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PF

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Pro

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wh

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chin

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ads

Ove

rhea

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Neu

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Pro

ble

m w

oth

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Nu

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Uti

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Met

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s

Industry Utility

European Copper Institute (2001): 1400 sites in 8 countries

> Power Quality Monitoring: Basic Principles and Application Examples19

Financial cost of poor Power Quality

Semi conductor Industry 3,800

Financial Trading 6,000 per hour

Computer centre 750

Telecommunications 30 per minute

Steel Works 350

Glass Industry 250

Typical financial loss per event € ‘ 000s

> Power Quality Monitoring: Basic Principles and Application Examples20

Power Quality Benefits

SUB TRANSMISSION

DISTRIBUTION

SECONDARY DISTRIBUTION

LV NETWORK

G

G

G

G

G

SECONDARY (RURAL)DISTRIBUTION

HeavyIndustry

Medium Industry

Light Industry

POW GEN

IPPPOW GEN

IPP

Renewable Sources/IPP/ Municipal

CO-GENDOMESTIC

URBANTRANSFORMERS

CHEMICAL PLANTS

STEEL WORKS

GRID LOAD FLOW IMPROVEMENT

END USER VOLTAGE IMPROVEMENT

DEFINED IN PQ STANDARDS

DEFINED BY PLANNING LEVELS

TRANSMISSION NETWORK

> Power Quality Monitoring: Basic Principles and Application Examples21

Solutions: Improving Power Quality

UN-INTERRUPTIBLE POWER SUPPLIES

Dips, surges, spikes and interruptions

EARTHING PRACTICES

Harmonics

FILTERS (passive and active)

Harmonics

STATIC VAR COMPENSATION (SVC)

Dips, surges and Power Factor

FERRO-RESONANCE TRANSFORMERS (Stored Energy)

Dips, surges, spikes and interruptions

Important to place at the correct location

> Power Quality Monitoring: Basic Principles and Application Examples22

M570 Compact Family Typical IED

Fixed option configurations

20A fault current

Up to 14 Channels

Optional 4 DI & 4 DO

Unlimited AO by Analog Output Controller

Optional Ethernet

70 Series Firmware

70 Series Software

> Power Quality Monitoring: Basic Principles and Application Examples23

Magnitude- Duration list

Global view of the events over the

assessmentperiod

Win DR Manager (QR Monitor+ viewer)

Event viewing:

> Power Quality Monitoring: Basic Principles and Application Examples24

1/2 cycle

Programmed thresholds

%RMS

Win DR Manager (QR Monitor+ viewer)

Event viewing:

Zoom of the events global view: 1/2 cycle

> Power Quality Monitoring: Basic Principles and Application Examples25

Voltage

Frequency

Win DR Manager (QR Monitor+ viewer)

Trend viewing (average 10min)

> Power Quality Monitoring: Basic Principles and Application Examples26

EN50160 viewing of history data(average 10 min)

Display of events during the assessment period.

Win DR Manager (QR Monitor+ viewer)

Trend viewing

> Power Quality Monitoring: Basic Principles and Application Examples27

Simultaneous display of evolution of THD and the accordingly full harmonic content with peak detection :

THD evolution

Spectrum at time cursor position

Peak detection

Win DR Manager (QR Monitor+ viewer)

Trend viewing

Harmonic investigation

> Power Quality Monitoring: Basic Principles and Application Examples28

TIHD

Inter-harmonics at cursor 1 position

06h00 22h30

Group 2(150-200Hz)

(average 10 min)

Win DR Manager (QR Monitor+ viewer)

Trend viewing

History viewing: inter-harmonic spectrum view

> Power Quality Monitoring: Basic Principles and Application Examples29

Win DR Manager (QR Monitor+ viewer)

PQ report creation and generation

Creation

> Power Quality Monitoring: Basic Principles and Application Examples30

Win DR Manager (QR Monitor+ viewer)

PQ report creation and generation

Creation: use of an existing profile (template)

Available actions

> Power Quality Monitoring: Basic Principles and Application Examples31

Win DR Manager (QR Monitor+ viewer)

PQ report creation and generation

Generation: PQ report on a single unit

Events PQ reports

> Power Quality Monitoring: Basic Principles and Application Examples32

Win DR Manager (QR Monitor+ viewer)

PQ report creation and generation

Generation: PQ report on a single unit

Events PQ reports

> Power Quality Monitoring: Basic Principles and Application Examples33

Istat M2x3 Measurement Centre Family

M253 Network Analyser (Power Quality)

> Power Quality Monitoring: Basic Principles and Application Examples34

PQ to EN50160

Permanent monitoring for up to 3 years

Monitoring parameters:

Frequency variations

Voltage variations

Voltage Dips

Voltage Interruptions

Voltage Unbalance

Transients

Flicker

THD

Harmonics

M253 Power Quality compliance monitoring

> Power Quality Monitoring: Basic Principles and Application Examples35

True RMS measurements over 140 parameters

128 samples per cycle

Programmable analogue outputs

Measured parameters:

U, I, P, Q, S, PF, PA, f, φ

Maximum Demands

THD

Harmonics up to 63

Energy

Cost Management

Min / Max values

M253 Harmonic Measurements