Monitoring Power Quality Beyond en 50160 and IEC 61000-4-30 - April 2008

Originally presented at EPRI PQA/ADA Conference 2007 – Long Beach, CA

Monitoring Power Quality Beyond EN 50160 and IEC 61000-4-30

Scott SchindlbeckElspec North America23 April 2008Room s401d – 1:00pm

IEEE Transmission & Distribution Conference

Monitoring Electric Power Quality

Chicago, IL

www.elspecna.com

2 Copyright © 2007 ELSPEC Engineering, Ltd.. All rights reserved.

Monitoring Power Quality BeyondEN 50160 and IEC 61000-4-30

Objectives for Power Quality Monitoring• Power Quality Statistics• Power Quality Contracts• Power Quality Troubleshooting • Resolving Disputes• Verifying Compliance With Standards


Can Power Quality Really Be Measured?

• Power quality has many meanings depending on what the power is used for

• Measuring PQ is all about deviations from normal state• USERS are interested in any deviation that is large

enough to cause a problem• SUPPLIERS are interested in ensuring that deviations are

maintained below a level that might cause problems



Quality Measurement Considerations

• PQ events are multi dimensional dips,voltage,current,time,harmonics,flicker,frequency

• PQ effects have thresholds ( they become problematic above a certain level)



Power Quality Parameters

• Supply voltage unbalance• Voltage and current harmonics• Interharmonics• Rapid voltage changes• Power frequency• Magnitude of supply voltage• Flicker• Supply voltage dips and swells• Voltage interruptions• Transient voltages



Existing Standards• IEC 61000-4-30

– Measurement methods– Measurement formulas– Accuracy levels– Aggregation period definition

• EN 50160– levels for power quality parameters– time-based percentage

(e.g., limiting voltage flicker to 95% of the time per week)



Supply Standard EN 50160

• Governs supply voltage parameters• “95%”• Excludes fault conditions, adverse weather • Important standard but not a guarantee• Written from suppliers point of view



Measurement Standard IEC 61000-4-30

• Defines the method of measurement and interpretation of results for power quality parameters in single and three phase 50/60 Hz power systems



• Any instrument conforming to the IEC61000-4-30 Class A standard regardless of manufacturer will read the same when subjected to the same inputs( V,I)

• Creates a level playing field• With today's technology we can measure beyond this

standard providing power quality professionals the information they need to solve real issues






Current Trends in Power Quality Standards• Several countries are modifying Standards to improve network

power quality. Examples:– Norway (Norwegian Water Resources and Energy Directorate):

• Reduce averaging periods from 10 minutes to 1 minute • Force maximum 100% levels of compliance,

(compared to 95% in EN 50160).– Hungarian Regulatory Agency:

• Force averaging period every 3 seconds


The impact of existing standards on Power Quality Analysis and Solutions

• Time aggregation hides power quality issues• Parameter values are limited and time-restricted• Power quality variables are bound to only 3 voltages• Source identification and propagation analysis becomes

extremely difficult (or near impossible) due to limited information available from power anomalies




Requirements for Optimizing Power Quality Analysis• Data compression technology• Continuous measurement of available information all the time in1024 sample/cycle

• 2 parallel computation engines: IEC 61000-4-30 Class A andcycle-by-cycle, up to the 511th harmony

• Full scale readings 6000V / 75A at high accuracy• Real time flickering – 2, 10 and 60 second periods• Periodic storage of 4 quadrant energy (active and reactive) fortotal 16 parameters

• Detailed Inter- and Sub-harmonics



EN 50160 Compliance• Main service of an industrial customer• Unexplained production interruptions and equipment failures • According to EN50160 everything is OK although the site is

experiencing significant damage

ElectricalElectricalUtilityUtility

industrialindustrialConsumerConsumer

22kV

Compliance with EN 50160 at Industrial Customer's Main Service


Not Recording All Parameters: Hidden Line-to-Ground Event• EN50160 limits measurements on Delta connections to Line-to-Line voltages• The following event causes accumulative damage to MV Delta connected• Source: Short circuit between the blue phase and the ground• Result: No Record of a potentially damaging Line-to-Ground event


05

10152025

05

10152025

3 Cycles / Div, Total 60 Cycles

L-L

Vol

tage

s [k

V]L-

N V

olta

ges

[kV]


Not Recording All Parameters: Event Analysis• Conclusion from 16 cycles: Line-to-Line Voltage Sag• Insufficient information to identify the source(s)

21

18

15

12

9

24

12

0

-12

-24

24

12

0

-12

-24

24

12

0

-12

-24

29-04-2007 07:33:49.974

Elspec PQSCADA Investigator

29-04-2007 07:33:50.278

Volts

,L-N

[kV]

Volts

, L-L

[kV]

Volts

,L-N

[kV]

Volts

,L-N

[kV]

21

18

15

12

9

24

12

0

-12

-24

24

12

0

-12

-24

24

12

0

-12

-24

29-04-2007 07:33:49.974


29-04-2007 07:33:50.278

Volts

,L-N

[kV]

Volts

, L-L

[kV]

Volts

,L-N

[kV]

Volts

,L-N

[kV]



Not Recording All Parameters: Sequence of Events (Zoom-Out)• 1 second of information reveals two sequential events

Volts

,L-N

[kV]

Volts

, L-L

[kV]

Volts

,L-N

[kV]

Volts

,L-N

[kV]

21

18

15

12

9

24

12

0

-12

-24

2412

0

-12

-24

24

12

0

-12

-24

29-04-2007 07:33:49.777 29-04-2007 07:33:50.771


Volts

,L-N

[kV]

Volts

, L-L

[kV]

Volts

,L-N

[kV]

Volts

,L-N

[kV]

21

18

15

12

9

24

12

0

-12

-24

2412

0

-12

-24

24

12

0

-12

-24

29-04-2007 07:33:49.777 29-04-2007 07:33:50.771




Not Recording All Parameters: Sequence of Events (L-N Added)• Adding Line-to-Neutral voltages reveals the cause

22

20

18

16

14

12

10

222018161412

10

24

8642

0

29-04-2007 07:33:49.777 29-04-2007 07:33:50.771


Volts

,L-N

[kV]

Volts

, L-L

[kV]

22

20

18

16

14

12

10

222018161412

10

24

8642

0

29-04-2007 07:33:49.777 29-04-2007 07:33:50.771


Volts

,L-N

[kV]

Volts

, L-L

[kV]



Not Recording All Parameters: Sequence of Events (Aftershock)• Aftershock event caused by simultaneous re-connection of many

loads after the event22

20

1816

14

12

10

2421181512

9630

28

24

20

16

12

8

4

29-04-2007 07:33:49.777 29-04-2007 07:33:50.771


Volts

,L-N

[kV]

Volts

, L-L

[kV]

Volts

,L-N

[kV]

22

20

1816

14

12

10

2421181512

9630

28

24

20

16

12

8

4

29-04-2007 07:33:49.777 29-04-2007 07:33:50.771


Volts

,L-N

[kV]

Volts

, L-L

[kV]

Volts

,L-N

[kV]

Cur

rent

[A] Monitoring the

Current adds information



High Sampling Rate

-100%

Vol

tage

100% Event at 64 samples per cycle – a Voltage Sag?

Same event at 1,024 samples per cycle –Transients!

Vol

tage

Vol

tage

--100%100%

100%100%



Averaging vs. Rapid Parameter Monitoring• Standards recommend averaging periods for parameters• What averaging achieves:

– Fewer resources required, such as less storage space and bandwidth

– More stable readings– Similar information on every analyzer

• What averaging causes:– A large amount of vital power quality information remains hidden– No ability to understand the network and the propagation of events



Averaging vs. Rapid Parameter Monitoring• Source: SINTEF Energy Research, Norway

Different Results:•10 minute averaging = Voltage is below 207V 3.5% of the time(nominal 230V minus 10%)

•1 minute averaging = Voltage is below 207V 28% of the time.

•Cycle-by-cycle RMS Voltage Monitoring is essentialin order to understand the cause and provide a solution



Continuous Logging - 16 Cycles• Voltage drop at a large industrial area.• Rule of thumb: Voltage drop plus current rise => downstream event

Cur

rent

s [A

]Fr

eq. [

Hz]

2220181614

14

12

10

8

26130

-13-26

20100

-10-20

5251504948


Volts

,L-N

[kV]

Volts

, L-L

[kV]

Cur

rent

s [A

]C

urre

nts

[A]

Freq

. [H

z]

2220181614

14

12

10

8

26130

-13-26

20100

-10-20

5251504948


Volts

,L-N

[kV]

Volts

, L-L

[kV]

Cur

rent

s [A

]

16 waveforms sampling16 waveforms sampling



Continuous Logging - ~300 Continuous Cycles (Zoom-Out)• The change in frequency points to an external source

2220181614

14

12

10

8

26130

-13-26

20100

-10-20

5251504948

03-01-2007 17:36:17.750


03-01-2007 17:36:23.893

Cur

rent

s [A

]Fr

eq. [

Hz]

Volts

,L-N

[kV]

Volts

, L-L

[kV]

Cur

rent

s [A

]

2220181614

14

12

10

8

26130

-13-26

20100

-10-20

5251504948

03-01-2007 17:36:17.750


03-01-2007 17:36:23.893

Cur

rent

s [A

]Fr

eq. [

Hz]

Volts

,L-N

[kV]

Volts

, L-L

[kV]

Cur

rent

s [A

]

7 Seconds7 Seconds



Continuous Logging – 45,000 Continuous Cycles (2nd Zoom-Out)• The current changes before the event again points to a downstream problem

22

20

18

16

14

21

18

15

12

9

50.28

50.22

50.16

50.1

50.04

49.98

31:43.505


45:08.867

Volts

, L-L

[kV]

Freq

. [H

z]C

urre

nts

[A]

22

20

18

16

14

21

18

15

12

9

50.28

50.22

50.16

50.1

50.04

49.98

31:43.505


45:08.867

Volts

, L-L

[kV]

Freq

. [H

z]C

urre

nts

[A]

15 minutes15 minutes



Continuous Logging – 250,000 Continuous Cycles (3rd Zoom-Out)• Now we see that the current rises are typical to this site

22

20

18

16

14

21

18

15

12

9

50.3

50.2

50.1

50

49.9

16:58:33.273


18:16:22.235

Volts

, L-L

[kV]

Freq

. [H

z]C

urre

nts

[A]

22

20

18

16

14

21

18

15

12

9

50.3

50.2

50.1

50

49.9

16:58:33.273


18:16:22.235

Volts

, L-L

[kV]

Freq

. [H

z]C

urre

nts

[A]

More then 1 hourMore then 1 hour



Large Scale Event• These sites are located 106km (66miles)

from each other and 62km/54kmfrom the original one

• Voltage & Frequency look exactly the same

• Current drops during the event

106km (66miles)106km (66miles)

23.122

20.9

19.8

18.7

50.3

50.2

50.1

50

49.9

24.2

17.6

16.5

150

140

130

120

110

160

100


Volts

, L-L

[kV]

Freq

. [H

z]C

urre

nts

[A]

03-01-2007 17:08:42 03-01-2007 18:24:21

23.122

20.9

19.8

18.7

50.3

50.2

50.1

50

49.9

24.2

17.6

16.5

150

140

130

120

110

160

100


Volts

, L-L

[kV]

Freq

. [H

z]C

urre

nts

[A]

03-01-2007 17:08:42 03-01-2007 18:24:21

172168164160156

50.3

50.2

50.1

50

49.9

176

152148144140136

39383736

40

353433

50.25

50.15

50.05

49.95

49.85

03-01-2007 17:08:42

Volts

, L-L

[kV]

Freq

. [H

z]C

urre

nts

[A]

03-01-2007 18:24:21


172168164160156

50.3

50.2

50.1

50

49.9

176

152148144140136

39383736

40

353433

50.25

50.15

50.05

49.95

49.85

03-01-2007 17:08:42

Volts

, L-L

[kV]

Freq

. [H

z]C

urre

nts

[A]

03-01-2007 18:24:21

Elspec PQSCADA Investigator2233

11

22

33

22

20

18

16

14

21

18

15

12

9

50.3

50.2

50.1

50

49.9

16:58:33.273


18:16:22.235

Volts

, L-L

[kV]

Freq

. [H

z]C

urre

nts

[A]

22

20

18

16

14

21

18

15

12

9

50.3

50.2

50.1

50

49.9

16:58:33.273


18:16:22.235

Volts

, L-L

[kV]

Freq

. [H

z]C

urre

nts

[A]

11



Rapid Parameter Monitoring – RMS in a Welding factory (Germany)• IEC 61000-4-30 instructs: 10/12 Cycle averaging

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 58 61 64 67 70 73 76 79 82 85 88 91 94300

310

320

330

340

350

360

370

380

390

400

Sliding Window AverageSliding Window Average

Fixed AverFixed Aver

Cycle-by Cycle

5 different voltage drops

IEC 61000-4-30one voltage drop

Cycle CurrentCycle Voltage

Sliding Window Averageone voltage drop

Current [A] Voltage [V]

Cycle



Multipoint Analysis – Multiple Sources• Two different events sources may be wrongly identified as same type• Solving at one transformer will not prevent the event(s) from reoccurring and is likely the wrong analysis

80%

90%

100%

Voltage

First EventFirst EventFirst EventFirst Event Second EventSecond Event

Second EventSecond Event



Multipoint Analysis - Time Delay and propagation Analysis• Time synchronization allows time delay analysis

0.1 Sec/Div80%

90%

100%

Voltage

First Event



Knowledge Availability

Knowledge

Certainty

Controllers

Power meters

Educated guess

0%

100%

When What Where From Why What to do

Source of Information Educated guess

“Today at 09:00”“From Customer X”

“Motor Startup”“Synch. Startups”

“20% Sag”



Ideal Knowledge Availability

Knowledge

Certainty

Controllers

Power meters

Educated guess

0%

100%

When What Where From Why What to do

Source of Information Educated guess

“Today at 09:00”“From Customer X”

“Motor Startup”“Synch. Startups”

“20% Sag”

Continuous measurement of available information

all the time in 1024 sample/cycleusing data compression technology

Source of Information:



Thank YouThank You

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www.elspec.com


Documents

Monitoring Power Quality Beyond en 50160 and IEC 61000-4-30 - April 2008