immunity issues related to revenue meters -...

Immunity Issues Related to

Revenue Meters

Paper number: 15PESGM0911

Panel Session: Harmonics from 2 kHz to 150 kHz: Immunity,

Emission, Assessment and Compatibility

1

Jiri Drapela, Zdenek HAVRANEK

and Tomas Jurka Brno University of Technology, Czech Republic

IEEE PES General Meeting 2015, July 26-30, Denver CO

2

Introduction and motivation

█ In the last few years (mainly) utilities noticed increase in number of complains to amount of

(active) energy recorded by Electricity Meters (ELM).

█ The complains are typically based on:

1) significant difference between records from utility meter and from secondary

(complementary) meter(s) owned by customer (for instance PV power plants),

2) significant increase in electricity bill comparing to billing history.

█ In many cases it was possible to connect the problem with the utilized ELM. Once the meter was

replaced by different type the problem was solved.

█ Nevertheless all of the replaced meters were sent to an authorized metrological center to be

verified according to the valid standards and they passed.

█ Therefore, even if the ELMs are certified according to the valid standards and they are regularly

(even irregularly) verified, recorded energy in real deployment may differ unacceptably from

absolutely correct value.

3

Introduction and motivation

█ Based on recorded indices the conducted differential mode disturbance in the range from 2 to

150 kHz was recognized to be the possible cause, where this type of disturbance is produced

mainly by switching converters.

█ We can identify three reasons why we are witnesses of the interference:

1) Weak design of the revenue meters (type tests do not guarantee functional ripeness and

measurement accuracy in real deployment,

2) Changing electromagnetic environment of distribution systems,

3) Gap in standardization aimed at differential mode disturbance (basic EMC and product

standards for compatibility levels, emissions, (immunity)).

4

Case studies

█ Case study 1

A PV power plant, 5.4 kWpk,

composed of two strings and

two single phase inverters

A PQ meter ENA 500.22 was

used as a reference

Optical (LED) impuls output

was monitored

Time behaviour of one-minute active energy

calculated from E9A-09 impulse output

and measured by ENA analyzer in 6 days monitoring period

Connection diagram LV

network

ELM

under test

E9A-09

Optical

head

Complementary ELM

PV

PV

10/08 10/09 10/10 10/11 10/12 10/13 10/14 10/150

10

20

30

40

50

60

70

80

90

Time (mm/dd)

Active e

nerg

y p

er

min

ute

, E

W1

min

(W

h)

Elm S13 impulse output ENA 500.22E9A-09

5

Case studies

█ Case study 1

Time behaviour of E9A-09 average active power calculated from time between pulses and one-

minute average active power measured by ENA analyzer in 6 days monitoring period

10/08 10/09 10/10 10/11 10/12 10/13 10/14 10/1510

0

101

102

103

104

105

Time (mm/dd)

Avera

ge a

ctive p

ow

er,

PA

VG

(W

)

E9A-09 impulse output ENA 500.22 - 1 min average

6

Case studies

█ Case study 1

Zoom in first day

Deviation in registered energy within the monitoring period (about 6 days) was about

+13%

15:30 16:00 16:30 17:00 17:30 18:000

10

20

30

40

50

60

Time (HH:MM)

Active e

nerg

y p

er

min

ute

, E

W1m

in (

Wh)

Elm S13 impulse output ENA 500.22

15:30 16:00 16:30 17:00 17:30 18:0010

1

102

103

104

105

Time (HH:MM)

Avera

ge a

ctive p

ow

er,

PA

VG

(W

)

Elm S13 impulse output

ENA 500.22 - 1 min average

E9A-09

E9A-09

7

Case studies

█ Case study 2

A PV power plant of about 3 MWpk and composed of 6 high-power three-phase inverters

connected to MV network.

Since significant inconsistency between the inverters and employed revenue meter registers was

observed from beginning of the plant operation, a complementary reference revenue meter was

installed.

Both the meters support 15 minute power profiles monitoring.

Time behaviour of the meters‘ 15 min average active power profile in a 2 months period.

11/01 12/01 01/010

1000

2000

3000

Avera

ge a

ctive p

ow

er,

PA

VG

(kW

)

Time (mm/dd)

E1Ax-08 - 15 min power profile Reference ELM - 15 min power profile

11/01 12/01 01/01

-1000

-500

0

Devia

tion in m

easure

dactive p

ow

er,

P (

kW

)

Time (mm/dd)

E1Ax-08

8

Case studies

█ Case study 2

Zoom in few days

Deviation in registered energy within the monitoring period (about 2 months) was

about -15%

█ Other examples based on complains received from LV customers but without any other evidence

After regular exchange of electricity meter in residential sector, the active energy registered by the

newly installed meter (type E1B-06 to -10) within half a year up to one year was 10 times up to 30

times bigger then energy registered in comparable period in the past.

A meter measuring consumption of a LV installation with significant number of frequency

converters (with passive rectifiers) and w/o any generation had recorded significant amount of

active energy in delivery register (about 43 % of energy found in consumption register).

12/06 12/07 12/08 12/09 12/10-1000

-800

-600

-400

-200

0

Devia

tion in m

easure

dactive p

ow

er,

P (

kW

)

Time (mm/dd)

E1Ax-08

12/06 12/07 12/08 12/09 12/100

500

1000

1500

2000

2500

3000

Avera

ge a

ctive p

ow

er,

PA

VG

(kW

)

Time (mm/dd)

E1Ax-08 - 15 min power profile

Reference ELM - 15 min power profile

9

Static electricity meters

█ Eventual sensitivity of an electricity meter to the differential mode disturbance in the frequency

range up to 150 kHz or more applied on the meter input ports as disturbing voltage or current is

given by its HW design and by implemented metrics.

█ Block diagram of a single phase static electricity meter

CT

RB/2

RB/2

RDH RDL

(RLPF)

RLPF

RLPF

RLPF

CLPF

CLPF

CLPF

CLPF

LIN

LOUT

L'IN

NIN

NOUT

=~

YCLK

A/D

MPU

PS

T

DLEDRLED

EEPROM

Display

uC

Interface

driver

Display

DIR_TX

DIR_RX

CASE

Power supply – transformer/capacitor

devider with rectifier

Transducers – V: resistor devider, I:

transformer/shut resistor/Hall sensor

Anti-aliasing filters – the same

for all inputs

A/D converter – final sampling

rate from 1600 to 6400 S/s

uP unit - ELM metrics,

proprietary solution

Interface

10


█ Signal scheme of a single phase static active electricity meter

i(t)

v(t)

FCT(s)

FVT(s)|F|

|F|

f

f

f

f

FA-AF(s)|F|

f

f

FA-AF(s)|F|

f

f

G

G

A/D

i(t)

i(n)

N-bit, fs

A/D

u(t)

u(n)

N-bit, fs

in

un

HHPF(z) HD(z)=z-NDi

|H|

f/fs

f/fst

t

nn

i(n)

HHPF(z) HD(z)=z-NDu

|H|

f/fs

f/fs

n

u(n)

un.inpn

n

u(n)

NPER

trigPER

reset=

NDi

NDu

EW,mw

CP/E

EWr+

>0EWr-

EIMP

abs

trigIMP

TIMP

uIMP(t)trigIMP(n)

tn

LED(t)

t

LED(t)

1

2

3

4

5

6

7

8

22

9

10

11

12

13

14 15

16

1718

19a19b2021

A

C

B

uCC(t)

D

=~

Legend:

1, 2 - Transducers

3, 4 - A-A filters

5, 6 - (Amplification)

7, 8 - A/D converter(s)

20 - Pulse gen.

21 - Pulse LED

22 - Power source

9, 10 - DC comp. removal

11,12 - Phase shift compensation

13 - Inst. power calculation

14 - Synchronization block

15 - Fund. period counter

16 - Measuring window energy

calc. (Integrator)

17 - Classifier

18 - Integrator(s)/

register(s)

19a - Comparator

19b - Comparator

Legend:

Analog signal transfer

Digital signal transfer

Not mandatory

Alternativelly

11


█ Standard metrics summary

Active energy is measured in terms of successive integration of product of phase-corrected

voltage and current in synchronized Measuring Window (MW) which is derived from system

frequency period

The measuring window length is typically from 5 to 50 (60) periods of the fundamental

voltage, i.e. from 100 ms to 1 s.

Active energy in a kth measuring window is then:

The energies from individual measuring windows are consequently sorted and cumulated in

corresponding registers (delivery or consumption)

In a case of three phase meters the MV energies measured in individual phases are

processed using one of the following way (the green one is preferred):

NpernNn

nn

FFEPmwW ninuCkE/1

1

)()()( /,

)(1

, kE L

mwW

)(2

, kE L

mwW

)(3

, kE L

mwW

)(

)(

1

,

1

,

kE

kE

L

mwW

L

mwW

)(

)(

2

,

2

,

kE

kE

L

mwW

L

mwW

)(

)(

3

,

3

,

kE

kE

L

mwW

L

mwW

3

1

,

3

,

3

1

,

3

,

)()(

)()(

L

LF

F

mwW

F

mwW

L

LF

F

mwW

F

mwW

kEkE

kEkE

3

1

,

3

, )()(L

LF

F

mwW

F

mwW kEkE)(

)(

3

,

3

,

kE

kE

F

mwW

F

mwW

k

F

mwW

F

mwWr

k

F

mwW

F

mwWr

kEE

kEE

)(

)(

3

,

3

,

3

,

3

,

12


█ Conversion of continuously measured energy to impulse output

The process description takes a part in the presented signal scheme

Integration period for comparison of integrated energy with the threshold for one impuls

there is: sampling period Ts (block 19b) or half-period of fundamental voltage T1/2p, or

integral multiple of the period N.Tper or even the integration period is identical to measuring

window time Tmw (block 19a)

Positive and negative energy integrated (T1/2p or N.Tper or Tmw) within measuring interval can

be aggregated and compared separately

Impulses corresponding to delivered and consumed energy are generated independently

and together on an optical output (LED) or separately on S0 outputs

The impulses generation process (mainly impulses generation homogeneity) can by

significantly influenced by specific energy to frequency conversion logic and also by control

of interruptions for processes service purposes

An example of variation in time between pulses from LED and S0 outputs of a ELM under

reference conditions

100 150 200 250 300 350 4006.26

6.27

6.28

6.29

6.3

Time (s)

Tim

e b

etw

een p

uls

es (

s)

LED

100 150 200 250 300 350 40011.5

12

12.5

13

13.5

Time (s)

Tim

e b

etw

een p

uls

es (

s)

S0

13


|F|

f

f

|F|

f

f

|F|

f

f

fS/2 fS

|U(f

)| (

V)

fS/2 fS

|I(f

)| (

A)

|H|

f/fs

f/fs

n

u(n)

n

u(n)

00101101 -> ? 11110111

█ Phenomena which may affect an ELM response

due to presence of the differential mode disturbance

on input port were preliminary identified as follows:

Freq. response of a voltage and current transducers

especially in the case of transformers

Freq. response of Anti-aliasing filters

Parasitic couplings in analog front-end

A/D converter horizontal resolution ->Aliasing effect

Freq. response of a digital HP filter

(DC components elimination)

Freq. response of a lag unit –compensation

of a phase shift at fundamental frequency

Signal synchronization for measuring window

estimation (multiplies of TPER)

Parasitic couplings and signal transmission

over analog and digital circuits->

alteration in digital word

14

Standardization in electricity meters testing (EU)

█ According to the related EU regulations every electricity meter for active energy measurement

and registration (used for billing) has to comply with so called MID standards

█ The MID standards set for static meters cover following standards: (IEC) EN EN 50470-1, (IEC)

EN 50470-3, (IEC) EN 62058-11, (IEC) EN 62058-31, etc.

█ A part of the meters type tests there is also verification of their electromagnetic immunity

█ Nevertheless testing of their immunity to the conducted differential mode disturbances was not

introduced to the MID standard series yet

█ The first document dealing with testing of ELMs immunity to the differential mode disturbance

there is a technical report CLC/TR 50579 published in 2012

█ The report specifies particular requirements and immunity test for direct connected and

transformer connected electricity meters as an extension of EN 50470-1 and EN 50470-3 stds.

█ “The tests are designed to achieve immunity against disturbing currents of up to 2 A (2 kHz-30

kHz) and up to 1 A (30 KHz-150 kHz) for direct connected meters and 2 % Imax (2 kHz-30 kHz)

and 1 % Imax (30 KHz-150 kHz) for transformer connected meters.”

█ Nevertheless testing according to the report is not obligatory.

15

Standardization in electricity meters testing (EU)

█ In 2014 there was released a new basic EMC std. IEC 61000-4-19 designated for immunity tests

to conducted differential mode disturbances in the frequency range from 2 kHz to 150 kHz at AC

power ports

█ The standard specifies test signal profiles, test levels for both the disturbing voltage and the

disturbing current and test procedure including specifications and requirements for test

equipment

█ The standard partly adopts the technical report CLC/TR 50579 and gives some notes to

electricity meters testing

█ But again, it is not obligatory to comply with the standard for type certification of the electricity

meters.

16

Immunity testing to differential mode disturbance

█ Test signal profiles

The std. IEC 61000-4-19 specifies two types of test signals with carrier frequency from 2 to 150

kHz which are superimposed on fundamental waveform

- Continuous wave (CW) pulses with pauses between pulses at specified frequency. Frequency

of the first pulse signal starts at 2 kHz and is increased for the next pulse for 2% (frequency

step introduced by CLC/TR 50579 is 1%)

- Rectangularly modulated (MOD) pulses with four different modulation frequencies (3, 101,

301 and 601 Hz at 50 Hz system and 4, 121, 361 and 721 Hz at 60 Hz). Modulation duty

cycle is 50%.

- An example of MOD test current

According to the CLC/TR 50579 the meter under test should be loaded by active power under

reference test conditions specified by the EN 50470-3. Inputs of a meter under test should be

connected to reference (rated) voltage of rated frequency and should be loaded by reference

fundamental current with zero (minimum) phase shift to voltage.

-10

-5

0

5

10

0 0.01 0.02 0.03 0.04 0.05

Zku

šeb

níp

rou

d, i

(A)

Čas (s)Time (s)

Test curr

ent, I

(A

)

17


0.5

5

1 10 100

Test curr

ent

magnitude,

I T(A

)

Frequency, fT (kHz)

Cl. 4 Cl. 3 Cl. 2 Cl. 1

0.1

1

10

1 10 100Test voltage m

agnitude,

VT

(V)

Frequency, fT (kHz)

Cl. 4 Cl. 3 Cl. 2 Cl. 1

█ Test levels according to the std. IEC 61000-4-19 (CLC/TR 50579)

Test levels for differential voltage testing

(IEC 61000-4-19)

Frequency, fT (kHz) Test voltage, VT (Vrms) 2 to 9 9 to 95

95 to 150

1 0.5 0.5 to 0.1 0.1

2 3 3 to 0.6 0.6

3 12 12 to 2.4 2.4

4 20 20 to 10 10

Level/ Environment

class

X - - -

Frequency, fT (kHz) Test current, IT (Arms) 2 to 30 30 to 150

1 1 0,5

2 2 1

3 3 1,5

4 4 2

Level/ Environment

class

X - -

Test levels for differential current testing

(IEC 61000-4-19) – for direct current inputs

Test levels for differential current testing

(CLC/TR 50579) – for direct current inputs

Frequency, fT (kHz) Test current, IT (Arms) 2 to 30 30 to 150

1 1 % Imax 0,5 % Imax

2 2 % Imax 1 % Imax

3 3 % Imax 1,5 % Imax

4 4 % Imax 2 % Imax

Level/ Environment

class

X - -

being Imax maximum input current defined

by producer (usually Imax=1.2*Iref)

CLC/TR 50579 specifies test levels for

class 2 only; the other levels are assigned

using a symmetry rule

18

█ Test equipment and test setup

The IEC 61000-4-19 provides specific requirements for tests system and particular information on

test setup applicable to the ELMs testing

█ Test evaluation

The maximum allowed additional measurement percentage deviation (error) provided by the report

CLC/TR 50579 with reference to the MID standards.


Accuracy class of a meter A (2) B (1) C (0.5)

Maximum allowed additional deviation ± 6 % ± 4 % ± 2 %

19

CDN-I-LF

CDN-V-LFA-VI-LF TR-LF

Ethernet

Eth

ernet

GP

IB

ELM (DUT)

GPIB

WM (REF)CDN-V-HF A-V-HF

A-I-HFCDN-I-HF

CT VT

+5V DI0 +5V DI0

AO0

AO0AI0AI1

AI1

AI0

+12V +9V-12V -9V

+5V

DI0

AO

0

D/A A/DMCU

PXI

IS

=

.. 4x

PC

Ethernet

Developed test system

█ Test stand

A-VI-LF: Fundamental voltage and current

generator, OMICRON CMC 256plus

CDN: coupling and decoupling networks

A-V(I)-HF: Disturbing voltage (current) signal

generators, APS 125 (B&K 2719)

WM (REF): reference power (energy) meter,

LMG 500

20

█ Control SW application

Test system control based on virtual instrumentation in LabVIEW

Test application front panel

Test setup Test behaviour


21

█ Test system characteristics and performance

Test system is suitable for testing of three and single phase electricity meters designed for

indirect, semi-direct (indirect current measurement) or direct voltage and current

measurement, moreover for direct meters with disconnectable or even with permanently

connected voltage and current input ports

Available fundamental test voltage and current: 0-300 Vrms (1/3f), 0(10 mArms)-20 Arms

(1/3f, limited by the CDN-I-LF parameters), current phase shift: 0-360°

Disturbing signal availability (on :

voltage: 2-150 kHz, 10 mVrms - 25 Vrms (10 Vrms @150 kHz),

current: 2-150 kHz, 3 mA - 7 Arms (limited by the CDN-I-HF, 2.5 Arms@150 kHz),

waveform profiles: continuous wave – CW / modulated wave - MOD (variable modulation

frequency and duty cycle : 0.1 Hz to 10 kHz, 1% to 99%)

Test system impedance seen on ELM (DUT) voltage input ports: (11,51-10,1) Ohms in the

frequency range 2 - 200 kHz; Decoupling resistors in LF and HF current circuit:

inductionless, 1 Ohm ±5%

The test levels at each test point are maintained in required tolerances by means of

corrections application which are obtained from disturbing signal system gain measurement

prior every test

Typical perceptual deviation measurement uncertainty is of 0.13%


22

█ Test system characteristics and performance

Typical disturbing signal parameters achieved by the test system for test level 3

Disturbing current (3/1.5 Arms) Disturbing voltage (12/2.4 Vrms)

103

104

105

-5

0

5

Devia

tion o

f te

sting

level fr

om

setp

oin

t,

T (

%)

Disturbing signal frequency, fT (Hz)

Typical deviation (disturbing current)

Limit

103

104

105

-5

0

5

Devia

tion o

f te

sting

level fr

om

setp

oin

t,

T (

%)


Typical deviation (disturbing voltage)

Limit

103

104

105

0

1

2

3

4

5

Harm

onic

dis

tort

ion

of

dis

turb

ing s

ignal, T

HD

T (

%)


Typical distrotion (disturbing current)

Limit

103

104

105

0

1

2

3

4

5

Harm

onic

dis

tort

ion

of

dis

turb

ing s

ignal, T

HD

T (

%)


Typical distortion (disturbing voltage)

Limit


23

Measurement system Impulse output constants (Imp/kWh) Identifier

Produ- cer

Type Produc-tion year Direct/

indirect 1f/Aron

/3f Rated voltage Current range

Disconnect- able V&I inputs

Energy registers

Accuracy class in active energy meas. LED S0

Immune enough

E1Aa-08 1 Aa 2008 semi-dir 3f 3x230/400 V 50 Hz 5 A n.a. 4Q 0.5S 10000 5000 N

E1Ab-11 1 Ab 2011 semi-dir 3f 3x230/400 V 50 Hz 5 A n.a. 6Q 1 10000 5000 N

E1Ab-13 1 Ab 2013 semi-dir 3f 3x230/400 V 50 Hz 5 A n.a. 6Q 1 10000 5000 Y

E1Ac-08 1 Ac 2008 direct 3f 3x230/400 V 50 Hz 5 (100) A Y 4Q 1 500 250 Y

E1B-06 1 B 2006 direct 3f 3x230/400 V 50 Hz 5 (100) A Y 1P 2 500 250 N




E1B-11 1 B 2011 direct 3f 3x230/400 V 50 Hz 0,25-5 (100) A Y 1P A 500 250 Y (?)



E1C-09 1 C 2009 direct 1f 230 V 50 Hz 5 (60) A N 1P 2 3200 3200 Y



E2Aa-13 2 Aa 2013 semi-dir 3f 3x230/400 V 50 Hz 0,01-1 (10) A n.a. 6Q B 10000 ? Y

E2Ab-12 2 Ab 2012 direct 3f 3x230/400 V 50 Hz 0,25-5 (120) A Y 6Q B 1000 100 Y

E3Aa-13 3 Aa 2013 semi-dir 3f 3x230/400 V 50 Hz 0,05-5 (6) A n.a. 6Q B 10000 40 Y

E3Ab-13 3 Ab 2013 direct 3f 3x230/400 V 50 Hz 0,25-5 (100) A Y 6Q B 1000 ? Y

E4A-03 4 A 2003 direct 1f 230 V 50 Hz 5 (80) A Y 1P 2 10000 250 Y

E4Ba-14 4 Ba 2014 direct 3f 3x230/400 V 50 Hz 0,2-5 (100) A Y 2P A 10000 250 Y

E4Bb-14 4 Bb 2014 direct 1f 230 V 50 Hz 0,2-5 (80) A Y 1P A 10000 250 Y

E5Aa-13 5 Aa 2013 direct 3f 3x230/400 V 50 Hz 0,25-5 (80) A N 1P B 1000 ? N (?)

E5Ab-11 5 Ab 2011 direct 1f 230 V 50 Hz 0,25-5 (80) A N 1P B 1000 n.a. N (?)

E6A-03 6 A 2003 direct 1f 230 V 50 Hz 5-60 A Y 1P 2 3200 3200 Y

E7A-03 7 A 2003 direct 1f 230 V 50 Hz 5 (60) A Y 1P 2 1000 1000 N

E8A-03 8 A 2003 direct 1f 230 V 50 Hz 5 - 60 A Y 1P 2 1600 800 Y

E9A-09 9 A 2009 direct 3f 3x230/400 V 50 Hz 5 (65) A Y 1P 2 1000 1000 N

Tested revenue meters and testing conditions

█ Table of chosen tested meters with summarizing result of performed tests

24

Test results

█ Test data evaluation

Except average power measured by a meter under test (1) and resulting deviation in measured average

active power (2), there are other testing indicies in view: real test level (3) and its deviation from setpoint

(4), total harmonic distortion of disturbing signal (5), transfer function of the disturbing signal circuit (6) and

dispersion in time between pulses (7).

1 2

3 4 5

6 7

█ An example of results for a meter which passed all performed tests without noticeable change in

response

CW test signal with test level 3

For disturbing current For disturbing voltage

█ Since we have not find out any ELM sensitive to disturbance in voltage applied on input ports the

results for disturbing current are presented only in the next

25

103

104

105

-5

0

5


Devia

tion in m

easure

dactive p

ow

er,

P (

%)

E3Aa-13

Deviation dispersion

Deviation limit

E3Aa-13

103

104

105

-5

0

5


Devia

tion in m

easure

dactive p

ow

er,

P (

%)

E3Aa-13


Deviation limit

E3Aa-13

Test results

█ Results for meters which are not immune to the disturbance in input current (CW test signal with

test level 3)

26

103

104

105

0

200

400

600

800

1000

1200


Devia

tion in m

easure

dactive p

ow

er,

P (

%)

E1B-06


Deviation limit

E1B-06

103

104

105

-100

-50

0

50

100

150


Devia

tion in m

easure

dactive p

ow

er,

P (

%)

E1Ab-11


Deviation limit

E1Ab-11

103

104

105

-100

-50

0

50

100

150


Devia

tion in m

easure

dactive p

ow

er,

P (

%)

E9A-09

Deviation limit

E9A-09

Test results

103

104

105

-10

-5

0

5

10

15


Devia

tion in m

easure

dactive p

ow

er,

P (

%)

E7A-03


Deviation limit

E7A-03

█ Comparison of results obtained for meters which are of different HW versions (CW test signal

with test level 3)

█ The HW “face lift” to be immune to the differential disturbance is evident in both examples

27

103

104

105

0

200

400

600

800

1000

1200

1400


Devia

tion in m

easure

dactive p

ow

er,

P (

%)

E1B-06

E1B-07

E1B-08

E1B-10

E1B-11

E1B-12

E1B-13

Deviation limit

{{

103

104

105

-100

-80

-60

-40

-20

0


Devia

tion in m

easure

dactive p

ow

er,

P (

%)

E1B-06

E1B-07

E1B-08

E1B-10

E1B-11

E1B-12

E1B-13

Deviation limit

103

104

105

-100

-50

0

50

100

150


Devia

tion in m

easure

dactive p

ow

er,

P (

%)

E1Aa-08

E1Ab-11

E1Ab-13

E1Ac-08

Deviation limit

Test results

zoom

█ Chosen electricity meters response with changing disturbing signal frequency step

Test results

28

1.505 1.5055 1.506 1.5065 1.507 1.5075 1.508 1.5085 1.509 1.5095 1.51

x 104

0

500

1000

1500

2000

2500


Devia

tion in m

easure

dactive p

ow

er,

P (

%)

E1B-06IT~lvl2, f=0.1 Hz

103

104

105

-6

-4

-2

0

2

4

6


Devia

tion in m

easure

dactive p

ow

er,

P (

%)

E1B-13


Deviation limit

IT~lvl3, f

T=2 % E1B-13

1.5071 1.5072 1.5073 1.5074 1.5075 1.5076 1.5077 1.5078

x 104

-40

-30

-20

-10

0

10

20


Devia

tion in m

easure

dactive p

ow

er,

P (

%)

E1B-13


Deviation limit

IT~lvl3, I

T=0.05 Hz

E1B-13

100 150 200 250 300 350 4000

0.5

1

1.5

2

x 104

Time (s)

Avera

ge a

ctive p

ow

er

(W)

E1B-06 Ref. power IT=1 A @15074.66 Hz

103

104

105

0

500

1000

1500

2000

2500

3000


Devia

tion in m

easure

dactive p

ow

er,

P (

%)

E1B-06IT~lvl2, f=2%

IT~lvl2, f=0.1%

zoom

The same type of

meter with newer

HW version

zoom

█ Chosen electricity meters response to change disturbing signal frequency step

█ Due to very discrete character of some

of unacceptable deviations the frequency

step of 2 % seems to be too big

29

103

104

105

-50

0

50


Devia

tion in m

easure

dactive p

ow

er,

P (

%)

Deviation limit

IT~lvl3, f

T=2 %

IT~lvl3, f

T=0.1 %

E4Bb-14

2464 2466 2468 2470 2472 2474-40

-20

0

20

40

60


Devia

tion in m

easure

dactive p

ow

er,

P (

%)


Deviation limit

IT~lvl3, f

T=0.1 Hz E4Bb-14

1.5072 1.5074 1.5076 1.5078 1.508

x 104

-40

-30

-20

-10

0

10

20

30


Devia

tion in m

easure

dactive p

ow

er,

P (

%)


Deviation limit

E4Bb-14

IT~lvl3, f

T=0.1 Hz

400 500 600 700 800 900 1000 1100 12001000

1100

1200

1300

1400

1500

Time (s)

Avera

ge a

ctive p

ow

er

(W)

E5Ab-11 Reference power IT=3 A @2470.9 Hz

Test results

zoom

0

500

1000

1500

2000

2500

3000

0 50 100 150

Test poit frequency (kHz)

Fre

quency s

tep (

Hz)

0.1%

0.5%

1%

2%frequency step number of test points

2% 220

1% 435

0.5% 867

0.1% 4321

1 Hz 148001

█ Chosen electricity meters response to various disturbing current levels

The test was designed to demonstrate what will be the change in deviation in measurement

of the meters over the range of test levels proposed by IEC 61000-4-19

█ As it can be seen the dependence can be even inverse proportional

Test results

30

103

104

105

-100

-50

0

50


Devia

tion in m

easure

dactive p

ow

er,

P (

%)

0.1 A

0.2 A

0.5 A

1.0 A

1.5 A

2.0 A

3.0 A

4.0 A

Ih1

=5 A,

IT=

E1B-06

103

104

105

0

500

1000

1500


Devia

tion in m

easure

dactive p

ow

er,

P (

%)

0.1 A

0.2 A

0.5 A

1.0 A

1.5 A

2.0 A

3.0 A

4.0 A

Ih1

=5 A,

IT=

E1B-06

1.4 1.42 1.44 1.46 1.48 1.5 1.52 1.54 1.56 1.58 1.6

x 104

0

200

400

600

800

1000

1200

1400

1600


Devia

tion in m

easure

dactive p

ow

er,

P (

%)

0.1 A

0.2 A

0.5 A

1.0 A

1.5 A

2.0 A

3.0 A

4.0 A

Ih1

=5 A,

IT=

E1B-06

103

104

105

-100

-50

0

50

100

150


Devia

tion in m

easure

dactive p

ow

er,

P (

%)

0.06/0.03 A (lvl1-1/0.5%)

0.12/0.06 A (lvl2-2/1%)

0.18/0.09 A (lvl3-3/1.5%)

0.24/0.12 A (lvl4-4/2%)

0.48/0.24 A (8/4%)

0.72/0.36 A (12/6%)

0.96/0.48 A (16/8%)

E1Ab-11

Ih1

=5 A

IT=

zoom

█ Chosen electricity meters response to change in fundamental current magnitude while disturbing

current magnitude changes proportionally (first case) or remain the same (second case)

█ The second ELM (this specific test) exhibits again inverse proportional sensitivity if the

fundamental magnitude is changed, in this time

Test results

31

103

104

105

0

500

1000

1500


Devia

tion in m

easure

dactive p

ow

er,

P (

%)

Ih1

=9 A, IT=5.4/2.7 A

Ih1

=5 A, IT=3.0/1.5 A

Ih1

=1 A, IT=0.6/0.3 A

E1B-06

103

104

105

-100

0

100

200

300

400


Devia

tion in m

easure

dactive p

ow

er,

P (

%)

E1B-06Ih1

=9 A, IT=5.4/2.7 A

Ih1

=5 A, IT=3.0/1.5 A

Ih1

=1 A, IT=0.6/0.3 A

103

104

105

-100

0

100

200

300

400

500


Devia

tion in m

easure

dactive p

ow

er,

P (

%)

E1Aa-11Ih1

=5.0 A, IT=0.18/0.09 A (lvl3-3/1.5%)

Ih1

=2.0 A, IT=0.18/0.09 A (lvl3-3/1.5%)

Ih1

=0.5 A, IT=0.18/0.09 A (lvl3-3/1.5%)

zoom

█ Chosen electricity meters response to modulated disturbance

The test is introduced by IEC 61000-4-19

█ Modulated test signal did not evoke any essential deterioration in the ELMs measurement

accuracy in any test

Test results

32

103

104

105

-100

-50

0

50

100


Devia

tion in m

easure

dactive p

ow

er,

P (

%)

CW

MOD fmod=3 Hz/ d.c.=50 %



Deviation limit

E1B-07

103

104

105

-100

-50

0

50

100

150


Devia

tion in m

easure

dactive p

ow

er,

P (

%)

CW


Deviation limit

E1Aa-08

103

104

105

-100

-50

0

50

100

150


Devia

tion in m

easure

dactive p

ow

er,

P (

%)

CW

MOD fmod=3 Hz/ d.c. 50 %




Deviation limit

E9A-09

103

104

105

-6

-4

-2

0

2

4

6

8


Devia

tion in m

easure

dactive p

ow

er,

P (

%)

CW

MOD fmod=3 Hz/ d.c=50 %




Deviation limit

E4Bb-14

33

Discussion and conclusions

█ There will be necessary to introduce the electricity meters immunity tests against the differential

mode disturbances to the related MID standards as soon as possible.

█ Even if a basic EMC standard for immunity testing (IEC 61000-4-19) was released in 2014, this

type of test is not obligatory within type-test process, until it is adopted by MID standards (EU

regulations).

█ Besides, details on electricity meters testing procedure for MID standard ((IEC) EN 50470-3)

purposes will be necessary to define (like test signals, levels, specific test procedures, test setup

for all types of meters).

█ As for testing levels, there is evident unbalance between specified levels for direct (current)

meters and levels for semi-direct (indirect current) meters published anywhere. It covers even

levels for fundamental current (for instance 5 A for both the meter types, even if the maximum

measurable current is typically 60 A – direct vs. 6 A - indirect).

█ It has been shown that a meter may pass (comply with requirements to immunity) if the

frequency step of 2% is applied, as it is specified in the IEC 61000-4-19 standard. Nevertheless

the same meter fails if another (smaller) frequency step is used. It is due to very discrete

(frequency range limited) state related to employed sampling frequency and aliasing effect.

Taking account probability of interference and possible impact on deviation in energy

measurement and time-consuming testing on other hand; is it effective to reduce the frequency

step?

34

Discussion and conclusions

█ Modulated test signal did not evoke any essential deterioration in the ELMs measurement

accuracy in any performed test. Then it is a question if this type of test (for various modulation

frequencies) is suitable.

█ The obtained test results do not satisfactory explain some of the meters response at customers’

sites (from 10 to 30 times bigger annual bill). We will see if another test signal profile will be

useful to introduce in the future.

█ Since electricity meters may change direction of measured energy or even may indicate no load

when they are subject to the disturbance and taking into account that all of these events are

processed to the same metrological impulse output (LED), it may significantly influence test

results. Moreover reactive energy may be recorded within disturbance, even if fundamental

voltage and current are perfectly in phase. Therefore it is more effective to monitor metallic

impulse outputs related to individual energy registers if they are available.

35

References

• EN 50470-1: 2006. Electricity metering equipment (a.c.) -- Part 1: General requirements, tests and test conditions -

Metering equipment (class indexes A, B and C)

• EN 50470-3: 2006. Electricity metering equipment (a.c.) -- Part 3: Particular requirements - Static meters for active

energy (class indexes A, B and C)

• EN 62058-31: 2010. Electricity metering equipment (a.c.) – Acceptance inspection – Part 31: Particular requirements

for static meters for active energy (classes 0,2 S, 0,5 S, 1 and 2, and class indexes A, B and C)

• EN 62052-11: 2010. Electricity metering equipment (AC) - Acceptance inspection - Part 11: General acceptance

inspection methods

• IEC 61000-4-19: 2014. Electromagnetic compatibility (EMC) – Part 4-19: Testing and measurement techniques – Test

for immunity to conducted, differential mode distur-bances and signalling in the frequency range 2 kHz to 150 kHz at

a.c. power ports

• TNI CLC/TR 50579: 2012. Electricity metering equipment (a.c.) - Severity levels, immunity requirements and test

methods for conducted disturbances in the frequency range 2 kHz - 150 kHz

• CENELEC. SC 205A Mains Communication Systems, TF EMI. ELECTROMAGNETIC INTERFERENCE BETWEEN

ELECTRICAL EQUIPMENT/SYSTEMS IN THE FREQUENCY RANGE BELOW 150 kHz ED. 2. Study Report, 2013,

89pp.

• Kirchhof, J., Klein, G. Results of the OPTINOS project – Deficits and uncertainties in Photovoltaic inverter test

procedures. 24th European Photovoltaic Solar Energy Con-ference and Exhibition, 2009, Germany, 4 pp.

• Bartak, G.F., Abart, A. EMI of Emissions in the Frequency Range 2 kHz - 150 kHz. 22nd CIRED, Stockholm, 2013,

4pp.

36

Thank you for your attention

QUESTIONS?

Contact:

Jiri Drapela

Brno University of technology

Faculty of Elekctrical Engineering and Communication

Department of Electrical Power Engineering

Technická 3082/12

61600 Brno, Czech Republic

tel: +420 541146211

email: [email protected], [email protected]

mailto:[email protected]

mailto:[email protected]

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