vector phasor diagrams

Started by ndousm January 1, 2013
hi

I am new to this group,I need help .

I have a project that uses microcontrollers ,i need to measure
3 phase current,voltage and phase angle .

I must then must be able to produce a vector representation of what I have measured in graphics form.
Any help or links will be highly appreciated .

Hello,

1. For this you need a good hardware.

2. You need 3 ZCDs for 3 phase voltage.

3. 3 ZCDs for the 3 phase AC current.

4. You must use external interrupts or pin change interrupts for
these inputs.

5. You need a 10 bit timer/counter, which shall count from 1 to 1023
during 50hz; which must be start with R phase low to high & again reset
at next low to high.

6. So you shall have 1023 ticks during 50hz period.

7. So at any interrupts you have to check the tick timer value;
which will give you phase difference with respect to R phase start
(ZCD). Thus your phasor issue can be solved.

8. Now regarding measurement; the key is, you must choose AVR having
high speed ADC; for e.g. around 200ksps; even 100ksps shall also give
good result.

9. With this ADC measure the 6 inputs at a stretch; continuously.
And average it out at R phase ZCD.

10. You must use max freq available with the AVR. Try if you get AVR
more than 20Mhz.

11. If you do the measurement & phasor task then think to put it on
Grphical disply.

ALL THE BEST.

Prashant D. Kharade

India

From: a... [mailto:a...] On Behalf
Of ndousm
Sent: 31 December 2012 17:22
To: a...
Subject: [AVR club] vector phasor diagrams

hi

I am new to this group,I need help .

I have a project that uses microcontrollers ,i need to measure
3 phase current,voltage and phase angle .

I must then must be able to produce a vector representation of what I
have measured in graphics form.

Any help or links will be highly appreciated .



Thanks Prashant D. Kharade

from Samson
From: a... [mailto:a...] On Behalf Of Prashant D. Kharade
Sent: 02 January 2013 06:12 AM
To: a...
Subject: RE: [AVR club] vector phasor diagrams

Hello,

1. For this you need a good hardware.

2. You need 3 ZCDs for 3 phase voltage.

3. 3 ZCDs for the 3 phase AC current.

4. You must use external interrupts or pin change interrupts for
these inputs.

5. You need a 10 bit timer/counter, which shall count from 1 to 1023
during 50hz; which must be start with R phase low to high & again reset
at next low to high.

6. So you shall have 1023 ticks during 50hz period.

7. So at any interrupts you have to check the tick timer value;
which will give you phase difference with respect to R phase start
(ZCD). Thus your phasor issue can be solved.

8. Now regarding measurement; the key is, you must choose AVR having
high speed ADC; for e.g. around 200ksps; even 100ksps shall also give
good result.

9. With this ADC measure the 6 inputs at a stretch; continuously.
And average it out at R phase ZCD.

10. You must use max freq available with the AVR. Try if you get AVR
more than 20Mhz.

11. If you do the measurement & phasor task then think to put it on
Grphical disply.

ALL THE BEST.

Prashant D. Kharade

India

From: a... [mailto:a...] On Behalf
Of ndousm
Sent: 31 December 2012 17:22
To: a...
Subject: [AVR club] vector phasor diagrams

hi

I am new to this group,I need help .

I have a project that uses microcontrollers ,i need to measure
3 phase current,voltage and phase angle .

I must then must be able to produce a vector representation of what I
have measured in graphics form.

Any help or links will be highly appreciated .


I'm part of the 49Million initiative.
http://www.49Million.co.za

NB: This Email and its contents are subject to the Eskom Holdings Limited EMAIL LEGAL NOTICE which can be viewed at http://www.eskom.co.za/e-mail_legalnotice



Hi Sam,

in my opinion Prashant's explanation will lead you to
reinvent the wheel. If you'd like to start from scratch, his
solution would be fine to learn a lot. If you want to get a
running solution without racking your brains about
hardware issues (because other people have done this
extensively in the past) have a look at their results:

http://www.analog.com/en/analog-to-digital-converters/energy-measurement/products/index.html#Poly_Phase_Measurement

I've done projects using the ADE7758 with current
transformers for 3phase-solutions so from my point of view
the worst part you'll have to deal with is your firmware
because you'll get any needed parameter via serial interface
from the chip - likewise via SPI . The hardware is not
tricky at all except you'll have to keep an eye on an adequate
isolation barrier between "hot" circuits (mains) and your
signal processing (which should be on a cold side for your
safety, except you are well-experienced and have the proper
equipment to do hot-side engineering / debugging /
testing). Have a look at the AD U/I-couplers or any other
multi-channel digital isolator and (if not choosing one
with internal supply-isolation) a DC-DC-converter with a
proper isolation-voltage (look for medical parts or such
specified with "reinforced" isolation) - one of the ADUM6xxx
my fit you needs.

No, I'm not a guy from Analog Devices and other vendors may
have equal or even better chips. I'm just talking
about my own experience.

The part about isolation and safety can (and should) be
applied to Prashant's suggestion - working on high voltage
or mains should not be done by someone whe does not know
exactly what and why he / she is doing and what the
risks of this action may be.

Let us know how you managed your task.

Kind regards

Marcus
Sam Ndou wrote:
> Thanks Prashant D. Kharade
>
> from Samson
> From: a... [mailto:a...] On Behalf Of Prashant D. Kharade
> Sent: 02 January 2013 06:12 AM
> To: a...
> Subject: RE: [AVR club] vector phasor diagrams
>
> Hello,
>
> 1. For this you need a good hardware.
>
> 2. You need 3 ZCDs for 3 phase voltage.
>
> 3. 3 ZCDs for the 3 phase AC current.
>
> 4. You must use external interrupts or pin change interrupts for
> these inputs.
>
> 5. You need a 10 bit timer/counter, which shall count from 1 to 1023
> during 50hz; which must be start with R phase low to high & again reset
> at next low to high.
>
> 6. So you shall have 1023 ticks during 50hz period.
>
> 7. So at any interrupts you have to check the tick timer value;
> which will give you phase difference with respect to R phase start
> (ZCD). Thus your phasor issue can be solved.
>
> 8. Now regarding measurement; the key is, you must choose AVR having
> high speed ADC; for e.g. around 200ksps; even 100ksps shall also give
> good result.
>
> 9. With this ADC measure the 6 inputs at a stretch; continuously.
> And average it out at R phase ZCD.
>
> 10. You must use max freq available with the AVR. Try if you get AVR
> more than 20Mhz.
>
> 11. If you do the measurement & phasor task then think to put it on
> Grphical disply.
>
> ALL THE BEST.
>
> Prashant D. Kharade
>
> India
>
> From: a... [mailto:a...] On Behalf
> Of ndousm
> Sent: 31 December 2012 17:22
> To: a...
> Subject: [AVR club] vector phasor diagrams
>
> hi
>
> I am new to this group,I need help .
>
> I have a project that uses microcontrollers ,i need to measure
> 3 phase current,voltage and phase angle .
>
> I must then must be able to produce a vector representation of what I
> have measured in graphics form.
>
> Any help or links will be highly appreciated .

Hi Sam,

Marcus is right.

Apart from Analog devices you have similar other products also.

1. Microchip MCP3909 - refer

http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1
406&dDocName=en520559

2. CS5460/5463 From cypress.

These Ics have built in DSPs, which does all the calculations for you &
give the data on SPI to other microcontroller. So you have a ready data.

The solution I gave, has been implemented by myself with Microchip
DSPIC30. It is tricky & time consuming.

Thanks

Prashant

India

From: a... [mailto:a...] On Behalf
Of Marcus Klein
Sent: 03 January 2013 18:05
To: a...
Subject: Re: [AVR club] vector phasor diagrams

Hi Sam,

in my opinion Prashant's explanation will lead you to
reinvent the wheel. If you'd like to start from scratch, his
solution would be fine to learn a lot. If you want to get a
running solution without racking your brains about
hardware issues (because other people have done this
extensively in the past) have a look at their results:

http://www.analog.com/en/analog-to-digital-converters/energy-measurement
/products/index.html#Poly_Phase_Measurement

I've done projects using the ADE7758 with current
transformers for 3phase-solutions so from my point of view
the worst part you'll have to deal with is your firmware
because you'll get any needed parameter via serial interface
from the chip - likewise via SPI . The hardware is not
tricky at all except you'll have to keep an eye on an adequate
isolation barrier between "hot" circuits (mains) and your
signal processing (which should be on a cold side for your
safety, except you are well-experienced and have the proper
equipment to do hot-side engineering / debugging /
testing). Have a look at the AD U/I-couplers or any other
multi-channel digital isolator and (if not choosing one
with internal supply-isolation) a DC-DC-converter with a
proper isolation-voltage (look for medical parts or such
specified with "reinforced" isolation) - one of the ADUM6xxx
my fit you needs.

No, I'm not a guy from Analog Devices and other vendors may
have equal or even better chips. I'm just talking
about my own experience.

The part about isolation and safety can (and should) be
applied to Prashant's suggestion - working on high voltage
or mains should not be done by someone whe does not know
exactly what and why he / she is doing and what the
risks of this action may be.

Let us know how you managed your task.

Kind regards

Marcus

Sam Ndou wrote:
> Thanks Prashant D. Kharade
>
> from Samson
> From: a...
[mailto:a... ] On
Behalf Of Prashant D. Kharade
> Sent: 02 January 2013 06:12 AM
> To: a...
> Subject: RE: [AVR club] vector phasor diagrams
>
> Hello,
>
> 1. For this you need a good hardware.
>
> 2. You need 3 ZCDs for 3 phase voltage.
>
> 3. 3 ZCDs for the 3 phase AC current.
>
> 4. You must use external interrupts or pin change interrupts for
> these inputs.
>
> 5. You need a 10 bit timer/counter, which shall count from 1 to 1023
> during 50hz; which must be start with R phase low to high & again
reset
> at next low to high.
>
> 6. So you shall have 1023 ticks during 50hz period.
>
> 7. So at any interrupts you have to check the tick timer value;
> which will give you phase difference with respect to R phase start
> (ZCD). Thus your phasor issue can be solved.
>
> 8. Now regarding measurement; the key is, you must choose AVR having
> high speed ADC; for e.g. around 200ksps; even 100ksps shall also give
> good result.
>
> 9. With this ADC measure the 6 inputs at a stretch; continuously.
> And average it out at R phase ZCD.
>
> 10. You must use max freq available with the AVR. Try if you get AVR
> more than 20Mhz.
>
> 11. If you do the measurement & phasor task then think to put it on
> Grphical disply.
>
> ALL THE BEST.
>
> Prashant D. Kharade
>
> India
>
> From: a...
[mailto:a... ] On
Behalf
> Of ndousm
> Sent: 31 December 2012 17:22
> To: a...
> Subject: [AVR club] vector phasor diagrams
>
> hi
>
> I am new to this group,I need help .
>
> I have a project that uses microcontrollers ,i need to measure
> 3 phase current,voltage and phase angle .
>
> I must then must be able to produce a vector representation of what I
> have measured in graphics form.
>
> Any help or links will be highly appreciated .