Subject: Re: [eman] Power Quality versus Power Characteristics

From: Brad Schoening <[email-masked]>
Date: Thu, 8 Mar 2012 10:59:42 -0600

Bruce,

Since you have not replied, may we consider this issue closed?

Brad Schoening
e: [email-masked] ⟐ m: 917-304-7190

<http://www.coraid.com/> Redefining Storage Economics

From: Brad Schoening <[email-masked]<mailto:[email-masked]>>
Date: Wed, 29 Feb 2012 16:42:41 -0600
To: Bruce Nordman <[email-masked]<mailto:[email-masked]>>
Cc: "[email-masked]<mailto:[email-masked]>" <[email-masked]<mailto:[email-masked]>>
Subject: Re: [eman] Power Quality versus Power Characteristics

Bruce,

I already gave two examples on Feb 20th :

For example, total harmonic distortion is a ratio of the distortion relative to the reference frequency.  Or consider, power factor which is a ratio of the real power to the apparent power, where real power is the reference point.

Brad Schoening
e: [email-masked]<mailto:[email-masked]> ⟐ m: 917-304-7190

<http://www.coraid.com/> Redefining Storage Economics

From: Bruce Nordman <[email-masked]<mailto:[email-masked]>>
Date: Wed, 29 Feb 2012 16:39:28 -0600
To: Brad Schoening <[email-masked]<mailto:[email-masked]>>
Cc: Benoit Claise <[email-masked]<mailto:[email-masked]>>, "[email-masked]<mailto:[email-masked]>" <[email-masked]<mailto:[email-masked]>>
Subject: Re: [eman] Power Quality versus Power Characteristics

What are the reference values for each then?
Listing them specifically would help us understand
how EMAN evaluates them.
--Bruce

On Wed, Feb 29, 2012 at 2:30 PM, Brad Schoening <[email-masked]<mailto:[email-masked]>> wrote:
Bruce,

I believe we are talking past each other.  The majority of these 24 MIB variables *do* have a reference value as noted in my earlier email.  Could you be specific about which ones you feel don't have a reference parameter.

Brad Schoening
e: [email-masked]<mailto:[email-masked]> ⟐ m: 917-304-7190<tel:917-304-7190>

<http://www.coraid.com/> Redefining Storage Economics

From: Bruce Nordman <[email-masked]<mailto:[email-masked]>>
Date: Wed, 29 Feb 2012 16:25:28 -0600

To: Benoit Claise <[email-masked]<mailto:[email-masked]>>
Cc: Brad Schoening <[email-masked]<mailto:[email-masked]>>, "[email-masked]<mailto:[email-masked]>" <[email-masked]<mailto:[email-masked]>>
Subject: Re: [eman] Power Quality versus Power Characteristics

I agree this should be closed ASAP.

To try to summarize, we have a definition of Power Quality in:
   http://datatracker.ietf.org/doc/draft-parello-eman-definitions/
that reads (emphasis added by me):
Characteristics of the electric current, voltage and frequencies at a given point in
an electric power system, evaluated against a set of reference technical parameters.
These parameters might, in some cases,relate to the compatibility between electricity
supplied in an electric power system and the loads connected to that electric power system.
Further, there are 24 MIB variables with Quality as part of their name in:

            eoACPwrQualityConfiguration       INTEGER,
            eoACPwrQualityAvgVoltage          Integer32,
            eoACPwrQualityAvgCurrent          Integer32,
            eoACPwrQualityFrequency           Integer32,
            eoACPwrQualityPowerUnitMultiplier UnitMultiplier,
            eoACPwrQualityPowerAccuracy       Integer32,
            eoACPwrQualityTotalActivePower    Integer32,
            eoACPwrQualityTotalReactivePower  Integer32,
            eoACPwrQualityTotalApparentPower  Integer32,
            eoACPwrQualityTotalPowerFactor    Integer32,
            eoACPwrQualityThdAmpheres         Integer32,
            eoACPwrQualityThdVoltage          Integer32
                eoACPwrQualityPhaseAvgCurrent      Integer32,
                eoACPwrQualityPhaseActivePower     Integer32,
                eoACPwrQualityPhaseReactivePower   Integer32,
                eoACPwrQualityPhaseApparentPower   Integer32,
                eoACPwrQualityPhasePowerFactor     Integer32,
                eoACPwrQualityPhaseImpedance       Integer32
            eoACPwrQualityDelPhaseToNextPhaseVoltage      Integer32,
            eoACPwrQualityDelThdPhaseToNextPhaseVoltage   Integer32,
            eoACPwrQualityDelThdCurrent                   Integer32
                eoACPwrQualityWyePhaseToNeutralVoltage       Integer32,
                eoACPwrQualityWyePhaseCurrent                Integer32,
                eoACPwrQualityWyeThdPhaseToNeutralVoltage    Integer32

As the definition of power quality makes clear, these are "characteristics".
By my reading, they become "power quality" when "evaluated against a set of reference technical parameters. "
It seems to me that EMAN does not contain "reference technical parameters"
and does no evaluation.
Outside of the scope of EMAN, some management systems may have such
reference parameters and may do such evaluations.

Finally, I see no advantages to including the definition and the use of the term
quality.  I see definite disadvantages.  No implementation will ever be different
based on the outcome of this decision.

A simple solution is to simply drop the word Quality out of these MIB names,
at which point the definition becomes unnecessary to include.

--Bruce

On Tue, Feb 28, 2012 at 7:18 AM, Benoit Claise <[email-masked]<mailto:[email-masked]>> wrote:
Bruce, Brad,

Can we please close this issue.

Regards, Benoit. (as a contributor for  the EMAN-FMWK)
Hi Bruce,

My count is 18 measurement attributes having an explicit reference point or ratio with three additional attributes are informational for the table: Configuration, UnitMultiplier, and Accuracy.

Which attributes are you having an issue with?

Regards,

Brad

Brad Schoening
e: [email-masked]<mailto:[email-masked]> ⟐ m: 917-304-7190<tel:917-304-7190>

<http://www.coraid.com/> Redefining Storage Economics

From: Bruce Nordman <[email-masked]<mailto:[email-masked]>>
Date: Wed, 22 Feb 2012 12:28:25 -0600
To: Brad Schoening <[email-masked]<mailto:[email-masked]>>
Cc: Benoit Claise <[email-masked]<mailto:[email-masked]>>, "[email-masked]<mailto:[email-masked]>" <[email-masked]<mailto:[email-masked]>>
Subject: Re: [eman] Power Quality versus Power Characteristics

On Mon, Feb 20, 2012 at 7:03 AM, Brad Schoening <[email-masked]<mailto:[email-masked]>> wrote:
Hi Bruce,

Your statement here is incorrect.  If you carefully review the details, you will see that the majority of these attributes incorporate a reference point.  For example, total harmonic distortion is a ratio of the distortion relative to the reference frequency.  Or consider, power factor which is a ratio of the real power to the apparent power, where real power is the reference point.

Below I have extracted the 24 entries in draft-ietf-eman-requirements-05
that are labeled "PwrQuality".  The interested reader can count how many of
these incorporate a reference point in the EMAN reporting context.

--Bruce

        powerACPwrQualityMIBTableGroup OBJECT-GROUP
                             eoACPwrQualityConfiguration,
                             eoACPwrQualityAvgVoltage,
                             eoACPwrQualityAvgCurrent,
                             eoACPwrQualityFrequency,
                             eoACPwrQualityPowerUnitMultiplier,
                             eoACPwrQualityPowerAccuracy,
                             eoACPwrQualityTotalActivePower,
                             eoACPwrQualityTotalReactivePower,
                             eoACPwrQualityTotalApparentPower,
                             eoACPwrQualityTotalPowerFactor,
                             eoACPwrQualityThdAmpheres,
                             eoACPwrQualityThdVoltage
        powerACPwrQualityPhaseMIBTableGroup OBJECT-GROUP
                             eoACPwrQualityPhaseAvgCurrent,
                             eoACPwrQualityPhaseActivePower,
                             eoACPwrQualityPhaseReactivePower,
                             eoACPwrQualityPhaseApparentPower,
                             eoACPwrQualityPhasePowerFactor,
                             eoACPwrQualityPhaseImpedance
        powerACPwrQualityDelPhaseMIBTableGroup OBJECT-GROUP
                            eoACPwrQualityDelPhaseToNextPhaseVoltage ,
                            eoACPwrQualityDelThdPhaseToNextPhaseVoltage,
                            eoACPwrQualityDelThdCurrent
        powerACPwrQualityWyePhaseMIBTableGroup OBJECT-GROUP
                            eoACPwrQualityWyePhaseToNeutralVoltage,
                            eoACPwrQualityWyePhaseCurrent,
                            eoACPwrQualityWyeThdPhaseToNeutralVoltage

Clearly, measuring distortion and reactive power (wasted energy) are 'power quality' characteristics.

Regards,

Brad

Brad Schoening
e: [email-masked]<mailto:[email-masked]> ⟐ m: 917-304-7190<tel:917-304-7190>

<http://www.coraid.com/> Redefining Storage Economics

From: Bruce Nordman <[email-masked]<mailto:[email-masked]>>
Date: Mon, 20 Feb 2012 00:43:34 -0600
To: Benoit Claise <[email-masked]<mailto:[email-masked]>>
Cc: Brad Schoening <[email-masked]<mailto:[email-masked]>>, "[email-masked]<mailto:[email-masked]>" <[email-masked]<mailto:[email-masked]>>

Subject: Re: [eman] Power Quality versus Power Characteristics

It seems to me that the definition of power quality
implies a reference point for evaluating quality
that is absent in the EMAN context - making it
unsuitable to reference.
There is actually no need to reference the term
"power quality" at all in the drafts, and therefore
no need to have a definition for it.
While it would be best to not use the term at all in
the drafts, using it as a general descriptor of power
characteristics would likely not mislead people, but
this would not require a definition.
The monitoring MIB draft does use "PwrQuality"
in many of the entries.  These can simply be changed
to "Power".
Problem solved.
--Bruce

On Tue, Feb 14, 2012 at 7:39 AM, Benoit Claise <[email-masked]<mailto:[email-masked]>> wrote:
Hi Brad,

Benoit,

I hope that the terminology draft has clarified the meaning of 'power quality' and put this issue to rest.
I hope so. Therefore, I consider this issue close.

Regards, Benoit.

Brad Schoening
e: [email-masked]<mailto:[email-masked]> ⟐ m: 917-304-7190<tel:917-304-7190>

<http://www.coraid.com/> Redefining Storage Economics

From: Benoit Claise <[email-masked]<mailto:[email-masked]>>
Date: Mon, 13 Feb 2012 10:31:21 -0600
To: Brad Schoening <[email-masked]<mailto:[email-masked]>>
Cc: Bruce Nordman <[email-masked]<mailto:[email-masked]>>, "[email-masked]<mailto:[email-masked]>" <[email-masked]<mailto:[email-masked]>>
Subject: Re: [eman] Power Quality versus Power Characteristics

Dear all,

I would like appreciate if someone could rephrase the problem description (if any), as there is some confusion.
According to this email thread, the power quality definition is fine and the EMAN requirements draft is in line with this definition.

Is the problem that the eoACPwrQualityTable EMAN monitoring MIB module contains at the same time:
- "power quality" variables
- non "power quality" variables, i.e not "evaluated against a set of reference technical parameters"? Example: current
Hence the table name should NOT contain "Power Quality" and the [EMAN-FMWK] wordings might have to be updated.

Please let us know.

Regards, Benoit.
Hi Bruce,

I don't understand the context for choosing those three categories., 1, 2 & 3 or how they were derived?  These categories seem pretty much ad hoc .

In contrast, our EMAN Terminology states, directly quoting IEC 60050:

http://tools.ietf.org/html/draft-parello-eman-definitions-04

  Power Quality

       Characteristics of the electric current, voltage and

       frequencies at a given point in an electric power

       system, evaluated against a set of reference technical

       parameters. These parameters might, in some cases,

       relate to the compatibility between electricity

       supplied in an electric power system and the loads

       connected to that electric power system.

       Reference: [IEC60050<http://tools.ietf.org/html/draft-parello-eman-definitions-04#ref-IEC60050>]

This seems both adequate and clear.

The EMAN requirements draft states:

Power quality parameters include the actual voltage, the actual frequency, the Total Harmonic Distortion (THD) of voltage and current, the impedance of an AC phase or of the DC Supply.

That also seems perfectly fine and clear.

The framework draft lists the following 22 attributes, but many are redundant due to separate tables for single-phase, delta-phase, and wye-phase.  Of these, only current isn't obviously a power quality characteristic.

         +------------------+--------------------+

         |         ACQuality                     |

         |---------------------------------------|

         | acConfiguration : enum {SNGL, DEL,WYE}|

         | avgVoltage   : long                   |

         | avgCurrent   : long                   |

         | frequency    : long                   |

         | unitMultiplier  : int                 |

         | accuracy  : int                       |

         | totalActivePower  : long              |

         | totalReactivePower : long             |

         | totalApparentPower : long             |

         | totalPowerFactor : long

         +---------------------------------------+

         +------------------------------------+

         |         ACPhase                    |

         |------------------------------------|

         | phaseIndex : long                  |

         | avgCurrent : long                  |

         | activePower : long                 |

         | reactivePower : long               |

         | apparentPower : long               |

         | powerFactor : long                 |

         +------------------------------------+

         +-------------------------------+---+

         |        DelPhase                   |

         |-----------------------------------|

         |phaseToNextPhaseVoltage  : long    |

         |thdVoltage : long                  |

         |thdCurrent : long                  |

         +-----------------------------------+

         +------------------+-----------+

         |        WYEPhase              |

         |------------------------------|

         |phaseToNeutralVoltage : long  |

         |thdCurrent : long             |

         |thdVoltage : long             |

         +------------------------------+

Reviewing this, I can't understand the issue here from the meeting. Can we perhaps get more clarity or simply close this issue?

e: [email-masked]<mailto:[email-masked]> ⟐ m: 917-304-7190<tel:917-304-7190>

<http://www.coraid.com/> Redefining Storage Economics

From: Bruce Nordman <[email-masked]<mailto:[email-masked]>>
Date: Tue, 31 Jan 2012 18:05:50 -0600
To: Benoit Claise <[email-masked]<mailto:[email-masked]>>
Cc: "[email-masked]<mailto:[email-masked]>" <[email-masked]<mailto:[email-masked]>>
Subject: Re: [eman] Power Quality versus Power Characteristics

Per Benoit's email below, I agree that the current Power Quality definition is 2.
Since Power Quality has a specific meaning other than how we use it, I don't
think using it works.

The Requirements draft (http://www.ietf.org/id/draft-ietf-eman-requirements-05.txt)
uses Power Quality to refer to a collection of useful attributes of power.

The framework draft uses Power Quality to refer to everything other than
Power, Energy, and Demand.  PQ groups 22 values beginning with voltage
and current.

The framework uses the phrase "electrical characteristics".  The requirements
refers to "qualitative properties".  These generic terms are clear enough on their
own to not require definition, and are not trying to impart highly specific information.

So, I think the answer to our problem is to not define "power quality", and so not
use it to have specific meaning.  We can use it as a generic term, along with
"characteristics", "properties", "measurements", or similar terms.

Going through the IEEE Dictionary, there is no defined term that matches how
we use Power Quality.  This is because we are using it as a catchall phrase to
cover all metrics other than Energy, Power, and Demand.  It is a "Other" or "Miscellaneous"
grouping.

This seems a very workable solution for all the drafts except possibly the Monitoring MIB
draft (http://www.ietf.org/id/draft-ietf-eman-energy-monitoring-mib-01.txt).
It defines a powerQualityMIB to hold these various values.  Is it a problem if Power Quality
is not defined?  If we need a term, then it is simplest to define it as we use it - all
characteristics other than Energy, Power, and Demand.  Some term like 'additional',
'extra', 'optional', 'detailed', or such would be clear.

--Bruce

On Thu, Jan 26, 2012 at 1:51 AM, Benoit Claise <[email-masked]<mailto:[email-masked]>> wrote:
Dear all,

From the meeting minutes (http://www.ietf.org/proceedings/82/minutes/eman.txt):

Three categories of power quality:
1. Nominal power supply
2. Power quality, deviation from nominal
3. Power usage

[MC] - Power Quality has a very specific meaning in some contexts.  Power
quality mostly encompasses #2.  Many of the variables we are considering
would be considered more generally additional power characteristics than
power quality.

[BN] - Proposed to refer to these as Power Characteristics instead of Power
Quality to avoid confusion.

So the current definition of "Power Quality" in http://tools.ietf.org/html/draft-parello-eman-definitions-04 covers correctly "2.", right?
So, is Power Characteristics "1.", "2.", and "3."?

At the end, I'm not sure which problem we try to solve...

Regards, Benoit.

I am mindful that whatever we decide, it doesn't change the
implementation of EMAN, but you make some good points.

My reading of the Power Quality definition below is that it is
a judgment of suitability of some power with respect to its
usage context, so is a value judgment.
Power Characteristics was intended to not be judgmental,
and independent of any usage context.
For something like voltage, EMAN is just reporting what it
measures.  From what we know from an EMAN perspective,
there is no knowledge of what values are preferred to others.

I don't have my IEEE Dictionary handy to see if there is anything
suitable there.  I do agree that Quality and Characteristics do
mean different things.

--Bruce

On Tue, Jan 24, 2012 at 9:38 AM, John Parello (jparello) <[email-masked]<mailto:[email-masked]>> wrote:
Hi,

I'm looking at the minutes from IETF-82 and it looks as if there was a
request to change the term "power quality" to "power characteristics"

I was about to make the change but saw that I am using the term "power
quality" as directly defined by IEC 60050 and there is no such term as
"power characteristics"

The definition from IEC60050 is:
http://www.electropedia.org/iev/iev.nsf/display?openform&ievref=617-01-0
5

"""
Power Quality
Characteristics of the electric current, voltage and frequencies at a
given point in an electric power system, evaluated against a set of
reference technical parameters. These parameters might, in some cases,
relate to the compatibility between electricity supplied in an electric
power system and the loads connected to that electric power system.
"""

I'm reluctant to change that to power characteristics as the method of
definition is that we take from a source directly at first. I see no
source for power characteristics only power quality.

Since I can't find a source for power characteristics, a quick search on
how "power characteristics" is used shows that it refers more times on
how a device uses power.

So to contrast  "power quality" describes the electrical characteristics
(voltage and frequency). "Power characteristics" however  more commonly
refers to (example) a device using say 100W at boot up and the 50W at a
steady state over time.

So while the minutes state this...
"""
[BN] - Proposed to refer to these as Power Characteristics instead of
Power
Quality to avoid confusion.

[BC] - Asks room if Power Characteristics is OK.  Notes no objections.

Other terms that discussed on the list:
- Power State Set
- Energy Object Relationship

[BN] - Proposed to just continue the discussion on the list.
"""

Very easy research shows that  "power quality" and "power
characteristics" are two distinct terms and not  interchangeable.

So I'm asking "Are you sure?"

I proposed to keep "power quality" as defined by IEC60050 and if needed
I can add "power characteristics" as described above if someone has a
reference. I strongly propose not to use them interchangeably.

Feedback?
Jp

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--
Bruce Nordman
Lawrence Berkeley National Laboratory
eetd.lbl.gov/ea/nordman<http://eetd.lbl.gov/ea/nordman>
[email-masked]<mailto:[email-masked]>
510-486-7089<tel:510-486-7089>
m: 510-501-7943<tel:510-501-7943>

_______________________________________________
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--
Bruce Nordman
Lawrence Berkeley National Laboratory
eetd.lbl.gov/ea/nordman<http://eetd.lbl.gov/ea/nordman>
[email-masked]<mailto:[email-masked]>
510-486-7089<tel:510-486-7089>
m: 510-501-7943<tel:510-501-7943>

--
Bruce Nordman
Lawrence Berkeley National Laboratory
eetd.lbl.gov/ea/nordman<http://eetd.lbl.gov/ea/nordman>
[email-masked]<mailto:[email-masked]>
510-486-7089<tel:510-486-7089>
m: 510-501-7943<tel:510-501-7943>

--
Bruce Nordman
Lawrence Berkeley National Laboratory
eetd.lbl.gov/ea/nordman<http://eetd.lbl.gov/ea/nordman>
[email-masked]<mailto:[email-masked]>
510-486-7089<tel:510-486-7089>
m: 510-501-7943<tel:510-501-7943>

--
Bruce Nordman
Lawrence Berkeley National Laboratory
eetd.lbl.gov/ea/nordman<http://eetd.lbl.gov/ea/nordman>
[email-masked]<mailto:[email-masked]>
510-486-7089<tel:510-486-7089>
m: 510-501-7943<tel:510-501-7943>

--
Bruce Nordman
Lawrence Berkeley National Laboratory
eetd.lbl.gov/ea/nordman<http://eetd.lbl.gov/ea/nordman>
[email-masked]<mailto:[email-masked]>
510-486-7089
m: 510-501-7943

---

From: Bruce Nordman <[email-masked]>
Date: Fri, 9 Mar 2012 01:14:48 -0500

Not closed, but I'll take your point on those two.

How about the other 22 values.  Most of them do not seem like
power quality to me, e.g. current.  Can you identify which are?  For those
that
are not, the MIB variable names could be adjusted and then I
think we can close this issue.

Thanks,

--Bruce

On Thu, Mar 8, 2012 at 8:59 AM, Brad Schoening <[email-masked]> wrote:

>  <http://www.coraid.com/> Redefining
> Storage Economics****
>
> ** **
>
> From: Brad Schoening <[email-masked]>
> To: Bruce Nordman <[email-masked]>
>
> Cc: "[email-masked]" <[email-masked]>
> For example, total harmonic distortion is a ratio of the distortion
>> relative to the reference frequency.  Or consider, power factor which is a
>> ratio of the real power to the apparent power, where real power is the
>> reference point.
>>
>
> Brad Schoening
>  <http://www.coraid.com/> Redefining
> Storage Economics****
>
> ** **
>
> From: Bruce Nordman <[email-masked]>
> To: Brad Schoening <[email-masked]>
> Cc: Benoit Claise <[email-masked]>, "[email-masked]" <[email-masked]>
> On Wed, Feb 29, 2012 at 2:30 PM, Brad Schoening <[email-masked]> wrote:
>
>> Bruce,
>>
>> I believe we are talking past each other.  The majority of these 24 MIB
>> variables *do* have a reference value as noted in my earlier email.  Could
>> you be specific about which ones you feel don't have a reference parameter.
>>
>>
>> Brad Schoening
>>  <http://www.coraid.com/> Redefining
>> Storage Economics****
>>
>> ** **
>>
>> From: Bruce Nordman <[email-masked]>
>> To: Benoit Claise <[email-masked]>
>> Cc: Brad Schoening <[email-masked]>, "[email-masked]" <[email-masked]>
>> given point in
>> an electric power system, *evaluated against a set of reference
>> technical parameters*.
>> By my reading, they become "power quality" when "*evaluated against a
>> set of reference technical parameters*. "
>> On Tue, Feb 28, 2012 at 7:18 AM, Benoit Claise <[email-masked]> wrote:
>>
>>>  Bruce, Brad,
>>>
>>>  My count is 18 measurement attributes having an explicit reference
>>> point or ratio with three additional attributes are informational for the
>>> table: Configuration, UnitMultiplier, and Accuracy.
>>>
>>>   <http://www.coraid.com/> Redefining
>>> Storage Economics****
>>>
>>> ** **
>>>
>>>  From: Bruce Nordman <[email-masked]>
>>> To: Brad Schoening <[email-masked]>
>>> Cc: Benoit Claise <[email-masked]>, "[email-masked]" <[email-masked]>
>>> On Mon, Feb 20, 2012 at 7:03 AM, Brad Schoening <[email-masked]>wrote:
>>>
>>>>   Hi Bruce,
>>>>
>>>>  Your statement here is incorrect.  If you carefully review the
>>>> details, you will see that the majority of these attributes incorporate a
>>>> reference point.  For example, total harmonic distortion is a ratio of the
>>>> distortion relative to the reference frequency.  Or consider, power factor
>>>> which is a ratio of the real power to the apparent power, where real power
>>>> is the reference point.
>>>>
>>>
>>>>  From: Bruce Nordman <[email-masked]>
>>>> To: Benoit Claise <[email-masked]>
>>>> Cc: Brad Schoening <[email-masked]>, "[email-masked]" <[email-masked]>
>>>>
>>>>  On Tue, Feb 14, 2012 at 7:39 AM, Benoit Claise <[email-masked]>wrote:
>>>>
>>>>>  Hi Brad,
>>>>>
>>>>>   Benoit,
>>>>>
>>>>>  I hope that the terminology draft has clarified the meaning of
>>>>> 'power quality' and put this issue to rest.
>>>>>
>>>>>  From: Benoit Claise <[email-masked]>
>>>>> To: Brad Schoening <[email-masked]>
>>>>> Cc: Bruce Nordman <[email-masked]>, "[email-masked]" <[email-masked]>
>>>>> I would like appreciate if someone could rephrase the problem
>>>>> description (if any), as there is some confusion.
>>>>> According to this email thread, the power quality definition is fine
>>>>> and the EMAN requirements draft is in line with this definition.
>>>>>
>>>>> - non "power quality" variables, i.e not "evaluated against a set of
>>>>> reference technical parameters"? Example: current
>>>>> Hence the table name should NOT contain "Power Quality" and the
>>>>> [EMAN-FMWK] wordings might have to be updated.
>>>>>
>>>>> Please let us know.
>>>>>
>>>>> Regards, Benoit.
>>>>>
>>>>>  Hi Bruce,
>>>>>
>>>>>  I don't understand the context for choosing those three categories.,
>>>>> 1, 2 & 3 or how they were derived?  These categories seem pretty much ad
>>>>> hoc .
>>>>>
>>>>>   Power quality parameters include the actual voltage, the actual
>>>>> frequency, the Total Harmonic Distortion (THD) of voltage and current, the
>>>>> impedance of an AC phase or of the DC Supply.
>>>>>
>>>>>
>>>>>  The framework draft lists the following 22 attributes, but many are
>>>>> redundant due to separate tables for single-phase, delta-phase, and
>>>>> wye-phase.  Of these, only current isn't obviously a power quality
>>>>> characteristic.
>>>>>
>>>>>
>>>>>  Reviewing this, I can't understand the issue here from the meeting.
>>>>> Can we perhaps get more clarity or simply close this issue?
>>>>>
>>>>>
>>>>>
>>>>>  From: Bruce Nordman <[email-masked]>
>>>>> To: Benoit Claise <[email-masked]>
>>>>> Cc: "[email-masked]" <[email-masked]>
>>>>> The Requirements draft (
>>>>> http://www.ietf.org/id/draft-ietf-eman-requirements-05.txt)
>>>>> draft (
>>>>> http://www.ietf.org/id/draft-ietf-eman-energy-monitoring-mib-01.txt).
>>>>> On Thu, Jan 26, 2012 at 1:51 AM, Benoit Claise <[email-masked]>wrote:
>>>>>
>>>>>>  Dear all,
>>>>>>
>>>>>> From the meeting minutes (
>>>>>> http://www.ietf.org/proceedings/82/minutes/eman.txt):
>>>>>>
>>>>>>  So the current definition of "Power Quality" in
>>>>>> http://tools.ietf.org/html/draft-parello-eman-definitions-04 covers
>>>>>> correctly "2.", right?
>>>>>> On Tue, Jan 24, 2012 at 9:38 AM, John Parello (jparello) <
>>>>>> [email-masked]> wrote:
>>>>>>
>>>>>>> Hi,
>>>>>>>
>>>>>>> [email-masked]
>>>>>> *Bruce Nordman*
>>>>>> eetd.lbl.gov/ea/nordman
>>>>>> [email-masked]
>>>>>> eman mailing [email-masked]://www.ietf.org/mailman/listinfo/eman
>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> *Bruce Nordman*
>>>>> eetd.lbl.gov/ea/nordman
>>>>> [email-masked]
>>>> *Bruce Nordman*
>>>> eetd.lbl.gov/ea/nordman
>>>> [email-masked]
>>> *Bruce Nordman*
>>> eetd.lbl.gov/ea/nordman
>>> [email-masked]
>> *Bruce Nordman*
>> eetd.lbl.gov/ea/nordman
>> [email-masked]
> *Bruce Nordman*
> eetd.lbl.gov/ea/nordman
> [email-masked]

-- 
*Bruce Nordman*
eetd.lbl.gov/ea/nordman
[email-masked]
510-486-7089
m: 510-501-7943

---

From: Brad Schoening <[email-masked]>
Date: Fri, 9 Mar 2012 01:05:31 -0600

Bruce,

I agree with you that current in a single-phase system is not a power quality attribute, but a reference.  But, current needs to be reported for both single phase and multi-phase circuits.  In multi-phase circuits, balanced voltages lead to balanced currents.  The relative values of current(A), current(B) and current(C) can be measured to determine if the multi-phase system is balanced.  All the other attributes I believe have reference values also.

If you read down this email thread, you'll see that on January 31st, I wrote:

I would suggest that since we are reporting ThdCurrent, having the average current in these table makes sense.  Both as a reference point, relative value in multi-phase circuits, and for simplicity of implementation.

Brad Schoening

Date: Fri, 9 Mar 2012 00:14:48 -0600

How about the other 22 values.  Most of them do not seem like
power quality to me, e.g. current.  Can you identify which are?  For those that
are not, the MIB variable names could be adjusted and then I
think we can close this issue.

Thanks,

--Bruce

On Thu, Mar 8, 2012 at 8:59 AM, Brad Schoening <[email-masked]<mailto:[email-masked]>> wrote:
Bruce,

Brad Schoening

Bruce,

Brad Schoening

Brad Schoening

--Bruce

Regards,

Brad

Brad Schoening

--Bruce

Regards,

Brad

Brad Schoening

Benoit,

Regards, Benoit.

Brad Schoening

Dear all,

Please let us know.

Regards, Benoit.
Hi Bruce,

  Power Quality

         |         ACQuality                     |

         | avgVoltage   : long                   |

         | avgCurrent   : long                   |

         | frequency    : long                   |

         | unitMultiplier  : int                 |

         | accuracy  : int                       |

         |         ACPhase                    |

         | phaseIndex : long                  |

         | avgCurrent : long                  |

         | activePower : long                 |

         | reactivePower : long               |

         | apparentPower : long               |

         | powerFactor : long                 |

         |        DelPhase                   |

         |thdVoltage : long                  |

         |thdCurrent : long                  |

         |        WYEPhase              |

         |thdCurrent : long             |

         |thdVoltage : long             |

--Bruce

Regards, Benoit.

--Bruce

"""
Power Quality

Feedback?
Jp

---

From: Bruce Nordman <[email-masked]>
Date: Fri, 9 Mar 2012 15:15:20 -0800

OK, we are making progress.  I've agreed that THD and Power Factor are
power quality.
You agree that current is not power quality.  I'll defer to you on whether
ThdCurrent is power quality.

An important point in all of this is that that all these values are
"characteristics" (the word used
in the power quality definition).  The question is which are or are not
also power quality, which
requires "...*evaluated against a set of reference technical parameters*. ".

This leaves various entries for voltage, power, frequency, multiplier, and
accuracy.

For voltage, I am assuming that a device may want to receive power at some
nominal
voltage, with an acceptable range of +/- a second value (e.g. 200 V +/- 10
V).
To be power quality EMAN would have to know these reference parameters and
since it doesn't voltage seems to be just a regular characteristic.  The
management
system may be able to bring outside information to bear and then make such
judgments, but that is outside our scope.

So, if we can put each of the 24 into the Power Quality bucket or the other
bucket
then I think we will have closed out the issue.

Thanks

--Bruce (as contributor)

Note: The great majority of my emails to the list are as a contributor but
as I am
not in the habit of remembering to include that note, I usually forget.  I
will try to
add "(as co-chair)" for those emails that are of that type, with the rest
being as
a contributor.

On Thu, Mar 8, 2012 at 11:05 PM, Brad Schoening <[email-masked]> wrote:

> Bruce,
>
> I agree with you that current in a single-phase system is not a power
> quality attribute, but a reference.  But, current needs to be reported for
> both single phase and multi-phase circuits.  In multi-phase circuits,
> balanced voltages lead to balanced currents.  The relative values of
> current(A), current(B) and current(C) can be measured to determine if the
> multi-phase system is balanced.  All the other attributes I believe have
> reference values also.
>
>>> I would suggest that since we are reporting ThdCurrent, having the
> average current in these table makes sense.  Both as a reference point,
> relative value in multi-phase circuits, and for simplicity of
> implementation.
>
>
> Brad Schoening
>>> On Tue, Feb 28, 2012 at 7:18 AM, Benoit Claise <[email-masked]>wrote:
>>>
>>>>  Bruce, Brad,
>>>>
>>>>> Storage Economics
>>>>>> Storage Economics
>>>>>>  I don't understand the context for choosing those three
>>>>>> categories., 1, 2 & 3 or how they were derived?  These categories seem
>>>>>> pretty much ad hoc .
>>>>>>
>>>>>> Storage Economics

---

From: Brad Schoening <[email-masked]>
Date: Fri, 9 Mar 2012 19:55:29 -0600

Bruce,

Fortunately, we need not "assume" anything, since our measured values here have been cross-correlated with IEC 61850-7-4.   We have the benefit of international standards for this.  Laurent Guise, Smart Grid Standardization Director at Schneider Electric, was a big help designing our model for this.

Reference points for AC voltage and frequency should be self-apparent:  120V/60Hz or 220V/50Hz.  As you know, multiplier and accuracy help us to interpret the measurements in the table.  Thus, they are bound together with the power quality attributes.   If you review how power factor is computed, it should be clear how active, reactive, and apparent power are related as quality metrics.  My email earlier explained [see below] how current in a 3-phase system can be balanced, hence its inclusion here.  If you want to understand further what each of the measurements mean, I would strongly suggest you look at IEC 61850-7-4.

[B Nordman] "This leaves various entries for voltage, power, frequency, multiplier, and accuracy."

Hope this helps clear up these.

Regards,

Brad

Brad Schoening

Date: Fri, 9 Mar 2012 17:15:20 -0600

OK, we are making progress.  I've agreed that THD and Power Factor are power quality.
You agree that current is not power quality.  I'll defer to you on whether ThdCurrent is power quality.

An important point in all of this is that that all these values are "characteristics" (the word used
in the power quality definition).  The question is which are or are not also power quality, which
requires "...evaluated against a set of reference technical parameters. ".

This leaves various entries for voltage, power, frequency, multiplier, and accuracy.

For voltage, I am assuming that a device may want to receive power at some nominal
voltage, with an acceptable range of +/- a second value (e.g. 200 V +/- 10 V).
To be power quality EMAN would have to know these reference parameters and
since it doesn't voltage seems to be just a regular characteristic.  The management
system may be able to bring outside information to bear and then make such
judgments, but that is outside our scope.

So, if we can put each of the 24 into the Power Quality bucket or the other bucket
then I think we will have closed out the issue.

Thanks

--Bruce (as contributor)

Note: The great majority of my emails to the list are as a contributor but as I am
not in the habit of remembering to include that note, I usually forget.  I will try to
add "(as co-chair)" for those emails that are of that type, with the rest being as
a contributor.

On Thu, Mar 8, 2012 at 11:05 PM, Brad Schoening <[email-masked]<mailto:[email-masked]>> wrote:
Bruce,

Brad Schoening

Thanks,

--Bruce

Brad Schoening

Bruce,

Brad Schoening

Brad Schoening

--Bruce

Regards,

Brad

Brad Schoening

--Bruce

Regards,

Brad

Brad Schoening

Benoit,

Regards, Benoit.

Brad Schoening

Dear all,

Please let us know.

Regards, Benoit.
Hi Bruce,

  Power Quality

         |         ACQuality                     |

         | avgVoltage   : long                   |

         | avgCurrent   : long                   |

         | frequency    : long                   |

         | unitMultiplier  : int                 |

         | accuracy  : int                       |

         |         ACPhase                    |

         | phaseIndex : long                  |

         | avgCurrent : long                  |

         | activePower : long                 |

         | reactivePower : long               |

         | apparentPower : long               |

         | powerFactor : long                 |

         |        DelPhase                   |

         |thdVoltage : long                  |

         |thdCurrent : long                  |

         |        WYEPhase              |

         |thdCurrent : long             |

         |thdVoltage : long             |

--Bruce

Regards, Benoit.

--Bruce

"""
Power Quality

Feedback?
Jp

---

From: Bruce Nordman <[email-masked]>
Date: Sun, 11 Mar 2012 22:31:49 -0700

All 24 entries in the MIB are "power characteristics" (per the definition of
power quality.  We have 2 entries in the power quality bucket - THD and
power factor.

For voltage and frequency, evaluating quality requires knowing the reference
parameter, not just guessing.  A nice graph on this is:

http://en.wikipedia.org/wiki/File:Weltkarte_der_Netzspannungen_und_Netzfrequenzen.svg
which is referenced from:
  http://en.wikipedia.org/wiki/Mains_electricity_by_country
There is no single "reference value" that can be assumed.
EMAN does not have reference parameters and does no
evaluation, and so not power quality.
Also, we also do DC, which also has many standard voltages today.

For three phase power, I fully agree that the various power characteristics
are necessary inputs to an evaluation of power quality, though these inputs
themselves are not power quality assessments.

I do agree that power factor is an example of power quality as it is the
result of a computation against a reference parameter - it is not just the
data that are used as inputs to such a calculation.

--Bruce (as contributor)

On Fri, Mar 9, 2012 at 5:55 PM, Brad Schoening <[email-masked]> wrote:

> Bruce,
>
> Fortunately, we need not "assume" anything, since our measured values here
> have been cross-correlated with IEC 61850-7-4.   We have the benefit of
> international standards for this.  Laurent Guise, Smart Grid
> Standardization Director at Schneider Electric, was a big help designing
> our model for this.
>
> Reference points for AC voltage and frequency should be self-apparent:
>  120V/60Hz or 220V/50Hz.  As you know, multiplier and accuracy help us to
> interpret the measurements in the table.  Thus, they are bound together
> with the power quality attributes.   If you review how power factor is
> computed, it should be clear how active, reactive, and apparent power are
> related as quality metrics.  My email earlier explained [see below] how
> current in a 3-phase system can be balanced, hence its inclusion here.  If
> you want to understand further what each of the measurements mean, I would
> strongly suggest you look at IEC 61850-7-4.
>
>>> On Wed, Feb 29, 2012 at 2:30 PM, Brad Schoening <[email-masked]>wrote:
>>>
>>>> Bruce,
>>>>
>>>>>>> Cc: Bruce Nordman <[email-masked]>, "[email-masked]" <[email-masked]
>>>>>>> >
>>>>>>>  The framework draft lists the following 22 attributes, but many
>>>>>>> are redundant due to separate tables for single-phase, delta-phase, and
>>>>>>>  Reviewing this, I can't understand the issue here from the
>>>>>>> meeting. Can we perhaps get more clarity or simply close this issue?
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>> http://tools.ietf.org/html/draft-parello-eman-definitions-04covers correctly "2.", right?

---

From: Brad Schoening <[email-masked]>
Date: Tue, 13 Mar 2012 00:03:34 -0500

Bruce,

First, you have made two misstatements I'd like to correct:

[BN] "We have 2 entries in the power quality bucket - THD and power factor."

 'THD' is an abbreviation for 'Total Harmonic Distortion'.  Alone, it doesn’t mean anything and there is not a stand-alone 'THD' variable in the MIB.  What is in the MIB is three THD measurements in the table, for current, voltage, and amperes.

[BN] "Also, we also do DC, which also has many standard voltages today"

These tables are AC power quality, not DC as indicated by the name prefix 'eoACPwrQuality%'

---------------------

Regarding the other points here

"EMAN does not have reference parameters and does no evaluation, and so not power quality."

1. Good, we both agree that voltage and frequency are almost always national standards.  Thus, these can be configured as fixed values in the EnMS.  You certainly wouldn't need to read these every time you read the table.   Thus, reading a voltage of 118 when your national standard is 120, that is a power quality metric, as these are voltage sags.

If your issues is that these are absolute (118V), not relative values (-2V), I think that is a pedantic concern.  We could certainly add a write MIB variable to the MIB that would allow one to set 120V as the reference value and to return these as relative values.  However, that is a task much more easily done by an EnMS.

A table for DC power quality could be added in the future, but it doesn't seem to be of significant concern because DC power networks are isolated, while AC ones interact with the grid.  If you have for example, significant reactive power, it affects the grid.

2. PowerUnitMultiplier and PowerAccuracy are required modifiers for other MIB variables in the table.  Simply stated, they tell you 'how accurate' and 'which fixed-point scale' are the measurements being reported in this table.

From the text of the MIB
"For example, if current power usage of a Power Monitor is 3, it could be 3 W, 3 mW, 3 KW, or 3 MW, depending on the value of pmPowerUnitMultiplier. Note that other measurements throughout the two MIB modules in this document use the same mechanism, including pmPowerStatePowerUnitMultiplier, pmEnergyIntervalEnergyUnitMultiplier, and pmACPwrQualityPowerUnitMultiplier."

3. Previously, I've explained how current in a 3-phase system should be balanced by phase and current & how reactive, active, and apparent power are power quality measurements.

        "--Bruce (as contributor)"

4.  I think you mean Bruce (as chair).

Brad Schoening

Date: Mon, 12 Mar 2012 00:31:49 -0500

All 24 entries in the MIB are "power characteristics" (per the definition of
power quality.  We have 2 entries in the power quality bucket - THD and power factor.

--Bruce (as contributor)

On Fri, Mar 9, 2012 at 5:55 PM, Brad Schoening <[email-masked]<mailto:[email-masked]>> wrote:
Bruce,

Regards,

Brad

Brad Schoening

Thanks

--Bruce (as contributor)

Brad Schoening

Thanks,

--Bruce

Brad Schoening

Bruce,

Brad Schoening

Brad Schoening

--Bruce

Regards,

Brad

Brad Schoening

--Bruce

Regards,

Brad

Brad Schoening

Benoit,

Regards, Benoit.

Brad Schoening

Dear all,

Please let us know.

Regards, Benoit.
Hi Bruce,

  Power Quality

         |         ACQuality                     |

         | avgVoltage   : long                   |

         | avgCurrent   : long                   |

         | frequency    : long                   |

         | unitMultiplier  : int                 |

         | accuracy  : int                       |

         |         ACPhase                    |

         | phaseIndex : long                  |

         | avgCurrent : long                  |

         | activePower : long                 |

         | reactivePower : long               |

         | apparentPower : long               |

         | powerFactor : long                 |

         |        DelPhase                   |

         |thdVoltage : long                  |

         |thdCurrent : long                  |

         |        WYEPhase              |

         |thdCurrent : long             |

         |thdVoltage : long             |

--Bruce

Regards, Benoit.

--Bruce

"""
Power Quality

Feedback?
Jp

---

From: "Mouli Chandramouli (moulchan)" <[email-masked]>
Date: Wed, 14 Mar 2012 06:52:44 -0500

The shark_manual.pdf gives an intro (page 1-13)  to Power Quality – which might be useful.  

1.5: Power Quality

􀁑 Power quality can mean several different things. The terms ‘power quality’ and ‘power quality  problem’ have been applied to all types of conditions. A simple definition of ‘power quality

problem’ is any voltage, current or frequency deviation that results in mis-operation or failure of customer equipment or systems. The causes of power quality problems vary widely and may

originate in the customer equipment, in an adjacent customer facility or with the utility.  Some of that information is summarized in Table 1.3 below.

 

From: [email-masked] [mailto:[email-masked]] On Behalf Of Brad Schoening
Sent: Tuesday, March 13, 2012 10:34 AM
To: Bruce Nordman
Cc: [email-masked]
Subject: Re: [eman] Power Quality versus Power Characteristics

Bruce,

---------------------

From the text of the MIB  

 
Brad Schoening

 

--Bruce (as contributor)

Bruce,

Regards,

Brad

Brad Schoening

Error! Filename not specified. <http://www.coraid.com/>  Redefining Storage Economics

Thanks

--Bruce (as contributor)

Bruce,

Brad Schoening

Error! Filename not specified. <http://www.coraid.com/>  Redefining Storage Economics

Thanks,

--Bruce

Bruce,

Brad Schoening

Error! Filename not specified. <http://www.coraid.com/>  Redefining Storage Economics

Bruce,

Brad Schoening

Error! Filename not specified. <http://www.coraid.com/>  Redefining Storage Economics

Bruce,

Brad Schoening

Error! Filename not specified. <http://www.coraid.com/>  Redefining Storage Economics

--Bruce

Bruce, Brad,

Hi Bruce,

Regards,

Brad

Brad Schoening

Error! Filename not specified. <http://www.coraid.com/>  Redefining Storage Economics

 

On Mon, Feb 20, 2012 at 7:03 AM, Brad Schoening <[email-masked]> wrote:

Hi Bruce,

--Bruce

	Regards,

	Brad

	Brad Schoening

	Error! Filename not specified. <http://www.coraid.com/>  Redefining Storage Economics

	On Tue, Feb 14, 2012 at 7:39 AM, Benoit Claise <[email-masked]> wrote:

	Hi Brad, 

	Benoit,

	
	Regards, Benoit. 

	 

	Brad Schoening

	Error! Filename not specified. <http://www.coraid.com/>  Redefining Storage Economics

	Dear all,

	
	Please let us know.
	
	Regards, Benoit.

	Hi Bruce,

	  Power Quality

	       Reference: [IEC60050 <http://tools.ietf.org/html/draft-parello-eman-definitions-04#ref-IEC60050> ]

	         |         ACQuality                     | 

	         | avgVoltage   : long                   | 

	         | avgCurrent   : long                   | 

	         | frequency    : long                   | 

	         | unitMultiplier  : int                 | 

	         | accuracy  : int                       | 

	         |         ACPhase                    | 

	         | phaseIndex : long                  | 

	         | avgCurrent : long                  | 

	         | activePower : long                 | 

	         | reactivePower : long               | 

	         | apparentPower : long               | 

	         | powerFactor : long                 | 

	         |        DelPhase                   |      

	         |thdVoltage : long                  |      

	         |thdCurrent : long                  |      

	         |        WYEPhase              | 

	         |thdCurrent : long             | 

	         |thdVoltage : long             | 

	 

	 

	Error! Filename not specified. <http://www.coraid.com/>  Redefining Storage Economics

	

	

	
	--Bruce

	On Thu, Jan 26, 2012 at 1:51 AM, Benoit Claise <[email-masked]> wrote:

	Dear all,

	 

	
	
	Regards, Benoit. 

	

	--Bruce

	On Tue, Jan 24, 2012 at 9:38 AM, John Parello (jparello) <[email-masked]> wrote:

	Hi,

	
	
	"""
	Power Quality

	

	

	

	Feedback?
	Jp

	

	

	_______________________________________________
	eman mailing list
	[email-masked]://www.ietf.org/mailman/listinfo/eman

---

From: Brad Schoening <[email-masked]>
Date: Tue, 20 Mar 2012 09:59:40 -0500

I hope my explanation below from last week have resolved this now.

Brad Schoening

Date: Tue, 13 Mar 2012 00:03:34 -0500

Bruce,

---------------------

From the text of the MIB

Brad Schoening

--Bruce (as contributor)

Regards,

Brad

Brad Schoening

Thanks

--Bruce (as contributor)

Brad Schoening

Thanks,

--Bruce

Brad Schoening

Bruce,

Brad Schoening

Brad Schoening

--Bruce

Regards,

Brad

Brad Schoening

--Bruce

Regards,

Brad

Brad Schoening

Benoit,

Regards, Benoit.

Brad Schoening

Dear all,

Please let us know.

Regards, Benoit.
Hi Bruce,

  Power Quality

         |         ACQuality                     |

         | avgVoltage   : long                   |

         | avgCurrent   : long                   |

         | frequency    : long                   |

         | unitMultiplier  : int                 |

         | accuracy  : int                       |

         |         ACPhase                    |

         | phaseIndex : long                  |

         | avgCurrent : long                  |

         | activePower : long                 |

         | reactivePower : long               |

         | apparentPower : long               |

         | powerFactor : long                 |

         |        DelPhase                   |

         |thdVoltage : long                  |

         |thdCurrent : long                  |

         |        WYEPhase              |

         |thdCurrent : long             |

         |thdVoltage : long             |

--Bruce

Regards, Benoit.

--Bruce

"""
Power Quality

Feedback?
Jp

---

From: Bruce Nordman <[email-masked]>
Date: Tue, 20 Mar 2012 11:08:52 -0700

Brad, EMAN--

   I think Brad and I have hit an impasse; I don't think further discussion
between
the two of us will make progress.  Others need to chime in somehow to
resolve this.
I agree this is a minor issue since no implementation will be changed by
the outcome.
  Mouli's email of a week ago provided some examples of power quality from
one reference.  Only harmonic distortion overlaps with the variables labeled
as power quality in the MIB.
  Brad and I have agreed that Power Factor and THD are measures of power
quality, and both agree on the definition of power quality in the
definitions draft.
  We do not seem to agree on what a "reference value" or "evaluated against"
mean in the EMAN context.

  The full definition from the Framework (and Definitions) document is
(emphases added)
Power Quality
*Characteristics* of the electric current, voltage and frequencies
at a given point electric power system, *evaluated against of
reference technical parameters*.
These parameters might, in some cases, relate to the compatibility
between electricity supplied in an electric power system and the
loads connected to that electric power system.
Reference: [IEC60050]

Thanks,

--Bruce

On Tue, Mar 20, 2012 at 7:59 AM, Brad Schoening <[email-masked]> wrote:

>  'THD' is an abbreviation for 'Total Harmonic Distortion'.  Alone, it
> doesn’t mean anything and there is not a stand-alone 'THD' variable in the
> MIB.  What is in the MIB is three THD measurements in the table, for
> current, voltage, and amperes.
>
> 1. Good, we both agree that voltage and frequency are almost always
> national standards.  Thus, these can be configured as fixed values in the
> EnMS.  You certainly wouldn't need to read these every time you read the
> table.   Thus, reading a voltage of 118 when your national standard is 120,
> that is a power quality metric, as these are voltage sags.
>
> If your issues is that these are absolute (118V), not relative values
> (-2V), I think that is a pedantic concern.  We could certainly add a write
> MIB variable to the MIB that would allow one to set 120V as the reference
> value and to return these as relative values.  However, that is a task much
> more easily done by an EnMS.
>
> A table for DC power quality could be added in the future, but it doesn't
> seem to be of significant concern because DC power networks are isolated,
> while AC ones interact with the grid.  If you have for example, significant
> reactive power, it affects the grid.
>
> 2. PowerUnitMultiplier and PowerAccuracy are required modifiers for other
> MIB variables in the table.  Simply stated, they tell you 'how accurate'
> and 'which fixed-point scale' are the measurements being reported in this
> table.
>
> From the text of the MIB
>
> "For example, if current power usage of a Power Monitor is 3, it could be
> 3 W, 3 mW, 3 KW, or 3 MW, depending on the value of pmPowerUnitMultiplier.
> Note that other measurements throughout the two MIB modules in this
> document use the same mechanism, including
> pmPowerStatePowerUnitMultiplier, pmEnergyIntervalEnergyUnitMultiplier,
> and pmACPwrQualityPowerUnitMultiplier."
>
> **
> **
>> Fortunately, we need not "assume" anything, since our measured values
>> here have been cross-correlated with IEC 61850-7-4.   We have the benefit
>> of international standards for this.  Laurent Guise, Smart Grid
>>>>> I believe we are talking past each other.  The majority of these 24
>>>>> MIB variables *do* have a reference value as noted in my earlier email.
>>>>>  Could you be specific about which ones you feel don't have a reference
>>>>> parameter.
>>>>>
>>>>> Brad Schoening
>>>>>> Cc: Benoit Claise <[email-masked]>, "[email-masked]" <[email-masked]
>>>>>> >
>>>>>>>> According to this email thread, the power quality definition is
>>>>>>>> fine and the EMAN requirements draft is in line with this definition.
>>>>>>>>
>>>>>>>> - non "power quality" variables, i.e not "evaluated against a set
>>>>>>>> of reference technical parameters"? Example: current