Subject: [OPSAWG] pmPowerAccuracy in claise-energy-monitoring-mib-03

From: "Brad Schoening" <[email-masked]>
Date: Fri, 21 May 2010 11:15:35 -0400

Hi Juergen, dear all,

Thank you for reading the MIB and your incisive comments.

'Accuracy' is an attribute used by both the ANSI 12.x and IEC 61850 models
standards.  It is used ubiquitously by the power monitoring community and
energy management systems.    Accuracy can both  a) quantify an individual
devices error range and b) group devices with similar measurement
characteristics into "accuracy classes". 

Juergen raises a good point, which is how do we translate an accuracy rating
into an actual error range in watts or kilowatts?  Our description of
pmPowerAccuracy is not clear on this, but the answer is straightforward.
For example, the pmPowerUnitMultiplier can be used to convert an accuracy
percentage into a unit range.

One method and example,

pmPowerUnits                                 0              i.e,  "watts"

pmPowerAccuracy                          2%

pmPower                                            120

                error range = 0.02 * 10^0 * 100 = +/- 2 watts

However, I want to review more carefully how the IEC 61850 uses this in
practice and we can consider further refinements to our model.  Using merely
an error range would be would be hard for an Energy Management System (EMS)
to correlate across existing standards models using accuracy. 

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Brad Schoening
Consultant
Product Development
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From: "Juergen Quittek" <[email-masked]>
Date: Sat, 29 May 2010 11:09:41 +0200

Hi Brad,

You are right, I confused the standards.

According to IEC 62052-11 (that provides the definition of accuracy applied
in the IEC 61850 series) the error is exactly what you described and I agree
that we should have an accuracy object such as the one that you defined as
pmPowerAccuracy.

Thanks,

    Juergen 

On 21.05.10 17:15  "Brad Schoening" <[email-masked]> wrote:

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