Request for Feedback - Friday noon deadline!

[Matt Lafferty]

Hi everybody,

 

For those of you who don't know, the 5% Inverter Integrated Performance Specification was submitted for inclusion in the upcoming CSI Handbook. The Advice Letter, including the proposed handbook, can be found here:  http://www.pge.com/nots/rates/tariffs/tm2/pdf/ELEC_3506-E.pdf   The 5% document is Appendix D and starts on Adobe Page 155 of the Advice Letter.

 

Since being posted, a number of issues or perceived issues have come to light. Most have been typos which are being corrected via a Supplement to the Advice Letter. Stuff like the table of Tests showing all tests as Production tests... That's being corrected, and so on. Final corrections are due Friday, September 25. That is tomorrow.

 

This is where you have a chance to be a hero:  Test #4. Variation of Frequency. The tolerances & range for the test setpoints are incorrect, at least in the table. I remember discussing it, seeing it drawn on the board, but I cannot remember exactly what we came up with in our last meeting back in March. I excerpted the section into a 2-page document and made what I <think> are the proper corrections to the High & Low specs in the table, which are based on the body text of the test. I am at a complete loss for what the tolerance for the Nominal/Reference Frequency is supposed to be. As drafted, the Nominal/Reference frequency would overlap the High & Low test ranges, not to mention excede the legal operational window altogether.

 

The attached Word file shows my proposed changes. (If it doesn't view showing changes, Tools > Track Changes). The Worksheet evaluates different methodologies based on the inputs in the yellow cells. Simple, small, fast.

 

Please review and post your feedback to the group ASAP.

 

Thanks!

 

Matt Lafferty

gilli...@gmail.com

Skype @ Gilligone

+1 707 736-6212

 

[Marv Dargatz]

Matt,

First of all, thanks for the due-diligence.  You've saved us a fair amount of future headache.

My comments:

D-4.4.1 is titled "Purpose", but then contains a procedure.  Shouldn't the purpose and procedure sections be separate and distinct?

D-4.4.1(c) -- currently says "If the overfrequency or underfrequency settings are adjustable, set the inverter to the minimum overfrequency and underfrequency settings".  To mimic IEEE1547.1, it could say "If the overfrequency or underfrequency settings are adjustable, set the overfrequency trip point to its' minimum value, and set the underfrequency trip point to its' maximum value".

D-4.4.1(e) -- should be broken into two steps.  First step sets the initial nominal frequency, and the second step initiates the ramp.

D-4.4.1(g) -- The 1% value is too much, as this equals 0.6Hz, which is outside the normal upper frequency trip limit.  A value of 0.1Hz would be reasonable.  IEEE1547 does not explicitly state what accuracy is required for the nominal setting.

The "2x manufacturer's stated accuracy" exactly mimics the IEEE1547 method, so I agree with this.

Call my cell if you want to discuss.  530 392-0356.

See Ya!

Marv
Enphase Energy
707 763-4784 x7016

[Matt Lafferty]

All,

 

Thanks to Marv for the input! I did some comparison with IEEE 1547.1 and found that Test 3 (Voltage) needed some changes, too. I included the changes to Test 3 & Test 4 in my comments to the Advice Letter Crew a few minutes ago. Attached are the modified versions of Test 3 & 4 that will be submitted in the Supplemental Advice Letter for incorporation into the CSI Handbook, effective 1/1/2010.

 

Cheers,

 

Matt Lafferty

gilli...@gmail.com

Skype @ Gilligone

+1 707 736-6212

 

---

From: onboard...@googlegroups.com [mailto:onboard...@googlegroups.com] On Behalf Of Marv Dargatz
Sent: Friday, September 25, 2009 11:42 AM
To: onboard...@googlegroups.com
Subject: Re: {CSI 5 Meters} Request for Feedback - Friday noon deadline!

Matt,

First of all, thanks for the due-diligence.  You've saved us a fair amount of future headache.

My comments:

D-4.4.1 is titled "Purpose", but then contains a procedure.  Shouldn't the purpose and procedure sections be separate and distinct?  (Little late for such a bold style change, don't you think?... This is the style throughout the document.) 

D-4.4.1(c) -- currently says "If the overfrequency or underfrequency settings are adjustable, set the inverter to the minimum overfrequency and underfrequency settings".  To mimic IEEE1547.1, it could say "If the overfrequency or underfrequency settings are adjustable, set the overfrequency trip point to its' minimum value, and set the underfrequency trip point to its' maximum value".  (Funny thing.... The language as drafted is how 1547.1 reads. What is interesting is that the same language was used in our Voltage test, but 1547.1 calls out something a little different for the high-voltage so there isn't any overlap with nominal. I incorporated this methodology into Test 3 (Voltage) to prevent the issue. See attached) 

D-4.4.1(e) -- should be broken into two steps.  First step sets the initial nominal frequency, and the second step initiates the ramp.  (Done) 

D-4.4.1(g) -- The 1% value is too much, as this equals 0.6Hz, which is outside the normal upper frequency trip limit.  A value of 0.1Hz would be reasonable.  IEEE1547 does not explicitly state what accuracy is required for the nominal setting.  (Done) 

The "2x manufacturer's stated accuracy" exactly mimics the IEEE1547 method, so I agree with this.  (Done) 

Call my cell if you want to discuss.  530 392-0356.