Materially Affected Party Comments to awea draft Standard 1 – 2009, “Small Wind Turbine Performance and Safety Standard”




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НазваниеMaterially Affected Party Comments to awea draft Standard 1 – 2009, “Small Wind Turbine Performance and Safety Standard”
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Page (9), Section (8.1.2): Misunderstanding lurks here. There is a major difference between safety “margins” and safety “factors.” What is intended? Suppose a safety factor of 1.5 is required and a safety factor of 1.7 is demonstrated. The safety margin is 0.2. Reducing the safety margin by 10% would result in a safety factor of 1.68, which is fine. Reducing the safety factor by 10% would result in a safety factor of 1.33, which is inadequate. I suspect what is desired is a statement that “Any changes … that could reduce the safety factors by 10% … will require…”

IEC 61400-2 uses the term “safety factor”, though it does use “strength margin” one time. The suggested clarification has merit.

Change “safety margins” to “safety factors”

No. 7: Claude Bourget, Energie PGE (manufacturer)

Note: This commenter edited numerous sections of the draft in addition to offering specific comments. The edited version of the standard by Mr. Bourget is attached. The items below are the specific comments and edits deemed significant enough for a response. All of the other recommended edits are not accepted because they are not deemed significant enough to warrant deviation from the “BWEA version”.

Number

Comment

Recommended Response

Rcmd. Action

7.1

In Section 1.3.2: This standard applies to wind turbines having a rotor swept area of 200 m2 or less. In a horizontal-axis wind turbine this equates to a rotor diameter of ~ 16 m (~ 52 ft)nominal power output of 100 kW [200, 250, 300 kW?] or less.

Comment: The scope of this small-wind standard should not be based on swept area. Manufacturers extend rotor diameter in order to attain optimal yield at less windy sites. Since benefits of larger rotor sizes have been well demonstrated, this criterion does not add value to this standard, and actually constitute a barrier to wider market penetration of small wind turbines which is in contradiction with AWEA’s objective to increase the use of wind as an alternate source of energy.

See response to Comment 1.1

Defer issue for next edition or IEC

7.2

In Section 1.3.5: Except as noted in Sections 2.1.1, 4.2, 5.2.5, 5.2.6, and 6.1.7.1, towers and foundations are not part of the scope of this standard SHOULD BE IN SCOPE!!! because it is assumed that conformance of the tower structure to the International Building Code, Uniform Building Code or their local equivalent will be required for a building permit.

Comment: We believe that reference to ANSI/TIA-222-G-2005 (or its local equivalent), Germanischer Lloyd (GL) guidelines or IEC 61400 standards would be more appropriate for wind turbine tower design and construction, in spite of their limitations. Ideally, this standard would provide its own specs for the most important considerations to be addressed. Towers and foundations are an integral part of a wind turbine system, and are of paramount importance for a safe and reliable operation throughout the lifetime of the system. This is a matter of public safety. Therefore this standard should, as a minimum, contain specific requirements relative to tower design such as loading conditions, safety factors, natural frequencies, bolted connections, etc.

See response to Comment 6.5

None

7.3

In Section 1.7.1: “Tested wind turbines and their associated electronics shall conform to the specific requirements of the governing IEC wind generator standard for each test, but incorporating any amendments contained in this standard.”

Comment: This requirement seems to be in contradiction with article 1.2.2

Agreed, some clarification is needed.

Add the word “referenced” after “… IEC wind generator standard …” in Section 1.7.1

7.4

In Section 2.1: “Wind turbine performance shall be tested and documented in a test report per the latest edition of IEC 61400-12-1 Ed. 1 (1998-02), but incorporating the additional guidance provided in this section.”

Comment: Ed.1 released in December 2005 does not have the same structure as the 1998 edition. Section 2.1 entitled Wind Turbine Generator System does not exist in the 2005 edition. Why is 1998 version used instead of the 2005 version?

The first draft of the proposed AWEA standard was drafted in early 2004 and referenced the then current IEC documents. These references do need to be updated.

Update IEC references to the latest documents.

7.5

In Section 3.1.2: “3.1.2 WMeasuring wind speeds shall be measured directly with an anemometer instead of deriving wind speed through power is the preferred method .”

Comment: A standard that aims at “(…) comparing the performance of competing products” (art 1.1.Purpose) normally specifies how a measurement has to be made and does not allow less stringent alternatives or alternatives that may lead to interpretations.

The committee was comfortable with this guidance and did not feel that it weakened the standard.

None

7.6

Add new Section 3.1.4: “As a minimum, acoustic emissions shall be taken at integer wind speeds of 4, 5, 6, 7, 8, 9 and 10 m/s.”

Comment: This standard should state objective and/or measurable technical requirements

The draft standard does cover the testing and reporting of acoustics in an adequate manner

None

7.7

Add New Section 3.1.5 When overspeed protection mechanisms (such as furling, pitching or fluttering) become active, acoustic noise levels shall not exceed the wind induced background sound level by more than 5 dBA. (THIS IS ONLY AN EXAMPLE OF A REQUIREMENT ONE WOULD EXPECT TO FIND IN THIS STANDARD)

There is no basis for setting such a limit and the committee never considered taking this approach. Testing and reporting is deemed sufficient for consumers.

None

7.8

Eliminate Section 3.1.3

There is no basis for doing so.

None

7.9

Eliminate Section 3.1.4

There is no basis for doing so.

None

7.10

Eliminate Section 3.1.5

There is no basis for doing so.

None

7.11

Eliminate Section 3.1.6

Comment: Such an evaluation will necessarily be subjective and therefore, is unacceptable in a standard.

It has value and is acceptable in this standard. The committee felt that octave band analysis was not worth the difficulty and expense, but that unusual instances of tonality should be reported.

None

7.12

Revise 4.1 as follows: “Except as noted below, mechanical strength of the turbine system shall be assessed using either the simple equations in Section 7.4 of IEC 61400-2 Ed. 2 (2006-03) in combination with the safety factors in Section 7.8, or the aeroelastic modeling methods according to Section 7.5. Evaluation of, as a minimum, the blade root, main shaft and the yaw axis (for horizontal axis wind turbines) shall be performed using the outcome of these equations. The rest of the structure shall be assessed using appropriate design standards (ex.: IEC, GL) to prevent from flaws or safety hazards.

The point of 4.1 is to set the bounds for the analysis and the proposed wording would undo this intent.

None

7.13

Revise 4.2 as follows: “All turbine/tower combinations shall be checked against harmful dynamic interactions.

The draft language is based on decades of field experience with a wide variety of small wind turbines and strikes a balance between the costs and value of certification.

None

7.14

Revise 5.2.4 as follows: “Minor repairs that exclude replacement of major/safety-critical components as defined in paragraph 5.2.5 are allowed, but must be reported.”

The suggested language would prevent replacement of major components, which would not be in keeping with committee intent.

None

7.15

Revise 5.2.5 as follows: “In the event a major/safety-critical component needs to be replaced during the test, the test must be restarted. These components include, as a minimum, blades, main shaft, generator, gearbox, tower, controller, inverter or any component considered critical to the safe operation and/or emergency stopping of the wind turbine.”

The suggested language would imply that only “safety critical” components are significant. This would seem to weaken the restart requirement. Ultimately, the decision on what is minor and what is major will be made by the certifying agency.

None

7.16

Various edits to Section 7 to require inclusion of Rated Power and Estimated Sound Level.

Comment: Can a turbine be “AWEA certified” without Rated Power and Rated Sound Level?

AWEA will not be certifying turbines. Yes, a turbine could be certified to the AWEA standard and not report a rated power. As stated, “AWEA Rated Annual Energy” is the new basis for consumer comparisons of small wind turbine performance.

None

No. 8: Ron Fuller, State of Washington (Dept. of Labor and Industries)

Number

Comment

Recommended Response

Rcmd. Action

8.1

From my reading, it is clear that it is a performance standard and cannot be used to ascertain that a manufacturer’s product has been built to an appropriate electrical safety standard(s). The proposed standard does not include or reference any electrical safety standards appropriate to generators or interconnection with other electrical sources.

True, the proposed standard does not include electrical safety in its scope. Since the State of Washington and two other States are requiring either UL listing of the wind turbine itself or a field inspection, it is not clear what would be gained by including this consideration. States are unlikely to allow SWCC or other certifying bodies other than NRTL’s to substitute for the “UL listing” they require. Perhaps some guidance from AWEA could influence the sections of existing generator codes, etc that are applied when a NRTL evaluates the wind turbine for safety. This issue has emerged since the last committee review of the draft and it probably should be discussed at committee before a recommendation on action is proposed.

Discuss with committee at Windpower 2009.

8.2

There is a direct conflict in Section 2.1.5 with the requirements of the 2008 National Electric Code (NEC). Section 2.1.5 says that the manufacturer’s instructions prevail over any NEC requirement. That is in direct conflict with any electrical regulatory body that enforces the NEC.

There is no such conflict. The NEC does not specify the length of wires and this standard does not review the manufacturer’s compliance with the NEC. The only time this will be a consideration is during any local electrical inspection of a test site installation.

None

8.3

Section 7, labeling, is also incomplete in that it does not address the very specific requirements for labeling in NEC 445.11 for generators. All of the labeling information required in NEC 445.11 is essential for an inspector or installer of a generator. In addition, there is no reference in the proposed standard for invertors or other electrical control devices for how they operate or are manufactured. There are also very specific requirements (e.g. disconnection, overcurrent protection, labeling, etc.) in NEC 705 for electrical power sources that are used to interconnect with other electric power sources.

Compliance with the NEC is not within the scope of this standard.

None

No. 9: David Snowberg, Southwest Windpower (manufacturer)

Number

Comment

Recommended Response

Rcmd. Action

9.1

The SWCC standard makes no reference to the qualifications of the entities referred to as the "Independent Certifying Agency".  Self-certification is not allowed (see 1.4.1), but who are these "Independent Certifying Agencies"?  I suggest AWEA define what accreditations will qualify an agency as an “Independent Certifying Agency” or create an accreditation program to qualify agencies/individuals as qualified "Independent Certifying Agencies".

We mean SWCC or NRTL’s, but the AWEA Standards Coordinating Committee has removed references to SWCC. It should be more specific.


This also brings up the issue of reciprocity with the BWEA standard because they specifically require the European equivalent of a NRTL (“EN 45011 by UKAS”). We need to establish that SWCC certification in the U.S. will be accepted in the U.K. as a condition that certification from the U.K. will be accepted here.

Clarify meaning by specifying “SWCC or NRTL”


Explore this aspect of reciprocity with BWEA.

9.2

I believe a substantial part of any wind turbine safety standard should be the requirement to explicitly state the design life of the wind turbine structure.  The stated design life should include the entire wind turbine assembly including the tower.  The design life should be stated as a number of years at an average wind speed or SWT Class, in accordance with Table 1 from IEC 61400-2. 

This is beyond the scope of the current standard and would be a considerable expansion of the manufacturer’s burden, especially since the inclusion of towers is recommended.

Defer consideration for future update of the standard.

9.3

A complete fatigue analysis or suitable accelerated fatigue testing of the wind turbine assembly (including tower) is the only way to substantiate the design life claim proposed in 2).  The fatigue analysis should be done in accordance with the IEC 61400-2.  Accelerated fatigue testing to components using damage equivalent loads for the design life should be allowed as a substitute for a fatigue analysis.  All critical components such as the rotor blade, rotor shaft, nacelle, yaw shaft, and tower should be shown to have suitable fatigue strength to survive the design life.  I believe the general public's pending acceptance of small wind turbines in their neighborhoods will hinge upon the long-term survivability and safety of these structures.  Verification of the design life should not be overlooked in this SWCC standard, and I believe it is the critical element to the long-term success of the small wind turbine industry. 

See response to Comment 9.2

Defer consideration for future update of the standard.
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