Stakeholder Comment and Rationale Form AESO AUTHORITATIVE DOCUMENT PROCESS Stakeholder Consultation Draft

Stakeholder Comment and Rationale Form
AESO AUTHORITATIVE DOCUMENT PROCESS
Stakeholder Consultation Draft
Date: 2011-12-06
Proposed New ISO Rules Section 502.5 Generating Unit Technical Requirements (“New ISO Rules Section 502.5”)
Date of Request for Comment [yyyy/mm/dd]:
Period of Consultation [yyyy/mm/dd]:
2011/12/06
2011/12/06
Comments From:
TransAlta Corporation
Date [yyyy/mm/dd]:
February 14, 2012
through
2012/02/14
Contact:
Kevin T. Van Koughnett
Phone:
403-804-2319
E-mail:
[email protected]
Listed below is the summary description of changes for the proposed new, removed or amended sections of the ISO Rules. Please refer back to the Letter of Notice under the “Attachments to Letter of
Notice” section to view the actual proposed content changes to the ISO Rules. Please place your comments / reasons for position underneath (if any).
1. ISO Definitions
(a) New
There are no new ISO rules definitions associated with proposed New ISO Rules
Section 502.5
Stakeholder Comments and/or Alternate Proposal
Comment # 1: Insert Comments / Reason for Position (if
any)
AESO Replies
TransAlta suggests there should be a definition for
facilities modification, a term which is used
throughout the rule and which has important
consequences for the owner of a generating unit. The
threshold and circumstances of what is and is not
considered a facilities modification needs to be clear.
In the wind technical rule 502.1, for example, under
subsection 1(3) there is clarity added regarding
modifications.
Given the importance of a functional specification we
also suggest that this term should be defined.
We provide further comment regarding these definitions
below. We will bold these terms in our responses.
Issued for Stakeholder Consultation: 2011-12-06
Page 1
Public Information
(b) Removals
There are no ISO rules definitions removals associated with proposed New ISO
Rules Section 502.5.
Comment # 2: Insert Comments / Reason for Position (if
any)
(c) Amendments
There are no amendments to ISO rules definitions associated with proposed New
ISO Rules Section 502.5.
Comment # 3: Insert Comments / Reason for Position (if
any)
2. ISO Rules
(a) New
The AESO’s existing Generator and Load Interconnection Standard (“Technical
Standard”) was adopted in 2006. The Technical Standard has a 5 year term, and
therefore needs to be reviewed and amended during the 2011-12 timeframe.
However, the AESO is transitioning all of its technical requirements including the
Technical Standard into new ISO rules, in accordance with the principles and
procedures under the AESO’s Transition of Authoritative Documents (“TOAD”)
project. The AESO has further determined that it would be most efficient and
practical going forward to split the Technical Standard in to separate new load
and generating unit technical ISO rules. The first stage of this initiative is to redraft
and relocate the applicable generating unit provisions of the Technical Standard
into Proposed New ISO Rules Section 502.5.
The AESO is endeavoring to represent legally binding requirements and
obligations in one of its three authoritative document domains, those being ISO
rules, ISO tariff or the Alberta Reliability Standards. The proposed minimum
technical requirements of a legally binding nature for existing, modified and new
generating units have been set out in the proposed New ISO Rules Section 502.5.
It should be noted that, as provisions have been redrafted and relocated in
proposed New ISO Rules Section 502.5, the AESO has not intended any
essential changes to the policies currently reflected in the Technical Standard for
generating units, with some specific and limited exceptions referred to below.
The rationale for each of the subsections of proposed New ISO Rules Section
502.5 is provided below.
Issued for Stakeholder Consultation: 2011-12-06
Stakeholder Comments and/or Alternate Proposal
Comment # 4: Insert Comments / Reason for Position (if
any)
We suggest that the title of this Rule be “Generating
Unit Connection Technical Requirements” and that the
word “Connection” is important in giving context to the
Rule. In this sense the word “Connection” replaces
“Interconnection” in the 2006 standard title.
To fully assess if each of our generating units could
meet the requirements of rule 502.5 we need to
undertake (or review) engineering studies, testing, and
install monitoring for each facility. Such assessments
and studies take considerable time and require
significant resources, and given these resources it
would not be prudent to initiate these activities until the
final rule is approved by the AUC. Waiting until rule
approval allows an accurate gap assessment to be
done focused on compliance and solutions and/or as
necessary seeking a variance under subsection 4(2).
Solutions for larger older existing generating units are
complex, can require extensive outages, and can be
costly.
It is evident in some areas of the proposed rule that the
AESO has allowed grandfathering, exemptions, or
variances of existing units until modified. The approach
appears to be piecemeal and far from being
Page 2
AESO Replies
comprehensive in taking into consideration the
generating unit condition and capabilities particularly in
the case of older units designed decades ago to work
within the market structures, i.e. regulated rather than
competitive, and operational paradigms of those times.
Subsection 1 – Applicability
The applicability section of the Technical Standard did not clearly state which
market participant subcategories were responsible for meeting the requirements.
Subsection 1 clarifies that the requirements apply to legal owners of a generating
unit including those in an industrial complex, but excludes wind aggregated
generating facilities.
Comment # 5: Insert Comments / Reason for Position (if
any)
The Rule is silent on a minimum applicable generating
unit size.
It is common practice that a standard have a minimum
size for applicability as requirements are not the same
for small as for large units. The wind technical rule
502.1, for example, applies to generating units 5 MW
or larger.
Throughout the proposed rule 502.5 references to
various applicable minimum generating unit sizes are
used but in other places it is silent. For example,
subsection 21 is silent on this and would require a
Phasor Measurement Unit on a new 1 MW unit. The
same would apply to subsection 22 for sequence of
event monitoring. And so on for testing, etc. This is
likely unintended and needs to be remedied for
clarification.
We ask the AESO to consider changes to the proposed
rule which would exempt small generating units on the
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basis of significant expense and minimum impact on the
system in terms of operations or reliability.
For these and other requirements in the rule we ask the
AESO to provide evidence of the system benefits which
justify the inclusion of the requirement including the
threshold for invoking the requirement.
Given the size of the Alberta system with a peak
demand exceeding 10,600 MW, we think an applicability
threshold of 20 to 25 MW or more would be appropriate.
FERC, for example, distinguishes between large and
small using a 20 MW threshold. NERC reliability
standards usually have a much higher threshold as their
focus is on bulk system reliability. The AESO could
either have a separate standard/rule for small
generating units or, within this rule, define what is
required by unit size in each subsection. We ask the
AESO to consider the specific aspects of different unit
sizes of generating units, their age, and their condition
in deciding applicability. Further, we ask the AESO to
provide evidence of the benefits and costs for any
advocated approach.
As part of this consideration, there should be
assessment of multiple unit plants and a minimum
applicability size for a unit regardless of the aggregate
size of the facility. This assessment should also
consider the independence implied in subsection 15.
Subsection 2 – Requirements – New Generating Unit
Subsection 2 sets out, with clarity, the provisions that apply to a new generating
unit.
Issued for Stakeholder Consultation: 2011-12-06
Comment # 6: Insert Comments / Reason for Position (if
any)
Subsection 2(4) dealing with new units is the first
mention of “facilities modification” in the proposed
rule. It is also indicated in subsection 3(4) for existing
units. It is used in numerous other places in the
proposed rule. TransAlta suggests that facilities
modification be a defined term so that all parties are
clear what is and is not included.
Page 4
While we appreciate the intent of subsection 2(5) to
cover the time period between when a functional
specification is approved and when rule 502.5 is
effective, we also note the planned effective date per
the Letter of Notice is October 1, 2012. An effective date
needs to consider the resources of owners and the
AESO to assess, develop, and plan any required
changes. This in our view also includes ensuring all
generating units have a Functional Specification.
It may be that significant work has already been done
regarding a proposed generating unit and for which a
connection application has been made to the AESO but
for which a functional specification has not been
issued. In the overall permitting of a power plant there
are separate applications for the generating units and
the connection. It has been typical for the generating
unit process to be in advance of the connection process
and there are risks the functional specification may
come too late in the process for alignment with the
generating unit design.
We are also concerned that the effective date proposed
of approximately six months after approval is far too
short for generating units to meet new requirements
and should be similar to the approach of NERC for
reliability standards where the effective date after
approval provides adequate time for the owner to take
the necessary steps to comply.
Subsection 3 – Requirements – Existing Generating Unit
Subsection 3 sets out the provisions that apply to an existing generating unit,
including clarifications as to what subsections of proposed New ISO Rules
Section 502.5 are not applicable.
Comment # 7: Insert Comments / Reason for Position (if
any)
See comment above regarding facilities
modifications.
See comments below regarding functional
specifications.
Issued for Stakeholder Consultation: 2011-12-06
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Subsection 4 – Functional Specification
Consistent with current practice, subsection 4 enables the AESO to approve of
and issue a functional specification for a generating unit project, which will set out
technical details with regard to design, construction and operation of the
generating unit connection project and any associated transmission system
connection facilities.
Consistent with technical requirements under other ISO rules, Subsection 4(2)
allows for variances in a functional specification under certain conditions.
Comment # 8: Insert Comments / Reason for Position (if
any)
There is no distinction made in subsection 4 between a
new and an existing generating unit. For a new unit
there would be a Functional Specification as part of
the connection process whereas for most existing units
there would not be a Functional Specification. Does
the AESO plan to provide Functional Specifications
for existing units that do not have a Functional
Specification? If so, please outline a process and
timeline. TransAlta believes the functional
specification is an important and fundamental
component of the proposed rule.
Without the existence of a Functional Specification
the variance and flexibility provided by subsection 4(2)
is not available as the subsection states that the
Functional Specification itself may contain material
variances from section 502.5. No other mechanism is
provided for the existing generating facility owner to
avail themselves of the same provisions.
The Functional Specification for a generating unit is
an important document and it is referenced in the
following subsections apart from subsection 4:
2(5), 3(1), 6(2), 7(1), 7(3), 8(6), 8(7), 11(4), 11(9), 14(1),
16(2), 16(3), 17(3), 18(1), 18(4), 21(1) and 21(3).
Interpretation of rule 502.5 is problematic without a
Functional Specification for each generating unit
and, as such, we are concerned the proposed rule
502.5 will be technically deficient if this is not
addressed.
Given the importance of the Functional Specification
in interpretation of this rule the AESO should make it a
defined term as noted above. As well, the AESO needs
to ensure there is a functional specification for all
existing units.
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Subsection 5 – Successor to Prior Requirements
Comment # 9: Insert Comments / Reason for Position (if
any)
Subsection 5 clarifies that proposed New ISO Rules Section 502.5 succeed the
generating facilities provisions of the Technical Standard.
Subsection 6 – Operating Voltage Requirements
Subsection 6 requires the market participant to clearly state the voltages to which
the generating unit will be designed at both the point of connection and the
generator terminals.
In Alberta, the voltage levels may vary considerably from the nominal voltage,
therefore, having the legal owner clearly stating the values to be voltages at the
point of connection and the generating unit terminals allows the AESO to fairly
ensure the compliance of all legal owners with regard to:
(a) The voltage ride-through requirements;
(b) Voltage regulation; and
(c) The reactive power requirements of the generating unit.
This subsection also makes the legal owner aware of the voltage range at that
facility so that they may properly specify, design and purchase the appropriate
equipment.
Comment # 10: Insert Comments / Reason for Position
(if any)
TransAlta suggests that the wording “the connection of”
be added in subsection 6(1) so that it would read
“proposes to be used for the connection of the
generating unit:”
TransAlta suggests in subsection 6(2) that the wording
“in subsection 6(1)(a)” be added so that it would read
“approves of the operating voltage value in subsection
6(1)(a) proposed by the legal owner,”
The AESO should approve the voltage in subsection
6(1)(a), i.e. the transmission voltage, but should not
approve the voltage in subsection 6(1)(b) which is the
voltage at the generator terminals. We can understand
why the AESO would need to approve the transmission
voltage at the point of connection in 6(1)(a) but not the
generator voltage. We have no issue with provision of
the information in 6(1)(b) to the AESO but disagree that
it should be approved by the AESO.
The wording throughout subsection 6 and the rule
should reflect this distinction between approval and
information.
We suggest that subsection 6(5) be sequenced in order
of the subsections within the rule for clarity of
presentation.
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Subsection 7 – Maximum Authorized Real Power
Subsection 7 requires the participant to submit in writing the maximum value that
the generating unit can ever be operated at, under ideal circumstances while
meeting other requirements of proposed New ISO Rules Section 502.5.
Many generating units can operate above nameplate values under the proper
conditions, so to properly study the behaviour of the generating units in respect to
the transmission system, this maximum value needs to be clearly stated. This
value is also required to properly design the transmission system.
Comment # 11: Insert Comments / Reason for Position
(if any)
Subsection 7(4) should be worded such that “A
generating unit must not be operated in excess of its
maximum authorized real power unless directed by
the ISO.” We have added “unless directed by the ISO”
because it is foreseeable in emergency conditions that
the AESO may want every MW possible and subsection
7(4) as presently proposed would preclude the
generator from providing such MWs even though they
may be capable of doing so. Such time periods are
short in duration and are within the stable operating
capabilities of a generating unit.
MARP is defined in context of the proposed power
factor range, i.e. the reactive power range. If the
required power factor range changes, as we propose,
then MARP will change. As elaborated below we accept
the AESO view as expressed for PPA units that there is
a normal operating condition power factor range which
is a subset of the overall abnormal/emergency operating
range. We assert that MARP should be defined on the
normal operating condition range for all generating
units.
MARP, as defined, also determines the Maximum
Capability of the generating unit. Maximum
Capability is a market term which is the maximum
amount of MW a generating unit can and must offer
into the power pool.
In our view there is a clear distinction between normal
and abnormal operating conditions. Further, the AESO
has construed this rule as specifying the “minimum
requirements”. In our view MARP should be defined by
normal operating conditions and these are the minimum
requirements. The maximum requirements are under
abnormal operating conditions.
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MARP and MC as so defined have wide impacts on
what capacity is available in the energy market. Is it
FEOC to define MARP as proposed or is it inefficient,
reduces competitiveness, and unfair? If reactive power
can be provided by other than generators does this not
suggest a market for this ancillary service? Do reactive
power services provided by generators meet the need
for reactive power in the most fair, efficient and effective
manner, or are there better ways to meet the need?
Subsection 8 – Reactive Power Requirements for All Generating Units
Subsections 8(4) through 8(6) allow the participant to apply for a reduction in the
reactive power/power factor requirement in the under excited region of the
reactive capability curve.
The AESO is aware of the concerns that depending on the specific location of the
generator unit, operating near the bottom of the D-curve may result in the unit
becoming unstable. In the AESO’s opinion, it would be appropriate to reduce the
reactive power requirement, if provided with technical back up to this concern.
Comment # 12: Insert Comments / Reason for Position
(if any)
In subsection 8(1) we suggest striking the phrase “and
approved of by the ISO under subsection 6(2)”. As
above, we do not think it is appropriate for the AESO to
approve generator terminal voltages.
A generator capability curve separates regions of
allowed operation inside the curve from regions of
forbidden operation outside the curve. The curve is
provided at rated generator terminal voltage. It is
important to note that as the terminal voltage changes
within the generator continuous voltage rating of +/- 5%
that the curve shifts affecting the allowable operation
regions and reactive power capabilities.
We disagree that the appropriate power factor range for
normal operating conditions is 0.90 producing and 0.95
absorbing vars at the generator terminals at rated
voltage. This is notwithstanding that this range was
included in the 2006 standard. Subsequent to the 2006
standard there have been a series of concerns raised
by generator owners about the capability of existing
generating units to meet these requirements. While
some issues have been addressed for PPA units, in our
view the matter of reactive power remains unresolved.
We think that the AESO should undertake to provide
studies which would justify appropriate reactive power
requirements for generators consistent with Alberta’s
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market design, various system operating conditions,
and generator operating practices based on machine
condition and limiter margins.
The AESO has also ascribed a different power factor
range for normal operating conditions in this and other
documents. The AESO has also ascribed an abnormal
or emergency power factor range as being 0.90
producing and 0.95 absorbing vars at the generator
terminals.
The distinction between normal and abnormal is also
connected to the descriptions of long term and short
term, and static and dynamic. These distinctions are
important and require careful consideration in the
development of this rule.
For example, in the wind technical rule 502.1, the
reactive power range is 0.95 pf producing vars and
0.985 pf absorbing vars at the generator terminals
based on dynamic reactive power. This smaller range
is, as such, implied as being the most important to the
AESO. This suggests a smaller dynamic range should
be applicable for all generating units rather than the
0.90 producing and 0.95 absorbing vars at the
generator terminals.
We also note that for Purchase Power Arrangement
generating units a distinction is made between normal
and abnormal/emergency operating conditions and the
reactive power applicable to different operating
conditions. See additional comments under subsection
9.
In subsection 8(3) the reactive power capability should
be stated as subject to the limiter margins and the
machine condition. For clarity, a limiter is not usually set
at the value where the reactive power requirement
intersects the capability curve but at a margin less than
the capability curve value. As such the reactive power
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range is usually less than that shown on the capability
curve and the available power factor range is narrowed.
This is especially so for UEL settings. It must also be
noted that capability curves are stated at 1.0 pu terminal
voltage and reactive capability shifts as the voltage
changes between +/- 5% of the terminal voltage.
In many ways we think the approach taken for PPA
units is preferable because it was based on the actual
capabilities of the various units resulting from the
technical review of the Independent Assessment Team.
It is reasonable to expect generator operation within
tested limits and considering the machine condition.
We disagree with the characterization of the
requirements as being “the minimum requirements” in
subsection 8(3). TransAlta believes that all generating
units should provide real power and reactive power
recognizing the distinction made between “normal
operating conditions” and “abnormal or emergency
conditions”. We view the requirements of subsection
8(3) as being for abnormal or emergency conditions and
not for normal operating conditions. We suggest that
normal operating conditions define the minimum
requirements.
The “minimum gross real power” in subsection 8(3) is
vague in that it states “without any additional wear and
tear beyond normal operation.” Who is to decide what
the “minimum gross real power” is for a generating
unit? The purpose in including the phrase regarding
“wear and tear” requires clarification. This does not
appear to be language appropriate to a rule but to an
information document.
In subsection 8(4) the conditions for exception appear to
be only for “stability concerns”. The AESO also needs to
allow exceptions based on generator condition, core
end heating, and appropriate limiter margins for existing
units. This must be focused not only on defining normal
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operating conditions for each unit but the expectations
under abnormal and emergency conditions, and the
duration of such abnormal conditions.
Accommodation for different types of generation and the
age/condition of units needs to be carefully considered.
We note that subsection 8(7) goes beyond what is
specified in the wind technical rule 502.1 in that it
makes no distinction between dynamic and static
external reactive power and requires all external
resources to be dynamic. Further, the dynamic reactive
power for wind farms includes consideration of the one
second overload capability of the dynamic var
equipment. In essence this defines “dynamic” as being
equal to or less than one second. This dynamic range,
as noted above, is also smaller being 0.95 pf producing
vars and 0.985 pf absorbing vars at the generator
terminals. When accommodations are provided for one
type of generation then that accommodation should also
be available to other types of generation.
TransAlta disagrees with subsection 8(7). A generating
unit can produce real power and reactive power, and
we assert that they are two separate products. Reactive
power can be provided by other than generating units,
e.g. capacitor banks, Static Var Compensators, or
series compensation. It can be located in many places
on the power system. We ask if the AESO has
considered procuring reactive power through market
mechanisms rather than the approach of requiring
generators to expend significant resources to provide
this service to the system without compensation.
Different types of generating units have differing abilities
to provide reactive power. This is acknowledged by the
AESO in the proposed subsection 8(7) by noting the
use of external resources. When external resources are
required then this recognizes the limits of the
capabilities of the generating unit. The conclusion of the
AESO is that the generator owner needs to augment the
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capabilities of the generator and that this is FEOC. In
our view this conclusion is wrong. Our assertion is that
the market should be invoked to provide the most
economic response.
In an energy-only market, as in Alberta, generators do
not receive capacity payments and in other markets
which specify a power–factor deadband without
compensation, it is done in the context of such
generators receiving a capacity payment for providing
generation capability in those markets. In Alberta, apart
from ancillary services, the only compensation is for the
provision of real power. There is no compensation for
reactive power provided by generators. A transmission
facility owner that adds equipment such as capacitors or
a SVC to provide reactive power is compensated. This
is discriminatory.
Clearly the AESO views reactive power as important
and valuable. However, the AESO extracts this valuable
service from generators without compensation.
The points above, taken together, suggest that reactive
power is a separate product and producers of reactive
power should be compensated for provision of reactive
power.
We do not presuppose any particular methodology for
compensation for reactive power and suggest that the
AESO begin consultation on market mechanisms to
procure this valuable service. In addition to the FERC
report noted below we refer the AESO to the report
“Reactive Power As An identifiable Ancillary Service”
prepared for the Transmission Administrator of Alberta
in March 2003 by Laurits R Christian Associates.
It is punitive to impose additional reactive power
requirements on older generating units where external
resources would have to be installed. External reactive
power resources would only be used in abnormal or
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emergency operating conditions and these by definition
are low probability events. As such external equipment
could be put in place but unused for the vast majority of
time. The generation facility owner is forced to invest in
equipment which results in no additional revenue but
increased costs in a market structure that does not
provide any mechanism for recouping these costs
through market prices or through the tariff.
It is TransAlta’s view that the Maximum Capability
should be defined for normal conditions and with a
normal power factor range that is much smaller than
that proposed in this rule. This would allow the
generating units to more economically provide real
power through increased Maximum Capability for the
vast majority of its operating hours in any year. In
abnormal or emergency conditions the real power
output could be reduced so as to provide a wider range
of reactive power as needed. The proposed power
factor range is inefficient.
We would also expect that the above approach would
increase the competitiveness of generation and through
competitive forces have a positive impact on electricity
prices.
The AESO also needs to bear in mind that the
limitations on reactive power supply occur when the
generator is producing at its maximum real power
output. In a competitive market a specific generator at a
specific location may or may not be dispatched and if
dispatched may not be at its maximum real power
output. This to a generator makes the last increment of
capacity highly valuable and the reactive power
requirement eliminates and precludes dispatch of
available real power capacity given the constrained
Maximum Capability prescribed by the AESO.
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Subsection 9 – Additional Reactive Power Requirements for a Generating
Unit with a Power Purchase Arrangement
Comment # 13: Insert Comments / Reason for Position
(if any)
This section requires the applicable participant to meet certain requirement in
regards to reactive power obligations under normal and abnormal system
conditions.
Subsection 9(3) requires the hydro generating units
subject to PPAs to meet the requirements of subsection
8. From a preliminary review of TransAlta’s hydro units
we are not in compliance at this time with the
requirements as proposed. These units were never
intended to operate as described and their design does
not allow such operation. Extensive upgrades to the
generating units would be required to comply with this
requirement and/or significant reductions in the
Maximum Capability ratings of the units.
Most of this section covers policies already in place by the AESO, however for
clarity, these requirements have been incorporated into proposed New ISO Rules
Section 502.5 to allow participants to find all requirements to design, build,
maintain and/or modify facilities under dedicated ISO rules. For background
information please refer to the document Application Guideline Generator
Interconnection Requirements – Reactive Power available at:
http://www.aeso.ca/downloads/AESO_PPA_Reactive_Power_Guidelines.pdf
Of particular note, subsection 9(10) specifies the requirements that will be
applicable to generating units that are currently the subject of a power purchase
arrangement once that power purchase arrangement ends.
In subsection 9(5) what are described as “abnormal or
system emergency conditions” needs to be further
elaborated, for example, in delineating how long
generating units need to operate outside of normal
conditions.
Based on a preliminary review of our thermal plants,
TransAlta has concerns with several of our generating
units due to core end heating and stable rotor turn
faults which limit our capability to comply with the
reactive power requirements. The older the unit the
more this is a concern. Subsection 9(7) appears to not
consider these additional concerns and is only focused
on stability.
The wording in 9(8) and 9(9) is unclear as to what
reactive power requirements apply to the increment
which is the excess above existing MARP. The wording
should be clear as to what the MW quantity is and what
the required reactive power is related to that MW
quantity. There should be a clear statement that the
PPA committed capacity plus 2% is subject to 9(4) and
any excess above this amount is subject to 8(3) for
reactive power. The reactive power requirements for the
generating unit should then be detailed for the overall
modified unit. It is unclear as to what is required at
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various levels of output and under what operating
conditions.
The AESO is attempting to incorporate the guidelines
from the following document into this rule:
http://www.aeso.ca/downloads/AESO_PPA_Reactive_P
ower_Guidelines.pdf. The following is extracted from it:
“The reactive power capability and reactive margins
provided by synchronous generators are critical to
maintaining reliable and efficient operation of the
Alberta Interconnected Electric System (AIES) and must
be adequate for normal operation as well as fault and
post-contingency operating conditions.” (emphasis
added) We do not think the proposed rule adequately
includes some of the aspects of this guideline nor
provides adequate clarity.
It is interesting that this AESO document references the
following FERC report on reactive power:
http://www.ferc.gov/EventCalendar/Files/200503101444
30-02-04-05-reactive-power.pdf. The FERC report
deals extensively with compensation for reactive power.
TransAlta objects to subsection 9(10) and we suggest it
be deleted. The subsection contemplates an event eight
years in the future which is longer than the normal five
year update/review cycle for rules and standards. In the
intervening time or at the next review the requirements
in the rule referred to in subsection 8 may have been
changed. Our suggestions in this consultation would, for
example, substantially change subsections 8 and 9.
While it may be acceptable that the AESO may require
compliance of a generating unit if the unit is modified in
the future, it is not acceptable to tie such compliance in
a technical rule to a future contractual event.
Reactive power is an ancillary service. The fundamental
rationale for requiring reactive power is to ensure the
safe and reliable operation of the transmission system
by ensuring system voltages are stable. If reactive
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power is required for reliability then surely the need is
now and having an event eight years in the future
trigger a requirement means you don’t need it now and
you don’t need it for reliability. If it is needed now for
reliability then the requirement should be now and the
need for, the costs of provision, and how best to procure
this ancillary service have to be fully considered.
TransAlta believes that all generating units should
provide real power and reactive power recognizing the
distinction made between “normal operating conditions”
and “abnormal or emergency conditions”.
Further, the definition of MARP as in subsection 7 seeks
to limit the maximum output of a generator at all times
based on reactive power requirements for “abnormal or
emergency conditions”, i.e. 0.90 pf producing vars and
0.95 pf absorbing vars. It is inappropriate to limit a
generating unit all the time when extreme operating
conditions are only for short durations during those
conditions. It is inefficient and uneconomic to reduce
potential production in all hours when the reduction is
only needed in very few hours.
TransAlta proposes that all generating units (whether
PPA or not) have real power and reactive power
requirements specified for “normal operating conditions”
and “abnormal or emergency conditions”. Because
there is clearly a difference between such operating
conditions and that a generator could produce more real
power under normal conditions the AESO is putting the
generator in the position of withholding power by
understating its Maximum Capability under normal
operating conditions. We believe that Maximum
Capability should be specified under “normal operating
conditions” in keeping with FEOC. The withholding of
real power subverts FEOC and confiscates real power
capacity paid for by investors.
Clearly a generating unit can produce both real power
Issued for Stakeholder Consultation: 2011-12-06
Page 17
and reactive power, and we assert they are two
separate products. Reactive power is a separate
product and producers of reactive power should be
compensated for provision of reactive power.
It is discriminatory to generators to preclude them from
producing real power for which they are compensated
so that they may provide reactive power for which they
are not compensated. Reactive power is an ancillary
service and should not be procured by the AESO
without compensation as a condition of connection to
the system.
Subsection 10 – Voltage Ride-Through Requirements
All generating unit must have the capability to support the transmission system
during system disturbances. Therefore, each generating unit must have some
capability for voltage ride through.
The basic approach to the requirements for existing generating units has been
carried over from the existing Technical.
Subsection 10 allows new generating units to be able to ride through system
disturbances that result in voltages as low as 0% and as high 120% for specified
periods of time. This requirement has been amended to align with the direction
that the industry is taking for new generating units. Please refer to FERC orders
661 and 693.
Comment # 14: Insert Comments / Reason for Position
(if any)
The wording with subsection 10 generally refers to
either existing or new generating units but does not
refer to a modified generating unit. However, subsection
10(1) makes no distinction between existing and new
generating units. As elaborated below this distinction
should be made and/or subsection 10(1) should be
reduced to +/- 5% for all units.
TransAlta objects to subsection 10(1) which requires
continuous operation at +/-10% of the operating voltage
level specified in subsection 6(1)(a). Normal generator
operation is for +/- 5% continuous operating voltage
around that specified in 6(1)(b). Continuous operation is
different than transient periods where voltage
excursions may exceed the continuous operating
voltage for short periods of time. We request that
proposed subsection 10(1) be changed to reflect a +/5% continuous requirement. The +/-10% continuous
requirement is not highlighted as a new requirement in
the Letter of Notice and as such the proposed rule
should be changed to reflect the 2006 Standard.
This is the context of the existing requirement in
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subsections 3.1 and 3.4 of the 2006 standard.
Subsection 3.1 states “The combination of the generator
and transformer capabilities shall allow for a total
operating voltage range of +/- 10%.” and “The voltage
set point must be adjustable by the generating unit
operator and dispatchable from the AESO System
Controller within +/-5% of the nominal generator
interface voltage.” The intention is that the +/-5% range
of the generating unit in combination with off-load
transformer taps of +/- 5% would meet the overall +/10% range in subsection 3.1 as noted above.
Subsection 10 must be read in conjunction with
subsections 11 and 14 as the clear intent of subsection
11 is +/- 5% AVR and subsection 14 with +/- 5%
transformer taps.
Subsection 3.4 of the 2006 standard states “generating
units shall not trip for system voltage excursions within
0.9 and 1.1 per unit.” There is a clear distinction
between “continuous” and “excursions”.
Existing generating units were designed to operate
consistent with the 2006 or earlier standards. A review
of our existing generating units identified we could not
meet the +/-10% proposed continuous voltage
requirement in subsection 10(1) of rule 502.5. The
requirement could be met if every unit transformer was
replaced with a new transformer which utilized an
appropriate on-load tapchanger. On-load tapchangers
would be unusual for generator transformers given the
high currents and reliability concerns. Replacement of
such transformers, if so directed, would also need to be
coordinated with the PPA holders and be consistent
with the change in law provisions of the PPAs to provide
cost recovery. Non-PPA generating units would have no
such mechanism for cost recovery. The costs are
significant and this requirement needs to be carefully
considered. For new generators the generator design
would need to include the +/- 10% requirement which
could be met but with at increased cost.
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Page 19
In subsections 10(3), 10(4) and 10(5) the word
disturbance should be bolded as it is a defined term in
the Glossary.
In 10(3)(b) the first “for” should likely be “from”. See also
a further comment below regarding a ride through chart
for existing units.
We suggest in 10(3) that the normal and delayed
clearing times be as specified in the functional
specification for the generating unit. We note that
such times are “specific to the location” and yet the rule
does not indicate how and when such clearing times will
be provided to the owner.
Subsection 10 must be consistent with Alberta TPL
reliability standards as regards clearing times and
expectations for ride through beyond such clearing
times suggests a possible misalignment between
requirements. We suggest the AESO review for
consistency.
Subsections 10(3) and 10(4) apply to existing units
whereas subsection 10(5) applies to new units.
Subsection 10(4) deals with auxiliary equipment
connected at the generator terminal voltage which may
cease working and cause the unit to go off line. We
wonder why this does not apply to new units. Auxiliary
equipment is also dealt with in subsection 15(2) and we
would suggest consolidation of the requirements for
clarity. The simplest solution would be to delete 10(4)
and leave 15(2) as is or move the requirements to
15(2).
The distinctions between existing (10(3) and 10(4)) and
new (10(5)) units is confusing and while appendix 3
shows requirements for new units there is no Appendix
for existing units. We suggest an appendix be added for
existing units.
Issued for Stakeholder Consultation: 2011-12-06
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We are confused as to the distinction between 10(3)(b)
and 10(4) where the various requirements are 40 cycles
or 666 ms and 625 ms post disturbance. Why is it not
sufficient to state the requirements for normal and
delayed clearing times as in 10(3)(a) which appears
similar to what is shown in Appendix 3. If the fault is not
cleared by these clearing times then why should a
generating unit be required to ride through longer than
such clearing times? The times stated in 10(3)(b) and
10(4) appear to be more onerous than those shown in
Appendix 3. Why would this requirement be made more
onerous for existing units than for new units at the 15%
and 20% voltage levels? What are the criteria and
principles used by the AESO to propose different
requirements?
Appendix 3 related to subsection 10(5) is essentially the
same as the proposed NERC PRC-024-1 ride through
standard with the exception that Appendix 3 shows a +/10% continuous voltage range whereas NERC shows a
+/- 5% range. The proposed NERC standard is still in
the development process, has not been approved by
NERC and has not proceeded to the FERC approval
process. It is notable that the proposed implementation
of the NERC standard after approval is up to four years
after approval. The AESO’s proposed implementation is
within six months of approval for rule 502.5.
The NERC standard may not be approved by NERC or
may not be approved for a considerable time and so if
subsection 10(5) was approved in Alberta it may not be
aligned with and may exceed North American
requirements. Our understanding is that it is not the
intent of the AESO to impose more onerous reliability
standards in Alberta than approved by NERC. If the
AESO intends to proceed as proposed then our request
is for an explanation of the alternatives and
consideration of the benefits and costs to the system.
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Page 21
Subsection 11 – Automatic Voltage Regulator
Subsection 11 sets out the requirements for the automatic voltage regulator and
the basic approach has been carried over from the existing Technical Standard.
Comment # 15: Insert Comments / Reason for Position
(if any)
Subsection 11(6) is unclear. A distinction is being made
regarding the point of control but we are unsure what is
intended.
Subsection 11(8) is unclear. A distinction is being made
regarding the point of control but we are unsure what is
intended.
Subsection 11(9) is unclear. A distinction is being made
regarding multiple units and multiple AVRs but we are
unsure what is intended and what concern is being
addressed.
Subsection 12 – Frequency and Speed Governing Requirements
Subsection 12 sets out the requirements for the governor systems and the basic
approach has been carried over from the existing Technical Standard, with the
one exception noted below.
Subsection 12(4) contains the following:
“If the frequency of the generating unit while connected to the transmission
system remains greater than sixty one point seven (61.7) Hz or less than fiftyseven (57) Hz for more than ten (10) minutes, then the generating unit must be
immediately removed from service.”
Comment # 16: Insert Comments / Reason for Position
(if any)
There is confusion between Appendix 4 and subsection
12(3). Is the intent that a unit may trip immediately if the
frequency range of 57 HZ to 61.7 Hz is exceeded
(under-frequency or over-frequency) but is allowed to
not trip for up to 10 minutes? Please clarify and explain
the rationale for the 10 minutes. Normal practice would
be for an instantaneous trip < 57 Hz and > 61.7 Hz.
The AESO has discussed this requirement in work group sessions with
generating unit owners and a consensus was reached that this is appropriate to
include this in proposed New ISO Rules Section 502.5. It was, however,
recommended that the AESO seek broader input in particular from distribution
facility owners, industrial system owners, etc.
Subsection 13 – Power System Stabilizer
Comment # 17: Insert Comments / Reason for Position
(if any)
Subsection 13 sets out the requirements to install power system stabilizers and
has been amended to add requirements that had previously existed in WECC
policies, which the AESO has currently been enforcing.
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Page 22
Subsection 14 – Transmission System Step-Up Transformer
Subsection 14 sets out the requirements for the step-up transformer and the basic
approach has been carried over from the existing Technical Standard.
Comment # 18: Insert Comments / Reason for Position
(if any)
We take exception to the wording in 14(1) and suggest
that the phrase “and reactive power” be deleted.
Reactive power requirements are measured at the
generator terminals at the voltage as defined in 6(1)(b).
The transformer steps up the subsection 6(1)(b) voltage
to the subsection 6(1)(a) voltage. The transformer is
beyond the measurement point for reactive power.
While we appreciate that 14(4) effectively grandfathers
existing transformers except if replaced this can be
problematic and should cover existing spare
transformers or spare transformers that may be on
order. Recently when the transformer at Sundance 6
failed we used the spare transformer and it did not
exactly match the transformer it replaced. Allowances
must be made for use of spares which are designed to
be used for various generating units.
Transformer size has implications in determining
Maximum Capability and where the transformer size
should not limit MC. Thermal rating of transformers and
operational practices are the responsibility of the owner.
It appears that the AESO is inserting itself into
considerations of generating unit reliability as well as
operational risks assumed by the generating unit
owner. Transformers can be loaded consistent with
dynamic ratings based on guidelines, loading history,
test results and ambient temperatures.
It is not appropriate for the AESO to specify the details
of the transformers for a generating unit beyond that
which is necessary to deal with the aspects of how it
Issued for Stakeholder Consultation: 2011-12-06
Page 23
connects to the transmission system, i.e. we do not take
issue with 14(3)(a) through (c).
We note that a TFO can decide the ratings, including
overload ratings, of their facilities including, for example,
lines and transformers. Yet, here, the AESO is
attempting to specify the ratings and operations of
generator transformers. Taken further, it would not be
appropriate, for example, for the AESO to specify
whether the generating facility owner uses one or two
transformers in their substation or to specify the form of
cooling for transformers. The generating facility owner
has every incentive to design and operate their
transformers considering risks, reliability and
economics.
Section 15 – Auxiliary Systems
Subsection 15 sets out the requirements for the critical auxiliary system to meet
minimum standards so that multiple units will not go off line for single point of
failure and that these auxiliaries must be considered when studying the voltage
ride capability of the facility.
The AESO has experienced issues with facilities where the generating unit may
have been able to ride through disturbances but the critical auxiliary system
caused the generating unit to trip or go offline. As well, Alberta Reliability
Standard TPL-002-AB-0 System Performance Following Loss of a Single BES
Element does not allow for cascading for the loss of a single bulk electric system
element.
Comment # 19: Insert Comments / Reason for Position
(if any)
In addition, see comments above under subsection 10.
The question in subsection 15(1) is essentially to
identify potential common mode failures for multiple unit
power plants. A literal interpretation of “independent”
would mean no common or shared equipment and
systems.
Some of our multiple unit generating plants have
common systems and as such each generating unit is
not independent.
Further, it is typical for multiple unit power plants to
have common station service, for example. We are
unable to determine if station service itself as supplied
by a separate transmission connection is independent
of events beyond the point of connection of the
generating transformer.
It would be helpful if “auxiliary systems” and
“independent” were defined so that we would know what
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Page 24
is and what is not included and intended.
While we appreciate that in subsection 15(1) it says “for
new or modified existing generating unit”, a modification
may not be to any of the common systems. This
effectively says that if you touch the generating unit it
must meet all the requirements. This is not appropriate.
For example, if you changed the transformer you would
have to remediate all other aspects of the generating
unit to comply. We would suggest wording similar to
that found in subsection 22(3) which says if you modify
that particular piece of equipment then it must be
brought up to compliance.
Subsection 16 – Generating Unit Disconnection and Interrupting Devices
Subsection 16 sets out the requirements for the generating unit breakers and the
basic approach has been carried over from the existing Technical Standard.
Subsection 17 – Isolating Devices
Subsection 17 sets out the requirements for the generating unit disconnect
switch(es) and the basic approach has been carried over from the existing
Technical Standard.
Subsection 18 – Power Quality
Subsections 18(6) and (7) amends and clarifies the requirements for generating
units to not introduce excessive voltage unbalances on to the transmission
system and how they are calculated.
The previous requirement in the existing Technical Standard was to related
voltage unbalance at distribution voltages. This new requirement is more
appropriate for transmission systems.
Comment # 20: Insert Comments / Reason for Position
(if any)
Subsection 16 should be applicable to new units. Again
the subsection is heavily referenced to having a
functional specification for the generating unit. For
example, expected fault currents are provided in the
functional specification which informs equipment
selection for a new plant.
Comment # 21: Insert Comments / Reason for Position
(if any)
Similar comments as in subsection 16.
Comment # 22: Insert Comments / Reason for Position
(if any)
The applicable standards are referenced as to that
version in effect at the time a functional specification
for the generating unit is approved. Again, a
functional specification for each unit is needed to
ensure clarity of which version of standards apply..
Why does table 1 refer to <= 25 kV when this rule is for
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Page 25
generating units connected to the transmission
system?
Subsection 19 – Grounding
Comment # 23: Insert Comments / Reason for Position
(if any)
Subsection 19 sets out the requirements for the generating unit grounding and the
basic approach has been carried over from the existing Technical Standard.
Subsection 20 – Lightning and Other Surge Protection
Comment # 24: Insert Comments / Reason for Position
(if any)
Subsection 20 sets out the requirements for the generating unit surge protection
and the basic approach has been carried over from the existing Technical
Standard.
Subsection 21 – Synchrophasor Measurement System
Subsection 21 requires new or existing units with an upgraded protection system
to install a synchrophasor measurement system.
The application of synchrophasor measurement systems on generating units will
allow the AESO to better analyze the response of the generating units to system
disturbances, which assist the AESO in developing mitigating requirements for the
reliability of the transmission system. It will also allow the AESO to better monitor
compliance to the ISO rules and requirements.
The generating unit owners and operators will also be able to use this data to
analyze the behaviour of the generating unit for the model revalidation
requirements and determine if the generating unit is operating as designed.
Issued for Stakeholder Consultation: 2011-12-06
Comment # 25: Insert Comments / Reason for Position
(if any)
It is unclear whether a PMU is required to be added for
an existing unit which is uprated by a small amount.
This needs to be clarified in a definition of what a
facilities modification is and is not.
Subsections 21(3)(b) and 21(4) refer to “records”. We
suggest for clarity that subsection 21(2) be modified to
replace the word “made” with “recorded” so that it is
understood what “records” are referred in these
subsections.
Page 26
Subsection 22 – Internal Sequence of Event Monitoring
Subsection 22 adds additional requirements regarding what must be monitored
within the generating unit. The additional requirements only apply to new or
modified generating units.
In the AESO’s opinion, in order to properly analyze the root cause of some
system disturbances, greater detail is required from generating units in regards to
their behaviour during these disturbances.
Subsection 23 – Provision of Data and Modeling Information
Subsection 23 deals with the provision of data for both new and modified
generating units.
This section was added so that the AESO can ensure it has the information
required to properly model the behaviour of the generating unit in relation to the
transmission, and to confirm that the generating unit is in compliance with
sections of proposed New ISO Rules Section 502.5.
Comment # 26: Insert Comments / Reason for Position
(if any)
Subsection 22(3) as worded is applicable to only
existing units that have SOE equipment already
installed. The subsection is silent on the situation
where an existing unit does not have SOE equipment.
Subsection 22 does not specify how long SOE records
have to be retained nor what the process may be for
information requests related to such SOE records.
Comment # 27: Insert Comments / Reason for Position
(if any)
Subsections 23(4) and 23(5) require reports that
demonstrate a generating unit can meet the
requirements of subsection 10. It would be helpful if
they AESO were to convey what an acceptable
methodology would be and what the contents of such a
report should contain.
There is a typo in subsection 23(5) which refers to
subsection 9 and it should be subsection 10.
Subsection 24 – Testing Intervals
Subsection 24 sets out requirements to provide a model validation or reactive
power verification report in terms of both format and timing.
Comment # 28: Insert Comments / Reason for Position
(if any)
We suggest that in subsection 24(2) that this be 90
business days. We note 24(9) refers to 60 business
days. Where timelines are used in the rule then the
approach should be consistent and we prefer business
days.
Subsection 24(4)(e) is vague. Any modification is likely
to change the behaviour of a generating unit. We
suggest this be deleted.
Subsection 25 – Reporting
Issued for Stakeholder Consultation: 2011-12-06
Comment # 29: Insert Comments / Reason for Position
(if any)
Page 27
Subsection 25 sets out requirements to provide a model validation or reactive
power verification report in terms of both format and timing.
This subsection was added to clarify the reporting requirements to the market
participants.
Subsection 26 – Baseline Testing
Comment # 30: Insert Comments / Reason for Position
(if any)
Subsection 26 sets out the requirements for the generating unit baseline testing
and the basic approach has been carried over from the existing Technical
Standard.
Subsection 27 – Reactive Power Verification and Re-verification Testing
Subsection 27 sets out the requirements to test that the reactive power
requirements of proposed New ISO Rules Section 502.5 have been met.
Reactive power verification has been an existing WECC policy that the AESO has
been enforcing. This subsection has been added to clarify the testing
requirements to the participants.
Subsection 28 – Model Revalidation Testing
Comment # 31: Insert Comments / Reason for Position
(if any)
Re-verification testing must be subject to agreement
with the generator owner as testing must be scheduled
and coordinated with other activities providing adequate
lead time to efficiently undertake such tests. While
testing is normally scheduled as part of a new or
modified unit going into service, a re-verification is done
on request and may not be possible within the specified
time horizon. It may be planned within the specified
period but not undertaken and/or the report not yet be
prepared.
Comment # 32: Insert Comments / Reason for Position
(if any)
Subsection 28 sets out the requirements for the generating unit model
revalidation testing and the basic approach has been carried over from the
existing Technical Standard.
The following reference sections in the existing Technical Standard that have not
been included in proposed New ISO Rules Section 502.5:
Comment # 33: Insert Comments / Reason for Position
(if any)
Section 1.1 – Purpose
This section was removed to align with the principals of the TOAD project.
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Page 28
Section 1.3 – Definitions
This section was removed to align with the principals of the TOAD project.
Section 1.4 – Modifications
This section was removed to align with the principals of the TOAD project.
Section 1.5 – Requirement For Review
This section was removed to align with the principals of the TOAD project.
Section 1.6 – Document Change History
This section was removed to align with the principals of the TOAD project.
Section 2.5 – Clearance and Access
This section was removed as it referenced codes that do not fall under the
jurisdiction of the AESO.
Section 4.0 – Load Interconnection Requirements
Proposed New ISO Rules Section 502.5 does not include the requirements for
load facilities. These facilities will be the subject of separate ISO rules and be
consulted on separately as the requirements for generating facilities and load
facilities are significantly different.
(b) Removals
No removal of ISO rules provisions are being proposed for proposed New ISO
Rules Section 502.5.
Comment # 34: Insert Comments / Reason for Position
(if any)
(c) Amendment
No amendments to ISO rules provision are being proposed for proposed New ISO
Rules Section 502.5.
Comment # 35: Insert Comments / Reason for Position
(if any)
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(d) Other
(Stakeholders wishing to comment on specific provisions are requested to copy
the provision into this area and provide comments)
Comment # 36: Insert Comments / Reason for Position
(if any)
In the Letter of Notice dated December 6, 2011 the
AESO has indicated an effective date for Rule 502.5 of
October 1, 2012. The new requirements of Rule 502.5
are not trivial and would necessitate extensive review of
the capabilities and settings of each generating unit.
Such reviews would not be initiated until the rule is
approved by the AUC. Once reviews are complete and
gaps identified then the owner must either seek an
exemption or variance under subsection 4(2) or develop
mitigation plans to address the gaps.
The AESO is also invoking new processes for units
unable to meet specific requirements and which require
engineering studies to be undertaken. As well, any
changes, if required, must be thoroughly designed and
planned and coordinated with outage schedules for the
units. Coordination is also required, for example, if the
unit is governed by a PPA, with the PPA holders and be
consistent with the change of law provisions within such
PPAs. In TransAlta’s view the effective date should be
two years from AUC approval.
The implications of Rule 502.5 are significant and
TransAlta requests and suggests that the AESO host a
technical consultation meeting to review and clarify the
requirements of each subsection. Our preliminary
review of our generating units has disclosed numerous
concerns with various requirements and we need a
fuller understanding of the requirements than that
conveyed by what is written in the proposed rule. We
need to understand why these are the minimum
requirements. What studies have been done and what
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evidence supports the proposed requirements? The
issue of the draft rule on December 6, 2011 has in our
view provided insufficient time for the industry to
properly assess the implications of the new rule.
TransAlta also suggests the AESO host separate
consultation meetings focused on both a reactive power
market and technical requirements. This should also
focus on what is the appropriate reactive power range
for normal operating conditions. This could be
coordinated with the suggested studies in subsection 8.
Further the testing requirements within this rule are
extensive and again we suggest the AESO host a
technical consultation meeting on what the expectations
are for each test. We would, for example, like to see the
sections in the Information Document 2011-012R
regarding testing be expanded. We highlight, for
example, subsection 23(4) regarding demonstrating
capability to meet voltage ride through as an area of
particular interest.
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