Download Date of Request for Comment September 28, 2015 Period of Comment

Stakeholder Comment and AESO Replies Matrix
Proposed New ISO Rules Part 500 Facilities, Division 502 Technical Requirements, Section 502.13 Battery Energy Storage Facility Technical Requirements (“New Section 502.13”)
Date of Request for Comment:
Period of Comment:
September 28, 2015
September 28, 2015
through
October 26, 2015
1. ISO Rules
Stakeholder Comments and/or Alternate Proposal
AESO Replies
a) New
Capital Power Corporation (“Capital Power”)
1. Capital Power agrees with the proposed new
Section 502.13, subject to the following
clarifications:
1.
The AESO is seeking comments from stakeholders with regard to the following
matters:
1. Do you agree or disagree with the proposed New Section 502.13? If you
disagree, please provide comments.
2. Are there any subsections where the language does not clearly articulate the
requirement for either the AESO or a market participant? If yes, please indicate
the subsections and suggest language that would improve the clarity.
(a) 502.13, 5(1) – Voltage Ride-Through (VRT)
Requirements
Please explain the AESO’s rationale for using
the difference between a battery storage
facility’s maximum authorized charging power
and its maximum authorized discharging power
as the threshold for VRT requirements, as
opposed to specifying a charging and
discharging capacity.
The difference between the maximum authorized
charging power and maximum authorized
discharging power is a single number that better
reflects the overall size of the facility than
specifying the charging and discharging
capacities.
(b) 502.13, 6 – Voltage regulating system; and
502.13, 7 – Governor System Requirements
(b) 502.13, 6 – Voltage regulating system; and
502.13, 7 – Governor System Requirements
It is not common for battery storage facilities to
have both voltage and frequency regulating
systems. Please confirm that according to the
proposed Section 502.13 a battery storage
facility must be set up with both a voltage
regulating system and a governor (frequency
regulating) system. If yes, please explain the
reasoning for this requirement.
AESO Replies to Stakeholder Comments: 2016-02-25
(a) 502.13, 5(1) – Voltage Ride-Through (VRT)
Requirements
The AESO disagrees that battery energy storage
facilities do not commonly have both a voltage
regulating system and a governor. Battery
energy storage facilities can be used to provide
voltage regulation/reactive power support and
frequency support. These functions cannot be
carried out without both a voltage regulating
system and a governor, as described below.
Accordingly, the AESO confirms that, in
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accordance with subsections 6 and 7 of Section
502.13, a battery energy storage facility must
haveboth a voltage regulating system and a
governor.
Voltage Regulation Systems
Without a voltage regulating system, a battery
energy storage facility will impact the voltage on
the transmission system as the facility cycles
from charge to discharge. Even a small battery
energy storage facility in a weak area can have a
significant impact on transmission system
voltage. This cycling can occur quickly and
several times an hour, depending on the use of
the battery energy storage facility.
As battery energy storage facilities grow in size
and number (similar to wind facilities over the
past 15 years) this impact will increase.
Governing Systems
Primary frequency control, which is provided by a
governor system to assist in arresting and
stabilizing abnormal frequency, is essential for
maintaining the reliability of the Alberta
interconnected electric system.
In its Frequency Response Initiative Report,
NERC recommends that all resources, including
storage facilities, have a frequency responsive
governor system. See the Report at page 3:
http://www.nerc.com/pa/stand/project%20200712
%20frequency%20response%20dl/fri_report_1030-12_master_w-appendices.pdf
In accordance with the AESO’s Generation and
Load Interconnection Standard, conventional
generation is currently required to have a
governor system. In accordance with Section
502.1 of the ISO rules, Wind Aggregated
Generating Facilities Technical Requirements
(“Section 502.1”), wind facilities are required to
AESO Replies to Stakeholder Comments: 2016-02-25
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have over-frequency controls so that they are
able to provide primary frequency response to
system disturbances.
(c) 502.13, 17 – Synchrophasor Measurement
System:
Section 17 specifies Synchrophasor
Measurement System (Power Quality). Capital
Power requests that the AESO provide
guidance for device selection for this
measurement system.
By taking synchrophasor measurements at both
the low side and high side of the transmission
system step-up transformer of the battery
facility, is the intention to have one
measurement system act as primary and a
second to act as a backup? Please explain.
(c) 502.13, 17 – Synchrophasor Measurement
System:
Some requirements of proposed Section 502.13
refer to the high side of the transmission system
step up transformer of a battery energy storage
facility, while others refer to the low side. As the
transformer is an impedance, each side of the
transformer behaves in a different way. By
placing the synchrophasor on each side of the
transformer, the exact behavior of the battery
energy storage facility can be monitored.
Wind facilities are also required to take
synchrophasor measurements at both the high
and low sides of the transformer in accordance
with Section 502.1.
Accordingly, no changes have been made to
Section 502.13 in response to this comment.
NextEra Energy Canada (“NextEra”)
2. Section 2(1): The ISO will likely receive a wide
variance in the format and content of the
“functional specifications” that must be submitted
here, dependent on the submitting entity. The
AESO should consider developing a template for
this to ensure the ISO receives the level of detail
that they require to perform and analysis and
approve.
3. Section 2(3): “maximum charging power” could
include auxiliary loads (lighting, HVAC, etc.) which
are required for the facility to operate but not
AESO Replies to Stakeholder Comments: 2016-02-25
2. The AESO develops the functional
specification with information received from the
market participant. Therefore, there is no need
for a template to be supplied to the market
participant, and no changes have been made to
Section 502.13 in response to this comment.
3. The AESO assumes that NextEra’s comment
is in regard to subsection 3. The AESO agrees
with NextEra’s comment and has revised
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directly associated with the charging of the
batteries (this is dependent on where the auxiliary
load transformers are tapped relative to the
metering location). NextEra would like to suggest
adding a sentence stating “This maximum
charging power is not inclusive of any auxiliary
power utilized in the operation of the facility”.
4. Section 4(1): NextEra would like to suggest
adding language to clarify that for ULTC
transformers, the 1.00 per unit voltage should be
calculated with the ULTC at neutral tap, or the
normal operating tap if not at neutral.
subsection 3 accordingly.
4. In the AESO’s view, the 1.00 per unit voltage
is a design value that is independent of the tap
setting. Studies performed during the connection
process will determine the tap settings used to
achieve the 1.00 per unit voltage. The taps may
be adjusted from time to time in consultation with
the AESO (see OPP 1304) to assist in operating
the facility closer to the 1.00 per unit voltage
value.
Accordingly, no changes have been made to
Section 502.13 in response to this comment.
5. Section 4(2): it is feasible that if a battery energy
storage facility is co-located with an existing
generation resource such as wind, they may
share a common voltage/reactive control system if
they share a common point of interconnection. If
this is the case, it may not be desirable to have a
separate manually controllable set point of the
battery energy storage facility that is separate
from the control for the aggregate facility. NextEra
would like the AESO to please consider this
scenario in determining the requirements in
section 4, as to whether you may include an
exception process to exclude certain battery
energy storage facilities from these requirements
in certain scenarios.
6. Section 7(1, 8(1) and 8(2): although capable of
AESO Replies to Stakeholder Comments: 2016-02-25
5. The scenario described by NextEra is covered
by subsection 4(4).
Accordingly, no changes have been made to
Section 502.13 in response to this comment.
6. The AESO does not agree that governor
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simulating a typical generators governor
response, inverter based technologies such as
battery energy storage facilities provide a unique
capability not available with traditional generation
in their ability to respond very quickly (within
cycles) to either an input signal or a fluctuation in
a transmission system parameter such as voltage
or frequency. These capabilities can be utilized to
more quickly arrest frequency declines or loss of
large loads more efficiently than the slower typical
governor response. A number of ISO’s have seen
value in this type of response and have
established markets for this type of service. If
AESO is considering this direction now or in the
future, the governor requirements as well as the
ramp rate limitations in these sections would
prohibit implementing a market design or ancillary
service such as this.
requirements or ramp rate limitations will limit the
participation of battery energy storage facilities in
any potential markets.
Subsection 7(1) has been included to prevent a
large withdrawal or injection of real power into
the transmission system in a very small time
frame, and to provide a reasonable automated
response to frequency excursions. As battery
systems grow in size and number (similar to wind
facilities over the past 15 years) such large
changes taking place over a few cycles could
result in significant issues on the local
transmission system.
Subsections 8(1) and 8(2) are in place to prevent
similar issues from arising as a result of a
directive or dispatch.
Note that subsection 8(3) allows for ramp rates
that may exceed those specified in subsection
8(2) if the ancillary service requires a different
ramp rate.
Accordingly, no changes have been made to
Section 502.13 in response to this comment.
AESO Replies to Stakeholder Comments: 2016-02-25
7. Section 12(1) and 12(2): our interpretation is that
these breaker controls, remote functionality, etc
can be shared if the battery energy storage facility
is co-located with an existing generating site and
shares a common point of interconnection. Could
the AESO verify that our interpretation is
accurate?
7. The AESO agrees with NextEra’s
interpretation.
8. Section 17: It is not clear in section 17 as to
whether or not continuous syncrophasor
measurement data must be kept for at least one
8. Syncrophasor measurement data is to be
measured and stored continuously, not just for
triggered events (see Section 502.9 of the ISO
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calendar year, or if the intent is that this data is
available for any event that results in a trip of the
battery energy storage facility (similar to the SER
requirements in section 18). If the intent of the
requirement is to store the syncrohphasor
measurements only during the events in which the
battery energy storage facility experiences a trip,
and to then keep each of these trip event records
for a duration of one calendar year, the language
might be modified to state “17(1) A battery energy
storage facility must be equipped with a
syncrhophasor measurement system that triggers
and event record for every event that results in a
trip of the battery energy storage facility.” If the
intent is to have continuous PMU data stored for
the entire calendar year, we would like the AESO
to explain the value that this provides.
TransAlta Corporation (“TransAlta”)
9. TransAlta supports the AESO’s development of
technical and operating standards for battery
energy storage facilities.
AESO Replies to Stakeholder Comments: 2016-02-25
rules, Syncrophasor Measurement Unit
Technical Requirements) and must be kept for
one year from the date of data collection
pursuant to subsection 7 of Section 502.14. A
similar requirement exists for wind aggregated
generating facilities in accordance with Section
502.1.
The synchrophasor will provide valuable
information to both the operator of a battery
energy storage facility and the AESO regarding
the performance of the battery energy storage
facility for post-contingency analysis and model
validation.
Accordingly, no changes have been made to
Section 502.13 in response to this comment.
9. The AESO acknowledges TransAlta’s support.
10. TransAlta is seeking that battery energy storage
facilities receive the same treatment as generating
units to the extent possible. If provisions in the
proposed generating unit operating requirement
rule (proposed section 502.5 of the ISO rules) are
changed and are applicable to battery energy
storage facilities, TransAlta requests that those
changes also be reflected in proposed section
502.13.
10. The AESO acknowledges TransAlta’s
comment, but notes that the ISO rules applicable
to battery energy storage facilities may be
different from those relating to generating units to
reflect differences in the technologies.
11. TransAlta is concerned that the voltage ridethrough requirements for battery energy storage
facilities are significantly different than those for
11. The proposed voltage ride-through
requirements for battery energy storage facilities
in Section 502.13 are in alignment with NERC
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wind aggregated generating facilities (see
subsection 6 of section 502.1 of the ISO rules and
associated Appendix 1). TransAlta would like to
clarify whether the proposed ISO rule would
require that a battery energy storage facility and a
wind aggregated generating facility with a
common point of connection should individually
trip for differing voltage ride-through requirements.
Differing voltage ride-through requirements could
create issues and TransAlta would like to explore
the possibility of coordinating the voltage ridethrough requirements for a wind aggregated
generating facility and a battery energy storage
facility with a common point of connection.
12. Can the requirement in subsection 17(2)(a) for a
synchrophasor measurement system at the low
side of the transmission system step-up
transformer be fulfilled with a synchrophasor for a
generating asset with the same point of
connection as the battery energy storage facility?
PRC-024 Generator Frequency and Voltage
Protective Relay Settings. NERC PRC-024 is
currently scheduled to be considered for
adoption in Alberta later in 2016.
Differences in voltage ride-through requirements
arising as a result of a common point of
connection will be addressed through the
connection process at the time a battery is added
to an existing facility.
12. Generally a synchrophasor measurement
system can be shared by various technologies
within a common facility. However, dedicated
voltage and current channels will be required for
the battery energy storage facility.
Subsection 17 has been revised for clarity.
13. Can the requirement in subsection 17(2)(b) for a
synchrophasor measurement system at the high
side of the transmission system step-up
transformer be fulfilled with a synchrophasor for a
generating asset with the same point of
connection as the battery energy storage facility?
AESO Replies to Stakeholder Comments: 2016-02-25
13. Please refer to AESO Response #12.
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