Download Proposal for Battery Facility Technical and Operating Requirements October 22, 2013

Proposal for Battery Facility Technical and
Operating Requirements
RECOMMENDATION PAPER
Kevin Wiens
Date:
Prepared by:
October 22, 2013
Kevin Wiens
Senior Technical Specialist, Transmission Performance and Planning
Table of Contents
1. Executive Summary ................................................................................................... 3
2. Purpose ....................................................................................................................... 3
3. Background ................................................................................................................. 4
4. Technical Requirements ............................................................................................ 5
4.1
Source and Sink Resource ...........................................................................................6
4.2
Connection Rule and Operating Rules .........................................................................6
4.3
Other rules....................................................................................................................7
4.4
Applicability and Variances...........................................................................................7
4.5
Maximum Authorized Real Power ................................................................................7
4.6
Operating Voltage Requirements .................................................................................8
4.7
Voltage Ride-Through Requirements ...........................................................................8
4.8
Voltage Regulation .......................................................................................................9
4.9
Reactive Power Capability..........................................................................................10
4.10
Transmission System Step-Up Transformer...............................................................11
4.11
Off Nominal Frequency Requirements .......................................................................12
4.12
Frequency Responsive Control System Requirements ..............................................12
4.13
Real Power and Ramp Rate Control Requirements ...................................................13
4.14
Power Quality .............................................................................................................13
4.15
WECC Stability Control Requirements .......................................................................13
4.16
Facilities Synchrophasor Measurement......................................................................13
4.17
Facilities Testing Post Connection .............................................................................13
4.18
Other Requirements ...................................................................................................14
5. Next Steps ................................................................................................................. 14
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1.
Executive Summary
The AESO plans to engage industry through a battery facility technical working group
session in order to assist the AESO in developing the technical requirements for the
connection of battery facilities to Alberta’s transmission system. These requirements will
be incorporated into new ISO rules which are subject to approval by the AUC.
Driven by interest from industry to connect energy storage (ES) facilities to the Alberta
interconnected electric system (AIES) and enable their participation in the Alberta
electricity market (the Alberta Market), the AESO launched an Energy Storage integration
initiative in September 2012. Part of that initiative was to determine if the current
technical connection requirements are suitable for ES facilities and if not develop new
requirements.
In the spring of 2013 issued the Energy Storage Initiative Issue Identification which can
be found at:
http://www.aeso.ca/downloads/Formatted_ES_IS_Paper_Final_20130613.pdf.
Currently, facilities connecting to the AIES are required to meet various technical
1
7standards. Depending on the type of facility these include, but are not limited to, the
Generation and Load Interconnection Standard and the Wind Aggregated Generating
Facilities Technical Requirements.
This paper focuses on battery facilities as the AESO believes that the current rules and
standards do not address the unique technical and operational characteristics of
batteries. These characteristics are different from those of generation or load and as
such battery facilities may impact grid operation differently than other forms of generation
and load.
The AESO is proposing to establish new ISO rules that specify connection requirements
for battery facilities. These will be based upon the ISO rules in place for Wind Aggregated
Generating Facilities (WAGF) as well as the proposed ISO rules for generators (ISO rules
502.5 and 502.6). In addition, the new ISO rules for Battery facility connection will include
provisions unique to battery facilities to reflect the technical and operational
characteristics of batteries.
2.
Purpose
The purpose of this paper is to summarize the issues identified by the AESO during its
initial evaluation of battery facilities. It serves as a starting point for further discussions
with industry to develop the technical rules for the connection of battery facilities to the
transmission system within Alberta.
1
The transmission connection standards are listed at http://www.aeso.ca/rulesprocedures/8674.html.
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This paper is not intended to address the following:
• other ES technologies such as:
o pumped storage hydro;
o compressed air energy storage;
o flywheels; and
o super-conducting magnetic energy storage
• distribution-connected Battery Facilities;
• asset classification;
• markets-related ISO rules;
• operating reserve (OR) technical requirements or procurement practices; and
• ISO tariff.
3.
Background
In Alberta, ES has primarily been studied in conjunction with wind energy. In 2011, in
collaboration with the AESO, Alberta Innovates Technology Futures (AITF) conducted a
study on using ES to support dispatch of WAGFs. The final report, Energy Storage –
2
Making Intermittent Power Dispatchable, suggests that WAGFs could benefit from ES
through profit shifting in the form of creating energy arbitrage and energy firming. The
study also suggests the possibility of ES enabling wind participation in the OR market.
However, these ideas have not yet been implemented in the Alberta.
Driven by the direction of the U.S. Federal Energy Regulatory Commission (FERC) to
3
allow non-generating resources to participate in energy and OR markets and the need to
4
address the challenges of integrating more renewable resources, many jurisdictions in
the U.S. have started the process of developing initiatives to integrate ES facilities.
In 2012, interest in integrating ES facilities into the Alberta Market increased. This interest
was primarily driven by the funding initiative of the Climate Change and Emissions
5
Management Corporation (CCEMC), the approval of a new reliability standard for
6
contingency reserves by both the Western Electricity Coordinating Council (WECC) and
the North America Reliability Corporation (NERC), and the opportunity to use the
technical features of ES as additional wind power is integrated into the AIES.
2
http://www.albertatechfutures.ca/LinkClick.aspx?fileticket=CR1tyGfMACc%3D&tabid=40
3
Order No. 890, FERC Stats. & Regs. - 31, 241
4
http://www.eia.gov/todayinenergy/detail.cfm?id=4850
5
http://environment.alberta.ca/02486.html
6
WECC Standard BAL-002-WCC-1 – Contingency Reserves (pending approval from FERC).
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Increased market interest is also generated by the possibility that new reliability products
may be beneficial with respect to managing the grid more efficiently as increased wind
7
capacity is connected to the AIES. According to the AESO 2012 Long-Term Outlook,
total wind capacity is expected to increase to over 2,200 MW by 2022, from the current
7.5 per cent of total installed capacity to 11 per cent of total installed capacity. Significant
increases in wind power capacity may exacerbate the challenge of reliably balancing the
system and maintaining system frequency given the intermittent nature of the wind
resource. In its Phase Two Wind Integration recommendation paper, the AESO made a
recommendation “to explore the need for and development of a new system ramping
8
service” as part of the wind integration program. ES is one of the resource types that can
provide fast ramping and fast response services. The potential use of ES resulted in the
industry becoming more active in ES integration.
In December 2012, the AESO received a System Access Service Request (SASR) for
the first ES project in Alberta. In February 2013, another ES project submitted a SASR to
the AESO. Both of the projects are for battery facilities.
Batteries convert electric energy into chemical energy and store it in liquid or solution
form, so that at a later time when electric energy is needed, it can be converted back to
electric energy.
There are two main types of battery technologies. The first type includes lead-acid,
nickel-cadmium, nickel-metal hydride and lithium-ion batteries. The electrochemical
process in these types of batteries produces powerful bursts of energy; however,
continuous cycling can limit the battery life. Due to their fast response ability, these
batteries are used to provide power quality service such as frequency regulation.
The second type is high-energy batteries that include flow batteries and sodium-sulfur
batteries. Both of these technologies have long-cycle life. Flow batteries also have an
advantage in that the power component and energy component can be sized
independently. High-energy batteries are typically used in energy management, such as
load leveling, capacity firming, and transmission and distribution (T&D) replacement and
deferral.
4.
Technical Requirements
In general the AESO is proposing that battery facilities have similar connection
requirements as synchronous generating units. These requirements would be
performance-based and not equipment-based requirements (i.e., battery and inverter
technology neutral).
7
The AESO, AESO 2012 Long-term Outlook, P52.
8
The AESO, Phase Two Wind Integration.
PAGE 5
Figure 1 can serve as the basis for the performance points proposed in this paper. It is
based on a stand-alone battery facility.
Figure 1
Energy Storage - Battery Facility Single Line Diagram
Voltage Regulating System
&
Real Power & Reactive Power
Control System
Alternative point of measurement
Transmission System Step-up
Transformer
Inverter
Inverter Transformer
High voltage side of inverter
transformer
Battery
Allowable point of control
(High side of Inverter transformer to 50% of
transmission system step-up transformer
impedance)
4.1 Source and Sink Resource
When referring to batteries the ISO rules will need to make reference to the real power
(megawatts) and energy (megawatt hours) produced or used when batteries are charging
and discharging. The AESO is proposing that this be referred to as sourcing and sinking
real power or energy. As such a battery facility would be referred to as a source and sink
resource as opposed to “generation and load” or a “positive and negative generator”.
4.2 Connection Rule and Operating Rules
The AESO is proposing that there be two ISO rules created for battery facilities; one for
connection of a battery facility and would incorporate the engineering, design and
construction requirements; the other would be an operating rule for the ongoing operation
and testing requirements. This would be similar to the lay out of the proposed generator
rules (proposed sections 502.5 and 502.6 of the ISO rules) the format of which was well
received by participants during the consultation period on these rules.
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Point of
Connection
4.3 Other rules
While this paper focuses on developing the technical requirements for the connection of
battery facilities to the transmission system, other existing ISO rules may also need to be
reviewed and have incidental amendments, including:
•
section 502.4 Automated Dispatch and Messaging System and Voice
Communication System Requirements;
•
section 502.3 Protection Technical Requirements; and
•
section 502.8 SCADA Technical Requirements.
4.4 Applicability and Variances
The AESO is proposing that the technical requirements will be applicable to all
transmission connected battery facilities regardless of size. This is consistent with both
synchronous generating units and WAGFs. It is the AESO’s view that small battery
facilities are more likely to be distribution connected and the legal owner of an electric
distribution system (DFO) have their own technical and operating requirements, which
are outside the scope of this paper.
The AESO recognizes that some WAGF (and perhaps other generating facilities) may
wish to install battery facility systems within an existing facility; the proposed technical
rule will have a variance section that may be used in such cases. More specific
information is discussed in the individual sections below.
4.5 Maximum Authorized Real Power
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The AESO believes that the definition of the maximum authorized real power (MARP)
may need to be revised. The present definition for MARP may not adequately cover
battery facilities as it only refers to aggregated generating facilities and generating units.
In relation to MARP, these assets are only source assets whereas battery facilities will
operate as both a source and a sink and the power flow can ramp very quickly from one
to the other.
9
maximum authorized real power means:
(i) for aggregated generating facilities with one or more collector busses, the sum of the maximum gross
real power that the ISO has authorized the generating units to deliver to those collector busses;
(ii) for aggregated generating facilities without a collector bus, the maximum gross real power that the ISO
has authorized each generating unit to deliver to its generator terminal; or
(iii) for a generating unit that is not part of an aggregated generating facility, the maximum gross real
power that the ISO authorizes the generating unit to deliver to its generator terminal.
PAGE 7
Should MARP be applied to the full range of the battery capability or only to the sourcing
capability? The workgroup may need to consider battery facilities that do not have
symmetrical sourcing and sinking capabilities.
In regards to the rule requirement the AESO proposes that it would be the owner that
declares the MARP and be responsible for the MARP being in alignment with other
sections of the rule in regards to reactive power requirements, capability under optimal
conditions, etc. This aligns with technical requirements for WAGF’s and synchronous
generating units.
4.6 Operating Voltage Requirements
The AESO proposes that market participants provide the AESO with the values for the
high side voltage of the inverter transformer and the high side voltage of the transmission
system step-up transformer. The AESO needs to understand the design of the facility in
terms of the voltages that are to be used within the battery facility. The AESO is
interested in the following two values:
•
the high side voltage of the inverter transformer to be used to assess/confirm
compliance to the reactive power and the voltage regulation capabilities of the
facility; and
•
the high side voltage of the transmission system step-up transformer to be used
to assess/confirm compliance to the voltage ride through capabilities.
This aligns with technical requirements for WAGF’s and synchronous generating units.
4.7 Voltage Ride-Through Requirements
The AESO proposes that battery facilities meet the requirements of the NERC reliability
standard PRC-024-1 that is currently pending regulatory filing by NERC. Please refer to
Figure 2 for the voltage ride-through requirements in PRC-024.
The AESO will be adopting the NERC reliability standard PRC-024-1 as an Alberta
Reliability Standard as some point in the future. In the meantime this requirement will be
placed into this proposed ISO rules for battery facilities and then removed from these ISO
rules when the reliability standard is adopted.
PAGE 8
Figure 2
Voltage Ride Through Requirements
4.8 Voltage Regulation
The AESO proposes that battery facilities have a voltage regulating system (VRS) that is
in-service and controlling voltage whether the facility is operating as a source or sink.
Traditionally sources (generating units, WAGFs) and dynamic reactive power resources
(Static VAr Compensators, synchronous condensers) owned by a TFO are required to
have voltage control systems; sinks (loads) are not required to have them. Battery
facilities will operate as both a source and a sink and the power flow can be ramped very
quickly from one to the other.
Turning the VRS on and off as the battery facility ramps from sink to source and source
to sink may cause the transmission system voltage to fluctuate at unacceptable levels.
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This could occur several times in an hour for battery facilities providing regulating
reserves or leveling out WAGF real power fluctuations and could result in unacceptable
flicker on the transmission system.
The AESO proposes that other aspects of the voltage regulation requirements are to be
in alignment with the technical requirements for WAGFs and synchronous generating
units.
For battery facilities located within other generating facilities such as WAGFs the
participant may wish to use the existing VRS to control the battery facilities. Further
discussion on this subject will take place during the work group sessions.
4.9 Reactive Power Capability
The AESO proposes that battery facilities have a full dynamic reactive power capability
whether the facility is operating as a source or sink. This proposal is in alignment for the
proposed requirement for voltage regulation. The requirements will be based on the
capability described in figure 3 below.
For battery facilities located within other generating facilities such as WAGFs the
participant may wish to use the existing reactive power resources of that facility in place
of using the battery facility. To be consistent with other sources of real power the AESO
believes that this would be acceptable but that as a whole the reactive obligations of the
facility must be in alignment with the MARP associated with that facility. Further
discussion on this subject will take place during the work group sessions.
PAGE 10
Figure 3
Reactive Power Capability
4.10 Transmission System Step-Up Transformer
The AESO proposes that the requirements for the capability of the transmission system
step-up transformer in battery facilities be in alignment with the requirements for WAGFs
and synchronous generating units. The capability of the transformer must allow for the
vector sum of the real power capability and the reactive power obligations of the battery
facility.
There would also be requirements for:
•
a favorable circuit to block the transmission of harmonic currents;
•
isolation of transmission system side ground fault current contributions; and
•
an effectively grounded wye connection on the high voltage side of the transmission
system step up transformer.
PAGE 11
4.11 Off Nominal Frequency Requirements
The AESO proposes that battery facilities accommodate the off-nominal frequency
operation as set out in Table 1 below whether the facility is operating as a source or sink.
The operation described by Table 1 is the same as the requirements for WAGFs and
generating units and is in alignment with NERC’s PRC-024-1.
The AESO believes that the same level of reliability for off nominal frequency events
whether operating as a source or sink is a reasonable approach for battery facilities
especially those providing certain operating reserves or leveling out WAGF real power
fluctuations.
Table 1
Trip Settings of Off-Nominal Frequency Protective Relays
Frequency (Hz)
>61.7 Hz
Minimum Time Delay
0 seconds
61.6 Hz to 61.7 Hz
30 seconds
60.6 Hz to <61.6 Hz
3 minutes
>59.4 Hz to <60.6 Hz
Continuous Operation
>58.4 Hz to 59.4 Hz
3 minutes
>57.8 Hz to 58.4 Hz
30 seconds
>57.3 Hz to 57.8 Hz
7.5 seconds
>57.0 Hz to 57.3 Hz
45 cycles
≤57.0 Hz
0 seconds
4.12 Frequency Responsive Control System Requirements
The AESO proposes that battery facilities have frequency responsive control system
requirements when sourcing or sinking real power and that the battery facility should
respond to both over and under frequency events. The response characteristics would be
similar to that of generating units in terms of droop, dead band, etc. This would be in
alignment with WECC’s proposed reliability standard BAL-002-WECC-1.
PAGE 12
4.13 Real Power and Ramp Rate Control Requirements
The AESO proposes that battery facilities have real power and ramp rate control systems
that are in service whenever the battery facility is in service whether sourcing or sinking
real power. Battery facilities could ramp from full charge to full discharge in a few cycles,
and depending on the size and location of the facility this behavior could appear as a
system disturbance rather than assistance to transmission system. There are similar
issues with WAGFs and the AESO uses a default setting of 10% of the facility rating per
minute. This may or not be a useful number for battery facilities and there maybe
advantages of a higher ramp rate.
4.14 Power Quality
The AESO proposes that battery facilities have power quality requirements that are
applicable to the battery energy storage facility when sourcing or sinking real power. The
key parameters will be similar to WAGFs and synchronous generating units including:
•
voltage flicker;
•
harmonic control;
•
resonance; and
•
voltage unbalance.
4.15 WECC Stability Control Requirements
At this time there are no requirements from WECC to have stability control systems
similar to power system stabilizers. It is also the AESO’s understanding that battery
facilities will not contribute to either intra- or inter-area oscillations but may have the
ability to assist in decreasing the oscillations.
The AESO proposes that battery facilities have no requirements for stability control
systems but if in the future either the WECC or the AESO require such systems that
battery facilities have this capability.
4.16 Facilities Synchrophasor Measurement
The AESO proposes that synchrophasor measurement systems be installed at battery
facilities at the high voltage side of both the inverter transformer and transmission system
step up transformer. The AESO believes that such a system will provide valuable
information to both the participant and the AESO regarding the performance of the
battery facility.
4.17 Facilities Testing Post Connection
The AESO proposes that the voltage regulation and power conversion models be
validated during commissioning and be revalidated every five years. In addition the
reactive capability of the battery facility will also be verified at the same intervals.
The proposal is in alignment with the synchronous generating unit’s rules and upcoming
NERC reliability standards.
PAGE 13
4.18 Other Requirements
The AESO proposes that other requirements including:
•
facilities disconnection;
•
fault interrupting devices;
•
isolating devices;
•
operator availability;
•
grounding;
•
lightning surge protection;
•
requirements to operate and maintain a battery facility in accordance with ISO
rules;
•
operating data requests; and
•
requirements for operation at maximum authorized real power
will be similar to WAGFs and synchronous generating units.
5.
Next Steps
The AESO is holding a working session to present and discuss the AESO’s proposed
battery facility technical and operating requirements on November 20, 2013 at 9:00 am.
The AESO requests that all interested stakeholders RSVP to Kevin Wiens
([email protected]) by November 5, 2013.
The AESO invites stakeholders to provide comments on this paper by December 11,
2013 specifically on the proposals for the battery facility technical and operating
requirements brought forward in this paper. The AESO requests that stakeholders attend
the proposed working session before submitting comments.
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