20190924Avista to Staff 155-167.pdf

AVISTA CORPORATION
RESPONSE TO REQUEST FOR INFORMATION
JUzuSDICTION
CASE NO.:
REQUESTER:
TYPE:
REQUEST NO.:
IDAHO
AVU-E-19-04
IPUC
Production Request
Staff - 155
DATE PREPARED
WITNESS:
RESPONDER:
DEPARTMENT:
TELEPHONE:
09124t2019
Thomas Dempsey
Thomas Dempsey
GPSS
(s09) 49s-4960
REQUEST:
Please provide the Coyote Springs 2 combined cycle plant design operating c
RESPONSE:
No-Limit Maximum Net Capacity- 319 MW
No-Limit Maximum Net Capacity at Average Site Temperature- 302 MW
The current estimated gross maximum capability of Coyote Springs 2 is 207 MW on the
gas turbine plus -1 l6 MW on the steam turbine for a total of 323 MW gross. Avista estimates the
maximum auxiliary consumption to be approximately 4 MW. The maximum estimated net
capacity is therefore -319 MW. PLEASE NOTE: These are maximum possible values which
might be achieved under ideal cold weather conditions. The site average temperature in
Boardman, OR, where Coyote Springs 2 is located, is 55 degrees Fahrenheit. Under site average
temperature conditions the capability of the gas turbine is approximately 190 MW, which implies
an approximate average site ambient condition rating of 306 MW Gross/302 Net. These
capacities include full duct burner use. In addition, actual capacity will vary dependent upon not
only ambient temperature but also ambient pressure, ambient relative humidity, and turbine tuning
parameters. The estimates provided in these data responses is based on a Thermoflex computer
model of Coyote Springs 2.
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AVISTA CORPORATION
RESPONSE TO REQUEST FOR INFORMATION
JURISDICTION:
CASE NO.:
REQUESTER:
TYPE:
REQUEST NO.:
IDAHO
AVU-E-19-04
IPUC
Production Request
Staff - 156
DATE PREPARED: 0912412019WITNESS: Thomas Dempsey
RESPONDER: Thomas Dempsey
DEPARTMENT: GPSS
TELEPHONE: (s09) 49s-4960
REQUEST:
Please provide the present, limited operating capacity of Coyote Springs 2 plant as a result of the
GSU transformer de-rating.
RESPONSE:
Prior to Change to Duct Burner Permissives (Present):
Engineering Limited Maximum Net Capacity- 281 MW
Engineering Limited Maximum Net Capacity at Avg Site Temperature- 281 MW
Subsequent Change to Duct Burner Permissives (est. Jan 2020):
Engineering Limited Maximum Net Capacity- 302 MW
Engineering Limited Maximum Net Capacify at Avg Site Temperature- 302 MW
The GSU engineering limitation is specifically applied to the gas turbine. The limit on the
gas turbine is currently 190 MW. This does not establish a limit on the steam turbine side, per se,
however if less energy is available in the exhaust of the gas turbine the steam turbine output is
reduced. In the past, and up to now, we have operated in a mode in which the duct burner (which
provides supplemental energy for the steam turbine) is not put into service unless the gas turbine is
at full load. This means that under current operating conditions where the gas turbine is limited to
190 MW and thus not at base load, the steam turbine operates below its maximum capability as the
duct burner is not placed into service. The current engineering limited net total plant output is
therefore approximately 285 MW Gross/281 MW Net.
Avista has recognizedaneed for additional flexible load following capability. To that end,
we a.re planning a new operation mode which allows the duct burner to be in service even if the gas
turbine is running below its maximum capability. Operating the gas turbine at reduced load will
give us the ability to move either up or down in load, allowing the duct bumer to operate at slightly
reduced gas turbine loads will allow us to retain needed high end capacity.
We plan to test operation of the duct burner when the gas turbine is not at full load but other
safety permissives such as air flow are met. Once that testing is complete, we expect to be able to
operate the steam turbine at its full capacity of I 16 MW even if the gas turbine is limited to slightly
below its nominal full load rating. We therefore expect the plant limit at that time to be closer to
190 GT + 95 ST + 21 DB :306 MW Gross/ 302 Net. We estimate this change to be in place by
mid-January 2020. (lt is coincidental that our expected GSU-limited plant capability matches the
ability of the plant at average site conditions when there is no GSU limit- the reason for this is that
Page I of2
after reviewing actual plant data over the last year plant operations personnel determined that the
gas turbine happens to reach 190 MW at 54 degrees Fahrenheit - which nearly matches the average
annual site temperature of 55 degrees Fahrenheit),
Please note actual capacity will vary dependent upon not only ambient temperature but also
ambient pressure, ambient relative humidity, and turbine tuning parameters. The estimates
provided in these data responses is based on a Thermoflex computer model of Coyote Springs 2. A
large portion of time (summer) the GSU engineering limit will have no effect whatsoever because
the gas turbine will be unable to meet the limit. In shoulder months where weather is cool but not
cold, the limit will have some effect but not the full 17 MW reduction.
Page 2 of 2
AVISTA CORPORATION
RESPONSE TO REQUEST FOR INFORMATION
JURISDICTION:
CASE NO:
REQUESTER:
TYPE:
REQUEST NO.:
IDAHO
AVU-E-19-04
IPUC
Production Request
Staff-157
DATE PREPARED: 0912512019WITNESS: Clint Kalich
RESPONDER: Xin Shane
DEPARTMENT: Energy Resources
TELEPHONE: [phone]
REQUEST:
Please provide the pro forma net power cost adjustment and corresponding revenue requirement
difference with the Coyote Springs 2 plant operating at reduced capacity as a result of the GSU
transformer de-rate using the AURORA model to calculate proposed base rates. Please provide
AURORA model results and updated confidential and non-confidential schedules that are
contained in Mr. Kalich's Exhibit No. 7 workpapers.
RESPONSE:
In the original filing (see Kalich, Exhibit No. 7 - Schedule 3), the 2020 Pro Forma Power Expense
was $152,150,000 (system). Reducing the capacity at Coyote Spring II results in an increase in
overall power supply expense of $783,000 (or $270,996 Idaho share) or $152,933,000 (system).
Please see the table below for the assumed capacity in each respective AURORA model run.
Month Original Filing Updated Run for PR 157
1 377.6
2 316.2 299.3
3 370.4 299.3
4 307.0 299.3
5 300.7 299.3
6 298.2 298.2
294.8 294.8
8 294.8 294.8
9 299.7 299.L
10 306.2 299.3
11 314.3 299.3
L2 318.4 299.3
Page I of I
299.3
7l
AVISTA CORPORATION
RESPONSE TO REQUEST FOR INFORMATION
JURISDICTION
CASE NO.:
REQUESTER:
TYPE:
REQUEST NO.:
IDAHO
AVU-E-19-04
IPUC
Production Request
Staff - 158
DATE PREPARED: 0912412019WITNESS: Thomas Dempsey
RESPONDER: Thomas Dempsey
DEPARTMENT: GPSSTELEPHONE: (s09) 495-4960
REQUEST:
Please explain the feasibility of continuing to run at reduced capacity. Specifically, what are the
impacts and consequences of continuing to run the Coyote Springs 2 plant at the current level of
output?
RESPONSE:
See Company's responses to Staff PR_156 and Staff PR_I57. While operating at significantly
reduced load results in higher heat rate and lower efficiency, the heat rate curve is relatively flat at
small deviations from full load. Thus, any impact to efficiency of operating close to base load will
likely be small. Avista does not anticipate any other impacts or consequences of continuing to run
Coyote Springs 2 atthe current level of output.
AVISTA CORPORATION
RESPONSE TO REQUEST FOR INFORMATION
JURISDICTION: IDAHO
CASE NO.: AVU-E-I9-04
REQUESTER: IPUCTYPE: Production Request
REQUESTNO.: Staff- 159
DATE PREPARED
WITNESS:
RESPONDER:
DEPARTMENT:
TELEPHONE:
09/2412019
Thomas Dempsey
Thomas Dempsey
GPSS
(sOe) 4es-4960
REQUEST:
Please provide all the options available to the Company in addressing the future issues of the
Coyote Springs 2 facility. In addition, based on each option, please provide the following:
a. Please provide a description of all the activities and analysis the Company plans to perform
to choose the best option;
b. Please describe the criteria and factors that the Company will use to make its decision
while choosing the options; and
c. Please provide a timeline of all the activities, analysis, interim and final decision points
needed to choose the best option.
RESPONSE:
Avista assumes for the purpose of this data request that the question about "options available"
refers specifically to the GSU transformer.
a. Please see the Staff_PR_l59 Attachments to this data request. Here is a brief description of
each:o 20190919 Draft CS2 GSU Single Phase Transformer Business Case.docx- This attachment
basically ties everything together.
o "20190731 Decision Tree Narrative"- This provides a map as well as a detailed description of
options considered.
o "20190919 Power Supply Asset Management Consolidated Financial Analysis"- This
document summarizes the internal Avista financial analyses of the options.. "Appendix II CS2 GSU engineering recommendation"- This document summarizes an intemal
Avista engineering recommendation.
o "Xfrmr Rev Req5"- This is a spreadsheet used to calculate Avista internal financials
b. The criteria and factors that the Company will use to make decisions will depend on the
circumstances at the time. Avista generally considers cost, expected reliability, quality of the
suppliers, outage costs and durations, etc. The attachments to the response to part "a" provide
additional detail.
c. Avista hired Black & Veatch to perform a study of the costs we might expect to be associated
with going to a single phase solution. Please see Staff_PR_I59 Attachments, document
labeled "Avista-CoyoteSpgs-GSU-Replcmt-Concept-Report_Final_Rpt-w-ATT rev.pdf'.
Two different financial analyses were performed, and a single phase solution was determined
to be the best path forward, considering all of the circumstances. The request for proposal is
currently out for bid, with bids due October 4,2019. Avista will be performing detailed
Page I of2
analyses of the bids during the immediately following week. We expect to award by
December 2,2019.
Page2 of2
AVISTA CORPORATION
RESPONSE TO REQUEST FOR INFORMATION
JUzuSDICTION
CASE NO.:
REQUESTER:
TYPE:
REQUEST NO.:
IDAHO
AVU-E-19-04
IPUC
Production Request
Staff - 160
DATE PREPARED
WITNESS:
RESPONDER:
DEPARTMENT:
TELEPHONE:
0912412019
Thomas Dempsey
Thomas Dempsey
GPSS
(s09) 49s-4960
REQUEST:
What is the latest date that the Company will have a permanent solution in place?
RESPONSE:
The latest date the Company will have a permanent solution in place is dependent upon the
execution of a binding contract, with a successful bidder, that meets customer value requirements.
Currently, Avista expects to receive bids and manufacturing schedules from transformer suppliers
by October 4,2019. Avista anticipates the transformers to be delivered by the end of 2020, with
installation likely during hydro run-off - most likely June 2021 . If there is a failure of T4 prior to
June2021, Avista would begin installation of the new transformers as soon as possible.
AVISTA CORPORATION
RESPONSE TO REQUEST FOR INFORMATION
JURISDICTION:
CASE NO.:
REQUESTER:
TYPE:
REQUEST NO.:
IDAHO
AVU-E-19-04
IPUC
Production Request
Staff - 16l
DATE PREPARED: 0912412019WITNESS: Thomas Dempsey
RESPONDER: Thomas Dempsey
DEPARTMENT: GPSSTELEPHONE: (s09) 495-4960
REQUEST:
Regarding the option to reconfigure the facility using three single phase transformers, please
provide the total estimated cost needed to reconfigure the facility if this option is chosen and an
estimate of the time needed to complete re-construction.
RESPONSE:
The current total cost estimate is $13,600,000, including the required re-configuration of the
facility. Please note this amount is preliminary in nature based on an estimate provided by Black
& Veatch. Please see the Company's response to part (c) of Production request 159 for this
estimate. The transformer estimate will be updated once bids are received and reviewed the first
two weeks of October 2019. In addition, future firm bid costs will be required to include the costs
related to the isophase bus equipment, protection equipment, and other elements.
AVISTA CORPORATION
RESPONSE TO REQUEST FOR INFORMATION
JUzuSDICTION
CASE NO.:
REQUESTER:
TYPE:
REQUEST NO.:
IDAHO
AVU-E-19-04
IPUC
Production Request
Staff- 162
DATE PREPARED
WITNESS:
RESPONDER:
DEPARTMENT:
TELEPHONE:
0912412019
Thomas Dempsey
Thomas Dempsey
GPSS
(s09) 49s-4960
REQUEST:
Please provide reports of any plant investigations or analyses completed since starting plant
construction up to the present regarding GSU transformer failures at the Coyote Springs 2 plant.
RBSPONSE:
Please see Staff PR_162 Attachment A for a presentation which reviews the timeline of
Transformer #1 through the purchase of Transformer #3.
Please see the response to Staff PR_164 and its associated attachments
Transformer #3 is currently in a repair facility undergoing diagnostic testing and forensic analysis.
Avista will not receive the investigative reports for this unit until 2020.
Transformer #4 is currently in service.
See the response to Staf{_PR_l59. The attachments to 159 provide related relevant information to
the ongoing investigations and analysis related to the issues we are experiencing with T3 and T4.
See the Black & Veatch study that is included as an attachment to the response to Staff PR_l59.
AVISTA CORPORATION
RESPONSE TO REQUEST FOR INFORMATION
JURISDICTION:
CASE NO.:
REQUESTER:
TYPE:
REQUEST NO.:
IDAHO
AVU-E- l9-04
IPUC
Production Request
Staff- 164
DATE PREPARED: 0912412019WITNESS: Thomas Dempsey
RESPONDER: Thomas Dempsey
DEPARTMENT: GPSS
TELEPHONE: [phone]
REQUEST:
Please provide all Company analyses and reasoning when procuring each of the capital spare GSU
transformers (i.e. GSU #3 and GSU #4).
RESPONSE:
Please see the Company's response to Staff PR_164 Attachments for various documents
concerning the analyses and reasoning utilized when procuring each of the spare transformers.
Avista considered the following circumstances regarding its decision to purchase Transformer 3 as
a spa.re:
l. The Alstom/AREVA transformers had experienced a number of failures. Avista's internal
conclusion, as well as the conclusion of our third party expert consultant Charlie Raymond,
was that the transformer should have performed properly. Please see the document labeled
"CS2 06-25-07.pdf' provided in Staff PR_l64 Attachments. Avista's expert consultants
concluded:
"The transformer, if properly constructed, should have been capable of performing in the
service conditions encountered including operations in back-feed from the 500kV system.
This was investigated in detail previously by Dr. Degeneff both theoretically and in
conjunction with transients as measured by the Areva transient measuring equipment."
Please see "CS2 06-25-07.pdf'provided in Staf{_PR_I64 Attachments.
2. Avista believed that the problems with Tl and T2 were manufacturer issues, based on the
following information :
a. T1 failed after initial energization- prior to the transformer even being under load
b. T2 failed its first factory impulse test- this failure was obviously not attributable to
Coyote Springs 2 "extemal factors".
c. AREVA dropped T2 while still in its control- this failure was obviously not attributable
to Coyote Springs 2 "external factors". However, difficulty in transport is a
consideration in our current risk assumptions related to choosing the new configuration
in2019. This is particularly true since we are looking at upgraded transformers in
terms of insulation and capacity which would necessitate an even heavier three phase
solution if so chosen.
d. Multiple GSU interconnections to the same grid, including three transformers about
200 feet away, as well as other nearby facilities, did not and have not experienced
failure with much longer service histories.
Page I of2
3. Transformer 2 was in service. Avista determined that given the history of the GSUs, a
spare was warranted, and that the spare needed to be made by a different manufacturer. As
previously stated, at that time Avista had no reason to believe that the failure was
attributable to the three phase configuration.
4. Avista, and its consultants, looked at the areas where the AREVA units had failed
concluding "The problems to date have all involved insulation breakdown between the
high voltage lead entrances and ground." as stated in Charlie Raymond's Transformer
lnspection report dated October 29,2007 and included as an attachment to this data request
response titled "rpt-Chas Raymond CS2 10-07b.pdf'. Furthermore, the consultant's
review of the failures recommended additional clearance and better manufacturing on such
a transformer design to solve the problem. With this information in mind, Avista found
another manufacturer, Siemens, to provide transformers T3 and T4. T3 was in service fully
functioning for the past 11 years until the resent failure.
5. The possibility of switching to a single phase solution was briefly considered. Doing so
would have required complex reconfiguration of the isophase bus, reconfiguration of the
transformer pads and fire protection, and a redesign of the protection systems.
Importantly, at that time switching to a single phase solution would have required the
retirement of a fully functioning transformer. To the best of Avista's knowledge at the
time, the problem was squarely with AREVA and their specific manufacturing processes.
NOTE- The situation currently faced by Avista is distinctly different from the circumstances that
existed when Avista procured GSU #3 and GSU #4. A full discussion of this topic is included in
Avista's response to StaflPR_I65.
Page 2 of 2
AVISTA CORPORATION
RESPONSE TO REQUEST FOR INFORMATION
JURISDICTION:
CASE NO.:
REQUESTER:
TYPE:
REQUEST NO.:
IDAHO
AVU-E-19-04
IPUC
Production Request
Staff- 165
DATE PREPARED: 0912412019WITNESS: Thomas Dempsey
RESPONDER: Thomas Dempsey
DEPARTMENT: GPSS
TELEPHONE: (s09) 495-4960
REQUEST:
Has the Company or its partners considered alternative GSU transformer designs/configurations at
the Coyote Springs 2 plant prior to the GSU transformer failure that occurred in 2018? Please
provide any reports detailing these proposals.
RESPONSE:
See also Avista's response to Staff PR_164. Avista had considered the possibility of an
alternative configuration prior to 2018. The alternatives included 1) changing the manufacturer
and including improvements to the high voltage leads or 2) changing to a single phase solution
(and changing manufacturers). Option I was chosen given our third-party expert reports as
discussed in the response to StaflPR_164. The reports included as a response to Staff PR_164
did not specifically discuss the option of changing to a single phase solution; rather they
specifically stated that a properly constructed three phase solution should have worked.
As previously mentioned, the situation currently faced by Avista is distinctly different:
l. Importantly, we now have a body of evidence that suggests that the entire three
phase concept may be suspect given the specifics of this application. This risk is
assigned a monetary value in the current financial analyses.
2. In contrast, when we acquired GSU #3 and GSU #4, there was no fully functioning
transformer. We currently have a functioning, albeit damaged, transformer. If we
go to the single phase option, we would be replacing the current transformers with
four fully functioning transformers.
3. Under the current transformer configuration Avista will not be able to upgrade the
generation any further as the transformer currently is at facility limit. Should we
decide to go with single phase transformers, we would be able to upgrade the
capacity of the new transformer(s). Should we decide to upgrade the generation
capacity in the future, customers would benefit from the capacity increase.
4. We should be able to stage the construction so that we are able to perform the first
phase of work during runoff in 2020 withminimal power supply cost impacts. The
second phase will be completed in 2021 over a short time frame with minimal
power supply impacts.
5. See the attachment to this data request titled "20190920 RE_ Question regarding 3
phase transformers". This is an email from a Bonneville Power Administration
transmission engineer. In it he touches on the subject of transformer weight AND
insulation requirements as a reason they would typically choose single phase
transformers at this size and voltage class.
AVISTA CORPORATION
RESPONSE TO REQUEST FOR INFORMATION
JURISDICTION:
CASE NO:
REQUESTER:
TYPE:
REQUEST NO.:
IDAHO
AVU-E- l9-04
IPUC
Production Request
Staff-166
DATE PREPARED: 09/2312019WITNESS: Clint Kalich
RESPONDER: James Gall
DEPARTMENT: Energy Resources
TELEPHONE: [phone]
REQUEST:
Please provide the monthly data used to generate the Mid-Columbia Electric Forecast Range graph
(as illustrated in Figure 10.14, page l0-21 in the 2017 IRP) in Excel format with all working
formula intact. Please provide the same data and graph that was generated for the 2019 IRP.
RESPONSE:
Please see Avista's response 166C, which contains TRADE SECRET, PROPRIETARY or
CONFIDENTIAL information and exempt from public view and is separately filed under
IDAPA 31.01.01, Rule 067 and233, and Section 9-340D,ldaho Code.
Per conversations with IPUC staff, the required data is provided in the attached file
Staff PR l66C Confidential Attachment A.
Page I of I
AVISTA CORPORATION
RESPONSE TO REQUEST FOR INFORMATION
JURISDICTION:
CASE NO:
REQUESTER:
TYPE:
REQUEST NO.:
IDAHO
AVU-E- 19-04
IPUC
Production Request
Staff- 167
DATE PREPARED: 09/2312019WITNESS: Clint Kalich
RESPONDER: James Gall
DEPARTMENT: Energy Resources
TELEPHONE: (509) 49s-2189
REQUEST:
Please provide the average monthly Mid-Columbia electricity prices generated for each of the
Aurora Monte Carlo runs that were used to develop the Company's 2011 and 2015 Integrated
Resource Plans. Please provide the data in Excel format with all formula intact.
RESPONSE:
Please see Avista's response 167C, which contains TRADE SECRET, PROPRIETARY or
CONF'IDENTIAL information and exempt from public view and is separately filed under
IDAPA 31.01.01, Rule 067 and233, and Section 9-340D, Idaho Code.
Per conversations with IPUC staff, the required data is provided in the attached file
Staff PR l67C Confidential Attachment A.
Page I of I