20180501IPC to Staff 1-2.pdf

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LISA D. NORDSTROM
Lead Counsel
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May 1 ,2018
VIA HAND DELIVERY
Diane M. Hanian, Secretary
ldaho Public Utilities Commission
472 W est Washington Street
Boise, ldaho 83702
Re: Case No. IPC-E-18-06
2018-2019 Power Cost Adjustment - ldaho Power Company's Response to
the First Production Request of the Commission Staff
Dear Ms. Hanian:
Enclosed forfiling in the above matter please find an original and three (3) copies of
ldaho Power Company's Response to the First Production Request of the Commission
Staff.
Very truly yours,
o<u'AV(^t;-*-
Lisa D. Nordstrom
LDN:kkt
Enclosures
P.O. Box 70 (83707)
1221 W' ldaho St.
Boire, lD 83702
LISA D. NORDSTROM (lSB No. 5733)
Idaho Power Company
1221West ldaho Street (83702)
P.O. Box 70
Boise, ldaho 83707
Telephone: [phone]
Facsimile: [phone]
I n ord strom @ id a hopower. com
IN THE MATTER OF THE APPLICATION
OF IDAHO POWER COMPANY FOR
AUTHORITY TO IMPLEMENT POWER
COST ADJUSTMENT (PCA) RATES FOR
ELECTRIC SERVICE FROM JUNE 1,
2018, THROUGH MAY 31 , 2019
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Attorney for ldaho Power Company
BEFORE THE IDAHO PUBLIC UTILITIES COMMISSION
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CASE NO. tPC-E-18-06
IDAHO POWER COMPANY'S
RESPONSE TO THE FIRST
PRODUCTION REQUEST OF
THE COMMISSION STAFF
COMES NOW, ldaho Power Company ("ldaho Power" or "Company"), and in
response to the First Production Request of the Commission Staff to ldaho Power
Company dated April 25, 2018, herewith submits the following information:
IDAHO POWER COMPANY'S RESPONSE TO THE FIRST
PRODUCTION REQUEST OF THE COMMISSION STAFF - 1
REQUEST NO. 1: On line 25 of Exhibit No. 1, Ms. Blackwell provides forecast
monthly loads. On line 60 of her Sales Forecast workpapers (Workpapers 201 8-2019
Sales Forecast (00232778x8CD5C).xlsx), she provides system-wide retail sales.
Please reconcile and explain the discrepancies between forecast monthly load and
forecast monthly energy sales.
RESPONSE TO REQUEST NO. 1: Please see the attachment to this response
for a reconciliation of forecast monthly loads and billed energy sales. The monthly load
forecast provided on Iine 25 of Exhibit No. 1 is the Company's forecast of customer
energy requirements for each calendar month, referred to as calendar-month sales, for
the Power Cost Adjustment (.PCA") test period of April 2018 through March 2019. The
forecast of monthly energy sales provided on line 60 of the Sales Forecast workpapers
is the Company's expectation of energy sales billed in each month, referred to as billing-
month sales, for the PCA collection period of June 2018 through March 2019.
ldaho Power's customers are billed according to a schedule of 21 different billing
cycles. The physical delivery of electricity within a given calendar month does not
coincide with the amount of electricity billed in that month. Consequently, a portion of
calendar-month sales from each month coincides with a portion of billing-month sales
recorded in the subsequent month(s).
The variation in calendar-month sales and billing-month sales is typically larger
during changes in season, when changes in temperature and precipitation are more
prominent. For example, the month of August is typically marked with high energy
usage due to warmer-than-normal temperatures and drier-than-normal precipitation.
Although this higher energy usage is expected to occur in the month of August and is
IDAHO POWER COMPANY'S RESPONSE TO THE FIRST
PRODUCTION REQUEST OF THE COMMISSION STAFF - 2
reflected in August calendar-month sales, a portion of the higher energy usage is billed
in September, resulting in increased billing-month sales for September. Furthermore,
calendar-month sales are typically lower in September than August due to decreasing
temperatures and lower energy usage. The combined impact is a larger variance in
billing-month sales and calendar-month sales for the month of September.
The PCA forecast, including expense and calendar-month load, presented on
Exhibit No. 1, is on a system-level basis. The ldaho jurisdictional share of the PCA
forecast to be collected through customer rates is determined by applying a ratio of
forecast ldaho jurisdictional billing-month sales to forecast system billing-month sales to
the system-level differences in the PCA forecast of net power supply expense ("NPSE')
and currently approved base level NPSE, adjusted for sharing provisions. This
calculation is presented in Table 4 of Ms. Blackwell's testimony, which was provided
electronically with the Company's workpapers. The quantification of the ldaho
jurisdictional share of the PCA forecast is described below, as well.
The Company quantifies a PCA forecast rate, which is equal to the sum of: (1)
95 percent of the difference between the non-Public Utility Regulatory Policies Act of
1978 ("PURPA") expenses quantified in the March Operating Plan and those quantified
in the Company's last approved update of NPSE, divided by the Company's forecast of
system billing-month sales for June 2018 through May 2019, and (2) 100 percent of the
difference between PURPA-related expenses quantified in the March Operating Plan
and those quantified in the Company's last approved update of NPSE, divided by the
Company's forecast of system billing-month sales, and (3) 100 percent of the difference
between the ldaho jurisdictional demand response incentive payments quantified in the
March Operating Plan and those quantified in the Company's last approved update of
IDAHO POWER COMPANY'S RESPONSE TO THE FIRST
PRODUCTION REQUEST OF THE COMMISSION STAFF - 3
NPSE, divided by the forecast of ldaho jurisdictional billing-month sales for June 2018
through May 2019. Finally, applying the PCA forecast rate to forecast ldaho
jurisdictional billing-month sales for June 2018 through May 2019 results in the ldaho
jurisdictional share of the PCA forecast.
The response to this Request is sponsored by Nicole Blackwell, Regulatory
Analyst, ldaho Power Company.
IDAHO POWER COMPANY'S RESPONSE TO THE FIRST
PRODUCTION REQUEST OF THE COMMISSION STAFF - 4
REQUEST NO.2: On page 4 of Commission Order No. 33775, the Commission
discussed the December 2016 outage at Langly Gulch, and stated, "We look forward to
the Company providing reports and conclusions regarding the root cause of the failures
and why the extended downtime occurred." Has the Company completed its
investigation? lf so, please provide a copy of the Company's final report. lf not, please
explain why the Company has not completed its investigation.
RESPONSE TO REQUEST NO. 2: ldaho Power recently completed its
investigation of the root cause analysis of the 2016 extended outage at Langley Gulch,
the details of which are explained below. Although the Company devoted a significant
amount of time to the investigation and reviewed a vast amount of data, a definitive root
cause was not discovered.
During the planned fall outage for Langley Gulch, scheduled for October 24,
20'16, through November 30, 2016, work was planned to replace the seals on the high-
pressure steam turbine. This was being done in conjunction with the normal
maintenance cycle for the gas turbine as part of the service provided in the Long-Term
Service Agreement with Siemens. During inspections, additional wear and cracking
was found on the blade roots, blade tip seals, and inter-stage seals on the turbine rotor.
Due to these findings, the turbine rotor had to be shipped to the manufacturer's
recommended maintenance facility located in Seattle, Washington, for repairs. Repairs
for the turbine rotor occurred between November 11,2016, and December 1,2016.
The high-pressure steam turbine was reassembled and plant maintenance was
completed on December 15, 2016. Due to the turbine rotor seal wear found during
IDAHO POWER COMPANY'S RESPONSE TO THE FIRST
PRODUCTION REQUEST OF THE COMMISSION STAFF - 5
inspection, the October 2016 scheduled outage was extended approximately two weeks
beyond the target completion date of November 30, 2016, to December 15, 2016.
During last year's PCA proceeding, ldaho Power committed to determine the root
cause of the turbine rotor seal wear. The Company's efforts to determine the root
cause entailed reviewing plant operating data to pinpoint any conditions of excessive
heating or cooling that may have occurred on the steam turbine seals.
In its efforts to determine the root cause, ldaho Power began working to retrieve
historical plant operating data from the plant Distributive Control System ("DCS")
historian. This process began in May 2017, and involved installing a new onsite
computer, which was synched with Siemens' system, to retrieve historical operating
data for Langley Gulch from 2011 through 2016. The data captured in the DCS
historian includes numerous operating parameters, such as temperature, pressure, and
steam flow readings for the steam turbine.
Embrittlement of seals or seal rubs, like those found during the extended outage,
are typically caused by over-heating or cooling events. As a result, the Company
examined the data for events or causes that could have resulted in an over-heating or
cooling event on the steam turbine case or rotor, including wet insulation, temperature
stratification within the steam turbine enclosure, and steam admitted to the turbine case.
ldaho Power reviewed plant data and maintenance records to determine if there
were any instances in which the turbine operated with partial insulation installed or if
there were any events that may have led to wetting of insulation on top or bottom of the
turbine casing. A review of plant records showed no evidence of running the turbine
under any of these conditions.
IDAHO POWER COMPANY'S RESPONSE TO THE FIRST
PRODUCTION REQUEST OF THE COMMISSION STAFF - 6
ldaho Power also reviewed the data for changes to the steam turbine room
enclosure, such as removal/replacement of the roof or wall panels, to determine if the
turbine case may have been exposed to an external temperature event. There were no
recorded events of changes to the room enclosure from 2011 through 2016.
Finally, the Company inspected the Thermal Stress Evaluator ('TSE') program
for any operational issues. The TSE program is designed to help limit and protect the
steam turbine from any excessive heating or cooling events. The TSE program data is
stored in the DCS historian. ln reviewing the data, ldaho Power determined there were
no instances in which the TSE experienced operational issues or loss of protection
functionality. The Company also examined the TSE program's operational settings that
admit steam into the turbine case. There were no findings or evidence that the settings
would have allowed the turbine to operate outside the range of the TSE program
parameters during commissioning activities prior to ldaho Power operating the plant or
following turnover of the plant to ldaho Power through 2016.
Over the past several months, the Company spent a significant amount of time
and reviewed a voluminous amount of data to find a root cause for the extended outage
at Langley Gulch; however, a definitive root cause was not discovered nor did the
Company find any evidence that the steam turbine operated beyond Original Equipment
Man ufactu rer recommendations.
The response to this Request is sponsored by Mike Williams, Power Production
Manager, ldaho Power Company.
DATED at Boise, ldaho, this 1st day of May 2018.
ISA D. NORD M
Attorney for ldaho Power Company
IDAHO POWER COMPANY'S RESPONSE TO THE FIRST
PRODUCTION REQUEST OF THE COMMISSION STAFF - 7
CERTIFICATE OF SERVICE
I HEREBY CERTIFY that on the 1st day of May 2018 I served a true and correct
copy of IDAHO POWER COMPANY'S RESPONSE TO THE FIRST PRODUCTION
REQUEST OF THE COMMISSION STAFF upon the following named parties by the
method indicated below, and addressed to the following:
Commission Staff
Brandon Karpen
Deputy Attorney General
ldaho Public Utilities Commission
472 West Washington (83702)
P.O. Box 83720
Boise, ldaho 83720-007 4
_Hand Delivered
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Ki T , Executive Assistant
IDAHO POWER COMPANY'S RESPONSE TO THE FIRST
PRODUCTION REQUEST OF THE COMMISSION STAFF. S
BEFORE THE
IDAHO PUBLIC UTILITIES COMMISSION
GASE NO. !PC-E-l8-06
IDAHO POWER COMPANY
ATTAGHMENT
RESPONSE TO STAFF'S
REQUEST NO. 1
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