20221219PAC to Staff 25-34.pdf

Y ROCKY MOUNTAIN
POWER
A O,VISION OF MClFrcORP
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14Ol W North Temple, Suite 330
Salt Lake City, Utah 84116
December 19,2U2
Jan Noriyuki
Idaho Public Utilities Commission
472W. Washington
Boise,ID 83702-5918
[e-mail] (C)
RE:ID PAC.E-22.14
IPUC Set 2 (25-34)
Please find enclosed Rocky Mountain Power's Responses to IPUC 2nd Set Data Requests 33-34.
Ifyou have any questions, please feel free to call me at [phone].
Sincerely,
-Jsl-Mark Alder
Manager, Regulation
Enclosures
PAC-E-22-14 / Rocky Mountain Power
December 19,2022
IPUC Data Request 33
IPUC Data Request 33
The Company's response to Production Request Nos. 9, 13,14,16,17,18, and l9
discussed reconciliation between the 2021 IRP and 2021 tRP Update. Also,
response to Production Request No. 9 states that the capacity contribution in the
2021 IRP Update uses a method closely aligned with the Western Resource
Adequacy Program (WRAP). Please respond to the following:
(a) How is the method used inthe202l tRP Update closely aligned with the
WRAP method?
(b) What is the difference between the two methods?
(c) What needs to be reconciled?
(d) Why do they need to be reconciled?
(e) How are they being reconciled?
(f) When will the reconciliation effort be completed?
Response to IPUC Data Request 33
(a) The Western Resource Adequacy Program (WRAP) uses a series of Effective
Load Carrying Capability (ELCC) analyses to identiff the aggregate capacity
contribution of wind, solar, and run-of-river hydro. Attribution of capacity to
individual resources is based, in part, on a resource's generation during the top
5 percent net load hours, i.e. those hours in which the remaining load is
highest after subtracting out wind and solar generation. Please refer to the
Company's response to IPUC Data Request 9.
Pacifi Corp' s 2021 Integrated Resource Plan (IRP) Update allocated capacity
primarily based on generation during the top 5 percent net load hours, which
was also part of the WRAP design. Because ELCC analyses require very data
intensive studies with long run times, they were not performed for the 2021
IRP Update load and resource reporting. lnstead, the remaining capacity
between the net load peak and the coincident peak (CP) (including the
planning reserve margin (PRM)) was allocated based on a resource's
generation during the top 5 percent load hours.
(b) The 2021 IRP used a different capacity allocation methodology, based on the
amount of load in excess of the derated capacity of its long-duration
dispatchable resources, and proportionately allocated among all non-
dispatchable resources available in that hour. This results in allocation of
small amounts of capacity to'many more hours beyond the top 5 percent and
PAC-E-22-14 / Rocky Mountain Power
December 19,2022
IPUC Data Request 33
differences in the weighting of the different periods results in different
allocations to individual resources.
(c) For the202l IRP Update and parts of the 2021 IRP, the capacity calculations
were based on aggregate generation by resource type, making it diflicult to
identiff the contribution of individual resources within the categories
identified in the reported results.
(d) As a practical matter, it is not necessary to reconcile the resource-by-resource
capacity attributions between the202l IRP and the202l IRP Update. tn both
analyses, the achieved PRM and the remaining front office transaction (FOT)
requirements are calculated based on the hourly resource availability of the
portfolio as a whole. The hour(s) when the fewest additional resources are
available as a percentage of the hourly load represent the achieved PRM, and
if that is less than 13 percent, the shortfall has to be made up via FOTs. As a
result, attributing additional capacity to one resource based on different
methodologies necessarily results in other resources being attributed less
capacity, since the achieved PRM of the portfolio as a whole is fixed.
(e) Please refer to the Company's l" Supplemental response to IPUC Data
Request 9 which provides resource-specific capacity contribution values from
the202l IRP Update and the 2021 IRP. For the reasons described in the
Company's response to subpart (d) above, PacifiCorp has not prepared a
resource-by-resource comparison of capacity contribution to identi$
differences.
(f) Please refer to the Company's response to subpart (e) above.
Recordholder:Dan MacNeil
Sponsor:Dan MacNeil
PAC-E-22-14 / Rocky Mountain Power
December 19,2022
IPUC Data Request 34
IPUC Data Request 34
In the 2021 IRP, Ancillary Services are captured in the Planning Reserve Margin,
while, in the 2021 IRP Update, Ancillary Services are broken out as a line item in
the L&R. Response to Production Request No. l5 (b) states breaking out
Ancillary Services slightly increases both the obligation and the resources by an
equivalent amount. Please respond to the following:
(a) Please use an example to illustrate "[b]reaking out this category slightly
increases both the obligation and the nesources by an equivalent amount"
(b) If Ancillary Services is broken out from the Planning Reserve Margin, should
there be an adjustment to the Planning Reserve Margin? Please explain.
Response to IPUC Data Request 34
(a) As discussed in the Company's response to IPUC Data Request 33 subpart
(d), the planning reserve margin (PRM) achieved by the portfolio is based on
the minimum hourly resource availability in excess of load. In PacifiCorp's
2021Integrated Resource Plan (IRP), the sales of Ancillary Services were
treated as negative resources reducing the resource side ofthe equation, thus
resulting in lower remaining resource availability. This resource availability
represents the "achieved capacity" of the portfolio, and it was reported as a
slightly lower number, because it was reduced by the negative values for sales
of Ancillary Services. This is reflected in the allocation of capacity among a
large number of resources. Please refer to the simplified example below:
Load
(mesawatts (MW))113 113
Retail Load 100 100
Plannins Reserve Marsin (PRM)l3 l3
Resources (MW)113 113
Available Generation 133 r43
Wholesale Sales -20 -20
Requirements for Ancillary Services Not Applicable
Netted from Generation -10
(b) The referenced Ancillary Services are not part of the PRM, but rather are
closer to a type of Wholesale Sales as they are sales of ancillary services to
wholesale counterparties rather than energy. Ancillary Services do not have
entirely the same risks as load because the spinning and non-spinning reserve
obligation does not apply, as these Ancillary Services are not generation or
load (which incur the requirements), but rather the resulting requirements
themselves. Therefore, increasing these reserve requirements for the 3 percent
requirement associated with generation and/or load is not necessary or
appropriate. As a result, the 6 percent spinning and non-spinning reserve
PAC-E-22-14 / Rocky Mountain Power
December 19,2022
IPUC Data Request 34
obligation associated with load and generation to serve that load, which is
nearly half of the PRM, would not be applicable to Ancillary Services. The
Company provides some Ancillary Services for other wholesale transmission
customers' end-use loads, which could increase unexpectedly, and the
Company must have sufficient resources to cover these requirements, even in
bad hydro years or periods with higher than expected forced outages. Those
factors are also part of the PRM and would indicate that a portion of the
remaining PRM after subtracting 6 percent for spinning and non-spinning
reserve obligations could be applicable, however, the Company did not
attempt determine the specific level of stochastic risk associated with
Ancillary Services or to modiff the aggregate PRM requirement to account
for it. The 2021 IRP Update load and resource balance only included the
expected Ancillary Services obligation, so any additional resources to ensure
this obligation could be met under a range of possible conditions would result
in a larger resource need and a shorter system position, either a larger deficit
or smaller surplus. If the entirety of the 7 percent of the remaining PRM was
applied to the Sales and Ancillary Services line item inthe 2021 IRP Update,
it would represent approximately 33 megawatts (MW) of capacity need in
2023.
Recordholder:Dan MacNeil
Sponsor:Dan MacNeil