20171109PAC to Staff 3rd Suppl WY-17 OCA 1-3.pdf

ROCKY MOUNTAIN
POWER
A DIVISION OF PACIRCORP 1407 W North Temple,Suite 330
Salt Lake City,Utah 84116
October 23,2017
Christopher Leger,Counsel
Wyoming Bar #6-3963
Wyoming Office of Consumer Advocate
2515 Warren Avenue,Suite 304
Cheyenne,WY 82002
[e-mail] (C)
RE:Wyoming Docket 20000-520-EA-17
OCA 5th Set Data Request (5.01-5.03)
Please find enclosed Rocky Mountain Power's Responses to OCA 5th Set Data Requests 5.01-
5.03.Also provided is Attachment OCA 5.03.
If you have any questions,please call me at [phone].
Sincerely,
Stacy Splittstoesser,
Manager,Regulation
Enclosures
C.C.:Meridith Bell/WPSC In_eridjith._b_ell@wyon(C)
Lori L.Brand/WPSC lorij;ggi_d@wyo (W)
John Burbridge/WPSC (W)
Michelle Bohanan/WPSC [e-mail] (W)
Kara Seveland/WPSC [e-mail](W)
Morgan Fish/WPSC mgh_@Æo_.gov (W)
Dave Walker/WPSC d Mkg@wyogv (W)
Perry McCollom/WPSC [e-mail] (W)
Abigail C.Briggerman/WIEC [e-mail](C)
Patti Penn/WIEC [e-mail].m(W)
Bob Pomeroy/WIEC 12om_errofigholl idh_art.cama (W)
Thor Nelson/WIEC tue[s_on@holla_ndnart._c_oaa (W)
Emanuel Cocian/WIEC [e-mail] (W)
Nik Stoffel/WIEC [e-mail] (C)(W)
Crystal J.McDonough/NLRA (C)
Adele Lee/WIEC Blegkke art.conn (W)
Lisa Tormoen Hickey/[e-mail] (C)
20000-520-EA-17 /Rocky Mountain Power
October 23,2017
OCA Data Request 5.01
OCA Data Request 5.01
Please describe where in the work papers one can find,in detail,the net benefit to
customers that results from the new wind proposed by the Company in a stand alone
capacity.This information should describe what would the benefit of the new wind be if
the Company didn't have to build the transmission projects to interconnect the new
wind.Please provide any additional supporting analysis related to the answer to this
question.
Response to OCA Data Request 5.01
To clarify,the Aeolus-to-Bridger/Anticlinetransmission line is not being built because of
the new wind projects.Rather,the transmission line would provide reliability benefits
today and relieve existing transmission congestion.Currently,no new projects can
interconnect in Eastern Wyoming.In this case,the economic analysis identifies a time-
limited opportunity to construct the much-needed Aeolus-to-Bridger/Anticline
transmission project in a manner that delivers all-in customer benefits when combined
with the new wind projects.The new line enables interconnection of up to approximately
1,270 megawatts (MW)of new wind resources in the area.The transmission and wind
projects are mutuallydependent upon one another-the wind projects rely on the
transmission project for interconnection,and the transmission project is supported by the
economic benefits associated with the new wind resources.
Because it is not possible for the proposed wind projects to interconnect without the
proposed transmission line,the requested analysis has not been performed.
Respondent:Dan Swan
Witness:Rick Vail
20000-520-EA-17 /Rocky Mountain Power
October 23,2017
OCA Data Request 5.02
OCA Data Request 5.02
Please provide a detailed analysis showing a scenario where all costs and benefits are
held out of rates until the next general rate case.This scenario contemplates no revenue
tracking mechanism in any form.
Response to OCA Data Request 5.02
The Company has provided a detailed analysis of the costs and benefits of the Combined
Projects in the filing of the Direct Testimony of Company witness,Jeffrey K.Larsen and
the accompany Exhibit RMP (JKL-2)and Exhibit RMP_(JKL-3).These exhibits show
the costs and benefits without regard to any general rate case that may occur.These
exhibits also apply the ratemaking impact of the energy cost adjustment mechanism
(ECAM)on the incremental net power costs under current precedent.Line 23 of both
exhibits,"Revenue Requirement after ECAM Pass-through,"shows the net incremental
revenue requirement costs and benefits of the Combined Projects after application of the
ECAM but before applying the impacts of a general rate case or of the proposed RTM.
Respondent:Steve McDougal
Witness:Jeff Larsen
20000-520-EA-17 /Rocky Mountain Power
October 23,2017
OCA Data Request 5.03
OCA Data Request 5.03
Please provide a detailed analysis showing a with and without scenario on the proposed
new transmission impedance.This analysis should show and isolate the new
transmission's effect on line loss.
Response to OCA Data Request 5.03
Please refer to Attachment OCA 5.03 which provides the line impedance calculations and
related line loss analysis with and without the new D.2 segment.The followingprovides
a description of the methodology and considerations utilized.
Line Loss Calculation Overview
The addition of a transmission line in parallel with an existing line(s)or path will reduce
the impedance of the path,resulting in overall reduced energy line losses (megawatt-
hours (MWh)).The impedance of parallel transmission lines is determined by calculating
an equivalent resistance (R_equivalent)for the lines.Losses for any transmission line are
determined according to the formula I2R (where "I"is the current flow and "R"is line
resistance).Line losses before and after the addition of a new line are then compared,
with the difference being the line savings attributed to the new line.
EquivalentResistance of Parallel Lines
Using the Siemens PSS/E power flow program and a range of power flows for the
Wyoming area of study,line losses on various line segments were observed and recorded
(Attachment OCA 5.03,Tab 1).Using this information,an equivalent resistance
(R_equivalent)was calculated (see equations below)for the study area (Attachment
WIEC 7.2,Tab 2).The calculation was repeated with the new Aeolus-Bridger/Anticline
(D.2 Project)transmission segment.Additional information related to calculating
equivalent resistance is provided for reference below.
This analysis used hourlyhistorical (2015 and 2016)power flows for the three Wyoming
230 kilovolt (kV)lines that will be in parallel with the new D.2 Project were obtained.
The 230 kV lines and measurement points (*)utilized are as follows (Attachment OCA
5.03,tab 3,columns A-D):
(1)Standpipe*-Platte 230 kV
(2)Spence*-Mustang 230 kV
(3)Casper*-Riverton 230 kV
Line Loss Calculation
Utilizingthe formula indicated in equation "D"below (Line Losses =MW 2
R_equivalent),line losses for the existing 230 kV transmission system between eastern
Wyoming and Bridger were calculated (Attachment OCA 5.03,tab 3,columns E,G and
I).Line losses were then recalculated utilizing the same power flow with the new D.2
Project in-service (Attachment OCA 5.03,tab 3,columns F,H,and J).The difference
20000-520-EA-17 /Rocky Mountain Power
October 23,20 17
OCA Data Request 5.03
between the two calculations for each segment are the line loss savings directly
attributable to the new D.2 Project transmission line and total approximately 102
gigawatt-hours (GWh)each year,or 11.6 megawatt (MW)each hour of the year based on
historical power flow levels (Attachment OCA 5.03,tab 4).
Additional Re uivalent Information
To calculate current (I),megavolt amperes (MVA)x 1,000 divided by (square root (3)x
kV/1,000)is used.
(a)
I =MVA x 1,000 ÷ (93 x kV)
Since the predominant flow on PacifiCorp's transmission lines is real power (MW)rather
than reactive power,megavars (MVAr),the difference when calculating current is very
small between MW and MVA.Thus MW flow can be substituted for MVA in the loss
formula:Losses =I2R:
With substitution the equationbecomes:
(b)
Losses=(MW x1000)'xR
(§3 x kV)
Respondents:Craig Quist /Robyn Kara
Witness:Rick Vail