Microsoft Word - Generator Interconnection Study - 300 MW Solar at
Luna 345.docGENERATOR INTERCONNECTION
FEASIBILITY STUDY
August 2006
Generator Interconnection Feasibility Study i El Paso Electric
Company 300 MW Solar Photovoltaic Plant August 2006
TABLE OF CONTENTS 1.0 EXECUTIVE SUMMARY
...........................................................................Page
1 2.0
PURPOSE......................................................................................................Page
7 3.0 INTRODUCTION
.........................................................................................Page
8
3.1 Performance
Criteria................................................................................Page
9 3.1.1 Voltage Violation Criteria
..........................................................Page 10
3.1.2 Voltage Drop Violation
Criteria.................................................Page 11
3.1.3 PNM’s additions and exceptions to the NERC/WECC Criteria -
Voltages
......................................................................Page
11
3.1.4 Tri-State’s additions and exceptions to the NERC/WECC
Criteria - Voltages
......................................................................Page
11
3.1.5 Loading Violation Criteria
.........................................................Page 12
3.1.6 Reactive Margin (Q-V) Criteria
.................................................Page 12 3.1.7
Arroyo Phase Shifting Transformer (PST) Maximum Angle Requirement
...............................................................................Page
12 3.1.8 Criteria Violations
......................................................................Page
12 4.0 METHODOLOGY
........................................................................................Page
13 4.1
Assumptions..........................................................................................Page
13 4.2. Procedure
..............................................................................................Page
13 4.2.1 Base Case Development and Description of Cases without the
XXX Project: Benchmark Cases
................................................Page 13 4.2.2 Base
Case Development and Description with the XXX Project
Modeled..........................................................Page
16 4.2.3 Modeling of the XXX Project in the
Cases................................Page 17 4.2.4 Sensitivity
Cases with the XXX Project
Modeled......................................................................................Page
18 4.2.5 Powerflow Analysis
Methodology.............................................Page 18
4.2.6 List of
Contingencies..................................................................Page
19 4.2.7 Short Circuit Analysis
................................................................Page
20
Generator Interconnection Feasibility Study ii El Paso Electric
Company 300 MW Solar Photovoltaic Plant August 2006
5.0 POWERFLOW ANALYSIS RESULTS
.......................................................Page 21 5.1
All-Lines-in-Service (ALIS) Analysis Results for Overloaded
Elements Benchmark Cases (without the XXX Project)
......................Page 21
5.2 Single-Contingency (N-1) Analysis Results for Overloaded
Elements Benchmark Cases (without the XXX Project)
......................Page 21 5.3 Double-Contingency (N-2) Analysis
Results for Overloaded
Elements Benchmark Cases (without the XXX Project)
......................Page 22 5.4 All-Lines-in-Service (ALIS)
Analysis Results for Overloaded Elements in All Cases with the XXX
Project Modeled
................................................................................................Page
23 5.5 Single-Contingency (N-1) Analysis Results for
Overloaded
Elements in All Cases with the XXX Project Modeled……………..……………………….
.....................................Page 23
5.6 Sensitivity Case Modeling Only Two Diablo 345/115 kV
Autotransformers……..……………………….
...................................Page 24
5.7 Double-Contingency (N-2) Analysis Results for Overloaded
Elements in All Cases with the XXX Project Modeled……………..……………………….
.....................................Page 25
5.8 Non-Converging
Contingencies............................................................Page
26 5.9 Results of Voltage Violations
...............................................................Page
26 5.10 Sensitivity Involving No Third Party Generation Online (All
Third Party Generation Offline
...................................................Page 29 5.11
Sensitivity Involving New Alamogordo-Holloman 115 kV Line – Voltage
Effects...................................................................................Page
38 5.12 Arroyo PST Phase Angle Values
Analysis...........................................Page 41 6.0 Q-V
REACTIVE MARGIN ANALYSIS RESULTS
...................................Page 43 7.0 SHORT CIRCUIT
ANALYSIS.....................................................................Page
45 7.1 Short Circuit Analysis Modeling ……...………………..…………….Page 45
7.2 Results of the Short Circuit Analysis ………………..………………. Page 48
7.3 Short Circuit Analysis Conclusions ………….………..…………….. Page 53
8.0 COSTS ESTIMATES
....................................................................................Page
54 8.1 XXX Generator Interconnection Cost……...………………………….Page 55
8.2 SNM Facility Additions/Modifications Assumed to be in place
prior to the XXX Project ……………..……………… .. …..………………Page 56 8.3
System Upgrade Costs Due to the XXX project ……..……………….Page 57 8.4
Total Costs……………..………………..…………………..……….. Page 57 9.0 DISCLAIMER
...............................................................................................Page
58 10.0 CERTIFICATION
.........................................................................................Page
59
Generator Interconnection Feasibility Study iii El Paso Electric
Company 300 MW Solar Photovoltaic Plant August 2006
APPENDICES Generator Interconnection Feasibility Study: Study Scope
.................................Appendix 1 EPE‘s FERC Form 715
Filing
.............................................................................Appendix
2 Powerflow Maps – One-Line Diagrams
..............................................................Appendix
3 List of Contingencies
..........................................................................................Appendix
4 Base Case & Contingency Results Detailed Tables
...........................................Appendix 5 Base Case
& Contingency Results Detailed Tables – No Third Party
Generation Cases - Sensitivity
.............................................................................Appendix
6 Q-V Plots
.............................................................................................................Appendix
7
Generator Interconnection Feasibility Study 1 El Paso Electric
Company 300 MW Solar Photovoltaic Plant August 2006
1.0 EXECUTIVE SUMMARY In February 2006, XXXXXXXXXXXXXX (XXX) signed
an Interconnection Feasibility Study Agreement to study the
interconnection of a 300 MW Solar photovoltaic plant (the XXX
project) to the Luna 345 kV Switching Station in Deming, NM (“the
XXX Generator Interconnection”). El Paso Electric Company (EPE) has
performed this 300 MW Solar Photovoltaic Plant, Generator
Interconnection Feasibility Study for XXXXXXXXXXXXXXX (XXX)
pursuant to this study agreement. The purpose of this Feasibility
Study (FS) is to evaluate the feasibility of the proposed
interconnection to the New Mexico (NM) transmission system,
determine any violations of criteria due to the XXX project,
recommend facilities needed to accommodate the XXX project, and
provide associated non-binding good faith cost estimate for those
facilities and a non- binding good-faith construction timing
estimate. The XXX project was studied at two net MW output levels.
The cases modeled the net MW output from the XXX project as the
following: 180 MW and 300 MW for the years 2009 and 2011,
respectively, with the study period analyzed as the Heavy Summer
(HS) season. The output was scheduled to WECC. Each case was
studied using the criteria and methodologies described in
subsequent sections of this study report. The proposed
interconnection point, Luna 345 kV Substation, is jointly owned by
El Paso Electric Company (EPE), Public Service Company of New
Mexico (PNM), and Texas-New Mexico Power Company (TNMP). This Study
analyzed powerflow, Q-V reactive margin, and short circuit
analyses. Two (2) Western Electricity Coordinating Council (WECC)
GE format base case powerflow cases called the benchmark cases
(i.e. cases without the XXX project) were jointly developed by EPE
and PNM for this analysis. These benchmark cases reflect load
forecast, transmission configuration upgrades in southern New
Mexico (SNM) and northern New Mexico (NNM), and facilities
associated with each of the prior requestors’ interconnection
projects for the years 2009 and 2011. These cases represent the
“boundaries” in which the SNM and NNM system may operate with and
without the XXX project.
Generator Interconnection Feasibility Study 2 El Paso Electric
Company 300 MW Solar Photovoltaic Plant August 2006
These cases consist of the following, Case 1 and Case 2: 2009 HS
and 2011 benchmark cases consist of the base case with all third
party generation ahead of the XXX project in the study queue. The
third party generation included the following: a. 570 MW of
generation interconnected at the Luna 345 kV Substation (scheduled
to
WECC). b. 141 MW of generation interconnected at Afton 345 kV
Substation (scheduled
through the Arroyo Phase Shifting Transformer (PST) south-to-north
to PNM and reducing San Juan generation).
c. 160 MW of generation interconnected at TNMP’s Hidalgo 115 kV
substation (scheduled to WECC).
d. 80 MW of generation interconnected at TNMP’s Lordsburg 115 kV
substation (scheduled to WECC).
e. 94 MW of generation interconnected at Afton 345 kV Substation
(scheduled to WECC).
In addition to the third party generation above, the study assumes
that all EPE local generators are online, the schedule at the Eddy
County dc-tie in 200 MW east-to-west (133.3 MW for EPE, 66.7 MW to
TNMP), and that EPE’s Newman 5 generation is interconnected at the
Newman 115 kV bus. In the 2009 HS benchmark case (Case 1), this new
generator is modeled as a gas turbine generator with a net MW
output of 70 MW. In the 2011 HS benchmark case (Case 2), this new
generator is modeled as a gas turbine generator with a net MW
output of 123 MW and a steam turbine generator with a net MW output
of 90 MW (in a combined cycle arrangement). The additions and
modifications assumed to be associated with the above Newman 5
modeling are the following: 1. Add 2nd Arroyo 115/345 kV auto
transformer (modeled in the 2009 and 2011 HS
benchmark cases). 2. Add 3rd Caliente 115/345 kV auto transformer
(modeled in the 2009 and 2011 HS
benchmark cases). 3. Reconductor Newman-Shearman 115 kV line from
556.5 ACSR to 795 ACSR
conductor (modeled in the 2011 HS benchmark case). 4. Reconductor
Newman-FB2-GR-Vista 115 kV line from 556.5 ACSR to 795 ACSR
conductor (modeled in the 2011 HS benchmark case). 5. Add a 2nd
Milagro 115/69 kV autotransformer (modeled in the 2011 HS
benchmark
case).
Generator Interconnection Feasibility Study 3 El Paso Electric
Company 300 MW Solar Photovoltaic Plant August 2006
There were two additional system additions modeled in the benchmark
cases: 6. Reconductor Austin-Dyer 69 kV line from 4/0 CU to 556.5
ACSR conductor
(modeled in the 2011 HS benchmark case). 7. Add 3rd Diablo 115/345
kV auto transformer (modeled in the 2009 and 2011 HS
benchmark cases). Because Item 7 is not associated with the
additions and modifications assumed with Newman 5, the need for a
third Diablo 345/115 kV autotransformer was examined as a
sensitivity case. It was found that a third Diablo 345/115 kV
autotransformer is needed prior to the XXX project. The additions
and modifications above are needed prior to the XXX project modeled
as on in any case. Because these additions and modifications are
needed before the XXX project is modeled, these will be considered
an exception to the criteria, will not have a penalizing effect
when evaluating the XXX project, and the cost to correct them will
not be charged to the XXX project. All cases were evaluated with
the Arroyo PST in-service. All cases included 141 MW of generation
interconnected at Afton 345 kV Substation (scheduled through the
Arroyo PST south-to-north). Given that the Arroyo PST schedule is
usually 201 MW without Afton generation on, the cases modeled an
Arroyo PST schedule of 201 MW -141 MW = 60 MW north-to-south
reflecting PNM’s previous transmission purchase from Afton-to-
Westmesa. With the benchmark cases developed the XXX project was
added to the benchmark cases and two (2) additional WECC GE format
base case powerflow cases were developed in order to determine
which impacts resulted from this generator interconnection. The XXX
project was modeled in powerflow using data supplied by the XXX
consultant. Note that the cases with the XXX project are based on
the benchmark cases. As such, the facility additions and
modifications described in the previous section (items 1-7) appear
in the cases with the XXX project modeled. However, the costs of
these facility additions and modifications will be separated from
the costs of facilities due to the XXX project. Note that all cases
modeling the XXX project included the third party generation
described in Section 4.2.1.
These two cases with the XXX project modeled and with the Arroyo
PST in-service with a schedule of 60 MW north-to-south consist of
the following: Case 3: 2009 Heavy Summer (HS) benchmark case with
the XXX project modeled with the net output from the XXX project at
180 MW (as metered at Luna 345 kV). The output is scheduled to WECC
in the cases.
Generator Interconnection Feasibility Study 4 El Paso Electric
Company 300 MW Solar Photovoltaic Plant August 2006
Case 4: 2011 Heavy Summer (HS) benchmark case with the XXX project
modeled with the net output from the XXX project at 300 MW (as
metered at Luna 345 kV). The output is scheduled to WECC in the
cases. It should be noted that this Study was not meant to analyze
every scenario that could occur on the NM and AZ systems with the
XXX Project. The Study analyzed the primary boundaries around which
the NM and AZ systems may operate, under the scenarios agreed to by
EPE, XXX, and PNM. Utilizing engineering judgment, proposed system
modifications to correct the criteria violations found in the
analyses and estimated costs for those proposed modifications are
included in this Study. However, this feasibility study does not
include additional studies to validate the effectiveness of any
proposed remediations. Results of the powerflow analyses show that
various criteria violations occur on the existing AZ and NM systems
with the XXX project. Powerflow analysis results show that the
Green-AE 345/230 kV transformer owned by SWTC (Southwest
Transmission Cooperative, Inc) is overloaded during a single-
contingency of the PYoung-Winchester 345 kV line in the 2011 HS
case with the XXX project modeled. This overload is not present
prior to the addition of the XXX project. Therefore, for this
study, it will be assumed that adding a second Green-AE 345/230 kV
autotransformer will alleviate this overload that will be assigned
as a direct consequence of the XXX project for the net MW output
studied in the applicable study year identified in Section 5.5.
This is noted for this report. EPE did coordinate through XXX to
address the overloading of the Green-AE 345/230 kV under the above
N-1 condition. This overload will be examined in any follow up
study for the XXX project. The results in Section 5.11 indicate
that with the XXX project net MW of 300 MW at the Luna 345 kV bus),
the angle range of the Arroyo PST is affected. Specifically, with a
schedule of 201 MW N-S on the Arroyo PST an angle of – 33.07
degrees is required. This is near the angle range limit (of – 34
degrees at one end) of the Arroyo PST. There were also some voltage
violations caused by the XXX project. There were some undervoltage
voltage violations at PNM buses in SNM in which PNM has planned
system additions that would mitigate the low voltages caused by the
XXX project.
Generator Interconnection Feasibility Study 5 El Paso Electric
Company 300 MW Solar Photovoltaic Plant August 2006
Some post-XXX project post-contingency thermal violations were
observed on some SNM lines and transformers for some double
contingencies (see Table 7, Section 5.7). However, in this report,
it is assumed that the thermal violations during double
contingencies will be used to help identify which elements get
overloaded as a result of the XXX project. In this study, it will
be assumed that XXX will not be required to build, add or modify
elements showing a thermal violation for a double contingency (such
as the ones showing up in Table 7) as a result of the XXX project;
rather, these overload violations will help the owners of the these
facilities identify what procedures or new automatic or manual
operating procedures need to be in place as a result of the XXX
project. In order to study the XXX project further, there were some
cases developed in which cases 1-4 were examined without the third
party generation labeled a-e previously. The results of the
analysis on these cases revealed minor voltage violations caused by
the XXX project and no overloading violations as a result of the
XXX project. There are some future system additions in SNM that may
help with the voltage violations observed. Total Costs Due to the
XXX Project The total costs of the XXX project are the sum of the
interconnection costs plus the costs of the NM system modifications
to alleviate the impacts to the NM system because of the XXX
project. These total costs are shown on Table A.
Table A
of SNM Facility Additions/Modifications Needed due to the XXX
Project
SYSTEM MODIFICATION COSTS
ESTIMATED COST (2006$)
XXX Generator Interconnection costs to the Luna 345 kV Bus 2009 $
2,500,000 Total Costs to Interconnect the XXX Project $
2,500,000
Note that is the report, the costs associated with adding a second
Green-AE 345/230 kV transformer to relieve an overload caused by
the XXX project in 2011 were not included in the costs assigned to
the XXX project. Therefore, any equipment and related costs
associated with and including a second Green-AE 345/230 kV
transformer does not appear on Table A. However, this violation is
noted for this report and may be included as a cost in the next XXX
study.
Generator Interconnection Feasibility Study 6 El Paso Electric
Company 300 MW Solar Photovoltaic Plant August 2006
Note that a Static Var Compensator (SVC) device, described in
Section 4.2.3, is a critical component that was modeled in this
study as part of the XXX end of the XXX project and XXX costs. This
SVC must be in place as part of the XXX project prior to the
project’s interconnection. It was assumed that this SVC was
connected to the XXX 115 kV bus at the XXX substation. This + 130
MVAR SVC and associated equipment are estimated to cost $ 50,000-$
100,000/MVAR for a total of $6,500,000 to $ 13,000,000. As an
alternative to the SVC, if the inverters within the photovoltaic
system are proven to be capable of producing reactive load (VARs)
as designed, the SVC may be supplanted by inverters for the purpose
of supplying VARs to the grid. The inverters are designed to
produce 1 VAR for every 3-kW generated. Facilities determined to be
needed to accommodate the XXX project net output of 180 MW will be
required for 1 MW to 179 MW of net output from the XXX project.
Facilities determined to be needed to accommodate the XXX project
net output of 300 MW will be required for 181 MW to 299 MW of net
output from the XXX project.
Generator Interconnection Feasibility Study 7 El Paso Electric
Company 300 MW Solar Photovoltaic Plant August 2006
2.0 PURPOSE The purpose of this Feasibility Study (FS) is to
provide a fatal flaw feasibility analysis of the New Mexico (NM)
and Arizona (AZ) transmission systems, determine any violations of
criteria due to the XXX project described in the next section,
recommend facilities needed to accommodate the XXX project, and
provide associated non-binding good faith cost estimate for those
facilities. As such, this Study will to identify potential major
impacts associated with the XXX project.
Generator Interconnection Feasibility Study 8 El Paso Electric
Company 300 MW Solar Photovoltaic Plant August 2006
3.0 INTRODUCTION XXXXXXXXXXXXXXXXXX (XXX) has submitted a valid
request for a generator interconnection to the EPE system.
Therefore, as per the requirements of the Federal Energy Regulatory
Commission (FERC) Large Generator Interconnection Procedures
(LGIP), EPE is initiating a Feasibility Study (FS) to study the
interconnection of a 300 MW Solar photovoltaic plant (the XXX
project) to the Luna 345 kV Switching Station in Deming, NM (“the
XXX Generator Interconnection”). This FS was performed in response
to XXX’s request to determine any impacts on the New Mexico (NM)
and Arizona (AZ) systems including the El Paso Electric (EPE)
system due to the interconnection of the XXX project that was
studied at two net MW output levels. The cases modeled the net MW
output from the XXX project as the following: 180 MW and 300 MW for
the years 2009 and 2011, respectively. The output from the plant
was scheduled to WECC. The XXX project was connected through a
115/345 kV, 340/360 MVA step-up transformer. Each case was studied
using the criteria and methodologies described in subsequent
sections of this study report. The study was performed as a joint
analysis by EPE and Public Service Company of New Mexico (PNM).
EPE, XXX, and PNM developed a Study Scope for this study (Appendix
1). This scope included the examination of different Scenarios for
the XXX Generator Interconnection (see Base Case Development under
Methodology). The study periods analyzed in this study were the
2009 Heavy Summer (HS) and 2011 HS load seasons. EPE and PNM did
not analyze any other seasons with different import levels, load
levels, and/or generation patterns in this FS. This Study was
performed in order to identify potential major impacts associated
with the XXX Generator Interconnection, to provide a preliminary
view of the efforts, identify the facility additions and
modifications to the NM system that will mitigate those impacts
(remediations) that are a result of the XXX project for the
scenarios outlined in the Study Scope (Appendix 1), and to provide
good faith estimates of the costs that would be needed to achieve
the XXX project with a good-faith estimate of the construction
time. As part of the evaluation process in studying the impact of
the XXX generation on the NM and AZ transmission systems, this FS
included powerflow, Q-V reactive margin, and short circuit
analyses. The study results were evaluated using contingency
voltage and loading requirements and criteria under
All-Lines-in-Service (ALIS), single contingency (N-1) conditions,
double contingency (N-2) conditions, in addition to the reactive
margin criteria identified in the sections that follow. However,
this feasibility study does not include additional studies to
validate the effectiveness of any proposed remediations. The
impacts of the XXX project on the southern New Mexico (SNM) system
were noted and included for the purposes of remediations and
associated costs.
Generator Interconnection Feasibility Study 9 El Paso Electric
Company 300 MW Solar Photovoltaic Plant August 2006
The proposed interconnection point, Luna 345 kV Substation, is
jointly owned by EPE, PNM, and TNMP. However, any proposed
generation interconnection may affect any owner of the NM or AZ
systems. As such, the impacts on the owners of the SNM system were
focused on in this study. Besides EPE and PNM, the other owner of
the SNM system is Tri-State Generation and Transmission
Association, Inc. (TSGT). TNMP is owned by PNM. The criteria used
for the AZ and NM systems appear in Table 1. It must be noted that
this study was not meant to analyze every scenario that could occur
on the SNM system with the XXX project since that approach would
require more time. The study does not include transient stability
analysis, economic evaluations for the reinforcement alternatives,
detailed facility design, or equipment specification. This study
was meant to analyze the primary boundaries around which the SNM
system can operate, under the scenarios agreed to by EPE, XXX, and
PNM. The modifications called for will allow the XXX project to
interconnect to the NM system.
3.1 Performance Criteria This study shall adhere to the following
minimum criteria as described below or as referenced in specified
documents that are accessible through WECC.
1. The North American Electric Reliability Council (NERC)/WECC
Planning
Standards, December 2004. 2. WECC Reliability Criteria for
Transmission System Planning 3. WECC Voltage Stability Criteria,
Undervoltage Load Shedding Strategy, and
Reactive Power Reserve Monitoring Methodology. The reliability
criteria standards used in performing this study are readily
acceptable standards are listed in this report and in EPE’s latest
FERC Form 715 filing (Appendix 2). The XXX project in this analysis
will not decrease the performance level beyond what is stated as
acceptable in FERC Form 715. Any exception determined in the
benchmark case, however, will not have a penalizing effect when
evaluating the XXX project. This analysis was performed using the
GE PSLF program. Pre-contingency flows on lines and transformers
must remain at or below the normal rating of the element, and
post-contingency flows on network elements must remain at or below
the emergency rating. Flows above 100% of an element’s rating are
considered violations. If only one rating was given for an element,
it was used as both the normal and emergency rating. The minimum
and maximum voltages are specified in the appropriate FERC Form
715. Any voltage that does not meet criteria in the benchmark cases
(without the XXX project) was considered an exception to the
criteria for that specific bus and did not have a penalizing effect
when evaluating the XXX project.
Generator Interconnection Feasibility Study 10 El Paso Electric
Company 300 MW Solar Photovoltaic Plant August 2006
The performance criteria utilized in monitoring the SNM and
northern New Mexico (NNM) area are shown in Table 1.
Table 1: Performance Criteria.
0.95 - 1.05 69kV and above 0.95 - 1.10 Artesia 345 kV
0.95 - 1.08 Arroyo 345 kV PS source side Normal < Normal
Rating
0.90 - 1.05 Alamo, Farmer, Rgc Lobo,
Sierra Blanca and Van Horn 69kV
0.925 - 1.05 60 kV to 115 kV 0.95 - 1.10 7 % Artesia 345kV
0.95 - 1.08 7 % Arroyo 345kV PS source side
0.90 - 1.05 Alamo, Farmer, Rgc Lobo,
Sierra Blanca and Van Horn 69kV
EPE
0.95 - 1.05 7 % Hidalgo, Luna, or other 345 kV buses
Normal < Normal Rating 0.95 - 1.05 60kV and above LOS ALAMOS
Contingency < Emergency
Rating 6% 60kV and above
Normal < Normal Rating 0.95 - 1.05 60kV and above TSGT
Contingency < Emergency
Rating 0.90 - 1.10 60kV and above
Normal < Normal Rating 0.95 - 1.05 60kV and above
6 % 60kV and above PNM Contingency < Emergency
Rating 7 % Luna, Mimbres, Hermanas,
Hondale, and Deming 115kV
Normal < Normal Rating 0.95 - 1.05 60kV and above TNMP
Contingency < Emergency
Rating 0.925 - 1.05 6 % 60kV and above
Normal < Normal Rating 0.95 - 1.05 100kV and above AZ
Contingency < Emergency
Rating 0.925 - 1.05 5 % 100kV and above
3.1.1 Voltage Violation Criteria The voltage criteria used in this
study is shown in Table 1. All voltages 69 kV or above in cases
with ALIS must have per unit voltages between 0.95 and 1.05 pu.
Under contingency conditions, voltage drops cannot exceed the
voltage drop criteria. For all cases during contingencies the per
unit voltages cannot exceed 1.05 pu.
Generator Interconnection Feasibility Study 11 El Paso Electric
Company 300 MW Solar Photovoltaic Plant August 2006
3.1.2 Voltage Drop Violation Criteria The voltage drop criteria
used in this study is shown in Table 1. It should be noted that the
voltage drop criteria is specified as a percentage of the pre-
contingency voltage. For example, if the pre-contingency voltage at
the Luna 345kV bus is 1.030 pu, and the voltage drops to 0.9579 pu
during the contingency, the voltage drop would be 7%, calculated
as:
dv = (Vpre-Vpost) / Vpre = (1.030 – 0.9579) / 1.030 = 0.0721/1.030
= 7.0% Bus voltage drop (i.e. changes in bus voltages from pre- to
post-contingency) must be less than defined on Table 1 for single
contingencies and less than 10% for double contingencies. 3.1.3
PNM’s additions and exceptions to the NERC/WECC criteria -
Voltages
• For voltage levels above 1 kV, the minimum and maximum range is
0.95 p.u. and 1.05 p.u., respectively for N-1 contingencies. For
N-2 and breaker failures the minimum voltage level is 0.90 p.u. The
46 kV system voltages are not monitored since the distribution
primary voltages are monitored.
• Changes in bus voltages from pre- to post-contingency must be
less than 6% with the exception of the Deming area, which is held
to the southern New Mexico criterion of 7% voltage drop for N-1
outages. PNM allows no greater than a 10% voltage drop for N-2 and
breaker failures outages.
3.1.4 TSGT’s additions and exceptions to the NERC/WECC criteria -
Voltages
• All voltages will be maintained between 0.95 and 1.05 pu for all
lines in service. • All voltages will be maintained between 0.90
and 1.10 pu for outage conditions.
• Changes in bus voltages from pre- to post-contingency must be no
greater than
6% for Tri-State buses served from the PNM system for N-1
contingencies and no greater than 10% for N-2 contingencies.
• For TSGT buses served from the TSGT system, changes in bus
voltages from pre-
to post-contingency must be no greater than 8% for N-1
contingencies and no greater than 10% for N-2 contingencies.
Generator Interconnection Feasibility Study 12 El Paso Electric
Company 300 MW Solar Photovoltaic Plant August 2006
3.1.5 Loading Violation Criteria The loading criteria used in this
Study were the WECC loading criteria. An element (transmission
line, transformer) cannot be loaded to over 100% of its
continuous/normal rating for an ALIS condition. During single or
double contingency conditions, the element many not exceed 100 % of
its emergency rating. All violations will be monitored and noted
for the benchmark case (without the XXX project). Any flow which
does not meet the criteria in that case will be considered an
exception to the criteria for that specific element and will not
have a penalizing effect when evaluating the XXX project. For
elements outside of the EPE system, the loading criteria will be
100% of the capacity as listed in the powerflow basecase data.
3.1.6 Reactive Margin (Q-V) Criteria The load increase methodology,
for determining reactive margins, outlined in the WECC “Voltage
Stability Criteria, Undervoltage Load Shedding Strategy, and
Reactive Power Reserve Monitoring Methodology” report was used to
determine as the basis for the reactive margin criteria in this
study. Using this methodology, EPE load was increased by 5% and the
worst contingency was analyzed to determine the reactive margin on
the system. The margin is determined by identifying the critical
(weakest) bus on the system during the worst contingency. The
critical bus is the most reactive deficient bus. Q-V curves are
developed and the minimum point on the curve is defined as the
critical point for this study. If the critical point of the Q-V
curve is positive, the system is reactive power deficient. If it is
negative, then the system has sufficient reactive power margin and
meets the WECC criteria. For reactive capability analysis, only N-1
analysis was performed. 3.1.7 Arroyo Phase Shifting Transformer
(PST) Maximum Angle Requirement The Arroyo PST maximum angle range
shall not be exceeded in any case with the XXX project. 3.1.8
Criteria Violations Criteria violations will be identified and
summarized in tabular form. All comparisons will be made on a
relative performance basis (e.g. the change in line loading from
the benchmark system cases to that those cases modeling the XXX
project, stated in terms of percent of line rating) as well as an
absolute basis (i.e., the percentage of overload or outside of
voltage criteria). Results will be presented to show which, if any,
thermal or voltage violations are caused or significantly
exacerbated by the XXX project.
Generator Interconnection Feasibility Study 13 El Paso Electric
Company 300 MW Solar Photovoltaic Plant August 2006
4.0 METHODOLOGY
4.1 Assumptions The following assumptions are consistent for all
study scenarios unless otherwise noted. • Project dollar amounts
shown are in 2006 U.S. dollars. The cost of the XXX
Generator and associated equipment is separate and not included in
this study. • This study assumes that substation space is available
for the system recommended
modifications or will note assumptions taken in this regard. • The
cost estimates provided here include material, labor, and overhead
costs for
installing new equipment. There was no accounting for using spare
equipment but it should strongly be considered.
• The practicality of the solutions and space limitations at each
substation was of secondary concern in this study but should be
examined in any further studies.
4.2 Procedure As previously mentioned, the analyses in this study
include powerflow, Q-V, and short circuit analyses. Detailed
discussions for each topic have been included in this report (for
quick reference of any topic, refer to the Table of Contents). The
following is a description of the procedures used to complete the
analyses. 4.2.1 Base Case Development and Description of Cases
without the XXX Project:
Benchmark Cases Two (2) WECC GE format base case powerflow cases
called the benchmark cases (i.e. cases without the XXX project)
were jointly developed by EPE and PNM for this analysis. These
benchmark cases reflect load forecast, transmission configuration
upgrades in SNM and NNM, and facilities associated with each of the
prior requestors’ interconnection projects for the years 2009 and
2011. Previous studies have shown that the summer season is most
limiting for the SNM transmission system; as such, the study cases
will be based on the latest WECC Heavy Summer cases for each of
these years. These cases represent the “boundaries” in which the
SNM and NNM system may operate with and without the XXX
project.
Generator Interconnection Feasibility Study 14 El Paso Electric
Company 300 MW Solar Photovoltaic Plant August 2006
These cases consist of the following, Case 1 and Case 2: 2009 HS
and 2011 benchmark cases consist of the base case with all third
party generation ahead of the XXX project in the study queue. The
third party generation included the following: a. 570 MW of
generation interconnected at the Luna 345 kV Substation (scheduled
to
WECC). b. 141 MW of generation interconnected at Afton 345 kV
Substation (scheduled
through the Arroyo Phase Shifting Transformer (PST) south-to-north
to PNM and reducing San Juan generation).
c. 160 MW of generation interconnected at TNMP’s Hidalgo 115 kV
substation (scheduled to WECC).
d. 80 MW of generation interconnected at TNMP’s Lordsburg 115 kV
substation (scheduled to WECC).
e. 94 MW of generation interconnected at Afton 345 kV Substation
(scheduled to WECC).
In addition to the third party generation above, the study assumes
that all EPE local generators are online, the schedule at the Eddy
County dc-tie in 200 MW east-to-west (133.3 MW for EPE, 66.7 MW to
TNMP), and that EPE’s Newman 5 generation is interconnected at the
Newman 115 kV bus. . In the 2009 HS benchmark case (Case 1), this
new generator is modeled as a gas turbine generator with a net MW
output of 70 MW. In the 2011 HS benchmark case (Case 2), this new
generator is modeled as a gas turbine generator with a net MW
output of 123 MW and a steam turbine generator with a net MW output
of 90 MW (in a combined cycle arrangement). The additions and
modifications assumed to be associated with the above Newman 5
modeling are the following: 1. Add 2nd Arroyo 115/345 kV auto
transformer (modeled in the 2009 and 2011 HS
benchmark cases). 2. Add 3rd Caliente 115/345 kV auto transformer
(modeled in the 2009 and 2011 HS
benchmark cases). 3. Reconductor Newman-Shearman 115 kV line from
556.5 ACSR to 795 ACSR
conductor (modeled in the 2011 HS benchmark case). 4. Reconductor
Newman-FB2-GR-Vista 115 kV line from 556.5 ACSR to 795 ACSR
conductor (modeled in the 2011 HS benchmark case). 5. Add a 2nd
Milagro 115/69 kV autotransformer (modeled in the 2011 HS
benchmark
case). There were two additional system additions modeled in the
benchmark cases:
Generator Interconnection Feasibility Study 15 El Paso Electric
Company 300 MW Solar Photovoltaic Plant August 2006
6. Reconductor Austin-Dyer 69 kV line from 4/0 CU to 556.5 ACSR
conductor (modeled in the 2011 HS benchmark case).
7. Add 3rd Diablo 115/345 kV auto transformer (modeled in the 2009
and 2011 HS benchmark cases).
Because Item 7 is not associated with the additions and
modifications assumed with Newman 5, the need for a third Diablo
345/115 kV autotransformer was examined as a sensitivity case in
Section 5.6. The additions and modifications above are needed prior
to the XXX project modeled as on in any case. Because these
additions and modifications are needed before the XXX project is
modeled, these will be considered an exception to the criteria,
will not have a penalizing effect when evaluating the XXX project,
and the cost to correct them will not be charged to the XXX
project. All cases were evaluated with the Arroyo PST in-service.
All cases included 141 MW of generation interconnected at Afton 345
kV Substation (scheduled through the Arroyo PST south-to-north).
Given that the Arroyo PST schedule is usually 201 MW without Afton
generation on, the cases modeled an Arroyo PST schedule of 201 MW
-141 MW = 60 MW north-to-south reflecting PNM’s previous
transmission purchase from Afton-to- Westmesa (see Table 2, next,
for schedule details).
Table 2. Arroyo PST Schedule*
SCHEDULING
ENTITY
ARROYO) ARROYO PST SCHEDULE
ARROYO) ARROYO PST SCHEDULE
EPE (OATT) -104 -104 EPE (SSI) -20 -20 TSGT -50 -50 PNM -25 -25 PNM
(AFTON GENERATION THROUGH ARROYO PST TO PNM)
+141 0
* Negative denotes Westmesa to Arroyo schedule. Positive denotes
Arroyo to Westmesa schedule.
The Arroyo PST angle setting in each case is included in this
report in Section 5.12 in order to document that Arroyo PST maximum
angle criteria was not exceeded.
Generator Interconnection Feasibility Study 16 El Paso Electric
Company 300 MW Solar Photovoltaic Plant August 2006
4.2.2 Base Case Development and Description of Cases with the XXX
Project Modeled
With the benchmark cases developed the XXX project was added to the
benchmark cases and two (2) additional WECC GE format base case
powerflow cases were developed in order to determine which impacts
resulted from this generator interconnection. The XXX project was
modeled in powerflow using data supplied by the XXX consultant.
Note that the cases with the XXX project are based on the benchmark
cases. As such, the facility additions and modifications described
in the previous section (items 1-7) appear in the cases with the
XXX project modeled. However, the costs of these facility additions
and modifications will be separated from the costs of facilities
due to the XXX project. Note that all cases modeling the XXX
project included the third party generation described in Section
4.2.1.
These two cases with the XXX project modeled and with the Arroyo
PST in-service with a schedule of 60 MW north-to-south consist of
the following: Case 3: 2009 Heavy Summer (HS) benchmark case with
the XXX project modeled with the net output from the XXX project at
180 MW (as metered at Luna 345 kV). The output is scheduled to WECC
in the cases. Case 4: 2011 Heavy Summer (HS) benchmark case with
the XXX project modeled with the net output from the XXX project at
300 MW (as metered at Luna 345 kV). The output is scheduled to WECC
in the cases.
Generator Interconnection Feasibility Study 17 El Paso Electric
Company 300 MW Solar Photovoltaic Plant August 2006
4.2.3 Modeling of the XXX Project in the Cases The XXX model was
further refined and the model was agreed to by EPE, XXX, and PNM.
According to the Study Scope the Project was to provide for real
and reactive power losses up to the point of interconnection to 345
kV grid. This was interpreted to mean that for ALIS, the powerflow
model for the XXX project would output the net MW amounts described
next for their respective year and zero MVAR at the Luna 345 kV
bus). In addition, the ability of the XXX project to have the
capability to achieve the delivery of 97.8 % power factor
requirement to the system (during outages) was placed on the XXX
project powerflow model. This requirement was agreed to by EPE and
XXX in a Scoping Meeting for the XXX generator Interconnection that
took place in late February 2006. During this meeting, it was felt
that the XXX project should have no impact on the SNM and NNM
systems and the way to achieve this was to place a power factor
requirement on the XXX project so that it can contribute MVAR to
the system. A Static VAR Compensator (SVC) was modeled at the
original XXX plant. The size of the SVC was determined by
calculating the MVAR component from the 300 MW net output in order
to achieve a 97.8 % power factor (64 MVAR) and adding the MVAR
requirement when the XXX output was 300 MW to achieve 0 MVAR at the
Luna 345 kV bus (66 MVAR, from the powerflow under ALIS). This
resulted in a SVC size of 130 MVAR lagging (64 MVAR + 66 MVAR) and
with a minimum reactive capability limit of 0 MVAR (based on
preliminary study work). The model provided by XXX included
modeling of loads at the XXX plant. To provide for the XXX loads
and losses from the XXX 115 kV bus to the Luna 345 kV bus, the
output of the XXX project was set to a gross MW output consisting
of the net MW output needed at the Luna 345 kV bus plus auxiliary
loads plus any other losses occurring between the XXX 115 kV bus
and the Luna 345 kV bus such that the net MW output at the Luna 345
kV bus from the XXX project was 180 MW and 300 MW for the years
2009 and 2011, respectively. The complete model for the XXX project
consisted of a generator connected to a XXX 115 kV bus with a gross
output of 198.8 MW and 21.1 MVAR in the 2009 case and with a gross
output of 332.3 MW and 66 MVAR in the 2011 case. The generator had
a QMAX limit of 135 MVAR reflecting the SVC previously described.
The XXX plant loads were modeled on the XXX 115 kV bus as 18.5 MW
and 7.3 MVAR in 2009 and 31.5 MW and 20.9 MVAR in 2011. The
generator and the loads were connected through a 115/345 kV step-up
transformer with a normal rating of 340 MVA and emergency rating of
360 MVA. From here the XXX 345 kV bus was connected to the Luna 345
kV interconnection point through a short line (this line is called
the Luna-XXX 345 kV line in this study). Appendix B of the Study
Scope (Appendix 1) contains preliminary data supplied by XXX. The
SVC device described above and its cost will be discussed in
Section 8.1, as it is a critical component of the XXX
project.
Generator Interconnection Feasibility Study 18 El Paso Electric
Company 300 MW Solar Photovoltaic Plant August 2006
4.2.4 Sensitivity Cases with XXX Project Modeled There were other
cases (sensitivity cases) developed as part of this study in order
to examine other system conditions that merit study and also in
order to perform an analysis of the reactive margin at selected
buses for a set of system conditions. Because there was a need to
examine the addition of a third 345/115 kV autotransformer at EPE’s
Diablo Substation (as assumed in the 2009 and 2011 cases used in
this study, see Section 4.2.1), there was a sensitivity case
examined in which this third autotransformer is not in the case.
The results of this sensitivity are covered in Section 5.6. Another
set of sensitivity cases had the Arroyo PST angle setting in each
case at different Arroyo PST schedules and is included in this
report in Section 5.12 in order to document that Arroyo PST maximum
angle criteria was not exceeded. Also examined, is a sensitivity in
which all third party generation specified in Section 4.2.1 is
turned off and the effects of the XXX project are examined. This
sensitivity was examined with two Diablo 345/115 kV
autotransformers modeled. This analysis is included in Section
5.10. 4.2.5 Powerflow Analysis Methodology A relative approach was
used in the powerflow analysis in order to determine the impact of
the XXX project on the performance of the SNM transmission system.
First, performance of the benchmark system, without the XXX
project, was evaluated in order to establish the baseline. The
cases without the XXX project were evaluated with all-
lines-in-service (ALIS) for both loading and voltage criteria
violations. Next, single and double contingency powerflow analysis
was performed on these benchmark cases by taking single and double
contingencies on most lines and transformers with base voltages of
100 kV and above in the SNM area and 69 kV and above in the EPE
area as determined by engineering judgment (see Section 4.2.6). All
bus, lines, and transformers with base voltages greater than or
equal to 60 kV in the New Mexico area including the EPE control
area were monitored in all study cases. All generators were modeled
with regard to self-regulating or remote bus regulating as they are
modeled in the submitted WECC GE format powerflow data. All
generators which control a high side remote bus will be set at the
pre-disturbance voltage at the terminal bus. The single and double
contingencies were taken one at a time. When modeling a single or
double contingency involving an autotransformer or line that is
connected to the Luna 345 kV bus (e.g. any 345 kV line connected to
the Luna 345 kV bus: Springerville-Luna, Luna-Arroyo, Luna-
Hidalgo, Luna-Newman, and/or the Luna 345/115 kV autotransformer),
the XXX unit was modeled in two separate ways: 1) as tripped,
outage takes out the XXX project simultaneously, and 2) as not
tripped, outage does not take out the XXX project. Engineering
judgment was used to determine if the XXX project unit was also
tripped for a single or double contingency involving any other
element(s) in the system.
Generator Interconnection Feasibility Study 19 El Paso Electric
Company 300 MW Solar Photovoltaic Plant August 2006
For pre-contingency solutions, transformer tap phase-shifting
transformer angle movement and static VAR device switching was
allowed, as was tap changing under load (TCUL) tap changing ratio
adjustment and area interchange control. For each contingency
studied, the contingency was studied with all regulating equipment
being fixed at pre-contingency positions (transformer controls and
switched shunts). This was achieved by setting all solve options to
zero (up to 50 solution iterations were allowed with 3 iterations
before VAR limits). For the cases with the XXX project included,
the performance analysis, described for the benchmark cases, was
repeated. Next, for the sensitivity cases (with the XXX project
included) the analysis procedure described in the section covering
each sensitivity was used. The results for the cases with the XXX
project were evaluated against the baseline to determine criteria
violations in the NM systems that resulted from the XXX project.
4.2.6 List of Contingencies The same contingencies were evaluated
for all cases and are identified in Appendix 4. Note that the list
contains both single (N-1) and double (N-2) contingencies. Most of
the double contingencies were breaker failure contingencies. For
these breaker failure contingencies, if a power circuit breaker at
a substation fails to open during a fault, secondary zone relay
protection and breaker operation comes into play taking out the two
transmission elements on each side of the failing (stuck) circuit
breaker so as to remove the fault from the bus affected. Based on
engineering judgment, all contingencies taken were selected because
they are the ones most likely to stress the SNM system. After an
additional evaluation of the Arizona system representation, there
were some single-contingencies involving lines in southeastern
Arizona added to the analysis. These are included in Appendix 4.
There were three single contingencies involving PNM/TNMP 115 kV
lines in SNM executed as part of the study that required the
modeling of an automatic operating procedure called a remedial
action scheme (RAS) that is used to relieve certain voltage and/or
overloading that may occur on elements affected by the specific
single contingency. In this study the following RAS procedures were
assumed. 1. For the outage of the Hidalgo-Lordsburg 115 kV line
with the Lordsburg generation
operating, the Lordsburg 115/69 kV transformer is tripped when the
transformer loading is greater than 33.5 MVA.
2. For the outage of the Hidalgo-Turquoise 115 kV line, the
industrial load at Turquoise
is tripped. This involves tripping the Turquoise-PDTyrone 115 kV
line.
Generator Interconnection Feasibility Study 20 El Paso Electric
Company 300 MW Solar Photovoltaic Plant August 2006
3. For the N-2 (breaker failure or otherwise) outage of the
Central-Hurley-Luna 115 kV line and the Central-Turquoise 115 kV
line, the industrial load served from Central 115 kV along with the
shunt capacitor at Central 115 kV will be tripped. This involves
tripping the Hurley-Chino and Central-Ivanhoe 115 kV lines and the
Central 115 kV capacitor.
4.2.7 Short Circuit Analysis Short circuit studies were performed
with and without the XXX project. These consisted of substation
three phase and single phase-to-ground bus fault simulations at the
Luna 345 and 115 kV Substations as well as those substations with
direct 345 kV or 115 kV transmission line connections into it. The
objective was to make certain that the existing substation breakers
would safely accommodate fault currents for either scenario. The
analysis identified all breakers whose ratings were exceeded. The
short circuit analysis results are covered in Section 7.
Generator Interconnection Feasibility Study 21 El Paso Electric
Company 300 MW Solar Photovoltaic Plant August 2006
5.0 POWERFLOW ANALYSIS RESULTS 5.1 All-Lines-in-Service (ALIS)
Analysis Results for Overloaded Elements
Benchmark Cases (without the XXX Project) Each of the cases with
system benchmark conditions (without the XXX project) as described
in Section 4.2.1 was examined with all lines in service (ALIS).
Table 3 shows the base case overloads present in the cases without
the XXX project.
Table 3. Pre-Contingency Thermal Violations, Benchmark
Conditions
Element Case Owner Rating(MVA) % Loading
Blythe-Buckblvd 161 kV Line 2011 HS AZ 400 120.6 Blk Mesa 230
kV/BMA.3WP3 100 kV Transformer 2011 HS AZ 40 116.8 Blk Mesa 230
kV/BMA.4WP3 100 kV Transformer 2011 HS AZ 40 111.5
Cholla 345 kV/ Cholla 7 100 kV Transformer 2011 HS AZ 203 102.7
Cholla 230 kV/ Cholla 7 100 kV Transformer 2011 HS AZ 203
101.6
N.Havasu 230 kV/N.HAV3WP 100 kV Transformer 2011 HS AZ 80 100.1
Tucson 138 kV/TUC.3WP 100 kV Transformer 2011 HS AZ 100 100.1
Blythe-Buckblvd 161 kV Line 2011 HS AZ 440 109.6 Blk Mesa 230
kV/BMA.3WP3 100 kV Transformer 2011 HS AZ 44.8 104.3
Table 3 shows the overloaded element, element owner, and element
rating and the benchmark case in which the thermal overload
occurred. The percent loading on the element, based on the element
rating, is indicated in the rightmost column and includes the range
of overloading without the XXX project. There were some Arizona
elements loaded above their normal and/or emergency rating. These
overloads included one line and five transformers. Since the
violations listed in Table 3 were found to occur in the case before
the XXX project was modeled, they will be considered an exception
to the criteria, will not have a penalizing effect when evaluating
the XXX project, and the cost to correct them will not be charged
to the XXX project. 5.2 Single-Contingency (N-1) Analysis Results
for Overloaded Elements
Benchmark Cases (without the XXX Project) The benchmark cases as
described in Section 4.2.1 were examined under single contingency
conditions. Table 4 shows the base case post-contingency overloaded
SNM elements present in the cases without the XXX project under N-1
conditions. If an element (line or transformer) was overloaded
under pre-contingency (ALIS) conditions, it was considered a
pre-contingency overload and was not included in Table 4.
Generator Interconnection Feasibility Study 22 El Paso Electric
Company 300 MW Solar Photovoltaic Plant August 2006
Table 4 shows the overloaded element and element rating. The
percent loading range on the element, based on the element rating,
is listed next, and the contingency condition is indicated in the
rightmost column.
Table 4. Post-Contingency (N-1) Thermal Violations, Benchmark
Cases, SNM Elements
Element Case Owner Rating (MVA) % Loading Contingency
Description
Lordsbrg 115/69 Kv Transformer 2009 HS PNM/ TNMP 27.0 111.0
Hidalgo-Turquoise 115 kV
Line (RAS)
Lordsbrg 115/69 Kv Transformer 2011 HS PNM/ TNMP 27.0 107.2
Hidalgo-Turquoise 115 kV
Line (RAS)
Central-Silver 69 kV Line 2011 HS PNM/TN MP 27.0 102.0 Turquois
115/69 kV
Transformer
Leo-Milagro 69 kV Line 2009 HS EPE 69.4 121.4 Milagro-Newman 115 kV
Line
As shown in Table 4, some pre-XXX project post-contingency thermal
violations were observed on some SNM lines and transformers. These
contingency criteria violations listed in Table 4 will not have a
penalizing effect on the evaluation of the XXX project. 5.3
Double-Contingency (N-2) Analysis Results for Overloaded
Elements
Benchmark Cases (without the XXX Project) The benchmark cases as
described in Section 4.2.1 were examined under double contingency
conditions. Table 5 shows the base case post-contingency overloaded
SNM elements present in the cases without the XXX project under N-2
conditions. If an element (line or transformer) was overloaded
under pre-contingency (ALIS) conditions, it was considered a
pre-contingency overload and was not included in Table 5. Table 5
shows the overloaded element and element rating. The percent
loading range on the element, based on the element rating, is
listed next, and the contingency condition is indicated in the
rightmost column. As shown in Table 5, some pre-XXX project
post-contingency thermal violations were observed on some SNM lines
and transformers. These contingency criteria violations listed in
Table 5 will not have a penalizing effect on the evaluation of the
XXX project. EPE did coordinate through XXX to make arrangements
with AZ for the study of the overloading of these elements under
the above N-1 conditions to verify if these elements are
overloaded. These overloads will be examined in any follow up study
for the XXX project.
Generator Interconnection Feasibility Study 23 El Paso Electric
Company 300 MW Solar Photovoltaic Plant August 2006
Table 5. Post-Contingency (N-2) Thermal Violations, Benchmark
Cases, SNM Elements
Element Case Owner Rating (MVA) % Loading Contingency
Description
Lordsbrg 115/69 Kv Transformer 2009 HS PNM/ TNMP 27.0 120.5 Hidalgo
345/115 kV T1
& T3 Transformers
Lordsbrg 115/69 Kv Transformer 2011 HS PNM/ TNMP 27.0 121.4 Hidalgo
345/115 kV T1
& T3 Transformers
Hidalgo-Turquoise 115 kV Line 2009 HS PNM/ TNMP 153.0 131.4 Hidalgo
345/115 kV T1
& T3 Transformers
Hidalgo-Turquoise 115 kV Line 2011 HS PNM/ TNMP 153.0 133.8 Hidalgo
345/115 kV T1
& T3 Transformers
Hidalgo-Turquoise 115 kV Line 2009 HS PNM/ TNMP 153.0 100.9
Luna-Afton 345 kV Line & Luna 345/115 kV
Transformer
Hidalgo-Turquoise 115 kV Line 2011 HS PNM/ TNMP 153.0 100.4
Luna-Afton 345 kV Line & Luna 345/115 kV
Transformer
Central- Turquoise 115 kV Line 2011 HS PNM/ TNMP 133.4 112.2
Hidalgo 345/115 kV T1
& T3 Autotransformers
Central- Turquoise 115 kV Line 2009 HS EPE 133.4 110.6 Hidalgo
345/115 kV T1 & T3 Transformers
Mesa-Rio Grande 115 kV Line 2009 HS EPE 195.6 100.5 Newman-Afton
&
Caliente-Newman 345 kV Lines
Reducing generation at Lordsburg and Pyramid should mitigate the
overloads shown in Table 5 for the Hidalgo 345/115 kV T1 and T3
autotransformers outage. Reducing generation at Lordsburg and
Pyramid should also mitigate the overloads shown in Table 5 for the
Luna-Afton 345 kV line and Luna 345/115 kV transformer outage. 5.4
All-Lines-in-Service (ALIS) Analysis Results for Overloaded
Elements in All
Cases with the XXX Project Modeled There were no SNM elements
overloaded with the XXX project modeled that were not already
overloaded in the benchmark cases (without the XXX project) with
ALIS. 5.5 Single-Contingency (N-1) Analysis Results for Overloaded
Elements in All
Cases with the XXX Project Modeled Each of the cases with the XXX
project, as described in Section 4.2.2 was examined under single
contingency conditions. Table 6 shows the post-contingency
overloaded SNM elements present in the cases with the XXX project
modeled under N-1 conditions. If an element (line or transformer)
was overloaded under ALIS conditions or post- contingency
conditions in the cases modeling the same conditions without the
XXX project, the element was considered overloaded and not
attributable to the XXX project and was not included in Table
6.
Generator Interconnection Feasibility Study 24 El Paso Electric
Company 300 MW Solar Photovoltaic Plant August 2006
Table 6. Post-Contingency (N-1) Thermal Violations, Cases with the
XXX Project Modeled, SNM Elements
Element Case Owner Rating (MVA) % Loading Contingency
Description
Green-AE 345/230 Transformer 2011 HS ARIZONA SWTC 193 103.1
PYoung-Winchester 345 kV
Line As shown in Table 6, the Green-AE 345/230 kV transformer owned
by SWTC (Southwest Transmission Cooperative, Inc) is overloaded
during a single-contingency of the PYoung-Winchester 345 kV line in
the 2011 HS case with the XXX project modeled. This overload is not
present prior to the addition of the XXX project. Therefore, for
this study, it will be assumed that adding a second Green-AE
345/230 kV autotransformer will alleviate this overload that will
be assigned as a direct consequence of the XXX project for the net
MW output studied in the applicable study year identified on Table
6. The costs associated with adding a second Green-AE 345/230 kV
transformer to relieve an overload caused by the XXX project in
2011 were not included in the costs assigned to the XXX project.
However, this violation is noted for this report and may be
included as a cost in the next XXX study. Note that this
feasibility study will not re-examine the effectiveness of these
solutions or any new problems that may arise as a consequence of
the solutions identified. EPE did coordinate through XXX to make
arrangements with SWTC for the study of the overloading of the
Green-AE 345/230 kV under the above N-1 condition to verify if this
element is overloaded. This overload will be examined in any follow
up study for the XXX project. 5.6 Sensitivity Case Modeling Only
Two Diablo 345/115 kV Autotransformers Referring to Section 4.2.1,
there were certain elements modeled in the benchmark cases (cases
without the XXX project) associated with Newman 5. Because the
addition of a third Diablo 345/115 kV autotransformer is not
associated with the additions and modifications assumed with Newman
5, this third autotransformer was examined in a sensitivity case.
To accomplish this, the status of a third Diablo 345/115 kV
autotransformer (of three autotransformers total) was changed from
on to off in the 2009 HS benchmark case. Under a single contingency
involving the Afton-Newman 345 kV line, it was found that the two
remaining Diablo 345/115 kV autotransformers (existing today) that
were modeled as on in the case overload under this single outage.
Therefore, a third Diablo 345/115 kV autotransformer is needed
prior to the XXX project. Because this addition (a third Diablo
345/115 kV autotransformer) is needed before the XXX project is
modeled, this will be considered an exception to the criteria, will
not have a penalizing effect when evaluating the XXX project, and
the cost to correct it will not be charged to the XXX
project.
Generator Interconnection Feasibility Study 25 El Paso Electric
Company 300 MW Solar Photovoltaic Plant August 2006
5.7 Double-Contingency (N-2) Analysis Results for Overloaded
Elements in All Cases with the XXX Project Modeled
Each of the cases with the XXX project, as described in Section
4.2.2 was examined under double contingency conditions. Table 7
shows the post-contingency overloaded SNM elements present in the
cases with the XXX project modeled under N-2 conditions. Table 7
shows the overloaded element and element rating. The percent
loading range on the element, based on the element rating, is
listed next, and the contingency condition is indicated in the
rightmost column.
Table 7. Post-Contingency (N-2) Thermal Violations, Cases with the
XXX Project Modeled, SNM Elements
Element Case Owner Rating (MVA) % Loading Contingency
Description
Luna 345/115 kV Autotransformer 2009 HS PNM 224 101.2
Luna-Hidalgo & Luna-Diablo 345 kV Lines (the XXX project Stays
In
During the Outage) *
Luna-Hidalgo & Luna-Diablo 345 kV Lines (the XXX project Stays
In
During the Outage) *
Luna-Hidalgo 345 kV Line & Luna 345/115 kV
Autotransformer
(the XXX project Stays In During the Outage)
As shown in Table 7, some post-XXX project post-contingency thermal
violations were observed on some SNM lines and transformers for
some double contingencies. There was one transformer, Luna 345/115
kV, which was overloaded in the post-XXX project a double outage.
There was one TSGT 115 kV line that was overloaded in the post-XXX
project under double outages: the ElButte-Picacho 115 kV lines. For
the purposes of this report, it is assumed that the thermal
violations during double contingencies will be used to help
identify which elements get overloaded as a result of a the XXX
project. In this study, it will be assumed that XXX will not be
required to build, add or modify elements showing a thermal
violation for a double contingency (such as the ones showing up in
Table 7) as a result of the XXX project; rather, these thermal
violations will help the owners of the SNM system identify what
procedures or new automatic or manual operating procedures need to
be in place as a result of the XXX project.
Generator Interconnection Feasibility Study 26 El Paso Electric
Company 300 MW Solar Photovoltaic Plant August 2006
EPE did coordinate through XXX to make arrangements with TSGT for
the study of the overloading of the TSGT line under the above N-2
condition to verify if this element is overloaded. This overload
will be examined in any follow up study for the XXX project.
Powerflow maps for instances in which an element experienced the
highest overload under a single or double contingency for the XXX
project Cases are shown in Appendix 3. Maps for the benchmark cases
and all cases modeling the XXX project with ALIS also appear in
Appendix 3. 5.8 Non-Converging Contingencies The following
contingencies did not converge for this study: 1) ElBut_US-El_Butte
115 kV line, 2) Amrad-AlamoTap 115 kV line, 3) Caliente-Amrad 345
kV line, and Caliente- Amrad and Caliente-Newman 345 kV line double
contingency. See Section 5.10 for more on the Amrad-AlamoTap 115 kV
line single-contingency. PNM plans on installing the third source
to Alamogordo 115 kV and also plans on installing an SVC at
Alamogordo 115 kV in 2009 and this should help with the Caliente-
Amrad 345 kV line single contingency, and Caliente-Amrad and
Caliente-Newman 345 kV line double contingency. These
non-converging contingencies will be examined further in any follow
up study for the XXX project. 5.9 Results for Voltage
Violations
Because there were numerous minor voltage violations, engineering
judgment (in the interest of time) dictated that only the voltage
violations due to the XXX project be summarized in this report. The
voltage violations due to the XXX project are shown in Table 8 for
single-contingencies and in Table 9 for double contingencies. These
tables show the name, base voltage, and area of the affected bus,
and the per-unit voltage observed in each case with the XXX
project. A blank entry in the table indicates that the voltage was
within limits for the specified condition. If a voltage violation
occurred for the same case prior to the XXX project, the violation
was considered pre-existing and not attributable to the XXX project
and was not included in Table 8 or in Table 9.
Generator Interconnection Feasibility Study 27 El Paso Electric
Company 300 MW Solar Photovoltaic Plant August 2006
Table 8. Voltage Violations due to the XXX Project,
Single-Contingencies (N-1)
Bus Name kV (Area) Case ALIS Voltage
N-1 Voltage (pu)
ALIS or Single-Contingency Under which Voltage Violation
Occurred
OJO 115 (PNM) 2009 HS 1.0479 1.0505 Hidalgo-PYoung 345 kV
line
HERMANAS (PNM) 2009 HS 1.0385 1.0505 Mimbres-Airport 115 kV
Line
NORTON 1 115 (PNM) 2009 HS 1.0488 1.0506 Luna-Hidalgo 345 kV line,
the XXX project Stays In During Outage*
TESUQUE 115 (PNM) 2009 HS 1.0490 1.0509 Luna-Hidalgo 345 kV line,
the XXX project Stays In During Outage* HOLLYWOOD 115
(TNMP) 2011 HS 0.9849 0.925 6.08 Caliente-Newman 345 kV line
GAVILAN 115 (TNMP) 2011 HS 0.9849 0.925 6.08 Caliente-Newman 345 kV
line
RUIDOSO 115 (TNMP) 2011 HS 0.9849 0.925 6.08 Caliente-Newman 345 kV
line
ASPEN 115 (PNM) 2011 HS 1.0482 1.0505 Luna-Hidalgo 345 kV line, the
XXX project Stays In During Outage*
BECKNER 115 (PNM) 2011 HS 1.0483 1.0506 Luna-Hidalgo 345 kV line,
the XXX project Stays In During Outage*
SANDIA 1 115 (PNM) 2011 HS 1.0477 1.0519 Luna-Hidalgo 345 kV line,
the XXX project Stays In During Outage*
TYRONE 69 (TNMP) 2011 HS 0.9823 0.9236 5.98 Luna 345/115 kV
Autotransformer, the XXX project Stays In During Outage*
Table 9. Voltage Violations due to the XXX Project,
Double-Contingencies (N-2)
Bus Name kV (Area) Case ALIS Voltage
N-2 Voltage (pu)
Double Contingency Under which Voltage Violation Occurred
TYRONE 69 (TNMP) 2009 HS 0.9876 0.9249 6.35 Luna-Hidalgo 345 kV
line and Luna 345/115 kV Autotransformer, the XXX project Drops
During Outage
WHITE SANDS 115 (EPE) 2011 HS 1.0274 0.9249 9.98 Amrad-Artesia 345
kV line and
Amrad 345/115 kV Autotransformer SPARKS 69 (EPE) 2011 HS 1.038
0.9244 10.94 Caliente-Newman and Newman-Afton 345 kV lines
SE 1 115 (EPE) 2011 HS 1.0023 0.9235 7.86 Caliente-Newman and
Newman-Afton 345 kV lines
* This outage was examined with the XXX project dropping out upon
this outage and the voltage violations on Table 9 were not observed
for this outage.
Generator Interconnection Feasibility Study 28 El Paso Electric
Company 300 MW Solar Photovoltaic Plant August 2006
For voltage violations in which voltages of 1.05-1.0504 p.u.
occurring during a single- contingency or double-contingency in the
analysis, these overvoltages are assumed to be caused by the
modeling in the cases used in this study. There were no voltage
violations that did not already exist in the benchmark case for
cases with the XXX generation Interconnection modeled for the
Arizona area. As can be seen in Table 8, for single contingencies,
there are some under voltage violations of the study criteria
caused by the XXX generation Interconnection. In these occurrences,
it was found that in the benchmark cases, similar voltage drops at
the same buses happen for the same single contingencies although
the voltage drop is not enough to violate the study criteria. The
over voltage violations occur under the same single outages that
cause other NM buses to be above 1.05 p.u. in both the benchmark
cases and cases with the XXX generation Interconnection. As can be
seen in Table 9, for double contingencies, there are some under
voltage violations of the study criteria caused by the XXX
generation Interconnection. In these occurrences, it was found that
in the benchmark cases, similar voltage drops happen at the same
buses for the same double contingencies although the voltage drop
is not enough to violate the study criteria. PNM has planned system
additions that would mitigate the low voltages seen in Table 9 at
Hollywood 115 kV, Gavilan 115 kV, Ruidoso 115 kV and Tyrone 69 kV.
These system additions include the addition of an SVC at Alamogordo
by 2009 and may include the third source to Alamogordo by the end
of 2007.
Generator Interconnection Feasibility Study 29 El Paso Electric
Company 300 MW Solar Photovoltaic Plant August 2006
5.10 Sensitivity Involving No Third Party Generation Online (All
Third Party Generation Offline)
There were sensitivity cases developed in which the third party
generation described as a-e in Section 4.2.1 was turned off in the
benchmark cases without the XXX Project modeled (cases 1 and 2 in
Section 4.2.1) and in the cases with the XXX Project modeled (cases
3 and 4 in Section 4.2.2). The cases in which the third party
generation described as a-e in Section 4.2.1 was turned off will be
referred to as cases with no third party generation (and is
actually no third party generation in SNM). Because third party
generation project b (141 MW of generation interconnected at Afton
345 kV Substation) was turned off, the Arroyo PST schedule was set
to the 201 MW N-S schedule as described in Table 2 of Section 4.2.1
for all cases. Another change was that in the benchmark cases
(without the XXX Project modeled) there was one 54 MVAR
Springerville-Luna 345 kV line reactor on in the cases as opposed
to two 54 MVAR Springerville-Luna 345 kV line reactors in the cases
with the XXX Project modeled. Also examined, is a sensitivity in
which all third party generation specified in Section 4.2.1 is
turned off and the effects of the XXX project are examined. Another
change from cases 1-4 with all third party generation modeled in
which three Diablo 345/115 kV autotransformers were modeled was
that in this sensitivity cases were modeled with two Diablo 345/115
kV autotransformers. The detailed results for this sensitivity can
be found in Appendix 6. 5.10.1 All-Lines-in-Service (ALIS) Analysis
Results for Overloaded Elements
Benchmark Cases (without the XXX Project) – No Third Party
Generation Cases - Sensitivity
Each of the cases with system benchmark conditions (without the XXX
project) and no third party generation was examined with all lines
in service (ALIS). Table 10 shows the base case overloads present
in the cases without the XXX project.
Table 10. Pre-Contingency Thermal Violations, Benchmark Conditions
– No Third Party Generation Cases
Element Case Owner Rating(MVA) % Loading
Blythe-Buckblvd 161 kV Line 2011 HS AZ 400 120.6 Blk Mesa 230
kV/BMA.3WP3 100 kV Transformer 2011 HS AZ 40 116.1 Blk Mesa 230
kV/BMA.4WP3 100 kV Transformer 2011 HS AZ 40 110.9
Verde N-Yavapai 100 kV Line 2011 HS AZ 319 102.0 Tucson 138
kV/TUC.3WP 100 kV Transformer 2011 HS AZ 100 100.1
Blythe-Buckblvd 161 kV Line 2011 HS AZ 440 109.6 Blk Mesa 230
kV/BMA.3WP3 100 kV Transformer 2011 HS AZ 44.8 103.6
Generator Interconnection Feasibility Study 30 El Paso Electric
Company 300 MW Solar Photovoltaic Plant August 2006
Table 10 shows the overloaded element, element owner, and element
rating and the benchmark case in which the thermal overload
occurred. The percent loading on the element, based on the element
rating, is indicated in the rightmost column and includes the range
of overloading without the XXX project. There were some Arizona
elements loaded above their normal and/or emergency rating. These
overloads included two lines and three transformers. These
contingency criteria violations listed in Table 10 will not have a
penalizing effect on the evaluation of the XXX project. 5.10.2
Single-Contingency (N-1) Analysis Results for Overloaded
Elements
Benchmark Cases (without the XXX Project) – No Third Party
Generation Cases - Sensitivity
The benchmark cases with no third party generation were examined
under single contingency conditions. Table 11 shows the base case
post-contingency overloaded SNM elements present in the cases
without the XXX project under N-1 conditions. If an element (line
or transformer) was overloaded under pre-contingency (ALIS)
conditions, it was considered a pre-contingency overload and was
not included in Table 11. Table 11 shows the overloaded element and
element rating. The percent loading range on the element, based on
the element rating, is listed next, and the contingency condition
is indicated in the rightmost column.
Table 11. Post-Contingency (N-1) Thermal Violations, Benchmark
Cases, SNM Elements – No Third Party Generation Cases
Element Case Owner Rating (MVA) % Loading Contingency
Description
Central-Silver 115 kV Line 2011 HS PNM/ TNMP 27.0 101.2 Turquois
115/69 kV
Transformer As shown in Table 11, one pre-XXX project
post-contingency thermal violation was observed on one SNM line.
This contingency criteria violation listed in Table 11 will not
have a penalizing effect on the evaluation of the XXX
project.
Generator Interconnection Feasibility Study 31 El Paso Electric
Company 300 MW Solar Photovoltaic Plant August 2006
5.10.3 Double-Contingency (N-2) Analysis Results for Overloaded
Elements Benchmark Cases (without the XXX Project) – No Third Party
Generation Cases - Sensitivity
The benchmark cases with no third party generation were examined
under double contingency conditions. Table 12 shows the base case
post-contingency overloaded SNM elements present in the cases
without the XXX project under N-2 conditions. If an element (line
or transformer) was overloaded under pre-contingency (ALIS)
conditions, it was considered a pre-contingency overload and was
not included in Table 12. Table 12 shows the overloaded element and
element rating. The percent loading range on the element, based on
the element rating, is listed next, and the contingency condition
is indicated in the rightmost column. As shown in Table 12, some
pre-XXX project post-contingency thermal violations were observed
on two SNM lines. These contingency criteria violations listed in
Table 12 will not have a penalizing effect on the evaluation of the
XXX project.
Table 12. Post-Contingency (N-2) Thermal Violations, Benchmark
Cases, SNM Elements, No Third Party Generation
Element Case Owner Rating (MVA) % Loading Contingency
Description
Hidalgo-Turquoise 115 kV Line 2009 HS PNM/ TNMP 153.0 103.9
Luna-Afton 345 kV Line & Luna 345/115 kV
Transformer
Hidalgo-Turquoise 115 kV Line 2011 HS PNM/ TNMP 153.0 103.3
Luna-Afton 345 kV Line & Luna 345/115 kV
Transformer
Algodone-Moriarty 115 kV Line 2009 HS TSGT 66.0 101.3 Luna-Afton
& Springerville- Luna 345 kV Lines
Reducing generation at Lordsburg and Pyramid should also mitigate
the overloads shown in Table 12 for the Luna-Afton 345 kV line and
Luna 345/115 kV transformer outage.
Generator Interconnection Feasibility Study 32 El Paso Electric
Company 300 MW Solar Photovoltaic Plant August 2006
5.10.4 All-Lines-in-Service (ALIS) Analysis Results for Overloaded
Elements in All Cases with the XXX Project Modeled – No Third Party
Generation Cases - Sensitivity
There were no SNM elements overloaded in the cases with XXX project
and no third party generation modeled that were not already
overloaded in the benchmark cases (without the XXX project and with
no third party generation modeled) with ALIS. 5.10.5
Single-Contingency (N-1) Analysis Results for Overloaded Elements
in All
Cases with the XXX Project Modeled – No Third Party Generation
Cases – Sensitivity
Each case, with the XXX project and no third party generation
modeled, was examined under single contingency (N-1) conditions.
There were no SNM elements overloaded in the cases with XXX project
and no third party generation modeled that were not already
overloaded in the benchmark cases (without the XXX project and with
no third party generation modeled) under N-1. 5.10.6
Double-Contingency (N-2) Analysis Results for Overloaded Elements
in All
Cases with the XXX Project Modeled – No Third Party Generation
Cases – Sensitivity
Each case, with the XXX project and no third party generation
modeled, was examined under double contingency (N-2) conditions.
There were no SNM elements overloaded in the cases with XXX project
and no third party generation modeled that were not already
overloaded in the benchmark cases (without the XXX project and with
no third party generation modeled) under N-2. 5.10.7 Non-Converging
Contingencies – No Third Party Generation Cases –
Sensitivity The following contingencies did not converge for these
cases: 1) Hidalgo T1 & T3 345/115 kV double contingency, 2)
Amrad-AlamoTap 115 kV line, 3) Caliente-Amrad 345 kV line, and
Caliente-Amrad and Caliente-Newman 345 kV line double contingency.
Note that the Hidalgo T1 & T3 345/115 kV double contingency did
converge in the cases with all third party generation modeled. PNM
plans on installing the third source to Alamogordo 115 kV and also
plans on installing an SVC at Alamogordo 115 kV in 2009 and this
should help with the Caliente- Amrad 345 kV line single
contingency, and Caliente-Amrad and Caliente-Newman 345 kV line
double contingency. These non-converging contingencies will be
examined further in any follow up study for the XXX project.
Generator Interconnection Feasibility Study 33 El Paso Electric
Company 300 MW Solar Photovoltaic Plant August 2006
5.10.8 Results for Voltage Violations – No Third Party Generation
Cases – Sensitivity
Because there were numerous minor voltage violations, engineering
judgment (in the interest of time) dictated that only the voltage
violations due to the XXX project be summarized in this report. The
voltage violations due to the XXX project are shown in Table 13 for
single-contingencies and in Table 14 for double contingencies for
the cases with the XXX project and no third party generation
modeled. These tables show the name, base voltage, and area of the
affected bus, and the per-unit voltage observed in each case with
the XXX project. A blank entry in the table indicates that the
voltage was within limits for the specified condition. If a voltage
violation occurred for the same case prior to the XXX project, the
violation was considered pre-existing and not attributable to the
XXX project and was not included in Table 13 or in Table 14.
Generator Interconnection Feasibility Study 34 El Paso Electric
Company 300 MW Solar Photovoltaic Plant August 2006
Table 13. Voltage Violations due to the XXX Project,
Single-Contingencies (N-1) – No Third Party Generation Cases –
Sensitivity
Bus Name kV (Area) Case ALIS Voltage
N-1 Voltage (pu)
ALIS or Single-Contingency Under which Voltage Violation
Occurred
TYRONE 69 (TNMP) 2009 HS 0.9831 0.9249 5.92 Central-Hurley 115 kV
line
SILVERC 69 (TNMP) 2009 HS 0.9723 0.9204 5.34 Hidalgo-PYoung 345 kV
line
IVANHOE 115 (TNMP) 2009 HS 0.9916 0.9209 7.13 Hurley-Luna 115 kV
Line
Generator Interconnection Feasibility Study 35 El Paso Electric
Company 300 MW Solar Photovoltaic Plant August 2006
Table 14. Voltage Violations due to the XXX Project,
Double-Contingencies (N-2) – No Third Party Generation Cases –
Sensitivity
Bus Name kV (Area) Case ALIS Voltage
N-2 Voltage (pu)
Double Contingency Under which Voltage Violation Occurred
CHINO 115 (TNMP) 2011 HS 1.0066 0.9249 6.35 Luna 345/115 kV
Autotransformer, the XXX project Drops During Outage
PDTYRONE 115 (TNMP) 2011 HS 0.9975 0.9233 7.44 Luna 345/115 kV
Autotransformer, the XXX project Drops During Outage
CENTRAL 69 (TNMP) 2009 HS 0.9945 0.9187 7.62 Luna 345/115 kV
Autotransformer, the XXX project Drops During Outage
IVANHOE 115 (TNMP) 2009 HS 0.9916 0.9216 7.06 Luna 345/115 kV
Autotransformer, the XXX project Drops During Outage
TYRONE 69 (TNMP) 2009 HS 0.9831 0.9222 6.19 Luna 345/115 kV
Autotransformer, the XXX project Drops During Outage
CENTRAL 69 (TNMP) 2011 HS 0.9974 0.9072 9.04 Luna 345/115 kV
Autotransformer, the XXX project Drops During Outage
IVANHOE 115 (TNMP) 2011 HS 0.9942 0.9096 8.51 Luna 345/115 kV
Autotransformer, the XXX project Drops During Outage
CENTRAL 115 (TNMP) 2011 HS 1.0008 0.9168 8.39 Luna 345/115 kV
Autotransformer, the XXX project Drops During Outage
TYRONE 69 (TNMP) 2011 HS 0.9851 0.9189 6.72 Luna 345/115 kV
Autotransformer, the XXX project Drops During Outage
MORIARTY 115 (TSGT) 2011 HS 0.9670 0.9232 4.53 Luna 345/115 kV
Autotransformer, the XXX project Drops During Outage
SILVERC 69 (TNMP) 2011 HS 0.9740 0.9206 5.48 Afton-Newman &
Luna-Afton 345 kV Double Contingency, the XXX project Drops During
Outage
DEMINGPG 69 (TSGT) 2009 HS 0.9918 0.9173 7.51 Afton-Luna &
Springerville-Luna 345 kV Double Contingency, the XXX project Drops
During Outage
PLAYAS 69 (TSGT) 2011 HS 1.0036 0.9246 7.87 Afton-Luna &
Springerville-Luna 345 kV Double Contingency, the XXX project Drops
During Outage
WILLARD 115 (TSGT) 2011 HS 0.9650 0.9248 4.17 Afton-Luna &
Springerville-Luna 345 kV Double Contingency, the XXX project Drops
During Outage
ESTANCIA 115 (TSGT) 2011 HS 0.9611 0.9213 4.14 Afton-Luna &
Springerville-Luna 345 kV Double Contingency, the XXX project Drops
During Outage
TYRONE 69 (TNMP) 2011 HS 0.9851 0.9233 6.27 Springerville-Luna 345
kV, the XXX project Drops During Outage
Generator Interconnection Feasibility Study 36 El Paso Electric
Company 300 MW Solar Photovoltaic Plant August 2006
There were no voltage violations that did not already exist in the
benchmark case for cases with the XXX generation Interconnection
modeled for the Arizona area. As can be seen in Table 13, for
single contingencies, there are some under voltage violations of
the study criteria caused by the XXX generation Interconnection. In
these occurrences, it was found that in the benchmark cases,
similar voltage drops at the same buses happen for the same single
contingencies although the voltage drop is not enough to violate
the study criteria. As can be seen in Table 14, for double
contingencies, there are some under voltage violations of the study
criteria caused by the XXX generation Interconnection. In these
occurrences, it was found that in the benchmark cases, similar
voltage drops happen at the same buses for the same double
contingencies although the voltage drop is not enough to violate
the study criteria. PNM has planned system additions that would
mitigate the low voltages seen in Table 9 at Hollywood 115 kV,
Gavilan 115 kV, Ruidoso 115 kV and Tyrone 69 kV. These system
additions include the addition of an SVC at Alamogordo by 2009 and
may include the third source to Alamogordo by the end of
2007.
Generator Interconnection Feasibility Study 37 El Paso Electric
Company 300 MW Solar Photovoltaic Plant August 2006
5.10.9 Summary of Results for No Third Party Generation Cases –
Sensitivity The following are the results of this
sensitivity:
• In cases with no XXX project, one Springerville-Luna 345 kV line
reactor was modeled as on versus two Springerville-Luna 345 kV line
reactors modeled as on in the cases with the XXX project.
• With no third party generation modeled, the Arroyo PST schedule
was modeled as 201 MW N-S.
• With no third party generation modeled the Arroyo PST schedule
was modeled as 201 MW N-S, the two Diablo 345/115 kV
autotransformers modeled did not overload under any contingency run
(N-1 or N-2).
• There were no overloads under single or double contingencies
caused by the XXX project.
• With no third party generation modeled, the Hidalgo T1 & T3
345/115 kV transformer double outage did not converge. With third
party generation modeled, this contingency converges. This
non-converging double contingency will be examined further in any
follow up study for the XXX project.
• With no third party generation modeled, there were minor voltage
violations observed under single contingencies in the cases with
the XXX project modeled that were not violations in the cases
without the XXX project modeled. In these occurrences, it was found
that in the benchmark cases, similar voltage drops at the same
buses happen for the same single contingencies although the voltage
drop is not enough to violate the study criteria. PNM is planning
some system additions that may help the voltage profiles in
SNM.
• With no third party generation modeled, many of the elements that
were overloaded in the cases with third party generation were not
overloaded. Specifically, the Green-AE 230/115 kV transformer under
a single contingency in the cases with the XXX project modeled and
the Luna 345/115 kV and the ElButte-Picacho 115 kV line under a
double contingency in the cases with the XXX project modeled were
not overloaded in the cases without third party generation
modeled.
Generator Interconnection Feasibility Study 38 El Paso Electric
Company 300 MW Solar Photovoltaic Plant August 2006
5.11 Sensitivity Involving New Alamogordo-Holloman 115 kV Line –
Voltage Effects
There was a sensitivity case examined in this study involving the
addition of a new line from Alamogordo-Holloman 115 kV line. In the
2009 and 2011 cases with the XXX Generation Interconnection, this
Alamogordo-Holloman 115 kV line was added. The outages for this
study were performed for these two cases. The net effect of this
line addition was that this line resulted in no consequential
difference in the thermal overloading results already recorded in
the previous sections (in which this line is off). The main
difference this line made was in the voltages during outages:
specifically, in the voltages involving outages involving the
Alamogordo, Amrad, and Holloman buses. For the purposes of this
section, only single-contingencies will be addressed. There were no
voltage violations in these sensitivity cases for single-outages
involving 115 kV lines connecting to the Alamogordo, Amrad, and
Holloman buses. However, there are voltage violations in two
different single-contingencies, an outage of the Alamogcp-Amrad 115
kV line and an outage of the Amrad 345/115 kV transformer, which
merit further consideration. The results for these two key