XXXXXXXXXXXXXXXXXXXX
GENERATION INTERCONNECTION FACILITIES STUDY
SHORT CIRCUIT ANALYSIS
FOR PROPOSED GENERATION AT
NEWMAN 115 kV BUS
El Paso Electric Company
System Operations Department
System Planning Section
May 2003
I.
INTRODUCTION
XXXXXXXXXXXXXXXXXXXXXXXXXXX (XXX) has proposed the addition of a
generating plant near EPE’s Newman Substation. This proposed generation unit was
analyzed in two phases. Phase I analyzed a 140 MW combustion turbine (CT) in 2006.
Phase II analyzed a steam turbine integrated with the CT to form a Combined Cycle (CC)
unit in 2009. In both phases, the unit was modeled as being interconnected at EPE’s
Newman 115 kV bus.
When generating units are added to a transmission system, the available fault current on a
system increases. Therefore, as part of the Generation Interconnection Facilities Study
(GIFS), a short circuit study was performed to determine if the additional fault current on
the EPE system due to the proposed generation does not exceed the interruption ratings
of EPE’s existing substation circuit breakers. In the powerflow analysis of the GIFS, the
2006 CT was modeled at a 140 MW generation output level. The 2009 CC unit was
modeled at a 290 MW maximum generation output level. This Short Circuit Study was
performed by El Paso Electric Company’s Transmission & Distribution Division (EPE
T&D). The Powerflow, Q-V, and Stability analyses for this study are also being
performed by El Paso Electric Company’s Transmission & Distribution Division (EPE
T&D) and will be issued under a separate cover.
Short Circuit Analysis for a
Generation Interconnection Facilities Study
For Proposed Generation at Newman 115 kV Bus
1
El Paso Electric Company
May 2003
II. SHORT CIRCUIT STUDY MODELING
The new generation proposed by XXX is sited at EPE’s Newman 115 kV substation. The
combustion and steam-turbine generator portion of the proposed combined-cycle plant
will be connected to the 115 kV transmission through a 200 MVA, 18/115 kV step-up
transformer per generator. Each of the two step-up transformers has an impedance of 7.5
% on a 120 MVA base. The step-up transformer impedance modeled in the short circuit
analysis for both step-up transformers was:
Z (step-up) = 0.01489 + J0.0625 per unit (100 MVA base)
The new generators have the following reactance values on the generator MVA base:
Combustion-Turbine:
Xd = Direct Axis Synchronous Reactance = 1.810 per unit
X’d = Direct Axis Transient Reactance = 0.195 per unit
X’’d = Direct Axis Subtransient Reactance = 0.130 per unit
Steam-Turbine:
Xd = Direct Axis Synchronous Reactance = 2.260 per unit
X’d = Direct Axis Transient Reactance = 0.250 per unit
X’’d = Direct Axis Subtransient Reactance = 0.165 per unit
These reactance values were converted to a 100 MVA base and used to model the new
generators in the short circuit study.
In addition to the new generation connected to the Newman 115 kV bus, one existing and
four potential generation projects were also modeled in the analysis. These generation
projects included the following:
•
•
•
•
•
135 MW of generation at Afton Substation interconnected to the Luna-AftonNewman 345 kV line (existing).
614 MW of generation interconnected at the Luna 345 kV Substation.
160 MW of generation interconnected near Lordsburg, New Mexico.
150 MW of generation interconnected at Lordsburg, New Mexico.
130 MW of new generation interconnected at Afton 345 kV Substation and 14
MW of additional generation on the existing Afton generator.
These additional generators were modeled in the study to provide a “worst case” scenario
in the event that all are interconnected into EPE’s system before the proposed Newman
generation is interconnected.
Short Circuit Analysis for a
Generation Interconnection Facilities Study
For Proposed Generation at Newman 115 kV Bus
2
El Paso Electric Company
May 2003
Maximum fault currents were then determined at the Newman 115 kV bus and other EPE
substations of interest or importance.
These included the following:
Diablo 345 kV
Diablo 115 kV
Newman 345 kV
Rio Grande 115 kV
Rio Grande 69 kV
The resulting fault current was then compared to the circuit breaker interruption ratings
of the breakers at each of the above mentioned substations.
Among the proposed projects listed above is the addition of 14 MW of generation to the
existing 135 MW generator at Afton. This existing generator will be combined with a
proposed 130 MW generator and interconnected to the Luna-Afton-Newman 345 kV
line. Together, these projects (135 MW +14 MW + 130 MW) represent a combinedcycle configuration with a modeled output of 279 MW. Because there are two
transmission line interconnection configurations for this proposed project that are
currently being studied as part of a different analysis, the results for this Short-Circuit
Study will be presented in two different result groups.
The Transmission Configuration 1 used to interconnect the 279 MW generation plant
mentioned above involves the use of the existing Luna-Afton-Newman 345 kV
transmission configuration. The existing Afton generator interconnects the LunaNewman 345 kV line to now form two line segments, the Luna-Afton 345 kV line and
the Afton to Newman 345 kV.
In Transmission Configuration 2, EPE’s Luna-Diablo 345 kV line is routed such that this
existing line will be tied to Afton 345 kV substation to also form two line segments, the
Luna-Afton 345 kV line and the Afton-Diablo 345 kV line
Ultimately, a Study of the proposed Afton Project, currently in progress, will be used to
determine which Transmission Configuration will be used to interconnect the 279 MW
project described above.
Because the study referenced above has not yet been completed, results of this ShortCircuit Study will be divided into two groups corresponding to each of the two
Transmission Configurations described above.
Short Circuit Analysis for a
Generation Interconnection Facilities Study
For Proposed Generation at Newman 115 kV Bus
3
El Paso Electric Company
May 2003
III.
RESULTS OF THE SHORT CIRCUIT ANALYSIS
The circuit breakers used in the Southern New Mexico System at 345 kV, 115 kV, and 69
kV buses vary between the substations. The following is a list of the existing circuit
breakers, along with the interruption rating, at each of the relevant substations:
Breaker
Substation
Diablo
Breaker
Voltage
345
345
345
Number
1888B
2138B
2258B
Diablo
115
115
115
115
115
115
1586B
1636B
1706B
1806B
2876B
4326B
40,000
40,000
40,000
40,000
40,000
31,500
Newman
345
345
345
345
2448B
6018B
8378B
0538B
40,000
40,000
40,000
40,000
Newman
115
115
115
115
115
115
115
115
115
115
115
115
115
115
115
115
115
115
11950
11101
15601
N-115-1
11951
11401
N-115-7
11957
N-115-8
11952
11601
N-115-3
11953
15501
N-115-19
11967
N-115-20
N-115-21
40,000
50,000
40,000
40,000
40,000
40,000
43,000
43,000
43,000
40,000
50,000
40,000
40,000
40,000
40,000
40,000
40,000
40,000
Short Circuit Analysis for a
Generation Interconnection Facilities Study
For Proposed Generation at Newman 115 kV Bus
4
Interruption
Rating (Amps)
40,000
40,000
40,000
El Paso Electric Company
May 2003
Breaker
Substation
Newman
(continued)
Breaker
Voltage
115
115
115
115
115
115
Number
11968
N-115-22
N-115-23
11969
N-115-24
N-115-2
Interruption
Rating (Amps)
40,000
40,000
40,000
40,000
40,000
40,000
Rio Grande
115
115
115
115
115
115
115
115
115
115
115
115
1516B
3316B
4456B
4616B
1766B
2296B
2426B
5146B
1126B
2186B
3856B
5376B
40,000*
23,000
23,000
40,000
40,000
23,000
23,000
40,000
40,000*
23,000
23,000
40,000
Rio Grande
69
69
69
69
69
69
69
69
69
69
69
69
69
69
5009
5003
5907
5005
5006
5007
5701
5501
1254B
5601
5918
5401B
5010
5032
40,000*
40,000
24,000
40,000
40,000
26,000
31,500
31,500
31,500
31,500
40,000
31,500
40,000
40,000
* Currently these breakers have ratings ranging between 19,000-20,000 amperes. They
are expected to be replaced with breakers having 40,000 ampere ratings as part of
EPE’s normal breaker replacement program.
Short Circuit Analysis for a
Generation Interconnection Facilities Study
For Proposed Generation at Newman 115 kV Bus
5
El Paso Electric Company
May 2003
The short circuit analysis was first performed with no new generation at Newman 115 kV
(all other potential generation projects in). This gave the “base case” fault duties of the
circuit breakers. The new generation at Newman 115 kV was then modeled in two
phases. Phase I analyzed a 140 MW combustion turbine (CT) in 2006. Phase II analyzed
a steam-turbine added to the combustion turbine configuration to form a Combined Cycle
(CC) unit in 2009. In both phases the short circuit study was then reanalyzed (with all
other potential generation projects in). The incremental between the three studies gave
the impact of the new generators on the existing circuit breakers in the Southern New
Mexico system.
A. Short Circuit Results for Proposed New Generation at Newman 115 kV Using
Transmission Configuration 1
Transmission Configuration 1 assumes that the transmission configuration of
interconnecting the Afton generating station to the Luna-Afton-Newman 345 kV line will
remain as it exists now, with the line divided into two segments:
1) Luna to Afton 345 kV substation
2) Afton to Newman 345 kV substation.
The other proposed projects previously listed are also included in this configuration. The
short circuit (fault) currents of Configuration 1 at all the substations which may be
impacted due to the addition of the proposed Newman 5 project are listed below:
No New Generation at Newman 115 kV Bus Versus
Phase 1 CT Addition at Newman 115 kV Bus in 2006
Three Phase Line to Ground:
Substation Faulted
Diablo 345 kV Bus
Diablo 115 kV Bus
Newman 345 kV Bus
Newman 115 kV Bus
Rio Grande 115 kV Bus
Rio Grande 69 kV Bus
No New Generation
at Newman 115 kV
Fault Current (Amps)
5,418.0
19,500.0
8,874.0
25,801.0
21,123.0
19,723.0
Short Circuit Analysis for a
Generation Interconnection Facilities Study
For Proposed Generation at Newman 115 kV Bus
6
With New Generation
at Newman 115 kV
Fault Current (Amps)
5,498.0
20,070.0
9,348.0
29,755.0
21,845.0
20,051.0
El Paso Electric Company
May 2003
Single Phase Line to Ground:
Substation Faulted
Diablo 345 kV Bus
Diablo 115 kV Bus
Newman 345 kV Bus
Newman 115 kV Bus
Rio Grande 115 kV Bus
Rio Grande 69 kV Bus
No New Generation
at Newman 115 kV
Fault Current (Amps)
4,914.0
19,449.0
8,982.0
30,334.0
22,818.0
23,219.0
With New Generation
at Newman 115 kV
Fault Current (Amps)
4,958.0
19,820.0
9,396.0
35,063.0
23,373.0
23,518.0
No New Generation at Newman 115 kV Bus Versus Phase 2 CC Plant at
Newman 115 kV Bus in 2009
Three Phase Line to Ground:
Substation Faulted
Diablo 345 kV Bus
Diablo 115 kV Bus
Newman 345 kV Bus
Newman 115 kV Bus
Rio Grande 115 kV Bus
Rio Grande 69 kV Bus
No New Generation
at Newman 115 kV
Fault Current (Amps)
5,418.0
19,500.0
8,874.0
25,801.0
21,123.0
19,723.0
With New Generation
at Newman 115 kV
Fault Current (Amps)
5,562.0
22,323.0
9,746.0
33,695.0
22,430.0
20,308.0
Single Phase Line to Ground:
Substation Faulted
Diablo 345 kV Bus
Diablo 115 kV Bus
Newman 345 kV Bus
Newman 115 kV Bus
Rio Grande 115 kV Bus
Rio Grande 69 kV Bus
No New Generation
at Newman 115 kV
Fault Current (Amps)
4,914.0
19,449.0
8,982.0
30,334.0
22,818.0
23,219.0
Short Circuit Analysis for a
Generation Interconnection Facilities Study
For Proposed Generation at Newman 115 kV Bus
7
With New Generation
at Newman 115 kV
Fault Current (Amps)
4,992.0
22,231.0
9,738.0
39,787.0
23,819.0
23,753.0
El Paso Electric Company
May 2003
As can be seen in the table below, the fault currents of six (6) existing circuit breakers at
Rio Grande 115 kV exceed their interruption ratings during a single phase line to ground
fault in 2006.
SUBSTATION
Rio Grande 115
BREAKER
NUMBER
INTERRUPTION
RATING
(AMPS)
SC FAULT
CURRENT W/O
NEWMAN 5
(AMPS)
SC FAULT
CURRENT WITH
NEWMAN 5
(AMPS)
3316B
4456B
2296B
2426B
2186B
3856B
23,000
23,000
23,000
23,000
23,000
23,000
22,818
22,818
22,818
22,818
22,818
22,818
23,373
23,373
23,373
23,373
23,373
23,373
Therefore, under Transmission Configuration 1, XXX will be responsible for the cost of
replacing six new circuit breakers at the Rio Grande 115 kV bus.
B. Short Circuit Results for Proposed New Generation at Newman 115 kV Using
Transmission Configuration 2
Transmission Configuration 2 assumes that the transmission configuration of
interconnecting the Afton generating station to the Luna-Afton-Newman 345 kV line will
remain as it exists now, with the line divided into two segments:
1) Luna to Afton 345 kV substation
2) Afton to Newman 345 kV substation.
However, this Configuration also interconnects the Afton plant to EPE’s Luna-Diablo
345 kV line, also dividing the line into two segments,
1) Luna to Afton 345 kV substation
2) Afton to Diablo 345 kV substation.
The other proposed projects previously listed are also included in this configuration. The
short circuit (fault) currents under Configuration 2 at all the substations which may be
impacted due to the addition of the proposed Newman 5 project are listed on the
following page.
Short Circuit Analysis for a
Generation Interconnection Facilities Study
For Proposed Generation at Newman 115 kV Bus
8
El Paso Electric Company
May 2003
No New Generation at Newman 115 kV Bus Versus
Phase 1 CT Addition at Newman 115 kV Bus in 2006
Three Phase Line to Ground:
Substation Faulted
Diablo 345 kV Bus
Diablo 115 kV Bus
Newman 345 kV Bus
Newman 115 kV Bus
Rio Grande 115 kV Bus
Rio Grande 69 kV Bus
No New Generation
at Newman 115 kV
Fault Current (Amps)
7,692.0
21,061.0
9,283.0
25,829.0
22,193.0
20,091.0
With New Generation
at Newman 115 kV
Fault Current (Amps)
7,876.0
21,759.0
9,791.0
29,783.0
23,019.0
20,441.0
Single Phase Line to Ground:
Substation Faulted
Diablo 345 kV Bus
Diablo 115 kV Bus
Newman 345 kV Bus
Newman 115 kV Bus
Rio Grande 115 kV Bus
Rio Grande 69 kV Bus
No New Generation
at Newman 115 kV
Fault Current (Amps)
6,926.0
21,381.0
9,293.0
30,368.0
23,916.0
23,616.0
With New Generation
at Newman 115 kV
Fault Current (Amps)
7,025.0
21,823.0
9,727.0
35,097.0
24,549.0
23,935.0
No New Generation at Newman 115 kV Bus Versus Phase 2 CC Plant at
Newman 115 kV Bus in 2009
Three Phase Line to Ground:
No New Generation
at Newman 115 kV
Substation Faulted
Fault Current (Amps)
Diablo 345 kV Bus
7,692.0
Diablo 115 kV Bus
21,061.0
Newman 345 kV Bus
9,283.0
Newman 115 kV Bus
25,829.0
Rio Grande 115 kV Bus
22,193.0
Rio Grande 69 kV Bus
20,091.0
Single Phase Line to Ground:
Short Circuit Analysis for a
Generation Interconnection Facilities Study
For Proposed Generation at Newman 115 kV Bus
9
With New Generation
at Newman 115 kV
Fault Current (Amps)
8,022.0
22,323.0
10,217.0
33,723.0
23,692.0
20,717.0
El Paso Electric Company
May 2003
Substation Faulted
Diablo 345 kV Bus
Diablo 115 kV Bus
Newman 345 kV Bus
Newman 115 kV Bus
Rio Grande 115 kV Bus
Rio Grande 69 kV Bus
No New Generation
at Newman 115 kV
Fault Current (Amps)
6,926.0
21,381.0
9,293.0
30,368.0
23,916.0
23,616.0
With New Generation
at Newman 115 kV
Fault Current (Amps)
7,103.0
22,231.0
10,086.0
39,821.0
25,059.0
24,186.0
As can be seen in the table below, the fault currents of six (6) existing circuit breakers at
Rio Grande 115 kV exceed their interruption ratings during a single phase line to ground
fault in 2006. These circuit breakers will have to be replaced due to the increased shortcircuit current resulting from the addition of another proposed project in 2006.
Therefore, XXX is not responsible for the replacement of these breakers.
Rio Grande 115
BREAKER
NUMBER
INTERRUPTION
RATING
(AMPS)
SC FAULT
CURRENT W/O
NEWMAN 5
(AMPS)
SC FAULT
CURRENT WITH
NEWMAN 5
(AMPS)
3316B
4456B
2296B
2426B
2186B
3856B
23,000
23,000
23,000
23,000
23,000
23,000
23,916
23,916
23,916
23,916
23,916
23,916
24,549
24,549
24,549
24,549
24,549
24,549
However, in the 2009 case, the fault current to at the Rio Grande 115 kV bus exceeds the
interruption rating of one (1) existing circuit breaker. The table below shows that the
overloading of this breaker is due to the addition of the proposed Newman 5 project.
SUBSTATION
Rio Grande 69
BREAKER
NUMBER
INTERRUPTION
RATING
(AMPS)
SC FAULT
CURRENT W/O
NEWMAN 5
(AMPS)
SC FAULT
CURRENT WITH
NEWMAN 5
(AMPS)
5907
24,000
23,616
24,186
Therefore, under Transmission Configuration 2, XXX will be responsible for the cost of
replacing one new circuit breaker at the Rio Grande 69 kV bus.
Short Circuit Analysis for a
Generation Interconnection Facilities Study
For Proposed Generation at Newman 115 kV Bus
10
El Paso Electric Company
May 2003
IV. Results and Conclusions
A short circuit study was performed on the EPE system comparing the maximum fault
current on the system at various substations: Newman 115 kV Substation and selected
substations in the EPE system, both with and without the new generation proposed at
Newman 115 kV. In addition, two transmission configurations were analyzed to model
potential interconnections involving the interconnection of an additional 144 MW of
proposed generation at the existing Afton Substation.
Transmission Configuration 1 assumes that the transmission configuration of the LunaAfton-Newman 345 kV line remains as it exists now, with the line divided into two
segments
1) Luna to Afton 345 kV substation
2) Afton to Newman 345 kV substation.
Transmission Configuration 2 assumes that the Afton substation is interconnected to the
Luna-Afton-Newman 345 kV line as it is in Configuration 1 and it is also tied in to the
Luna-Diablo 345 kV line as follows
1) Luna to Afton 345 kV substation
2) Afton to Diablo 345 kV substation
Ultimately, a Study for the proposed Afton project that is currently in progress will
determine which transmission configuration will be used to interconnect the additional
144 MW of the potential generation to the EPE system. The tables below show the
results of the short circuit analyses for Transmission Configuration 1 and Transmission
Configuration 2.
A. Short Circuit Results for Proposed New Generation at Newman 115 kV
Using Transmission Configuration 1
Minimum Circuit Breaker
Substation
Interruption Rating (Amps)
Diablo 345 kV Bus
40,000.0
Diablo 115 kV Bus
31,500.0
Newman 345 kV Bus
40,000.0
Newman 115 kV Bus
40,000.0
Rio Grande 115 kV Bus*
23,000.0
Rio Grande 69 kV Bus*
24,000.0
Short Circuit Analysis for a
Generation Interconnection Facilities Study
For Proposed Generation at Newman 115 kV Bus
11
Maximum Fault Current
With Proposed
Generation Addition
(Amps)
5,562.0
22,323.0
9,746.0
39,787.0
23,819.0
23,753.0
El Paso Electric Company
May 2003
Results of the analysis for Transmission Configuration 1 indicate that the fault current at
the Rio Grande 115 kV bus for a single line-to-ground fault exceeded the breaker
interruption rating of six existing breakers. From the list of circuit breakers at the Rio
Grande 115 kV bus on page 5, the maximum fault current at this bus for a single line-toground fault exceeded the 23,000 ampere interruption rating of six breakers. This was
due to the addition of the proposed CT at Newman 115 kV bus in 2006. Therefore, the
addition of new generation at the Newman 115 kV bus in 2006 will require that six
existing circuit breakers at the Rio Grande 115 kV Substation with 23,000 amp ratings be
replaced with six new breakers with higher breaker interruption ratings in 2006.
B. Short Circuit Results for Proposed New Generation at Newman 115 kV
Using Transmission Configuration 2
Minimum Circuit Breaker
Substation
Interruption Rating (Amps)
Diablo 345 kV Bus
40,000.0
Diablo 115 kV Bus
31,500.0
Newman 345 kV Bus
40,000.0
Newman 115 kV Bus
40,000.0
Rio Grande 115 kV Bus*
23,000.0
Rio Grande 69 kV Bus*
24,000.0
Maximum Fault Current
With proposed
Generation Addition
(Amps)
8,022.0
22,323.0
10,217.0
39,821.0
25,059.0
24,186.0
Results of the analysis for Transmission Configuration 2 indicate that fault currents for a
single line-to-ground fault exceeded breaker interruption rating of six existing breakers at
the Rio Grande 115 kV bus and one breaker at the Rio Grande 69 kV bus. From the list
of circuit breakers at the Rio Grande 115 kV bus on page 5, the maximum fault current
for a single line-to-ground fault exceeded the 23,000 ampere interruption rating of six
breakers. In Transmission Configuration 2, the fault current exceeded 23,000 amps for a
single line-to-ground fault due to the addition of proposed generation interconnected at
the existing Afton Substation as modeled in this short circuit analysis in 2006. This
potential project occurs in the study queue prior to the addition of new generation at the
Newman 115 kV bus. Therefore, under this transmission configuration, the owner of this
proposed project is responsible for the cost of replacing the six existing 23,000 amp
circuit breakers at Rio Grande 115 kV Substation. However, the list of circuit breaker
ratings at the Rio Grande 69 kV bus on page 6 indicates that the maximum fault current
at this bus for a single line-to-ground fault exceeded the 24,000 amp circuit breaker
interruption rating of one existing circuit breaker due to the addition of the proposed new
generation at the Newman 115 kV bus in 2009. Therefore, under this configuration,
XXX is responsible for the cost of replacing one 69 kV breaker at the Rio Grande 69 kV
bus with a circuit breaker with an interruption rating above 24,000 amps in 2009.
Short Circuit Analysis for a
Generation Interconnection Facilities Study
For Proposed Generation at Newman 115 kV Bus
12
El Paso Electric Company
May 2003
The estimated costs to replace the breakers XXX will be responsible under each of the
configurations analyzed are shown below:
XXX ESTIMATED COSTS FOR BREAKER REPLACEMENT
UNDER TRANSMISSION CONFIGURATION 1
SUBSTATION
Rio Grande 115
BREAKER
NUMBER
YEAR
ESTIMATED COST
(2003$)
3316B
4456B
2296B
2426B
2186B
3856B
2006
2006
2006
2006
2006
2006
$60,000
$60,000
$60,000
$60,000
$60,000
$60,000
TOTAL XXX BREAKER REPLACEMENT COSTS
$360,000
XXX ESTIMATED COSTS FOR BREAKER REPLACEMENT
UNDER TRANSMISSION CONFIGURATION 2
SUBSTATION
Rio Grande 69
BREAKER
NUMBER
YEAR
ESTIMATED COST
(2003$)
5907
2009
$40,000
TOTAL XXX BREAKER REPLACEMENT COSTS
Short Circuit Analysis for a
Generation Interconnection Facilities Study
For Proposed Generation at Newman 115 kV Bus
13
$40,000
El Paso Electric Company
May 2003
V. Certification
This Short Circuit Analysis was performed pursuant with a Generation Interconnection
Facilities Study requested by XXXXXXXXXXXXXXXXXXXXXXXXXXXX (XXX).
The generator, step-up transformer and new transmission line parameters were supplied
by XXX. The Short Circuit Analysis was performed by El Paso Electric Company’s
Transmission & Distribution Division (EPE T&D).
Name:
Dennis H. Malone
Title:
Manager, System Planning
Signature:
Dennis H. Malone
Company: El Paso Electric Company
Date:
Short Circuit Analysis for a
Generation Interconnection Facilities Study
For Proposed Generation at Newman 115 kV Bus
14
El Paso Electric Company
May 2003