NWQ Joint Security Study Updated:2013-04-24 15:52 CS
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Transcript NWQ Joint Security Study Updated:2013-04-24 15:52 CS
Northwest Quadrant
Joint Security Study
Southern Company Headquarters
Birmingham, Alabama
August 12, 2002
Presented by Saeed Arabi
Outline
Scope
Assumptions
Results
Proposed Solutions
Powertech Labs Inc.
2
Joint Security Study Scope
•
Identify critical contingencies and constraints
Scanning about two-thirds of the State of Alabama, the
extreme northwest portion of Georgia, and a small portion
of eastern Mississippi
Determine generation limits for various system
conditions
Define the boundary of the security problem
•
•
Sensitivities
Worst-case scenario
Propose solutions to stability constraints
Powertech Labs Inc.
3
Joint Security Study Assumptions
•
•
•
•
•
•
•
2003 peak and 50% of expected peak (off-peak) load
level cases used
Off-peak case based upon economic dispatch
PSS assumed to be available on all new units
New units were added to the NWQ according to a
joint queue developed by the 3 companies
Firm Transmission Service confirmed
Firm Transmission Service requested
Interconnection confirmed
Interconnection requested
To validate stability results, “hypothetical” thermal
upgrades were added to relieve thermal constraints.
Not a thermal study!
Powertech Labs Inc.
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Joint Security Study Assumptions
(cont)
Four “Normal” source/sink scenarios
•
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EST-EST: Sink generation in the company territory where it is
located
EST-E: Sink generation in Entergy
EST-S: Sink generation in Southern
EST-T: Sink generation in TVA
One “Worst” source/sink scenario
•
EST_W-S: Source ordered by TDF
Do not violate interface capacities of 3 companies
Powertech Labs Inc.
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Joint Security Study Assumptions
(cont)
Standard criteria used
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Used each company’s current and voltage ratings and limits
Voltage collapse margin: 5%
Transient voltage dips: 75% for < 40 cycles
Minimum damping: 3%
Fault clearing margin: 2 cycles
Combinations of constant power, current, and
impedance load models used
Powertech Labs Inc.
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Joint Security Study Results
The most limiting contingency from a damping standpoint
was the Miller - Bellefonte 500 kV line (Line tripping event)
The most limiting contingency from a transient voltage
dip standpoint was the Farley – Raccoon Creek 500 kV
line (Normally cleared 3ph fault)
The most limiting normal scenario identified was EST-S
(Sinking to Southern under off-peak conditions)
SVC will raise stability limit some – Big increases will
require 500 kV lines
Powertech Labs Inc.
7
Joint Security Study Results (cont)
New generation added without PSS severely deteriorated
Table 3-2
w/ PSS
w/o PSS
system damping: PSS required
EST-S
>9500
0
Limit is very source/sink dependent: Sequential studies
required
5625 MW “Normal” limit based on the joint EST Queue
3500 MW “Worst” limit based on TDF of Farley-Raccoon
Line (Limits are above year 2000 generation)
Line re-conductoring had small impact on security limits
Powertech Labs Inc.
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Joint Security Study Results (cont)
Buf.
Case
Scenario
Contingency
1
2
3
4
50% of 2003 Expected Peak Load.
50% of 2003 Expected Peak Load.
50% of 2003 Expected Peak Load.
50% of 2003 Expected Peak Load.
EST-EST Without PSS for IPP&NLs
EST-E Without PSS for IPP&NLs
EST-S Without PSS for IPP&NLs
EST-T Without PSS for IPP&NLs
15: 94600-96280
15: 94600-96280
15: 94600-96280
15: 94600-96280
Bus voltage magnitude (pu)
1.250
1.000
Bus #
Bus Name
Buf.
90218
90218
90218
90218
S BAINBR230.
S BAINBR230.
S BAINBR230.
S BAINBR230.
1
2
3
4
Buf.
Case
Scenario
Contingency
1
2
3
4
50% of 2003 Expected Peak Load.
50% of 2003 Expected Peak Load.
50% of 2003 Expected Peak Load.
50% of 2003 Expected Peak Load.
EST-EST With PSS for IPP&NLs
EST-E With PSS for IPP&NLs
EST-S With PSS for IPP&NLs
EST-T With PSS for IPP&NLs
15: 94600-96280
15: 94600-96280
15: 94600-96280
15: 94600-96280
Bus voltage magnitude (pu)
1.250
0.750
Bus #
Bus Name
Buf.
90218
90218
90218
90218
S BAINBR230.
S BAINBR230.
S BAINBR230.
S BAINBR230.
1
2
3
4
1.000
0.500
0.750
0.250
0.500
0.000
0.000
4.000
8.000
12.000
16.000
20.000
Time in seconds
0.250
0.000
0.000
4.000
8.000
12.000
16.000
20.000
Time in seconds
Powertech Labs Inc.
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Joint Security Study- Proposed Solutions
Dynamic shunt compensation can increase the transient
security limit by 1400 – 2150 MW (In South Bainbridge and Auburn
regions)
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Minimal increase after 900 Mvar added
230 kV re-conductoring and static capacitors would be required
Cost of SVC: Approximately $5 million per 100 Mvar
Series compensation was evaluated, but found to not be
an effective solution
•
Candidate lines were already heavily loaded
Powertech Labs Inc.
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Critical Path Limits With Shunt
Compensation
Table 4-2: Shunt Compensation and EST–S Scenario Limits (MW) – Various Phenomena
for Contingency 15 (Critical Path Highlighted).
Shunt Compensation by MSC & TSC (MVAr)
0 &
0
300 &
100
200 &
300
400 &
500
300 &
700
200 &
900
Voltage Magnitude
(0.9 pu)
4,300
7,000
7,000
7,700
8,350
8,350
Transient Security
(Voltage Dip)
5,625
6,670
6,840
7,209
7,589
7,774
Thermal *
(at 120% Loading)
7,150
7,250
7,250
7,600
7,600
7,600
Voltage Stability
(with 5% Margin)
7,728
8,678
8,692
8,820
8,868
8,868
Limit Type
Powertech Labs Inc.
* Not representative of thermal studies for specific transfers.
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Questions?
Powertech Labs Inc.
12
Northwest Quadrant
Powertech Labs Inc.
13
Background
Southern company internal studies indicated ~5000
MW of new generation above year 2000 before
transient stability limit reached
~20,000 MW of new generation requests in the NWQ
Joint study initiated with Powertech Labs last summer
Entergy and TVA included in the study and model
TSR facility studies on hold pending the results of the
joint study
Powertech Labs Inc.
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