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.
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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.
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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
•
•
•
•
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
•
•
•
•
•

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.
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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)
•
•
•
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.
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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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