Transcript Dynamic Transfer Limits Study WIST Update 12/17/09

Dynamic Transfer Limits Study
WIST Update 12/17/09
Brian Tuck, BPA
Purpose of Dynamic Transfer Limit Study
• Assess the operational impacts and cost-effectiveness of using
dynamic transfers to support wind integration
• Reliability Concerns: No repeat of previous reliability problems
resulting from rapid, continuous changes in power flow.
• Operational Concerns: Care must be taken to reasonably assure
that system operators have the tools, skills, and information for real
time operations.
• Joint Concerns: The wide impact of rapidly changing flows are
likely to impact PNW systems adjoining BPA as well, possibly
requiring greater coordination of procedures, voltage control, and
other real-time activities by system operators of neighboring utilities.
Dynamic Transfer Limit Study Goals
•
Effect of Variability and Uncertainty on Path Operation
– What is “normal” variation? This study looks at how the system is operated and
system security is maintained as the system varies in real-time.
– How does continued development change the aggregate characteristics across
critical paths?
•
Dynamic Transfer Limitations for the Existing System
– What impact can be tolerated and how does that translate into dynamic transfer
limitations?
– Identify limiting concerns and interactions
– Develop a new performance criteria and method for analyzing dynamic transfer
effects.
– Develop a methodology for determining dynamic transfer limits across a path.
•
Increasing Dynamic Transfer Capability
– Evaluate operational improvements and system reinforcements that increase the
available dynamic transfer capability across paths.
– Identify upgrades and assess cost-effectiveness of implementation.
Limiting Concerns and Interactions
• Direct Effects
Electrical parameters interact: MW, MVAr, kV, topology (X) -- Ohm’s Law
– Voltage Sensitivity Measures and Criteria
• Voltage sensitivity will vary with path loading, area load, and reactive support
from nearby machines.
• The allowed MW variation can be calculated for a given operating voltage
range
– Measuring Dynamic Reactive Support
• FCRPS Dynamic Reactive Support requirements
• Switching duty on reactive elements.
• Indirect Effects
Electrical changes require Operator actions, or decisions, to take place
– Real-time Control / manpower impacts
• RAS arming – impact varies with path loading
• System Operator visibility and situational awareness
• Nomogram Interactions
Establishing the Dynamic Transfer Limit
• Dynamic Transfer Limit (DTL) =
– is the Variability our current systems can accommodate,
– less an amount set aside to accommodate historical use,
– less a margin for reliability
DTL = (Variability Limit) – (Historical Use) – (Reliability Margin)
• “Historical use”: estimate of variability based on actual SCADA data
across the path
– SCADA is used where the historical use cannot be easily tied to specific
arrangements for dynamic transfer
– Using SCADA as of 11/09.
• Reliability Margin
– Additional margin used to cover for uncertainties.
– May vary with path
Calculating the Variability Limit
• Theory
– Based on existing voltage stability
fundamentals
• Optimization Methods
– Optimization used to address simultaneous
interactions
– Automation to increase the number of
scenarios and begin monitoring real-time
cases
Using the PV curve to calculate System
Variability
dV
dP
Allowed
voltage
variability
Dynamic MW Range
Why Optimize?
• There are multiple paths to study and they interact with
each other
– Wind generation in the Columbia Gorge will affect many paths
such as COI, Idaho to NW and Montana to NW
• Bus voltages are impacted by different path flows
• Based on the current conditions one may want to restrict
the amount of dynamic transfer. For example if the bus
voltage is below the limit we do not want the dynamic
transfer to pull the voltage further down.
• Different topology and system condition can change the
dynamic transfer rating
• The goal is to maximize the Dynamic Transfer Limits for
different paths
Optimization Problem
• Objective: Maximize the Dynamic Transfer
Limits for different paths
– Max(DT1, DT2,………)
• Same time the bus voltages within NW
should not change more than
– 5 KV for 500 KV and 345 KV buses and
– 3 KV for 230 KV and 115 KV buses
• Any optimization technique can be used to
solve the above problem
Optimization Problem
Objective
Max ∑ DTi * DTi
i = 1 to n paths
Subject to
ΔVk ≤ 5 KV for 500 KV and 345 KV buses
k = 1 , m buses (all the 500 KV and 345 KV buses)
ΔVl ≤ 3 KV for 230 KV and 115 KV buses
l = 1 , p buses (all the 230 KV and 115 KV buses)
Where
DTi = Path i Dynamic Transaction Value
ΔVk = Bus voltage change at bus k due to dynamic
transfers
Optimization Setup
• 2009-2010 Heavy Winter
Operations case
• POR-POD for 4
interconnections
– NI: BCTC Hydro – LC
Wind (JDA, MCN)
– IPC: Hells Canyon – LC
Wind
– NWE: Colstrip – LC Wind
– COI: LC Wind - NCAH
W
Optimization Results
Test
COI
COI
NI
NI
NWE
NWE
IPC
IPC
IPC
Case
COI
1
2
3
4
5
6
7
8
9
Critical Buses
Test
Case
BCTC-US NWE-PNW
IPC-PNW
COI
4800
-1682
-913
12
4156
-1682
-909
-31
4106
-2606
-920
-31
4090
-3088
-925
-32
4141
-1682
-1512
-26
4125
-1682
-1917
-51
4090
-1682
-974
-606
4123
-1682
-824
881
4101
-1682
-808
1212
COI
BCTC-US NWE-PNW
IPC-PNW
COI
COI
NI
NI
NWE
NWE
1
2
3
4
5
6
4800
4156
4106
4090
4141
4125
-1682
-1682
-2606
-3088
-1682
-1682
-913
-909
-920
-925
-1512
-1917
IPC
IPC
IPC
7
8
9
4090
4123
4101
-1682
-1682
-1682
-974
-824
-808
BCTC-US
531
685
700
717
681
688
518
818
722
NWE-PNW IPC-PNW
210
121
813
365
120
961
251
119
963
223
107
816
367
103
971
368
97
974
386
0
524
379
65
517
389
43
211
COI
BCTC-US
678
685
NWE-PNW IPC-PNW
357
359
219
203
990
991
COI
SMLK 500
BKLY 500
SMLK 500
SMLK 500
SMLK 500
SMLK 500
SMLK 500
BCTC-US
NWE-PNW IPC-PNW
COI
BCTC-US
NWE-PNW IPC-PNW
CUST 500
CUST 500
CUST 500
CUST 500
CUST 500
GARR 500
GARR 500
GARR 500
GARR 500
GARR 500
GARR 500
SMLK 500
SMLK 500
CUST 500
CUST 500
GARR 500 RNDUP 230
GARR 500 RNDUP 230
-606 SMLK 500
881 SMLK 500
1212 SMLK 500
CUST 500
CUST 500
CUST 500
HURR 230
GARR 500 LGND 230
GARR 500 HURR 230
12
-31
-31
-32
-26
-51
RNDUP 230
RNDUP 230
RNDUP 230
RNDUP 230
RNDUP 230
RNDUP 230
Historical Use of Dynamic Transfers
• Where are we starting from?
• Historically, the system has been operated in a fairly static manner
– Moment to moment changes are typically very small
• Dynamic Transfer types
–
–
–
–
BCTC – CISO: dynamic transfers wheeled across the BPA system
Regulation for load following
NWPP Reserve Sharing
Accounting for small changes in generation at thermal plants
• Expanding the use of dynamic transfers to accommodate self-supply
and other uses
– New applications of dynamic transfers
– Potential to vastly increase the number of dynamic transfers
North Of Hanford Existing Use
North of Hanford Historical Variability
400
350
MW rate of change, based on 5 min
increments
• Historical Variation
calculated using archived
SCADA values
• 99% of the time, the 5
min variation is less than
200 MW
• Flattens Quickly: 80% of
the time dispatchers see
less than 50 MW
• What point captures
“historical variability”?
300
250
200
150
100
50
0
80% 81% 82% 83% 84% 85% 86% 87% 88% 89% 90% 91% 92% 93% 94% 95% 96% 97% 98% 99% 100%
Cumulative Distribution
Date 1/1/2003-6/30/2003
Date 1/1/2006-6/30/2006
Date 1/1/2009-6/30/2009
Northern Intertie Existing Use
Northern Intertie Historical Variability
400
350
MW rate of change, based on 5 min
increments
• Using SCADA to estimate
historical use is less
applicable due to the
existing dynamic
arrangement and the
radial nature of the path
• 99% of the time, the 5
min variation is less than
200 MW
• Situational Awareness
Issue: 80% of the time
dispatchers see less than
50 MW
300
250
200
150
100
50
0
80% 81% 82% 83% 84% 85% 86% 87% 88% 89% 90% 91% 92% 93% 94% 95% 96% 97% 98% 99% 100%
Cumulative Distribution
Date 7/1/2004-12/31/2004
Date 7/1/2008-12/31/2008
Date 7/1/2009-11/28/2009
- Example North Of Hanford DTL
•
DTL = (Studied Variability Limit) – (Historical Use) – (Reliability Margin)
• DTL = 500 MW – 200 MW – 100 MW = 200 MW
– Dynamic Transfer Limit: 200 MW
• Outages or other system conditions could reduce the DTL, as realtime reliability concerns demand
Available DTL (based on dV/dP analysis)
NOH Dynamic Transfer Limit
1400
Sickler
1200
DTC limited by RAS
Arming
Maximum DTC Limit
1000
NOH effects NJD
800
Historical Use
600
400
200
Normal
Variability
0
-4000
-3000
-2000
-1000
S-N
0
NOH Actual Transfer
1000
2000
N-S
3000
4000
Wind Historical Variations
Top 5 Single Largest Daily Positive (UP) Ramps
Top 5 Single Largest Daily Negative (DOWN) Ramps
60-Min Horizon
By MW
60-Min Horizon
By PerCent of Capacity
By MW
60-Min
Ramp as
PerCent of
Capacity
By PerCent of Capacity
Date
60-Min
Ramp
MW
5/2/2009
1143.6
66.7%
6/4/2009
-886.6
5/6/2009
1139.9
3/20/2008
1301.0
850.9
65.4%
6/11/2008
-729.3
12/29/2008
1065.8
3/7/2008
1301.0
747.8
57.5%
11/6/2009
5/10/2009
1047.5
5/2/2009
2105.0
1143.6
54.3%
6/4/2009
1037.2
5/6/2009
2105.0
1139.9
54.2%
Wind
Date Capacity
12/29/2008 1599.0
60-Min
Ramp
MW
1065.8
Date
60-Min
Ramp
MW
Date
6/11/2008
Wind
Capacity
1496.0
60-Min
Ramp MW
-729.3
6/4/2009
2105.0
-886.6
-42.1%
-723.4
6/21/2008
1496.0
-628.4
-42.0%
11/7/2009
-669.7
3/7/2008
1301.0
-509.7
-39.2%
6/21/2008
-628.4
10/2/2008
1496.0
-524.2
-35.0%
30-Min Horizon
By MW
By MW
30-Min
Ramp as
PerCent of
Capacity
By PerCent of Capacity
Date
30-Min
Ramp
MW
5/2/2009
816.4
50.8%
6/11/2008
-739.1
12/29/2008
806.2
12/29/2008
1599.0
806.2
50.4%
6/4/2009
-581.2
10/17/2009
788.1
3/2/2009
1871.0
767.0
41.0%
10/17/2009
3/2/2009
767.0
5/2/2009
2105.0
816.4
38.8%
5/10/2009
756.8
3/28/2008
1301.0
485.1
37.3%
30-Min
Ramp
MW
661.4
Date
30-Min
Ramp
MW
Date
30-Min
Ramp as
PerCent of
Capacity
6/11/2008
Wind
Capacity
1496.0
30-Min
Ramp MW
-739.1
6/21/2008
1496.0
-454.7
-30.4%
-535.3
6/4/2009
2105.0
-581.2
-27.6%
11/7/2009
-500.9
8/17/2008
1496.0
-406.9
-27.2%
7/12/2009
-476.8
1/4/2008
1301.0
-333.3
-25.6%
5-Min Horizon
By MW
-48.8%
30-Min Horizon
By PerCent of Capacity
Wind
Date Capacity
3/20/2008 1301.0
60-Min
Ramp as
PerCent of
Capacity
-49.4%
5-Min Horizon
By PerCent of Capacity
By MW
Date
5-Min
Ramp
MW
Date
5-Min
Ramp as
PerCent of
Capacity
Date
5-Min
Ramp
MW
11/22/2009
420.8
6/11/2008
-724.4
6/11/2008
11/5/2009
318.6
11/22/2009
2284.0
420.8
18.4%
7/12/2009
-388.0
3/7/2009
1871.0
-376.5
-20.1%
10/2/2008
313.7
1/16/2008
1301.0
203.0
15.6%
3/7/2009
-376.5
10/2/2008
1496.0
-295.4
-19.7%
10/17/2009
307.6
3/20/2008
1301.0
191.4
14.7%
11/5/2009
-369.2
7/12/2009
2105.0
-388.0
-18.4%
5/2/2009
236.2
8/17/2008
1496.0
214.0
14.3%
9/3/2009
-365.3
8/17/2008
1496.0
-274.2
-18.3%
Wind
Date Capacity
10/2/2008 1496.0
5-Min 5-Min Ramp
Ramp as PerCent of
Capacity
MW
313.7
21.0%
By PerCent of Capacity
Wind 5-Min Ramp
Capacity
MW
1496.0
-724.4
-48.4%
800
Ramps UP
WIND GENERATION RAMPS: FEB 12-MAR 21, 2009
Based on 1-Minute Total BPA Wind Gen Data
Ramps at 5Min, 15Min, and 30Min Intervals
This 6-week period had a stable Wind Capacity of 1871 MW
700
600
500
5Min MW Ramp
15Min MW Ramp
30Min MW Ramp
400
300
MW
200
100
0
-100
-200
-300
-400
Ramps DOWN
-500
0%
10%
20%
30%
40%
50%
60%
70%
PerCent of Time Observed Ramps At or Above Plotted Value
80%
90%
100%
800
750
WIND GENERATION RAMPS: FEB 12-MAR 21, 2009
Based on 1-Minute Total BPA Wind Gen Data
Ramps at 5Min, 15Min, and 30Min Intervals
This 6-week period had a stable Wind Capacity of 1871 MW
Ramps UP
700
650
600
5Min MW Ramp
15Min MW Ramp
30Min MW Ramp
550
This is the UPPER 5% of the distribution (UP Ramps)
500
MW
450
400
350
300
250
200
150
100
50
0
0.0%
0.5%
1.0%
1.5%
2.0%
2.5%
3.0%
3.5%
PerCent of Time Observed Ramps At or Above Plotted Value
4.0%
4.5%
5.0%
95.0%
0
95.5%
96.0%
96.5%
97.0%
97.5%
98.0%
98.5%
-50
-100
-150
MW
-200
-250
WIND GENERATION RAMPS: FEB 12-MAR 21, 2009
Based on 1-Minute Total BPA Wind Gen Data
Ramps at 5Min, 15Min, and 30Min Intervals
This 6-week period had a stable Wind Capacity of 1871 MW
-300
-350
5Min MW Ramp
15Min MW Ramp
30Min MW Ramp
This is the LOWER 5% of the distribution (DOWN Ramps)
-400
-450
Ramps DOWN
-500
PerCent of Time Observed Ramps At or Above Plotted Value
99.0%
99.5%
100.0%
Outstanding issues
• How will planned (1-3 years) wind projects effect dynamic transfers?
– Complete analysis of wind project variability relationship to location and
capacity.
• Establish DTL for all paths
– Finalize methodology for variability limit and “historical use”
– Complete analysis of light load scenarios (varations of load, generation
pattern, outages, etc.)
• Continue development of the optimization tools and processes
– Monitor and archive based on state estimator cases
– Include reactive switching actions and dynamic reactive support in
optimization
• Increasing the capability
– Identifying locations that require additional support for dynamic transfers
-Appendix –
Dynamic Transfer Definitions
• Many of these definitions cited are from
the NERC Dynamic Transfer Guide
Dynamic Transfer Limit Definitions
– Dynamic Transfer: A dynamic transfer contractually allows a resource to
continuously ramp over a pre-determined range. It may be implemented as either
a dynamic schedule, or a combination of pseudo-tie and dynamic schedule.
– Dynamic Transfer Limit: The maximum allowed deviation of actual MW flow
from schedule and the maximum continuous ramp rate allowed.
– Dynamic Transfer Limit Methodology: A systematic, repeatable evaluation of
the costs and capability to accommodate dynamic wheeling across the FCRTS
– Dynamic Schedule: A dynamic schedule represents a power transfer between
two separate Balancing Authorities. The real-time value associated with the
scheduled power transfer is treated as the interchange schedule in the ACE
equation. Like other schedules, a dynamic schedule is a reserved use of
transmission.
– Pseudo-Ties: A pseudo-tie is commonly used to represent generation or load
remote to the controlling Balancing Authority, but assigned dynamically between
balancing authorities. It is treated as actual interchange in the ACE equation.
The operational and jurisdictional responsibility for the generation or load rests
with the controlling Balancing Authority, as if the remote resource was connected
within the controlling BA transmission footprint. The pseudo-tie provides a
mechanism for control and shifting of ancillary service responsibility. It is not a
reserved use of transmission.
Dynamic Transfer Limit Definitions
– RAS: Remedial Action Schemes (in the NERC glossary, these are also known
as Special Protection Schemes). Method of gaining transmission capacity
through automatic post-contingency control actions (e.g. tripping generation,
inserting capacitors, etc.)
– SCADA: Supervisory Control and Data Acquisition. Used by Transmission
Operations System Operators to monitor and control the transmission system.
– WIST: Wind Integration Study Team. A component of Columbia Grid and
Northern Tier Transmission Group that is providing technical peer review of the
BPA Dynamic Transfer Limit Study.
– RODS: Real Time Operations and Dispatch System. An accounting and control
application that is used as a link between the Transmission Scheduling systems
and the Automatic Generation Control application.
– DSS: Dynamic Scheduling System. An application currently being supported
and developed by the Joint Initiative participants. The DSS is intended to provide
a common dynamic communication infrastucture and protocol that will allow
participating entities to purchase or sell capacity and energy on a dynamic basis.
– MVAR: The portion of electricity that establishes and sustains the electric and
magnetic fields of AC transmission equipment. Reactive power is provided by
generators, synchronous condensers, or capacitors and directly influences
system voltage.