Transcript SCED Penalty Factor 100809

SCED Power Balance Penalty
Curve
Resmi Surendran
Objective
• Explain the Power Balance Penalty Curve
• Discuss the values for the Power Balance
Penalty Curve
– MW break points
– Penalty for violation up to the MW break point
• Not to discuss the optimal mechanism for
setting scarcity pricing.
Power Balance Penalty
• System Lambda is the change in the objective
value obtained by relaxing the Power Balance
constraint by 1MW
• Power Balance Penalty is the maximum cost
paid for one addition/less MW of generation to
meet the Power Balance constraint.
SCED Constraints
• Power Balance Constraint
sum (Base Point) + under gen slack – over gen slack
= Generation to be dispatched
• Transmission constraint
sum( Shift Factor * Base Point) – violation slack ≤ limit
• Ramp Limit constraint
LDL ≤ Base Point ≤ HDL
SCED Objective
• Minimize
+ Cost of dispatching generation
integral (offer cost * MW dispatched)
+ Penalty for violating Power Balance constraint
sum (Penalty cost * violation amount)
+ Penalty for violating transmission constraint
sum (Penalty cost * violation amount)
PB Violation with no Transmission
Constraints
3500
3000
2500
$/MWh Penalty
• Only constraints active will be
System demand & ramp
• Given enough SURAMP, PB
will not be violated as long as
the aggregated offer curve
required to meet demand is
less than PB penalty
• If PB Penalty is lower than
SWCAP then PB will be
violated in SCED1 before
dispatching Resources on
Output Schedule
2000
1500
1000
500
0
0
-500
200
400
600
MW Violation
800
1000
PB Violation with Transmission
Constraints
• Gen with +ive SF
(a) SF * TC_Penalty + Offer cost
(b) PB_penatly
– If (a) > (b) - moved down for resolving constraints
– If (a) < (b) - moved up for meeting Power Balance
• Example
– Violated TC penalty $3500; 0.2 SF; $100 0ffer cost ; $500 PB penalty
– 1 MW reduction in generation will
• reduce TC violation by 0.2 MW
– will reduce objective by 0.2 * 3500 due to reduction in TC violation and $100 by not providing
1MW energy
• violate PB by 1 MW
– Will increase objective by 1* $500
Power Balance Penalty Curve Implementation
• MW break points
$ Penalty
• 10 segment step curve
– Sets amount violated for a given price
MW Violation
• Penalty for violation up to the MW break point
– Sets system lambda for a given amount of violation
Factors affecting Power Balance
Violation
• Ramp limited scenarios
– Operational Philosophies
– Extend of ramp being reserved for regulation
– Amount of capacity on Output Schedule
– Telemetry errors
• Capacity Scarcity
– Operational Philosophies
Current Power Balance Penalty
Curve Values
Over Generation Penalty ($/MWh)
MW Cap Segment (MW)
Under Generation Penalty ($/MWh)
MW Floor Segment (MW)
-3,001
10,000
3,001
10,000
-5,000
100,000
5,000
100,000
equivalent to having extra capacity for meeting power balance violation at
• (+/-) 3001 $/MWh for violated MW from 0MW to 9999.999MW, and
• (+/-) 5000$/MWh for violated MW from 10000MW to 99999.999MW
Proposed Power Balance Penalty
Curve
3500
Price
1
200
5
250
10
300
20
400
30
500
40
1000
50
2250
100000
3001
3000
2500
$/MWh Penalty
MW
2000
1500
1000
500
0
0
10
20
30
40
50
60
MW Violation
70
80
90
100
Factors Considered
•
•
•
•
•
•
Extend of regulation that can be sacrificed
Operational philosophies
System Wide Offer Cap - $3000
Interaction with transmission constraints
Interaction with proxy offer curves
Market Trials and close loop test results
Future Areas of Improvement for
Better Scarcity Pricing
• Prices not reflective of scarcity during UFR
Load Resource deployment
• Reduction in prices due to Output Schedule
adjustments during Non-Spin deployment from
Resources on Output Schedule
• Dependence on MP submitted EOC to set
scarcity pricing during Non-Spin and RRS
deployment
Appendix
SCED Objective
Min { Cost of generation dispatch + Sum ( Max Shadow Price * Slack variable)}
[ EnergyCurve Pr ice
r ,offer, seg ,t
Generation
dispatch cost
* Re sSegDispMW r ,offer,seg ,t
r ,offer, seg
 0.5 * EnergyCurveSloper ,offer,seg ,t * (Re sSegDispMW r ,offer,seg ,t )2 ]
Power Balance
Penalty Curve value
 PenaltyCost
p
Slack
Variable
p
ENG
Max Shadow
Price
Slack
Variable
* ( EnergySlackUpMWt p  EnergySlackDnMWt p +)
TranPenaltyCost
c
+
c ,t
* TranSlackMWc ,t
Slack
Variable
SCED constraints
Power Balance Constraints:
 Re sDispMW
r ,t
r
  ( EnergySlackUpMWt p  EnergySlackDnMWt p )  Load t
p
Transmission Network Constraints:
 SF
r , c,t
* Re sDispMW r ,t
 TranSlackMWc ,t  lim it c ,t
r
Resource Constraints:
0  Re sSegDispMW r ,offer, seg ,t  Re sOfferSegSizer ,offer, seg ,t
Re sDispMW r ,t
  Re sSegDispMW r ,offer, seg ,t
seg
Ramp Rate Constraints (HDL, LDL):
LDL r ,t  Re sDispMW r ,t
 HDL r ,t
Offer Mitigation for SCED2
Price
($/MWh)
Original Energy Offer
Curve
Capped Offer
Curve
Reference LMP
Mitigated Offer
Cap curve
Mitigated Offer
Floor
Quantity (MW)
0
(1)Cap the Energy Offer Curves at the greater of the Reference LMP at the
Resource Node or the Mitigated Offer Cap curve
(2) Bound it at the lesser of the Reference LMP at the Resource Node or the
Mitigated Offer Floor.
Proxy Offer Curve for Output
Schedule
Price
($/MWh)
System Wide offer cap $/MWh
System Wide offer cap - 0.01
Submitted
Output
Schedule
LSL
HSL
0
-249.99 $/MWh
Quantity (MW)
-250.00 $/MWh
Epsilon
LMP during Congestion
LMP     SF line  SP line
line
Resource moved down for congestion
Offer Pr iceunit[$ / MWh ]
max
Offer Pr iceunit
Lambda
LMP cong
LMP
cong
Punit
min
Offer Pr iceunit
Punit[MW ]
min
Punit
opt
Punit
max
Punit
LMP during Congestion
LMP     SF line  SP line
line
Resource moved up for congestion
Offer Pr iceunit[$ / MWh ]
max
Offer Pr iceunit
LMP
LMP cong
Lambda
cong
Punit
min
Offer Pr iceunit
Punit[MW ]
min
Punit
opt
Punit
max
Punit
Transmission Constraints Penalty
Current Values
• Maximum Shadow Price for Transmission
Constraints
– Base Case: $5,000/MW
– Generic constraints : $5,000/MW
– Post Contingency
• 345 kV: $4,500/MW
• 138 kV: $3,500/MW
• 69 kV: $2,800/MW