Operating
Procedure
Flexible Ramping Constraint
(New)
Procedure No.
Version No.
Effective Date
2250
1.1
1/31/14
Distribution Restriction:
None
Table of Contents
Purpose........................................................................................................................................... 1
1. Responsibilities ...................................................................................................................... 2
2.
Scope/Applicability .............................................................................................................. 2
2.1 Background ................................................................................................................... 2
2.2 Scope / Applicability..................................................................................................... 2
3. Procedure Detail.................................................................................................................... 3
3.1 Flexi-Ramping Capacity Require- ments..................................................................... 3
3.1.1 Require- ments Description .............................................................................. 3
3.1.2 Adjusting Require- ments ................................................................................. 3
4. Supporting Information ....................................................................................................... 6
Operationally Affected Parties ............................................................................................ 6
References ........................................................................................................................... 6
Definitions........................................................................................................................... 6
Version History ................................................................................................................... 7
5.
Periodic Review Procedure ................................................................................................. 7
Review Criteria ................................................................................................................... 7
Frequency............................................................................................................................ 7
Incorporation of Changes .................................................................................................... 7
Manager Approval ........................................................................................................................ 8
Director Approval ......................................................................................................................... 8
Appendix ........................................................................................................................................ 8
Attachment: None ............................................................................................................... 8
Purpose
Provides guidelines for the process, considerations and methodology for
setting the requirement for the flexi-ramping nomogram in the real-time
market.
Page 1 of 8
Operating
Procedure
Flexible Ramping Constraint
(New)
1.
2250
1.1
1/31/14
Distribution Restriction:
None
Responsibilities
Generation
Dispatcher
Shift
Supervisor
Renewable
Resource
Coordinator
2.
Procedure No.
Version No.
Effective Date
Estimate the quantity of the flexible ramping capacity for
each applicable CAISO Market run
Provide information to the generation dispatcher on upcoming events that may impact system ramping.
Provide Generation Dispatcher updates on weather and
other conditions that may impact the availability and or the
energy supply from intermittent resources.
Scope/Applicability
2.1 Background
2.2 Scope /
Applicability
The flexi-ramping nomogram is a constraint used in the Real Time markets.
The CAISO may enforce an upward Flexible Ramping Constraint in HASP
and RTPD (HASP, RTUC) and then RTD (RTED). If implemented in RTPD,
meeting the Flexible Ramping Constraint provides a minimum amount of
ramping capacity that can be ramped up in 10 minutes. A portion of the flexiramping capacity procured in RTPD and made available for RTD is protected
in future (advisory) RTD intervals (not the binding interval) of each RTD run.
All available ramping capacity including the ramp provided by the Flexible
Ramping Constraint is made available for balancing supply and demand in
RTD binding intervals.
The minimum requirement can be adjusted by ISO operators to meet the
operational needs in real-time based on forecast load changes, system
resource availability, potential intermittent resource volatility, system and
market conditions.
Page 2 of 8
Operating
Procedure
Flexible Ramping Constraint
(New)
3.
Procedure No.
Version No.
Effective Date
2250
1.1
1/31/14
Distribution Restriction:
None
Procedure Detail
3.1 Flexi-Ramping
Capacity
Requirements
The requirements for upward flexi-ramping capacity in RTPD are as
follows:
• Base requirement: 300 MW
• Normal range: 300 MW to 400 MW
• Maximum: 600 MW
3.1.1 Requirements
Description
Description
Base Requirement:
The base requirement of 300 MW shall be in place as a default setting in
the real-time market software for RTPD. This is the HASP and RTPD
minimum requirement for the Flexible Ramping Constraint. The default
setting may be reviewed for adjustment by the ISO’s Market Analysis and
Development (MAD) department based on flexi-ramping capacity
utilization and other market and operational considerations. In RTD the
Flexible Ramping Constraint in the binding interval is zero and increases
in advisory intervals up to ½ the HASP/RTPD requirement.
3.1.2 Adjusting
Requirements
Step
1
CAISO Renewable Resource Coordinator Actions
If there is load forecast uncertainty or a risk to intermittent
resources ability to supply energy, advise the Generator Dispatcher
of the magnitude and duration of the risk.
Page 3 of 8
Operating
Procedure
Flexible Ramping Constraint
(New)
Procedure No.
Version No.
Effective Date
2250
1.1
1/31/14
Distribution Restriction:
None
Step
2
CAISO Generation Dispatcher Actions
The Base Flexible Ramping Constraint may be increased within
Normal range under the following operating conditions:
 The normal adjustment range of 300 MW to 400 MW in RTPD/
HASP can be made by operators in the normal course of daily
real-time operations based on real-time conditions.
 A higher MW value for the Flexible Ramping Constraint is
expected to occur during large load ramping periods, periods
when there is a risk of intermittent resources ability to supply
energy as identified by the Renewable Resource Coordinator,
forecast uncertainty, and during peaking conditions when
ramping needs exist to meet load and supply uncertainty but
ramping availability may be limited.
3
The Flexible Ramping Constraint may also be increased to
Maximum range under the following operating conditions:
 Under more volatile conditions when demand and/or supply
deviates significantly or expect to deviate significantly,
operators may increase the Flexi Ramp Constraint requirement
up to 600 MW.
4
When possible, it is recommended initial adjustments to the Flexi
Ramp Constraint be done for HASP, allowing intertie energy
procurement to align with flexi-ramping procurement.
5
After the Flexible Ramping Constraint is adjusted in HASP/RTPD,
the Flexible Ramping Constraint needs to be adjusted in RTD. In
RTD the Flexible Ramping Constraint in the binding interval is
zero and increases in advisory intervals up to ½ the HASP/RTPD
requirement.
Page 4 of 8
Operating
Procedure
Flexible Ramping Constraint
(New)
Procedure No.
Version No.
Effective Date
2250
1.1
1/31/14
Distribution Restriction:
None
6
The Flexible Ramping Constraint may be turned off or reduced
under the following operating conditions:
 Excess supply conditions (Potential over generation condition)
 When there are extended periods of Flexible Ramping
Constraint infeasibility
 If the Flexible Ramping Constraint is having or is suspected of
having an impact on reliability.
 If the Flexible Ramping Constraint is suspected of using
excessive fast start resources early in the day and the remaining
available starts are anticipated to be needed later in the day.
(During a peak load period or during large load ramping
periods.)
7
The Flexible Ramping Constraint may be turned off on individual
resources when conditions indicate a resource would not be able to
provide flexi ramping. Reasons may include:
 When blocking upward A/S on a resource.
 A resource does not have the ability to provide flexi ramp due
to a constraint.
 A fast start resource that is being started and will not have a
remaining start for anticipated reliability needs later in the day.
8
When RTD is protecting flexible ramp on resources procured in
RTPD, only those resources that have been awarded flex ramp in
RTPD are protected in RTD for flex ramp.
9
After the Day Ahead market if current or previous similar day
experience indicates there may be a shortage of flexible ramping
resources available in RTD for the trade day, consult with Shift
Supervisor and consider if additional resource(s) will need to be
committed using Exceptional Dispatch. Refer to Operating
Procedure 2330C for commitment reasons.
Page 5 of 8
Operating
Procedure
Flexible Ramping Constraint
(New)
4.
Procedure No.
Version No.
Effective Date
2250
1.1
1/31/14
Distribution Restriction:
None
Supporting Information
Operationally
Shared on the Internet
Affected Parties
References
Definitions
Resources studied in the development of this procedure and that may have an
effect upon some steps taken herein include but are not limited to:
CAISO Tariff
27.10 Flexible Ramping Constraint
CAISO Operating Procedure
2330C Exceptional Dispatch Instruction
Type Codes
Unless the context otherwise indicates, any word or expression defined in the
Master Definitions Supplement to the CAISO Tariff shall have that meaning
when capitalized in this Operating Procedure.
The following additional terms are capitalized in this Operating Procedure
when used as defined below:
Flexible
Ramping
Constraint
A constraint that may be enforced in the optimization of a
given CAISO Market run to ensure that the unit
commitment or Dispatch of resources for intervals beyond the
applicable commitment or Dispatch period
provide for the availability of required capacity for Dispatch in
subsequent Real-Time Dispatch intervals as further described
in Section 27.10.
Page 6 of 8
Operating
Procedure
Procedure No.
Version No.
Effective Date
Flexible Ramping Constraint
(New)
2250
1.1
1/31/14
Distribution Restriction:
None
Version History
Version
Change
1.0
1.1
Initial document.
Changed normal upper range to 400MW
Changed maximum range to 600MW
By
Date
11/1/12
1/31/14
5. Periodic Review Procedure
Review Criteria
There are no specific review criteria identified for this procedure, follow
instructions in Procedures 5510 and 5520.
Frequency
Review as recommended in Procedures 5510 and 5520.
Incorporation
of Changes
There are no specific criteria for changing this document, follow instructions
in Procedures 5510 and 5520.
Page 7 of 8
Operating
Procedure
Flexible Ramping Constraint
(New)
Procedure No.
Version No.
Effective Date
2250
1.1
1/31/14
Distribution Restriction:
None
Manager Approval
Reviewed By Content
Expert
Operating Procedures
Program Supervisor
Day-Ahead Market
Lead
Signature
Date
1/30/14
1/30/14
1/30/14
Director Approval
Approved By
Director, System
Operations
Director, Operations
Engineering Services
Director Day-Ahead
Market and RealTime Operations
Support
Signature
Date
10/31/12
10/31/12
10/31/12
*Signed previous version only; changes to this version were minor and did not require full signature approval.
Appendix
Attachment: None
Page 8 of 8