Reliable Power
RAS Guideline Initiative
Reliable Markets
March 23, 2009
Reliable People
RAS Initiative Background
• Proposed Transmission Constraint Management (TCM)
rules manage real time congestion through system controller
action
– AUC decision pending
– If TCM rules approved, OPP’s will follow and system controller tools
will be built
– In the interim, OPP revisions or additions will align with TCM
proposal as far as practical
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RAS Initiative Background
• A Remedial Action Scheme (RAS) is designed to protect
system facilities without the need for system controller
intervention
– AESO committed to provide more formal documentation of RAS
policies and procedures
– RAS initiative will explore the need for RAS rules and discuss the
content of the RAS guideline seeking stakeholder feedback on
improvements to or clarification of the policies and procedures
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What is RAS?
• ISO Rule RAS Definition:
• RAS means a control system that makes automatic adjustments to power system
elements in order to preserve system reliability
• RAS can be categorized into two broad types:
– Interconnection RAS
• A RAS requirement that arises from a customer interconnection application which
is usually removed when needed facilities are built
• The potential RAS rules are expected to be directed toward interconnection RAS
only
– System RAS
• A RAS requirement that arises from changes to the AIES that develop over time
• System RAS requires a more flexible approach to creating solutions as it is more
unique, often permanent and is generally paid for by load
• RAS Guideline will provide some discussion and examples of system RAS
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RAS Legislative Authority
Transmission Regulation requirements:
• plan for 100% in merit energy under normal conditions
• non-wires solutions (RAS) allowed as a temporary solution
EUA duties:
• safe, reliable and economic operation
• Supports technical RAS requirements
• FEOC market
• Influences RAS polices and procedures
RAS must be used in a manner which is consistent with the Act, any
other obligations set out for the ISO in legislation, the ISO rules and
any other applicable Authoritative Document.
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RAS Documentation Format
• Potential RAS rules:
• Some aspects of RAS policy and procedure may belong in an ISO rule
• Regulatory authority
• Technical requirements
• Operational implementation
• Supporting RAS documentation:
• Most aspects of RAS policy and procedure are informational and may
not belong in the rules
• Some RAS policies may either be addressed in rules or outlined in an
informational format
• The term “guideline” may be too formal for the information document as
the contents may be best maintained outside the rules process
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RAS Policy Issues
• Interconnection RAS and transmission rights
• Constraints caused by interconnections often can not be dealt with by
the system controller in real time
• RAS is intended to be proactive allowing early interconnection
• RAS is assigned to and generally paid for by the interconnecting
customer
• Alternatively, system operating limit derates may be required which
manage the constraint in advance among existing and new generation
sources
• Early interconnection needs to balanced with fairness to existing
generators in the area and the AESO duties to operate the system
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RAS Policy Issues
• Interconnection RAS and real time operation
• Interconnection RAS operates automatically at preset levels to protect
system facilities
• Under the proposed Transmission Management Constraint rules, after a
RAS has been activated, the system controller will apply the TCM
protocol using RMO and pro-rata to allocate the constraint mitigation
among effective generators in the area; this is a change from past
practises
• Interconnection RAS generators have on occasion requested that
whenever possible the system controller issue curtailment instructions to
proactively prevent RAS activation; the AESO will need to consider
whether it is still appropriate to offer this service
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Energy Market Life Cycle Stage
RAS Guideline
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Next Steps
• Market Services stakeholder meeting March 23
• Discussion paper
• Complete internal reviews and publish in April
• Stakeholder comments will be requested
• Recommendation paper
• Discussion paper stakeholder comments will be reviewed and a set of
recommendations put forward for further comment
• ISO Rule process
• Potentially promote RAS rules thru the October rules process
• RAS guideline document would be developed in a parallel work stream
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