Implications of Energy-Only Procurement on Transmission Planning

CPUC Workshop: Revisions RPS Calculator v6.0

Robert SparksManager Regional Transmission - SouthFebruary 11, 2015

Implications of Energy-Only Procurement on Transmission Planning

• The ISO fully supports procurement and planning for energy only generation

• We have been asked to comment on the potential implications of this, so that we ensure successfully meeting the renewable goal

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Deliverability Overview

• FCDS generation– assumed to displace other

remotely located FCDS– does not mean that the new

generation can be delivered to the major load pockets.

– still expected to result in congestion.

• EO generation– generation displacing other

nearby generation. – expected to substantially

add more congestion to the system

FCDS

FCDS

Load

FCDS

EO

Load

All Resources Fully Deliverable

Combination of Fully Deliverable & Energy Only Resources

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Transmission Planning

• Traditionally, transmission planning in California focused on the summer peak load level with all transmission facilities in-service

• Allows transmission facilities to be removed from service for maintenance or upgrades during lower load period

• It also allows local generation capacity to be unavailable for maintenance conditions during the lower load period

• Transmission and generation capacity planning have been closely aligned.

• Generation planning appears to be changing direction

• Realigning transmission planning adds considerable complexity to the already complex transmission planning challenge.

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Energy Only Transmission Planning

• Need much more focus on studies of the transmission system under lower load periods with transmission facilities out for routine maintenance or upgrades.

• Deliverability study process assumes all lines are in-service.

• Production simulation studies do not monitor the underlying subtransmission system.

• Reliability studies focus on worst case conditions which in the past are a much more limited set of system operating conditions than what can be expected in a future where generation planning is based on energy

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Transmission Planning and System Operations

• The ISO market and system operating procedures have been proven to work very well under the conditions as they are currently planned

• Transmission planning is typically based on the assumption that the market and system operating procedures will be able to accommodate the system that will exist in the future

• The ISO and transmission and generation operators obviously need to ensure that this happens

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33% Transmission Plan

• Based on renewable generation also contributing to capacity needs, and we have done that successfully to plan on getting to 33%

• Resulted in the need for much less new transmission than many in the industry expected

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Energy Planning & Procurement

• Adds considerable complexity• ISO is committed to supporting this approach. • Expected to be iterative. • Production simulation models are reasonably accurate

only when they are analyzing system operating conditions that have been thoroughly studied using detailed powerflow and stability study models

• Generation needs to be studied as a portfolio to reasonably estimate how much of the energy can be expected to be delivered from a particular zone

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