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Nodal Pricing in an LMP Energy Market

APEX 2005 Annual Conference

Orlando, FLOctober 31, 2005

Stu BreslerGM, Market Operations PJM Interconnection, LLC

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What is LMP?

• Pricing method PJM uses to …– price energy purchases and sales in PJM Market– price transmission congestion costs to move energy

within PJM Control Area• Physical, flow-based pricing system

– how energy actually flows, – NOT contract paths

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Definition: Locational Marginal Pricing

Transmission Congestion

Cost

Transmission Congestion

Cost=

Generation Marginal

Cost

Generation Marginal

CostLMPLMP + +

Cost of Marginal

Losses

Cost of Marginal

Losses

Cost of Marginal Losses is not currently implemented

Cost of supplying next MW of load at a specific location, considering generation marginal cost, cost of

transmission congestion, and losses.

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Managing Congestion on the Power Grid

• LMP is not a new concept to power system operators. For many years, system operators have managed congestion using least-cost security constrained dispatch which are the same programs that calculate LMP.

• The PJM LMP-based market provides an open, transparent and non-discriminatory mechanism to manage transmission congestion under open transmission access.

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PJM LMP Implementation

• Least-cost security-constrained dispatch optimizes energy and reserves and calculates unit specific dispatch instructions for the next five-minute period. (ex-ante dispatch)

• LMP values calculated every five minutes based on actual generation response to dispatch instructions that were sent in the previous five minute period. (ex-post pricing)

• Real-time performance monitoring software determines if generator is following dispatch instructions.

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Keys to Locational Pricing

• Keys to successful implementation of locational pricing:– Prices must be consistent with dispatch

instructions.– Prices must be made readily available to

participants in real time.– Participants must have certainty that prices will not

change once finalized.• PJM ensures these objectives are met by:

– Posting real time prices every 5 minutes on its eData application.

– Maintaining a rigorous LMP verification process.

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eData Main Screen

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Nodal vs. Zonal Pricing

• Consistency between pricing and dispatch is critical.

• In the absence of this consistency, supplemental settlement accommodations must be made to preserve the incentive for generators to follow dispatch instructions.

• Correct price signals must also be seen by loads in order to support other long-term initiatives based on locational pricing such as economic transmission planning.

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Nodal vs. Zonal Pricing

• Zonal pricing cannot result in accurate price signals for all constrained conditions.

• Constraints that should cause prices to split within a pricing zone will result in inaccurate prices for a portion of the zone.

• While it may be possible to define zones that correctly capture all constraints at a given instant, the zones will need to be continually redefined as system conditions evolve, leading to participant uncertainty.

• The following actual PJM market results illustrate how significantly prices can vary within a zone due to certain transmission constraints.

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Intra-Zonal Congestion Examples

PSEGMax $683.74Min -$275.07

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Intra-Zonal Congestion Examples

AEPMax $97.21Min $56.46

DUQMax $70.45Min $24.43

DOMMax $127.33Min -$39.64

APSMax $135.81Min $26.40

PSEGMax $683.74Min -$275.07

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Hubs and Zones in a Nodal Market

• An LMP Market with nodal pricing can also include overlying trading hubs and zones to provide standard energy products for the commercial markets.

• These hubs and zones, however, must be a standard compilation of individual nodes for participants to have certainty regarding their definitions.

• The settlement scheme must also allow for “carve-outs” from the zonal aggregations to accurately model retail choice arrangements.

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Questions?