Real-Time Constraint Marginal Values (Settled)

Which five-minute transmission constraints bound in PJM's real-time dispatch and what each cost: the monitored facility, the contingency facility, and the shadow price.

Congestion & Constraints data PJM market

Query with the agent

Native record

event_time x monitored_facility x contingency_facility

hourly ingest, ~20h publication lag publication cadence

Evidence

Observed market data

Published observations from the named source

Time basis

Point-in-time records

UTC · event_time

Overview

NOT LIVE despite the name — PJM posts this feed about 20 hours in arrears (postingFrequency: Daily on Business Days), so it is the settled record, not the tip; see pjm_transmission_limits for that. Retained indefinitely back to 2010, and it alone (of the two real-time feeds) carries transmission_constraint_penalty_factor and limit_control_percentage. Source: PJM Market Data.

Query contract

Preserve one canonical row per (event_time, monitored_facility, contingency_facility) before aggregating.

Analysis rules

Group only after preserving the declared grain: event_time, monitored_facility, contingency_facility.

Access

Query from your own tools

Use the guarded HTTP endpoint directly, or connect an MCP client and load the dataset contract with describe_data before calling query_data.

PJM MCP API reference

HTTP endpoint

POST /api/v1/datasets/pjm_rt_marginal_value/query

Schema7

Column

Type

event_timeDateTime64(6, 'UTC')

monitored_facilityLowCardinality(String)

contingency_facilityLowCardinality(String)

shadow_priceNullable(Float64)

transmission_constraint_penalty_factorNullable(Float64)

limit_control_percentageNullable(Float64)

ingested_atDateTime64(6, 'UTC')

Sample data

event_time	monitored_facility	contingency_facility	shadow_price	transmission_constraint_penalty_factor	limit_control_percentage	ingested_at
2026-09-18 03:55:00.000000	PIERCE-DEARBORN B 345 KV	L345.TannersCreek-MiamiFort	-1000	1000	95	2026-09-19 18:46:07.216607
2026-09-18 03:55:00.000000	CONASTON-OTTCRKPL 2302 B 230 KV	L500.Conastone-PeachBottom.5012	-130.37	2000	94	2026-09-19 18:46:07.216607
2026-09-18 03:55:00.000000	PIERCE-DEARBORN B 345 KV	L345.TannersCreek-MiamiFort	-1000	1000	95	2026-09-19 17:46:07.826528
2026-09-18 03:55:00.000000	CONASTON-OTTCRKPL 2302 B 230 KV	L500.Conastone-PeachBottom.5012	-130.37	2000	94	2026-09-19 17:46:07.826528
2026-09-18 03:55:00.000000	PIERCE-DEARBORN B 345 KV	L345.TannersCreek-MiamiFort	-1000	1000	95	2026-09-19 16:46:15.011116
2026-09-18 03:55:00.000000	CONASTON-OTTCRKPL 2302 B 230 KV	L500.Conastone-PeachBottom.5012	-130.37	2000	94	2026-09-19 16:46:15.011116
2026-09-18 03:50:00.000000	PIERCE-DEARBORN B 345 KV	L345.TannersCreek-MiamiFort	-42.96	1000	95	2026-09-19 18:46:07.216607
2026-09-18 03:50:00.000000	Montgomery - Rootbeer 345kV l/o Callaway - Bland 345kV	Callaway - Bland 345kV	-116.12	116.1	100	2026-09-19 18:46:07.216607
2026-09-18 03:50:00.000000	Monroe - Lallendorf 345 kV l/o Lemoyne - Majestic 345 kV	Lemoyn-Majestic 345 line	-40.49	40.4	100	2026-09-19 18:46:07.216607
2026-09-18 03:50:00.000000	CRETSTJO-STJOHNS 94507 B 345 KV	L765.Dumont-WiltonCenter.11215	-82.99	2000	96	2026-09-19 18:46:07.216607
2026-09-18 03:50:00.000000	CONASTON-OTTCRKPL 2302 B 230 KV	L500.Conastone-PeachBottom.5012	-233.51	2000	94	2026-09-19 18:46:07.216607
2026-09-18 03:50:00.000000	PIERCE-DEARBORN B 345 KV	L345.TannersCreek-MiamiFort	-42.96	1000	95	2026-09-19 17:46:07.826528
2026-09-18 03:50:00.000000	Montgomery - Rootbeer 345kV l/o Callaway - Bland 345kV	Callaway - Bland 345kV	-116.12	116.1	100	2026-09-19 17:46:07.826528
2026-09-18 03:50:00.000000	Monroe - Lallendorf 345 kV l/o Lemoyne - Majestic 345 kV	Lemoyn-Majestic 345 line	-40.49	40.4	100	2026-09-19 17:46:07.826528
2026-09-18 03:50:00.000000	CRETSTJO-STJOHNS 94507 B 345 KV	L765.Dumont-WiltonCenter.11215	-82.99	2000	96	2026-09-19 17:46:07.826528
2026-09-18 03:50:00.000000	CONASTON-OTTCRKPL 2302 B 230 KV	L500.Conastone-PeachBottom.5012	-233.51	2000	94	2026-09-19 17:46:07.826528
2026-09-18 03:50:00.000000	PIERCE-DEARBORN B 345 KV	L345.TannersCreek-MiamiFort	-42.96	1000	95	2026-09-19 16:46:15.011116
2026-09-18 03:50:00.000000	Montgomery - Rootbeer 345kV l/o Callaway - Bland 345kV	Callaway - Bland 345kV	-116.12	116.1	100	2026-09-19 16:46:15.011116
2026-09-18 03:50:00.000000	Monroe - Lallendorf 345 kV l/o Lemoyne - Majestic 345 kV	Lemoyn-Majestic 345 line	-40.49	40.4	100	2026-09-19 16:46:15.011116
2026-09-18 03:50:00.000000	CRETSTJO-STJOHNS 94507 B 345 KV	L765.Dumont-WiltonCenter.11215	-82.99	2000	96	2026-09-19 16:46:15.011116
2026-09-18 03:50:00.000000	CONASTON-OTTCRKPL 2302 B 230 KV	L500.Conastone-PeachBottom.5012	-233.51	2000	94	2026-09-19 16:46:15.011116
2026-09-18 03:45:00.000000	Monroe - Lallendorf 345 kV l/o Lemoyne - Majestic 345 kV	Lemoyn-Majestic 345 line	-111.75	111.7	100	2026-09-19 18:46:07.216607
2026-09-18 03:45:00.000000	Chicago - Praxair3 138 kV l/o Wilton Center - Dumont 765 kV	Dumont-Wilton Center 765kV	-876.43	1005.9	100	2026-09-19 18:46:07.216607
2026-09-18 03:45:00.000000	CONASTON-OTTCRKPL 2302 B 230 KV	L500.Conastone-PeachBottom.5012	-202.58	2000	94	2026-09-19 18:46:07.216607
2026-09-18 03:45:00.000000	Monroe - Lallendorf 345 kV l/o Lemoyne - Majestic 345 kV	Lemoyn-Majestic 345 line	-111.75	111.7	100	2026-09-19 17:46:07.826528

Coverage

99.9% complete2 gap days3,091 days with data

Show coverage history

Coverage: 99.9%Days with data: 3,091Gaps: 2

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Related congestion & constraints data

Related congestion & constraints data
Dataset	Description
Constraint Shift Factor RunsPJM · nightly (one row per completed run)	One row per COMPLETED nightly estimation of PJM constraint shift factors, and the only record that a run finished. Resolve the latest usable run here — computed_at = (SELECT max(computed_at) FROM atg.pjm_constraint_sensitivity_runs) — and never off max(computed_at) of the sensitivities themselves, because a run writes its rows in blocks that all carry the new timestamp and an unfinished or abandoned run would otherwise look like the newest one. Each row also carries how much evidence that run had: interval_coverage is the fraction of published dispatch intervals that survived admission, intervals_refused_unexplained counts intervals showing congestion with no constraint recorded as binding (an unobserved binding set), constraint_feed_lag_minutes is how far the constraint feed trailed the price feed, and constraints_seen / constraints_in_fit / constraints_reported show how many constraints bound, how many were good enough to control for, and how many earned a published estimate.
Constraint Shift Factors (Estimated)PJM · nightly (60-day rolling estimation window)	Estimated sensitivity of every PJM pricing location's price to every binding transmission constraint: one row per constraint, contingency, and location, recomputed nightly over a rolling 60-day window. This is what answers 'which nodes drive this constraint' and 'which constraints is this node exposed to'. THE DAY-AHEAD MARKET, not real time: this estimate is fitted to day-ahead marginal values against day-ahead nodal congestion and it describes day-ahead congestion. It covers PJM's day-ahead binding constraints with their contingency over roughly 14,450 pricing nodes. PJM names no terminals, so from_station and to_station are always empty. PJM's real-time shadow prices ARE ingested now (pjm_rt_marginal_value, pjm_transmission_limits) but no estimate has been fitted to them and no atg.pjm_constraints_rt canonical table exists yet — a real-time PJM answer needs that fitting work, not a new ingest. shift_factor is in the ISO's orientation — POSITIVE means an incremental MW injected at that node increases loading on the constraint and the node is paid below system lambda while it binds; NEGATIVE means generation there relieves the constraint and earns a premium. These are ESTIMATES recovered from the price identity LMP = energy - sum(shift_factor x shadow_price), not a published PTDF matrix. They are measured RELATIVE TO THE MARKET'S REFERENCE — the identity yields SF(node) - SF(reference), so a single absolute value should be quoted as 'relative to the system reference' rather than as the node's PTDF, while DIFFERENCES between nodes are exact because the reference term cancels. Three further differences from a published matrix: they describe a NODE (a generator at that node inherits its location's value, and two units at one node are indistinguishable), they reflect the topology actually in effect across the window including outages rather than a stated base case, and every one carries a std_error from a 200-draw block bootstrap that resamples whole days. Read std_error before quoting shift_factor: an estimate whose absolute value is not at least twice its standard error is not distinguishable from zero. estimation_status says why a row has no number — 'thin_support' (in the fit, so it is controlled for, but under 12 binding intervals or under 3 distinct binding days), 'no_support' (under 3 binding intervals; not a regressor), or 'collinear' (it bound in lockstep with another constraint, so the two cannot be separated). Where from_station and to_station are populated they identify the monitored element and are NOT the constrained direction — the sign of shift_factor is what says which way. Every read must pin computed_at to one run, and must resolve that run through the companion atg.<iso>_constraint_sensitivity_runs ledger rather than off max(computed_at) here — rows are written in blocks that all carry the new timestamp, so an unfinished or abandoned run would otherwise look like the newest. Mixing runs averages a node across different network topologies.
Day-Ahead Constraint Marginal ValuesPJM · hourly (day-ahead)	What each binding day-ahead transmission constraint cost in PJM, hour by hour: the monitored facility, the contingency facility, and the constraint's marginal value — its shadow price, the saving from one more MW of headroom. This is the table that says how hard a constraint bound, where pjm_da_transconstraints says only that it did. PJM PUBLISHES THIS VALUE AS A NEGATIVE NUMBER: 2,654,985 negative rows against 43 positive over the table's full history, which reaches back to 2010. Read its magnitude as the cost of the constraint and do not compare its sign against another market's. This answers day-ahead congestion only; for real-time, see pjm_transmission_limits and pjm_rt_marginal_value. Source: PJM Market Data.
Day-Ahead Transmission ConstraintsPJM · daily (day-ahead)	The transmission constraints that bound in PJM's day-ahead market: the monitored facility, the contingency facility, the duration, and the congestion event. It names which elements are expected to limit flows for the next operating day. What it does not carry is what the constraint COST: the marginal value is published separately, in pjm_da_marginal_value. For real-time binding constraints, see pjm_transmission_limits (the live tip, ~9 minutes behind) and pjm_rt_marginal_value (the settled record, ~20 hours behind). Source: PJM Market Data.