aemo_constraints: Binding transmission and system constraints

Description

Returns the DISPATCHCONSTRAINT table from NEMweb: one row per binding (or near-binding) constraint per 5-minute dispatch interval. Each row records the constraint ID, the left-hand side (LHS) and right-hand side (RHS) values, the marginal value (shadow price on the constraint in AUD/MWh), and the violation degree if any.

Usage

aemo_constraints(
  start,
  end,
  constraint_id = NULL,
  intervention = FALSE,
  min_marginal_value = 0.01
)

Value

An aemo_tbl with columns settlementdate, constraintid, rhs, marginalvalue, violationdegree, lhs, plus the intervention flag.

Arguments

start, end: Window (inclusive), character or POSIXct.
constraint_id: Optional character vector of constraint IDs (e.g. "N>>N-NIL_1", "V::S_NIL_TBSE"). NULL returns all binding constraints in the window.
intervention: Logical. Default FALSE.
min_marginal_value: Numeric. Only return constraints with marginal value at or above this threshold (AUD/MWh). 0 returns every row; the default of 0.01 filters out near-zero shadow prices that are typically noise.

Details

This is the table that answers the question "why was the RRP so high at 17:35?": the sum of marginal values across binding constraints at the Regional Reference Node equals the regional price component attributable to network limits.

Constraint equations and RHS terms (GENCONDATA, GENCONSETINVOKE) are published through MMSDM on a separate cadence and are not exposed directly by this function; use aemo_nemweb_download() on an MMSDM URL for those.

Examples

Run this code

# \donttest{
op <- options(aemo.cache_dir = tempdir())
try({
  now <- Sys.time()
  c <- aemo_constraints(start = now - 3600, end = now)
  head(c)
})
options(op)
# }