Bidding Strategy

Overview

The Bidding Strategy module provides analysis tools for generators and BESS operators who participate in AEMO’s central dispatch process. Understanding the bid stack, tracking competitor rebids, and optimising bid bands are critical activities for maximising revenue in the NEM.

NEM Dispatch Mechanism

AEMO dispatches all market units every 5 minutes using a least-cost dispatch algorithm (NEMDE). Each generator submits a bid consisting of:

10 price bands: from −$1,000/MWh to $16,600/MWh
Volume availability in each band (MW)
Ramp rates: ramp up and ramp down limits (MW/minute)
FCAS availability offers: MW available for each FCAS service

The dispatch algorithm stacks all bids from cheapest to most expensive and clears the market at the intersection with forecast demand. The clearing price becomes the dispatch price for that 5-minute interval.

DUID Bid Stack Analysis

Current Bid Stack (`/middle-office/bid-stack`)

Stack chart: all DUIDs sorted by offer price, coloured by fuel type
Demand line: current and forecast demand overlaid on the stack
Marginal unit indicator: which DUID is setting the price
FCAS co-optimisation: how FCAS bids shift the effective stack

Screenshot: Bid stack chart for NSW1 showing stacked generation offers (MW vs $/MWh) with demand line and marginal unit highlighted.

Merit Order Analysis

The merit order ranks generating units by their short-run marginal cost (SRMC):

Fuel Type	Typical SRMC Range	Dispatch Priority
Wind	$0–$5/MWh	First in (zero fuel cost)
Solar	$0–$10/MWh	First in (zero fuel cost)
Hydro	$0–$20/MWh	Flexible dispatch
Black Coal	$30–$60/MWh	Base load
Brown Coal	$10–$40/MWh	Base load
CCGT	$70–$130/MWh	Mid-merit
OCGT	$100–$200/MWh	Peaking
Battery	Variable	Arbitrage / FCAS

Rebid Tracking

Rebidding is when a generator submits a new bid to change their price or volume availability. Rebids must be submitted before the 5-minute gate closure. Legitimate rebids reflect changed circumstances (equipment availability, fuel constraints); strategic rebids are monitored by the AER.

Rebid Feed (`/middle-office/rebids`)

Live rebid notifications as they occur
Rebid reason codes (as submitted to AEMO)
Price band changes visualised as before/after stack overlays
Volume availability changes per band
DUID filter to monitor specific competitors

-- Query today's rebids for a specific DUID
SELECT
    submission_timestamp,
    duid,
    rebid_reason,
    price_band_number,
    old_price,
    new_price,
    old_volume_mw,
    new_volume_mw
FROM energy_copilot.gold.nem_rebids
WHERE interval_date = CURRENT_DATE()
  AND duid = 'LYNE1'
ORDER BY submission_timestamp DESC;

Bid Band Optimisation

For BESS operators with battery optimisation access, the platform provides bid band optimisation suggestions:

Optimisation Objective

Maximise: Revenue_Energy + Revenue_FCAS - Degradation_Cost
Subject to:
    Charge_constraint: SOC >= SOC_min (typically 10%)
    Discharge_constraint: SOC <= SOC_max (typically 90%)
    Ramp_constraint: |ΔOutput| <= Ramp_rate × 5min
    FCAS_trapezium: FCAS offer consistent with dispatch headroom

Bid Band Suggestion

Given a 24-hour price forecast, the optimiser suggests bid bands to maximise revenue:

# Example optimised bid suggestion
{
  "duid": "HPRL1",
  "trading_day": "2025-03-22",
  "suggested_bands": {
    "band_1": {"price": -1000, "volume_mw": 0},    # No strategic negative bid
    "band_2": {"price": 0, "volume_mw": 20},        # Charge at zero (overnight)
    "band_3": {"price": 50, "volume_mw": 0},
    "band_4": {"price": 150, "volume_mw": 100},     # Discharge at $150+
    "band_5": {"price": 300, "volume_mw": 50},      # Peak hour arbitrage
    "band_6": {"price": 1000, "volume_mw": 30},     # Price spike capture
    ...
  }
}

API Endpoints

# Current bid stack for region
GET /api/bidding/stack?region=SA1

# Recent rebids
GET /api/bidding/rebids?duid=HPRL1&hours=24

# Merit order for region
GET /api/bidding/merit-order?region=NSW1

# Bid band optimisation for BESS
POST /api/bidding/optimise
{
  "duid": "HPRL1",
  "forecast_horizon_h": 24,
  "fcas_services": ["RAISEREG", "LOWERREG", "RAISE6SEC"],
  "soc_current_pct": 65
}