Unmet Load - Inputs

Unmet Load components act as "last resort" generators with very high penalty costs. They allow the optimizer to solve even when demand cannot be fully met, providing diagnostic information about system adequacy. Below are all input attributes that you can set for unmet load components.

WARNING

Unmet Load is a special generator type used to identify supply shortfalls. If unmet load is dispatched in your results, it indicates insufficient generation or transmission capacity to meet demand.

Basic

Attribute	Data Type	Unit	Default	Required	Storage Type	Description
type	string	n/a	n/a	No	static	Placeholder for unmet load type. Not yet implemented.
carrier	string	n/a	n/a	No	static	Prime mover Carrier (e.g. coal, gas, wind, solar); required for global constraints on primary energy in optimization
active	boolean	n/a	True	No	static	Whether this unmet load generator is active and should be included in network calculations. Set to False to temporarily disable the generator without deleting it.

Capacity

Attribute	Data Type	Unit	Default	Required	Storage Type	Description
p_nom	float	MW	10000000	No	static	The maximum rated capacity in MW. For unmet load, this is typically set very high (e.g., 10000000 MW) to allow the optimizer to serve any unmet demand. This sets the upper limit for power output in all calculations.
p_nom_extendable	boolean	n/a	False	No	static	Switch to allow the nominal power (p_nom) to be extended in optimization.
p_nom_min	float	MW	0	No	static	If the nominal power (p_nom) is extendable in optimization, set its minimum value.
p_nom_max	float	MW	inf	No	static	If the nominal power (p_nom) is extendable in optimization, set its maximum value (e.g. limited by technical potential).
build_year	int	year	0	No	static	The year when the unmet load generator can be built or commissioned. Essential for multi-year capacity expansion planning models, which determine optimal investment timing and generator retirement schedules.
lifetime	float	years	inf	No	static	The operational lifetime of the unmet load generator in years. Essential for multi-year capacity expansion planning models, which use this to determine when generators retire (build year + lifetime). Set to "inf" for generators that never retire.

Power Limits

Attribute	Data Type	Unit	Default	Required	Storage Type	Description
p_min_pu	float	per unit	0	No	static or timeseries	The minimum output for each snapshot per unit of the nominal power (p_nom) for the optimization. Note that if committable is False and p_min_pu > 0, this represents a must-run condition.
p_max_pu	float	per unit	1	No	static or timeseries	The maximum output for each snapshot per unit of the nominal power (p_nom) for the optimization.
p_set	float	MW	0	No	static or timeseries	Fixed active power output that the unmet load generator must produce. Used when the output is predetermined rather than optimized.
q_set	float	MVar	0	No	static or timeseries	Fixed reactive power output that the unmet load generator must produce. Used when the reactive power output is predetermined rather than optimized.
sign	float	n/a	1	No	static	Power flow direction convention: 1 for generation (positive power flows into the network), -1 for consumption (positive power flows out of the network).

Energy

Attribute	Data Type	Unit	Default	Required	Storage Type	Description
efficiency	float	per unit	1	No	static or timeseries	Ratio between primary energy and electrical energy, e.g. takes value 0.4 MWh_elec/MWh_thermal for gas. This is required for global constraints on primary energy in optimization.

Unit Commitment

Attribute	Data Type	Unit	Default	Required	Storage Type	Description
committable	boolean	n/a	False	No	static	Enable unit commitment, allowing the unmet load generator to be turned on or off with associated start-up and shutdown costs. Only available when the nominal power (p_nom) is not extendable.
start_up_cost	float	currency	0	No	static	Cost to start up the unmet load generator. Only read if committable is True.
shut_down_cost	float	currency	0	No	static	Cost to shut down the unmet load generator. Only read if committable is True.
min_up_time	int	snapshots	0	No	static	Minimum number of snapshots for status to be 1. Only read if committable is True.
min_down_time	int	snapshots	0	No	static	Minimum number of snapshots for status to be 0. Only read if committable is True.
up_time_before	int	snapshots	1	No	static	Number of snapshots that the unmet load generator was online before network.snapshots start. Only read if committable is True and min_up_time is non-zero.
down_time_before	int	snapshots	0	No	static	Number of snapshots that the unmet load generator was offline before network.snapshots start. Only read if committable is True and min_down_time is non-zero.

Ramping

Attribute	Data Type	Unit	Default	Required	Storage Type	Description
ramp_limit_up	float	per unit	1	No	static or timeseries	Maximum active power increase from one snapshot to the next, per unit of the nominal power (p_nom). Ignored if 1.
ramp_limit_down	float	per unit	1	No	static or timeseries	Maximum active power decrease from one snapshot to the next, per unit of the nominal power (p_nom). Ignored if 1.
ramp_limit_start_up	float	per unit	1	No	static	Maximum active power increase at start up, per unit of the nominal power (p_nom). Only read if committable is True.
ramp_limit_shut_down	float	per unit	1	No	static	Maximum active power decrease at shut down, per unit of the nominal power (p_nom). Only read if committable is True.

Costs

Attribute	Data Type	Unit	Default	Required	Storage Type	Description
marginal_cost	float	currency/MWh	100000000	No	static or timeseries	The variable cost of producing one additional MWh of electricity. For unmet load, this is typically set very high (e.g., 100000000 currency/MWh) as a penalty cost to discourage the optimizer from using this generator unless absolutely necessary. Used by the optimizer to determine the economic dispatch order.
capital_cost	float	currency/MW	0	No	static or timeseries	The cost per MW of adding new capacity. Includes investment costs (spread over the planning period) and fixed operations & maintenance costs. Only relevant when p_nom_extendable is True.

Electrical

Attribute	Data Type	Unit	Default	Required	Storage Type	Description
control	string	n/a	PQ	No	static	Power flow control mode: "PQ" (fixed active and reactive power), "PV" (fixed active power and voltage magnitude), or "Slack" (balances system power, typically one per network).