Transformer

The Transformer components represent 2-winding transformers that convert AC power from one voltage level to another. They connect a bus0 (typically at higher voltage) to a bus1 (typically at lower voltage). Power flow through transformers is not directly controllable, but is determined passively by their impedances and the nodal power imbalances. To see how the impedances are used in the power flow, see the transformer model.

attribute	type	unit	default	description	status
name	string	nan	nan	Unique name	Input (required)
bus0	string	nan	nan	Name of origin bus (typically higher voltage) to which transformer is attached.	Input (required)
bus1	string	nan	nan	Name of destination bus (typically lower voltage) to which transformer is attached.	Input (required)
type	string	nan	nan	Name of 2-winding transformer standard type. If this is not an empty string "", the transformer type impedance parameters are taken from the standard type along with num_parallel. This will override any values set in r, x, g, b, s_nom, tap_ratio, tap_side and phase_shift. If the string is empty, values manually provided for r, x, etc. are taken.	Input (optional)
model	string	nan	t	Model used for admittance matrix; can be "t" or "pi"; defaults to "t" following physics and DIgSILENT PowerFactory	Input (required)
x	float	per unit	0	Series reactance (per unit, using s_nom as base power); must be non-zero for AC branch in linear power flow. Series impedance \(z = r + jx\) must be non-zero for the non-linear power flow. Ignored if type defined.	Input (required)
r	float	per unit	0	Series resistance (per unit, using s_nom as base power); must be non-zero for DC branch in linear power flow. Series impedance \(z = r + jx\) must be non-zero for the non-linear power flow. Ignored if type defined.	Input (required)
g	float	per unit	0	Shunt conductivity (per unit, using s_nom as base power). Ignored if type defined.	Input (optional)
b	float	per unit	0	Shunt susceptance (per unit, using s_nom as base power). Ignored if type defined.	Input (optional)
s_nom	float	MVA	0	Limit of apparent power which can pass through branch in either direction. Ignored if s_nom_extendable=True.	Input (optional)
s_nom_mod	float	MVA	0	Modular unit size of transformer expansion of s_nom. Introduces integer variables.	Input (optional)
s_nom_extendable	boolean	nan	False	Switch to allow capacity s_nom to be extended in optimisation.	Input (optional)
s_nom_min	float	MVA	0	If s_nom_extendable=True, set the minimum value of s_nom_opt.	Input (optional)
s_nom_max	float	MVA	inf	If s_nom_extendable=True, set the maximum value of s_nom_opt.	Input (optional)
s_nom_set	float	MVA	nan	If s_nom is extendable in optimization, set the value of s_nom_opt.	Input (optional)
s_max_pu	static or series	per unit	1	The maximum allowed absolute flow per unit of s_nom for the oprimisation.	Input (optional)
capital_cost	float	currency/MVA	0	Fixed period costs of extending s_nom by 1 MVA (e.g. annuitized investment costs). Used directly unless overnight_cost is specified.	Input (optional)
overnight_cost	float	currency/MVA	nan	Overnight (upfront) investment cost per MVA. If specified, PyPSA calculates annuity using discount_rate and lifetime. Takes precedence over capital_cost.	Input (optional)
discount_rate	float	per unit	nan	Discount rate for annuity calculation when using overnight_cost. Supports 0% rate (simple depreciation).	Input (optional)
fom_cost	float	currency/MVA	0	Fixed period operation and maintenance costs, added to annuitized investment cost.	Input (optional)
num_parallel	float	nan	1	When type is set, this is the number of parallel transformers (can also be fractional). If type is empty "" this value is ignored.	Input (optional)
tap_ratio	float	per unit	1	Ratio of per unit voltages at each bus for tap changed. Ignored if type defined.	Input (optional)
tap_side	int	nan	0	Defines if tap changer is modelled at the primary 0 side (usually high-voltage) or the secondary 1 side (usually low voltage) (must be 0 or 1, defaults to 0). Ignored if type defined.	Input (optional)
tap_position	int	nan	0	If the transformer has a type, determines position relative to the neutral tap position.	Input (optional)
phase_shift	float	Degrees	0	Voltage phase angle shift. Ignored if type defined.	Input (optional)
active	boolean	nan	True	Whether to consider the component in optimisation or not	Input (optional)
build_year	int	year	0	Build year of transformer.	Input (optional)
lifetime	float	years	inf	Lifetime of transformer.	Input (optional)
v_ang_min	float	Degrees	-inf	Minimum voltage angle difference across the transformer.Placeholder attribute not currently used.	Input (optional)
v_ang_max	float	Degrees	inf	Maximum voltage angle difference across the transformer.Placeholder attribute not currently used.	Input (optional)
sub_network	string	nan	nan	Name of connected sub-network to which transformer belongs, as calculated by n.determine_network_topology(). Do not set by hand.	Output
p0	series	MW	0	Active power at bus0 (positive if branch is withdrawing power from bus0).	Output
q0	series	MVar	0	Reactive power at bus0 (positive if branch is withdrawing power from bus0).	Output
p1	series	MW	0	Active power at bus1 (positive if branch is withdrawing power from bus1).	Output
q1	series	MVar	0	Reactive power at bus1 (positive if branch is withdrawing power from bus1).	Output
x_pu	float	per unit	0	Per unit series reactance calculated by n.calculate_dependent_values() from x and n.buses.v_nom.	Output
r_pu	float	per unit	0	Per unit series resistance calculated by n.calculate_dependent_values() from r and n.buses.v_nom.	Output
g_pu	float	per unit	0	Per unit shunt conductivity calculated by n.calculate_dependent_values() from g and n.buses.v_nom.	Output
b_pu	float	per unit	0	Per unit shunt susceptance calculated by n.calculate_dependent_values() from b and n.buses.v_nom.	Output
x_pu_eff	float	per unit	0	Effective per unit series reactance for linear power flow, calculated by n.calculate_dependent_values() from x, tap_ratio for transformers and n.buses.v_nom.	Output
r_pu_eff	float	per unit	0	Effective per unit series resistance for linear power flow, calculated by n.calculate_dependent_values() from x, tap_ratio for transformers and n.buses.v_nom.	Output
s_nom_opt	float	MVA	0	Optimised nominal capacity for apparent power.	Output
mu_lower	series	currency/MVA	0	Shadow price of lower s_nom limit. Always non-negative.	Output
mu_upper	series	currency/MVA	0	Shadow price of upper s_nom limit. Always non-negative.	Output