data model prototype (wip)

[sanderclaeys]

Discussion points

• Do we need a vnom property on the buses? This would not be used anywhere in the mathematical model. One option is to non-dimensionalize the bounds with respect to this vnom for convenience.
• Non-dimensionalize lossy transformer parameters?
• How to deal with 'different' sub-types with their own specific sets of defined properties? (e.g. load and model)

Shared patterns

• Each component has a unique (amonst components of the same type) identifier id.
• Everything is defined in SI units, except when a base is explicitly mentioned in the description.
• The default sometimes only mentions the default element, not the default value (e.g. true and not fill(fill(true, 3), 3))

Data model

Bus

The data model below allows us to include buses of arbitrary many terminals (i.e., more than the usual four). This would be useful for

• underground lines with multiple neutrals which are not joined at every bus;
• distribution lines that carry several conventional lines in parallel (see for example the quad circuits in NEVTestCase).

name	default	type	description
terminals	[1,2,3,4]	Vector
vm_max	/	Vector	maximum conductor-to-ground voltage magnitude
vm_min	/	Vector	minimum conductor-to-ground voltage magnitude
vm_cd_max	/	Vector{Tuple}	e.g. [(1,2,210)] means |U1-U2|>210
vm_cd_min	/	Vector{Tuple}	e.g. [(1,2,230)] means |U1-U2|<230
grounded	[]	Vector	a list of terminals which are grounded
rg	[]	Vector	resistance of each defined grounding
xg	[]	Vector	reactance of each defined grounding

The tricky part is how to encode bounds for these type of buses. The most general is defining a list of three-tupples. Take for example a typical bus in a three-phase, four-wire network, where terminals=[a,b,c,n]. Such a bus might have

• phase-to-neutral bounds vm_pn_max=250, vm_pn_min=210
• and phase-to-phase bounds vm_pp_max=440, vm_pp_min=360 .

We can then define this equivalently as

• vm_cd_max = [(a,n,250), (b,n,250), (c,n,250), (a,b,440), (b,c,440), (c,a,440)]
• vm_cd_min = [(a,n,210), (b,n,210), (c,n,210), (a,b,360), (b,c,360), (c,a,360)]

Since this might be confusing for novice users, we also allow the user to define bounds through the following properties.

name	default	type	description
id	/		unique identifier
phases	[1,2,3]	Vector
neutral	4		maximum conductor-to-ground voltage magnitude
vm_pn_max	/	Real	maximum phase-to-neutral voltage magnitude for all phases
vm_pn_min	/	Real	minimum phase-to-neutral voltage magnitude for all phases
vm_pp_max	/	Real	maximum phase-to-phase voltage magnitude for all phases
vm_pp_min	/	Real	minimum phase-to-phase voltage magnitude for all phases

Line

This is a pi-model branch.

name	default	type	description
id	/		unique identifier
n_conductors	size(rs)[1]	Int>0	number of conductors in this line
f_bus	/
f_connections	/		indicates for each conductor, to which terminal of the f_bus it connects
t_bus	/
t_connections	/		indicates for each conductor, to which terminal of the t_bus it connects
rs	/		series resistance matrix, size of n_conductors x n_conductors
xs	/		series reactance matrix, size of n_conductors x n_conductors
g_fr	/		from-side conductance
b_fr	/		from-side susceptance
g_to	/		to-side conductance
b_to	/		to-side susceptance
c_rating	/		symmetrically applicable current rating
s_rating	/		symmetrically applicable power rating

Shunt

name	default	type	description
id	/		unique identifier
bus	/
connections	/
g	/		conductance, size should be |connections|x|connections|
b	/		susceptance, size should be |connections|x|connections|

Load

name	default	type	description
id	/		unique identifier
bus	/
connections	/
configuration	/	{wye, delta}	if wye-connected, the last connection will indicate the neutral
model	/		indicates the type of voltage-dependency
pd_ref	/
qd_ref	/
vnom	/
exp_p	/
exp_q	/

Generator

name	default	type	description
id	/		unique identifier
bus	/
connections	/
configuration	/	{wye, delta}	if wye-connected, the last connection will indicate the neutral
pg_min	/		lower bound on active power generation per phase
pg_max	/		upper bound on active power generation per phase
qg_min	/		lower bound on reactive power generation per phase
qg_max	/		upper bound on reactive power generation per phase

AL2W Transformer

These are transformers are assymetric (A), lossless (L) and two-winding (2W). Assymetric refers to the fact that the secondary is always has a wye configuration, whilst the primary can be delta.

name	default	type	description
id	/		unique identifier
n_phases	size(rs)[1]	Int>0	number of phases
f_bus	/
f_connections	/		indicates for each conductor, to which terminal of the f_bus it connects
t_bus	/
t_connections	/		indicates for each conductor, to which terminal of the t_bus it connects
configuration	/	{wye, delta}	for the from-side; the to-side is always connected in wye
tm_nom	/	Real	nominal tap ratio for the transformer
tm_max	/	Vector	maximum tap ratio for each phase (base=tm_nom)
tm_min	/	Vector	minimum tap ratio for each phase (base=tm_nom)
tm_set	fill(1.0, n_phases)	Vector	set tap ratio for each phase (base=tm_nom)
tm_fix	fill(true, n_phases)	Vector	indicates for each phase whether the tap ratio is fixed

TODO: add tm stuff

Transformer

These are n-winding, n-phase, lossy transformers. Note that most properties are now Vectors (or Vectors of Vectors), indexed over the windings.

name	default	type	description
id	/		unique identifier
n_phases	size(rs)[1]	Int>0	number of phases
n_windings	size(rs)[1]	Int>0	number of windings
bus	/	Vector	list of bus for each winding
connections		Vector{Vector}	list of connection for each winding
configurations		Vector{{wye, delta}}	list of configuration for each winding
xsc	0.0	Vector	list of short-circuit reactances between each pair of windings; enter as a list of the upper-triangle elements
rs	0.0	Vector	list of the winding resistance for each winding
tm_nom	/	Vector{Real}	nominal tap ratio for the transformer
tm_max	/	Vector{Vector}	maximum tap ratio for each winding and phase (base=tm_nom)
tm_min	/	Vector{Vector}	minimum tap ratio for for each winding and phase (base=tm_nom)
tm_set	1.0	Vector{Vector}	set tap ratio for each winding and phase (base=tm_nom)
tm_fix	true	Vector{Vector}	indicates for each winding and phase whether the tap ratio is fixed