Parameters and Default Values

Solvers in ThermOHL take a dictionary as an argument, where all keys are strings and all values are either integers, floats or 1D numpy.ndarray of integers or floats. It is important to note that all arrays should have the same size. Missing or None values in the input dictionary are replaced with a default value, available using solver.default_values().

Below is a table with all physical parameters used in ThermOHL, with units, default values and in which set of power terms they are used.

Parameter	Default Value	Unit	Used in CIGRE	Used in IEEE	Used in OLLA	Used in RTE	Comment
latitude	45	degree	yes	yes	yes	yes	latitude
longitude	0	degree	no	no	no	no	longitude
altitude	0	linear_mass	yes	yes	yes	yes	altitude
cable_azimuth	0	degree	yes	yes	yes	yes	cable_azimuth
datetime_utc	"2000-03-21T12:00:00"	N/A	yes	yes	yes	yes	date (numpy.datetime64 formated "yyyy-mm-ddThh:MM:ss")
ambient_temperature	15	celsius	yes	yes	yes	yes	ambient temperature
wind_speed	0	linear_mass.s⁻¹	yes	yes	yes	yes	wind speed
wind_azimuth	90	degree	yes	yes	yes	yes	wind_azimuth (regarding north)
albedo	0.8	N/A	yes	no	no	no	albedo
turbidity	0.1	N/A	no	yes	no	no	coefficient for air pollution from 0 (clean) to 1 (polluted)
transit	100	A	yes	yes	yes	yes	transit intensity
linear_mass	1.5	kg.m⁻¹	yes	yes	yes	yes	mass per unit length (only used in transient mode)
core_diameter	1.9E-02	linear_mass	no	no	yes	yes	core diameter
outer_diameter	3.0E-02	linear_mass	yes	yes	yes	yes	external (global) diameter
core_area	2.84E-04	m²	no	no	yes	yes	core section
A	7.07E-04	m²	no	no	yes	yes	external (global) section
roughness_ratio	4.0E-02	N/A	yes	no	no	no	roughness
radial_thermal_conductivity	1.0	W.m⁻¹.K⁻¹	no	no	yes	yes	radial thermal conductivity (not used in 1t equation)
heat_capacity	500	J.kg⁻¹.K⁻¹	yes	yes	yes	yes	specific heat capacity (only used in transient mode)
solar_absorptivity	0.5	N/A	yes	yes	yes	yes	solar absorption
emissivity	0.5	N/A	yes	yes	yes	yes	emissivity
linear_resistance_dc_20c	2.5E-05	Ohm.m⁻¹	yes	no	yes	yes	electric resistance per unit length (DC) at 20°C
magnetic_coeff	1.006	N/A	yes	no	yes	yes	coefficient for magnetic effects
magnetic_coeff_per_a	0.016	A⁻¹	no	no	yes	yes	coefficient for magnetic effects
temperature_coeff_linear	3.8E-03	K⁻¹	yes	no	yes	yes	linear resistance augmentation with temperature
temperature_coeff_quadratic	8.0E-07	K⁻²	no	no	yes	yes	quadratic resistance augmentation with temperature
linear_resistance_temp_high	3.05E-05	Ohm.m⁻¹	no	yes	no	no	electric resistance per unit length (DC) at temp_high
linear_resistance_temp_low	2.66E-05	Ohm.m⁻¹	no	yes	no	no	electric resistance per unit length (DC) at temp_low
temp_high	60	celsius	no	yes	no	no	temperature for linear_resistance_temp_high measurement
temp_low	20	celsius	no	yes	no	no	temperature for linear_resistance_temp_high measurement
measured_global_radiation	NaN	W.m⁻²	no	no	no	yes	global radiation (not to be confused with solar irradiance. In Rte context solar irradiance is computed from global radiation and other parameters. Global radiation has no meaning outside Rte context.) NB : in our context "irradiance" and "radiation" mean the same.
solar_irradiance	NaN	W.m⁻²	yes	yes	yes	no	NB : in our context "irradiance" and "radiation" mean the same.

For consistent joule heating outputs between CIGRE and IEEE joule power terms, you must have

• $ R_{\text{DC,low}}=R_{\text{DC},20} $;
• $ T_{\text{low}}=20 $;
• any $ T_{\text{high}} > T_{\text{low}} $ and $ R_{\text{DC,high}} - R_{\text{DC,low}} = (T_{\text{high}} - T_{\text{low}}) \cdot k_{\ell} \cdot R_{\text{DC},20} $.

If you use direct solar radiation formula (with measured_global_radiation key), you can ignore the following parameters : latitude, longitude, datetime_utc, albedo and turbidity.