Cabling Helper Classes

For detailed methodology, please see Cable Helper Design.

class ORBIT.phases.design._cables.Cable(cable_specs, **kwargs)

Base cable class.

Parameters:

• conductor_size (float) -- Cable cross section in \(mm^2\).

• current_capacity (float) -- Cable current rating at 1m burial depth, \(A\).

• rated_voltage (float) -- Cable rated line-to-line voltage, \(kV\).

• ac_resistance (float) -- Cable resistance for AC current, (ohms/km).

• inductance (float) -- Cable inductance, \(\frac{mH}{km}\).

• capacitance (float) -- Cable capacitance, \(\frac{nF}{km}\).

• linear_density (float) -- Dry mass per kilometer, \(\frac{tonnes}{km}\).

• cost_per_km (int) -- Cable cost per kilometer, \(\frac{USD}{km}\).

• char_impedance (float) -- Characteristic impedance of equivalent cable circuit, (ohms).

• power_factor (float) -- Power factor of AC current in cable, no units.

• cable_power (float) -- Maximum 3-phase power dissipated in cable in \(MW\).

• line_frequency (int, default: 60) -- Frequency of the AC current, \(Hz\).

required = ('conductor_size', 'current_capacity', 'rated_voltage', 'ac_resistance', 'inductance', 'capacitance', 'linear_density', 'cost_per_km', 'name')

calc_char_impedance()

Calculate characteristic impedance of an HVAC cable. HVDC cables are assumed to have no impedance. Note that the units for inductance and capacitance per unit length are normalized in the following formulae because the industry standards report inductance in mH/km (10^-3) and capacitance in nF/km (10^-9).

source: https://en.wikipedia.org/wiki/Characteristic_impedance

calc_power_factor()

Calculate power factor.

calc_cable_power()

Calculates the maximum power transfer through a 3-phase cable, in \(MW\).

calc_compensation_factor()

Calculates the compensation factor for the shunt reactor cost.

class ORBIT.phases.design._cables.Plant(config)

A "data class" to create the windfarm specifications for ArraySystemDesign.

layout

The layout of the windfarm. Can only be "grid", "ring", or "custom". ..note:: custom is not implemented at this time.

Type:

str

num_turbines

Number of turbines contained in the windfarm.

Type:

int

site_depth

Average depth at the site in km.

Type:

float

turbine_rating

Capacity of an individual turbine in MW.

Type:

float

row_distance

Distance between any two strings in a grid layout in km. This is not used for ring layouts or custom layouts.

Type:

float

turbine_distance

Distance between any two turbines in a string in km. This is not used for custom layouts.

Type:

float

substation_distance

The shortest distance between the offshore substation and the first turbine of each string in km. In the ring layout this distance is uniform across all strings. In grid layout this represents the perpendicular distance to the first row of turbines. This is not used in custom layouts.

Type:

float

expected_config = {'plant': {'layout': 'str', 'num_turbines': 'int', 'row_distance': 'km (optional)', 'row_spacing': 'rotor diameters (optional)', 'substation_distance': 'km', 'turbine_distance': 'km (optional)', 'turbine_spacing': 'rotor diameters'}, 'site': {'depth': 'm'}, 'turbine': {'rotor_diameter': 'm', 'turbine_rating': 'MW'}}

_initialize_distances(config)

Initializes the distance attributes that are created for a grid and ring layout.

Parameters:

config (dict) -- Configuration dictionary.

class ORBIT.phases.design._cables.CableSystem(config, cable_type, **kwargs)

Base cabling system class. This is the parent class to ArraySystemDesign and ExportSystemDesign.

cable_type

An input of "array" or "export" to signify which cabling system is being designed.

Type:

str

cables

Dictionary of cables being used with items as {"cable_name": Cable}.

Type:

dict

Raises:

• NotImplementedError -- The property detailed_output is not yet defined.

• Exception -- cables must be created in order to get outputs.

cables = None

_initialize_cables()

Creates the base cable objects for each type of array cable being modeled.

_get_touchdown_distance()

Returns the cable touchdown distance measured from the centerpoint of the substructure.

If depth <= 60, default is 0km (straight down assumed for fixed bottom). If depth > 60, default is 0.3 * depth.

static _catenary(a, *data)

Simple catenary equation.

_get_catenary_length(d, h)

Returns the catenary length of a cable that touches down at depth d and horizontal distance h.

Returns:

float -- Catenary length.

property free_cable_length

Returns the vertical length of a cable section, in \(km\).

property cable_lengths_by_type

Creates dictionary of lists of cable sections for each type of cable.

Returns:

lengths (dict) -- A dictionary of the section lengths required for each type of cable to fully connect the array cabling system. E.g.: {Cable.`name`: np.ndarray(float)}

property total_cable_length_by_type

Calculates the total cable length for each type of cable.

Returns:

total (dict) -- A dictionary of the total cable length for each type of cable. E.g.: {Cable.name: list(section_lengths)}

property cost_by_type

Calculates the cost of each array cable type.

Returns:

cost (dict) -- A dictionary of the total cost of each type of array cable. E.g.: {Cable.name: cost}

property total_cost

Calculates the cost of the array cabling system.

Returns:

float -- Total cost of the array cabling system.

property detailed_output

Returns detailed design outputs.

_abc_impl = <_abc._abc_data object>

property design_result

A dictionary of cables types and number of different cable lengths and linear density.

Returns:

output (dict) -- Dictionary of the number of section lengths and the linear density of each cable type.

• <cable_type>_system: dict

  • cables: dict

    • Cable.name: dict

      • sections: [(length of unique section, number of sections)],

      • linear_density: Cable.linear_density