Projects

All project types inherit from ProjectEssentials, which wraps one or more Line objects with an Economics model and computes net-present-value costs over a specified time horizon.

Common Parameters

All project types share these required fields:

Field	Type	Description
`power_mw`	`float`	Target power delivery (MW)
`voltage_kv`	`float`	Operating voltage (kV, ≥0)
`economics`	`Economics`	Economic and financial assumptions

And these optional fields:

Field	Default	Description
`structure_config`	`None`	Required for corona feasibility
`select_ampacity_feasible`	`True`	Filter lines that fail ampacity check
`select_sag_feasible`	`True`	Filter lines that fail sag check
`select_corona_feasible`	`True`	Filter lines that fail corona check

Constructor Patterns

LineDesign + conductor listPre-built line list

REFA builds one Line per conductor automatically.

project = Rebuild(
    conductor_list=[acsr_795_0_drake(), acss_795_0_cuckoo()],
    line_design=my_line_design,
    economics=my_economics,
    power_mw=400, voltage_kv=230,
)

Pass Line objects directly — useful when lines have different designs.

project = Reconductoring(
    line_list=[line1, line2, line3],
    economics=my_economics,
    power_mw=400, voltage_kv=230,
    structure_remaining_life=25,
)

Rebuild

Assumes all conductors and structures are replaced at the start of the time horizon. Conductor and structure replacement cycles both start at year 0.

from refa import Rebuild
from refa.defaults import default_structure_config_ac

rebuild = Rebuild(
    conductor_list=[acsr_795_0_drake(), acss_795_0_cuckoo(), accc_1035_dublin()],
    line_design=my_line_design,
    economics=my_economics,
    power_mw=400,
    voltage_kv=230,
    structure_config=default_structure_config_ac(),
)

costs = rebuild.total_costs(time_horizon=65)
# [{'prj_name': 'Rebuild', 'conductor': 'ACSS 795.0_CUCKOO',
#   'npv_total_project_costs_mill_dol': 12.16}, ...]

Reconductoring

Conductors are replaced but structures remain. The structure replacement cycle begins after structure_remaining_life years.

from refa import Reconductoring

recon = Reconductoring(
    line_list=[my_line_design + acss_795_0_cuckoo(),
               my_line_design + acsr_795_0_drake()],
    economics=my_economics,
    power_mw=400,
    voltage_kv=230,
    structure_remaining_life=25,
)

VoltageUpgrade

Raises the operating voltage. Requires an upfront cost for substation and transformer modifications.

from refa import VoltageUpgrade

vu = VoltageUpgrade(
    line_list=[my_line_design + acsr_795_0_drake()],
    economics=my_economics,
    power_mw=400,
    voltage_kv=345,
    structure_remaining_life=0,
    conductor_remaining_life=0,
    cost_substations_upgrade_dol=2_000_000,   # required
)

# Substation cost can be updated after construction
vu.cost_substations_upgrade_dol = 1_500_000

# View substation cost separately
print(vu.substations_upgrade_costs(time_horizon=40))

HVDC

Converts the corridor to high-voltage DC. Requires converter station costs. The nbr_dc_poles_per_circuit field overwrites nbr_bundles on the line to match the DC pole configuration.

from refa import HVDC
from refa.defaults import default_structure_config_dc

hvdc = HVDC(
    line_list=[my_line_design + accc_1035_dublin()],
    economics=my_economics,
    power_mw=400,
    voltage_kv=500,
    structure_remaining_life=0,
    conductor_remaining_life=0,
    cost_converters_dol=3_000_000,   # required
    nbr_dc_poles_per_circuit=2,
    structure_config=default_structure_config_dc(),
)

# Converter cost can be updated after construction
hvdc.cost_converters_dol = 2_500_000

# View converter cost separately
print(hvdc.converter_costs(time_horizon=40))

Existing

Models the current line as-is with no changes. Useful as the baseline in an analysis.

from refa import Existing

existing = Existing(
    line_list=[my_line],
    economics=my_economics,
    power_mw=400,
    voltage_kv=230,
    structure_remaining_life=25,    # required
    conductor_remaining_life=15,    # required
)

Cost Methods

All project types expose this set of cost methods:

Method	Returns
`total_costs(time_horizon)`	Total capital cost NPV
`total_costs_including_losses(time_horizon, load_factor)`	Total cost + losses cost NPV
`conductor_costs(time_horizon)`	Conductor-only NPV
`structure_costs(time_horizon)`	Structure-only NPV
`losses_costs(time_horizon, load_factor)`	Line losses cost NPV
`congestion_costs(time_horizon)`	Congestion cost NPV

All methods return a list of dict:

[
    {
        "prj_name": "Reconductoring",
        "conductor": "ACSS 795.0_CUCKOO",
        "npv_total_project_costs_mill_dol": 1.73,
    },
    ...
]

VoltageUpgrade project has an additional method:

| substation_upgrade_costs(time_horizon) | Substation costs |

HVDC project has an additional method:

| converter_costs(time_horizon) | Converter costs |

Pass report_all_years=True to receive the cumulative NPV at every year up to time_horizon rather than just the final value.

Remaining Life

structure_remaining_life and conductor_remaining_life control when the first replacement investment occurs in the NPV model:

0 → the asset is replaced immediately at year 0 (new capital outlay in year 1)
25 → the asset continues for 25 years before the first replacement