REFA

Reconductoring Economic and Financial Analysis Tool

The refa python module, based on the publicaly-available REFA tool, aims to unlock more flexible cases of project cost evaluation and enable advanced extensions by developers.

The REFA tool helps grid planners and policy makers understand the financial and economic costs of different capacity upgrade projects. The tool compares projects under the same economic basis by evaluating the net-present value of costs (NPC), while considering both conventional and advanced conductors.

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What REFA Does

Given an existing transmission corridor and a target power capacity requirement, REFA helps grid planners answer:

• Which least-cost conductor can carry the required current without exceeding current or temperature limits?
• What is the sag profile under normal and storm loading conditions?
• Does the operating voltage risk corona discharge?
• What is the net-present cost of each upgrade option over a time horizon (e.g. 40 years)?

REFA evaluates five project types — Rebuild, Reconductoring, Voltage Upgrade, HVDC conversion, and Existing — and compares them by total cost using the Analysis class.

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Key Features

Feature	Details
Techno-economic Analysis	NPC analysis considering key economic parameters, e.g. cost of capital, inflation, and replacement of structures and conductors
Ampacity	IEEE 738 steady-state thermal rating
Temperature and Resistance	IEEE 738 steady-state temperature and resistance at specified current rating
Sag-tension	CIGRÉ TB-324 sag calculations at peak current and under wind-ice loading profiles
Resistive Line Losses	Resistive line losses based on calculated condutor resistance and user-specified load factor
Congestion	Marginal congestion cost modelling
Conductor database	Example conductors
Corona Discharge	Inception voltage and voltage gradient clculations
AC and DC	Separate models for AC and HVDC systems

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Quick Example

from refa import LineDesign, Line, Reconductoring, Analysis
from refa.defaults import (
    default_clear_environment, default_economics,
    acsr_795_0_drake, acss_795_0_cuckoo, accc_1035_dublin,
)

# Describe the line corridor
line_design = LineDesign(
    environment=default_clear_environment(),
    nbr_circuits=1, nbr_bundles=3, nbr_conds_per_bundle=1,
    length_km=30, avg_span_m=300, max_span_m=300,
)

# Build candidate lines
lines = [line_design + acsr_795_0_drake(),
         line_design + acss_795_0_cuckoo(),
         line_design + accc_1035_dublin()]

# Evaluate reconductoring project
project = Reconductoring(
    line_list=lines,
    economics=default_economics(),
    power_mw=400, voltage_kv=230,
    structure_remaining_life=25,
)

print(project.total_costs(time_horizon=40))

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Standards Implemented

Standard	Scope
IEEE 738	Steady-state thermal rating of bare overhead conductors
CIGRÉ 324	Sag-tension calculation methods for overhead lines
NESC 250B	Heavy, medium, light, and warm-island loading districts

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License

REFA was developed at Lawrence Berkeley National Laboratory under U.S. Department of Energy funding. Use of this software is governed by the Berkeley Lab End User License Agreement.