Gas Contingency

Overview

Gas contingencies modify the network data dictionary before solving the optimization problem. These modifications simulate:

• Component failures (e.g., pipes or compressors going offline)

• Compressor power outages (reduced compression capability)

The contingency system is designed to:

1. Mutate the case data dictionary in-place

2. Return structured success/failure results

Core Types

Contingency (Abstract Type)

abstract type Contingency end

Base type for all contingency types.

FailedComponentContingency

Base.@kwdef struct FailedComponentContingency <: Contingency
    asset_type::String
    asset_id::String
end

Represents a complete outage of a network asset.

Effect on data dictionary:

asset["status"] = 0

The asset is disabled and excluded from the optimization model.

PowerOutageContingency

Base.@kwdef struct PowerOutageContingency <: Contingency
    asset_type::String
    asset_id::String
    available_power_fraction::Float64
end

Represents a compressor operating at reduced power.

Constraints:

0.0 ≤ availablepowerfraction ≤ 1.0

Currently only supports "compressor" asset type

Effect on data dictionary:

Compressor maximum compression ratio is scaled:

new_max=min+(max−min)×available_power_fraction

This preserves feasibility while restricting compression capability.

ContingencyScenario

Base.@kwdef struct ContingencyScenario
    name::String
    description::String = ""
    contingencies::Vector{<:Contingency}
end

Container for multiple contingencies applied together.

ContingencyResult

struct ContingencyResult
    contingency::Contingency
    success::Bool
    message::String
end

Returned for each applied contingency.

Helper utilities:

all_applied(results)
summarize_results(results)

Applying a Contingency

Main Entry Point

apply_contingency!(case::AbstractDict, scenario::ContingencyScenario)

Mutates the case dictionary in-place

Returns Vector{ContingencyResult}

Example:

scenario = ContingencyScenario(
    name = "Winter Storm",
    description = "Two pipes frozen, one compressor at reduced power",
    contingencies = [
        FailedComponentContingency(asset_type="pipe", asset_id="1"),
        FailedComponentContingency(asset_type="pipe", asset_id="2"),
        PowerOutageContingency(asset_type="compressor", asset_id="1", available_power_fraction=0.3),
    ]
)

results = apply_contingency!(case, scenario)