API Reference

Linearized MILP formulation using Ipopt that enforces exactly one binding line per transaction. Objective: minimize sum of absolute TTC errors (L1 norm).

calculate_all_ttc_results(Ybus, lines_df, tie_lines_df)

Computes TTC for all canonical transactions (a < b) WITHOUT storing PTDFs. Memory-optimized for large-scale systems.

calculate_single_injection_ptdfs(Ybus; reference_bus=1)

Core Engine: Factorizes B matrix once and solves for unit injections.

calculate_ttc_from_ptdfs(ptdf_df, line_capacities)

Calculate the Total Transfer Capacity (TTC) for every canonical transaction (A < B). Returns DataFrame with TTC values and limiting line information.

clean_line_data(lines_df::DataFrame)

Clean line data by removing self-loops and assigning fake EIC codes to missing entries.

convert_line_to_pu!(lines_df::DataFrame, Sbase::Float64; in_pu::Bool=false)

Convert line parameters to per-unit values based on system base power. If in_pu is true, assumes R, X, B are already in per-unit and only converts capacity.

create_ttc_results_from_optimization(
ttc_vals::Vector{Float64},
ttc_canonical::DataFrame;
model=model,
Type = CONFIG.optimization_type,
synth_lines::Vector{Tuple{Int,Int}} = Tuple{Int,Int}[],
binding_dict::Union{Dict,Nothing} = nothing
)

Create TTC results directly from optimization variables.

export_bus_id_map(node_info, export_path)

Export a CSV file containing the mapping between old bus names and new numerical IDs.

Arguments

• node_info::DataFrame: Node information with oldname and newid columns
• export_path::String: Path where the CSV file will be saved

Output CSV Format

• old_name: Original bus names from input data
• new_id: Numerical IDs assigned during processing

export_detailed_line_info(lines_df, tielines_df, export_path)

Export comprehensive line information including both original names and numerical IDs.

Arguments

• lines_df::DataFrame: Regular transmission lines data
• tielines_df::DataFrame: Tie lines data
• export_path::String: Path where the CSV file will be saved

Output CSV Columns

• EIC_Code: European Identification Code for the line
• Fromnode, Tonode: Original bus names
• NewIDFrom, NewIDTo: Numerical bus IDs
• Voltage_level: Operating voltage level
• Length_km: Line length in kilometers
• CapacityMW, Capacitypu: Line capacity in MW and per-unit
• Rpu, Xpu, B_pu: Line parameters in per-unit
• IsTieLine: Boolean flag indicating if this is a tie line

form_ybus_with_shunt(lines_df, tie_lines_df, node_info, Sbase)

Form the network admittance matrix (Y-bus) including shunt elements. Returns a sparse complex matrix representing the network admittance.

kron_reduce_ybus(Ybus, rep_node_ids)

Perform Kron reduction on the original Ybus matrix to eliminate non-representative nodes.

The Kron reduction technique eliminates internal nodes while preserving the electrical relationships between the representative nodes. This creates an equivalent network with fewer nodes but equivalent transfer characteristics.

Arguments

• Ybus::SparseMatrixCSC{ComplexF64}: Original network admittance matrix
• rep_node_ids::Vector{Int}: Indices of representative nodes to retain

Returns

• Y_kron::SparseMatrixCSC{ComplexF64}: Reduced admittance matrix

Mathematical Background

The Kron reduction partitions the admittance matrix as:

Y = [K   L_T]
    [L   M  ]

where K connects representative nodes, M connects eliminated nodes, and L connects representative to eliminated nodes.

The reduced matrix is: Ykron = K - LT * M^(-1) * L

load_excel_data(file_path::String)

Load network data from Excel file with multiple sheets. Returns a dictionary containing DataFrames for lines, tielines, nodes, and generators.

main_full_analysis()

Complete network reduction analysis workflow including:

1. Data loading and preprocessing
2. Original network PTDF/TTC analysis
3. Representative node selection
4. Kron reduction
5. Reduced network analysis
6. Optimization of equivalent capacities
7. Results comparison and export

Returns

Tuple containing:

• ttc_results: Original network TTC calculations
• ptdfreducedresults: Reduced network PTDF calculations
• equivalentcapacitiesdf: Optimized equivalent capacities

Data Directory

Modify the inputdatadir and outputdatadir variables to change the location.

Output Files

• BusIDMap_QP.csv: Mapping of bus names to numerical IDs
• LineDetailsQP.csv: Comprehensive line information
• RepresentativeNodesQP.csv: Selected representative nodes
• TTCOriginalNetwork_QP.csv: Original network TTC values
• PTDFReducedNetwork_QP.csv: Reduced network PTDF values
• EquivalentCapacitiesQP.csv: Optimized synthetic line capacities
• TTCComparisonQP.csv: Comparison of original vs equivalent TTC values

process_tielines(tielines_df::DataFrame)

Process tie-lines by sorting, removing duplicates, and handling missing EIC codes.

rename_buses(nodes_df, generators_df, lines_df, tie_lines_df, Sbase)

Rename buses to uppercase, create numerical mapping, and convert data to per-unit. Returns processed line DataFrames and node information.

reset_config!()

Resets the global CONFIG object to its default values. Useful for batch testing multiple case studies.

select_representative_nodes(Ybus, node_info)

Select a single representative node (RN) from each unique 'Zone' based on the highest interconnection degree.

Arguments

• Ybus::SparseMatrixCSC{ComplexF64}: Network admittance matrix
• node_info::DataFrame: Node information DataFrame

Returns

• rep_nodes::DataFrame: DataFrame with selected representative nodes
• node_info::DataFrame: Updated nodeinfo with isrepresentative flag set

Config

Central configuration struct for the entire network reduction workflow. Modify the default values below to run different case studies.