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PyPSAModeler

The PyPSAModeler provides the interface between WEC-Grid and the open-source PyPSA library.
It implements open-source power system analysis with modern Python algorithms and cross-platform validation capabilities.

Responsibilities

  • PyPSA Integration

    • Parse PSS®E RAW case files via GRG parser
    • Build PyPSA Network objects with buses, lines, generators, loads, transformers
    • Execute AC power flow solutions using PyPSA's solver

  • WEC Farm Implementation

    • Create new buses for WEC connections
    • Add WEC generators with carrier="wave" designation
    • Connect WEC farms to existing grid via transmission lines

  • Grid State Management

    • Extract comprehensive grid data from PyPSA network components
    • Convert PyPSA data formats to standardized GridState schema
    • Capture bus voltages, generator outputs, line flows, and load consumption

Key Features

Open-Source Power System Analysis

  • Accessible Research — No licensing requirements; reproducible scientific workflows
  • Modern Algorithms — Python-based optimization with SciPy/NumPy integration
  • Cross-Validation — Direct comparison with PSS®E results using identical case files
  • Flexible Modeling — Lightweight data structures and pandas integration

WEC-Specific Adaptations

  • Wave Energy Carriers — WEC generators tagged with carrier="wave"
  • Dynamic Updates — Per-snapshot generator power updates from WEC-Sim time series
  • Collection Systems — Automatic bus and line creation for WEC farms

PyPSA API Integration

Initialization Sequence

parse_psse_case_file() → pypsa.Network() → add components → network.pf()

Core API Calls

  • Power Flow

    • network.pf() — Solve AC power flow with optimization backend
    • network.snapshots — Time index for simulation periods

  • Data Access

    • network.buses[['v_nom','control']] — Bus voltages and control types [kV]
    • network.generators[['p_set','q_set','carrier']] — Generator setpoints [MW/MVAr]
    • network.loads[['p_set','q_set']] — Load consumption [MW/MVAr]
    • network.lines[['bus0','bus1','s_nom']] — Line connections and ratings [MVA]

  • Grid Modification

    • network.add("Bus") — Add new buses for WEC connections
    • network.add("Generator") — Add WEC generators with wave carrier
    • network.add("Line") — Create transmission lines between buses

Function Spotlight — import_raw_to_pypsa()

The core function that converts PSS®E .raw cases into PyPSA Network objects using the GRG parser.

Key Operations

  • Impedance Conversion: R_Ω = R_pu × (V_base² / S_base), X_Ω = X_pu × (V_base² / S_base)
  • Control Mapping: PSS®E IDE codes → PyPSA control types (PQ, PV, Slack)
  • Component Creation: Buses, lines, generators, loads, transformers, shunts

Usage

eng = Engine()
eng.case("ieee_39.raw")
eng.load(["pypsa"])  # Calls import_raw_to_pypsa() internally

System Requirements

  • PyPSA: Version 0.20.1 (as pinned) with pandas, NumPy, SciPy
  • GRG parser: grg-pssedata package for PSS®E RAW import
  • Python: 3.7+ (3.9 recommended)
  • Operating System: Cross-platform (Windows, macOS, Linux)

Common Issues

Case Import Problems

  • Ensure grg_pssedata can parse the RAW file format
  • Verify voltage bases and transformer ratings are present
  • Check for well-formed PSS®E RAW structure (versions 33-35)

Convergence Issues

  • Inspect network topology for islands and missing slack buses
  • Verify generator p_set and system load balance
  • Confirm transformer taps and line ratings are reasonable

Performance and Logging

  • Reduce console output by raising PyPSA logger level
  • Use vectorized operations for time-series updates
  • Consider smaller snapshot windows for testing workflows