Large-scale Electromagnetic Transient Simulation of the French grid: Challenges and Solutions

The paper presents large‑scale electromagnetic transient (EMT) simulation of the French grid, addressing network‑model fidelity and computation‑time challenges, and describing solutions that include an enhanced CIM/EMT interface and sparse solution techniques. The application case covers the entire French grid across 400 kV, 225 kV, 90 kV, and 63 kV, with 25824 three‑phase network nodes, a main system size of 129185, 4725 single‑phase nonlinear saturations, 40 synchronous machines with controls, and 7 HVDC links. The CIM/EMT interface uses planning‑tool data and CIM CGMES files (bus‑branch model), complemented by CSV inputs, and provides model visualization via a graph‑based automatic layout (MSAGL) and a database of substation coordinates with an algorithm to position unknown substations near the closest known coordinates. The sparse EMT solution employs a MANA formulation with discretized companion models, a modified KLU (MKLU) solver, block‑triangular factorization (BTF) for parallelization, fill‑in reduction for LU, and partial refactorization, including per‑BTF‑block updates. Reported performance indicates 47 minutes to simulate 1 second of the full grid, with Ax=b accounting for 93.1% of the time‑domain execution, and speedups up to 5.71×, lowering 1‑second runs to about 8 minutes; next steps include EMTP integration, adding offshore wind parks and manufacturer models, and a parallel co‑simulation platform. - Boris Bruned (RTE-France)