Enabling EMT and HIL Simulations for IBR-Dominated Grids: An Equivalent Model of the Chilean Power System

Unlike the electro-mechanical oscillations of conventional generators, IBRs introduce fastacting, converter-driven dynamics that are critical for system stability but lie beyond the analytical bandwidth of traditional RMS-based phasor simulations. This has precipitated a critical need for high-fidelity Electromagnetic Transient (EMT) studies to accurately investigate phenomena such as sub-synchronous control interactions, wideband harmonic resonances, and transient stability in low-inertia scenarios. However, the immense computational burden inherent in EMT simulations renders the modelling of entire nationalscale power systems impractical. While approaches such as parallel computing can partially alleviate computational demands, they impose constraints on the simulation timestep, particularly in grids that include short transmission lines with small propagation time delays.

This can be problematic, as many OEM models are validated only for specific timestep ranges and are themselves computationally demanding. Moreover, Hardware-in-the-Loop (HIL) simulations involve real-time execution constraints, which fundamentally limit the size and complexity of the simulated network. Consequently, the use of reduced systems that preserve the dynamics of the original grid becomes mandatory. This paper addresses this critical gap by detailing the development and comprehensive validation of a high-fidelity equivalent model of the Chilean National Power System (SEN).

The primary objective is to create a computationally efficient yet dynamically accurate representation of a real-world grid undergoing rapid decarbonization, specifically engineered for advanced EMT and HIL simulations for the design studies of the Kimal – Lo Aguirre HVDC project, using its confidential OEM model. The model’s retained area is strategically defined around a region of high IBR concentration and significant grid reinforcements, ensuring a faithful representation of the system’s steady-state power flow, dynamic voltage response, system inertia and oscillation modes in this critical area. The development process employed a sophisticated approach to network equivalencing that transcends traditional methods, meticulously preserving the dynamic influence of aggregated IBR clusters, FACTS devices, and coherent groups of synchronous generation.

To establish the model’s credibility, a rigorous validation protocol was executed. The static and dynamic performance of the equivalent model was systematically benchmarked against the full model of the Chilean grid under a matrix of operating conditions and N-1 contingencies. The results demonstrate a remarkable degree of correlation in both the phasor and time domains, confirming that the reduced model successfully captures the essential dynamic responses of the original system, including fault ride-through voltage profiles, and the complex interactions of power electronic controllers. By achieving an optimal balance between modelling granularity and computational feasibility, the model is proven suitable for implementation on real-time digital simulation platforms. This work ultimately provides the industry and academia with not only a robust, validated equivalent model of a key emerging power system, but also a proven framework for developing similar tools for other grids facing the challenges of the energy transition. This enables crucial and complex studies necessary to de-risk the integrations of new technologies and ensure the future security and reliability of IBR-dominated power systems.