This paper presents a multi-layered framework for modelling large-scale electrical loads in support of grid compliance studies. The framework provides consistent representations in both electromagnetic transient (EMT) and electromechanical (RMS) simulation domains, ensuring robust validation against Transmission System Operator (TSO) requirements. It is organized into three generic layers: a model logic layer that integrates control, protection, and physical dynamics; a communication layer that enables input/output handling and software interfacing; and a simulation tool specific layer that ensures accurate representation within different environments. The framework is implemented in MATLAB/Simulink®, compiled into encrypted Dynamic-Link Library (DLL) files, and deployed in PSCAD® and DIgSILENT PowerFactory®, guaranteeing cross-platform consistency. The physical

dynamics were captured using a data-driven system identification approach, where transfer functions were inferred directly from operational datasets rather than derived from first-principles modelling. Validation included both benchmarking against operational data and application of the open-source Model Test Bench (MTB) tool developed by Energinet, demonstrating robust and grid-compliant performance under both normal and abnormal conditions. The methodology is generic and can be applied across different demand-side technologies, supporting the integration of flexible demand into future power systems.