Modeling Hydro Power System Frequency Dynamics for Virtual Inertia Emulation

Under high renewable penetration, the reliability and resiliency of low-inertia microgrids depends on the system transient performance parameters, such as frequency nadirs and/or maximum rate-of-change-of-frequency (ROCOF). As such, mathematically tractable models are needed that can be used to analytically derive these performance parameters to facilitate control design. In this paper, model reduction techniques for a dynamic model of a hydro system (e.g., Routh-Pade and Schur approximation) are used to obtain reduced order models to ensure the transient performance indicators are properly captured. The analytically derived transient performance parameters are then empirically verified using a MATLAB/Simulink test environment. The accuracy of these transient parameters will have a critical role in determining the reliability of microgrids and designing controllers for dispatching fast-frequency services.