<p>Frequency is one of the most significant performance indicators of the power system security. Therefore, fast and accurate simulations of the post-disturbance frequency response (FR) are crucial for various applications. In this paper, an enhanced system frequency response (SFR) model is proposed, which considers the accurate generating units turbine-governor models and an enhanced integrated grid model. In addition to capturing common grid dynamics, the model includes a novel feedback block representing significant not-modeled frequency-related characteristics, such as active load voltage dependency. To validate the enhanced SFR model, accurate simulations from a detailed large-scale time-domain model are utilized. This process is founded on the exact adjustment of turbine-governor parameters and straightforward calculation of common grid parameters, i.e. equivalent inertia and load damping. Furthermore, a new algorithm is proposed to specify the structure of the compensation block and tune its parameters, ensuring the enhanced SFR model achieves the desirable accuracy while having an improved speed. Simulation results demonstrate the correctness, applicability, and effectiveness of the proposed model when compared to a real large-scale power system’s detailed frequency model across various types and sizes of incidents under different grid operating conditions.</p>