Online Frequency Strength Quantification for Power Systems with More Renewable Energy Sources

The continuous fast integration of renewable energy sources (RES) leads to high uncertainties and reduction of system inertia, which the system frequency strength highly relies on. It is thus of significance to quantify frequency strength continuously and accurately to determine the weak points, and then, to take effective control measures. In this paper, an online quantification method of the power system frequency based on a unified transfer function structure (UTFS) is then proposed. The low-order UTFS is modeled and reviewed first, which could characterize the global system frequency. Then, a UTFS parameter adaptive correction method is derived to avoid massive computation, being the foundation of real-time quantification. Furthermore, with the real-time frequency strength evaluation indices, the power system frequency strength is quantified online. Finally, the effectiveness of the proposed method is verified through simulations on the New England 39-bus system.