Analysis of the impact of non-real-time frequency sampling and damping coefficient on the dynamic frequency support...

Grid-forming type control has become an important control mode of renewable energy inverters in practice, since it makes renewable energy could provide the dynamic frequency support for power system like conventional synchronous generator. However, experiments shows that its dynamic frequency support response characteristics are contrary to the original design intention of grid-forming type control. For example, the inertia output doesn't increase to the maximum value as expected at the moment of disturbance. Instead, it follows a trend of initially increasing and then decreasing. This paper conducts the relative analyse research. It reveals the reason causing the above problem is the grid-forming type renewable energy does not sample the grid voltage frequency in real time for closed-loop control, but instead by constructing an intrinsic equivalent frequency. Furthermore, it constructs one frequency support response model taking into account the impact of non-real-time frequency sampling, and systematically explains the impact mechanism of non-real-time frequency sampling on the dynamic frequency support response of grid-forming type renewable energy, and the impact mechanism of damping coefficient on the primary frequency regulation response of grid-forming type renewable energy. Finally, the correctness of the analysis conclusions is verified through simulation.