Effectiveness boundary of frequency emergency control under transient power disturbances

With the increasing integration of high-proportion renewable energy, this leads to a reduction in system inertia, and the low voltage ride-through (LVRT) characteristics of renewable energy under short-circuit faults may subject the system to transient power disturbances, causing a rapid frequency drop. Frequency emergency control may lead to high or low-frequency issues due to improper control actions. To address this, a frequency response model considering frequency emergency control and grid-forming renewable energy is first established. Based on this model, the impacts of transient power deficit and frequency regulation parameters of renewable energy on the emergency control boundaries are analyzed using the simplification-approximation-verification iterative algorithm. Additionally, the relationship between the power reserve levels of renewable energy and the effectiveness boundary of frequency emergency control is systematically investigated.an iterative algorithm of simplification-approximation-verification is used to analyze the relationship between renewable energy power reserve and the effective boundary of frequency emergency control. Finally, the validity of the emergency control boundary is verified using the IEEE 10-machine 39-node system. The results show that the participation of grid-forming renewable energy in frequency regulation can effectively enhance the effective boundary of emergency control, and the boundary of frequency emergency control is significantly impacted by the power reserve of renewable energy.