Optimizing Fault Ride-through Control Parameters of Renewable Energy Generators for Frequency Stability Enhancement

With the increasing integration of power electronic devices, transient frequency stability has become a prominent challenge in power systems. Although the low voltage ride-through (LVRT) control of renewable energy generators (REGs) supports voltage stability, it can negatively impact system frequency stability. Specifically, during fault and post-fault recovery periods, REGs can exacerbate low-frequency issues in the receiving end of a hybrid AC-DC power system due to the reactive power priority setting in their LVRT control strategy. A sudden drop in transient frequency may trigger unnecessary emergency control actions, posing a serious threat to system stability. To address this issue, this paper proposes an optimization method for the LVRT control parameters of REGs in receiving-end systems. The approach begins by establishing the quasi-steady-state model of the system immediately after the fault. By linearizing this nonlinear algebraic model, we derive the sensitivity of REGs' control parameters with respect to the total unbalanced power of the system. Based on this sensitivity, the LVRT control parameters of REGs are optimized using a gradient descent algorithm. The proposed method is validated on the CSEE-VS test system, showing an improvement in the system frequency nadir from 48.5 Hz to 49.6 Hz, thereby preventing load shedding that could lead to cascading failures and blackouts.