Power Flow Optimization Redesign for Transient Stability Enhancement.

We develop an optimization program referred to as the $H_{2}$ -power flow modification $(H_{2}$ -pfm) that utilizes the potential of inverter-based resources (IBRs) for improving damping of the electro-mechanical dynamics of a power system, and, in turn, enhances its transient stability radius as well. The method tunes the active and reactive power setpoints of the IBRs generated from the standard AC-OPF solution to optimize the $\mathbf{H}_{2}$ -norm of the transfer function of the grid model considering any incoming disturbance as the input and the generator rotor speeds as the outputs. Power transfer distribution factors (PTDFs) are used to identify the most relevant sets of tunable setpoints to reduce the search space, thereby making the problem solvable online. Simulation results are shown using a 16-machine, 68-bus New York power system model integrated with 7 wind farms. Results indicate that $H_{2}$ - PFM leads to notable improvement in transient stability compared to that for nominal AC-OPF.