Energy Storage Requirements for Third-Winding Transformer Mitigation of HEMP E3

Document Type

Article

Publication Date

1-1-2026

Abstract

This paper presents four control laws and associated specifications for a third-winding-transformer geomagnetically induced current blocker designed to mitigate high-altitude electromagnetic pulse (HEMP) E3 waveforms. The third-winding transformer is modeled as a controllable current source within the magnetizing path to suppress HEMP-induced voltage offsets. The control laws are: (i) a proportional–integral (PI) controller, (ii) a linear quadratic regulator (LQR), (iii) an energy-minimized feedforward control law, and (iv) a Hamiltonian feedback controller that manages energy exchange within the flux-blocking device. Simulation results indicate that all controllers mitigate HEMP E3, with the Hamiltonian feedback controller and energy-minimized feedforward control law outperforming the PI and LQR controllers in nearly all metrics. Notably, the Hamiltonian feedback and energy-minimized feedforward laws facilitate complete rejection of exogenous power by absorbing current at approximately zero potential, yielding a peak power requirement of 0Win the idealized model. The required bandwidth for the Hamiltonian feedback controller (5 Hz) is slightly higher than that of the feedforward law (3.5 Hz). Both energy-minimized control laws neither absorb nor inject net energy in the idealized model. The LQR and PI controllers require approximately 3.5 Hz bandwidth but exhibit peak absorbed powers of approximately 2.5MWand 6.75MW, respectively. These results suggest that complete power rejection (current absorption at near-zero potential) is the energy-optimal method for protecting an individual transformer. Additionally, this paper shows that the Hamiltonian feedback controller is an energy-optimal feedback control law.

Publication Title

IEEE Access

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