Feasibility Study of Flywheel Mitigation Controls Using Hamiltonian-Based Design for <i>E</i>₃ High-Altitude Electromagnetic Pulse Events

This paper explores the feasibility of implementing a flywheel energy storage system designed to generate voltage for the purpose of mitigating current flow through the transformer neutral path to ground, which is induced by a high-altitude electromagnetic pulse (HEMP) event. The active flywheel system presents the advantage of employing custom optimal control laws, in contrast to the conventional approach of utilizing passive blocking capacitors. A Hamiltonian-based optimal control law for energy storage is derived and integrated into models of both the transformer and the flywheel energy storage system. This Hamiltonian-based feedback control law is subsequently compared against an energy-optimal feedforward control law to validate its optimality. The analysis reveals that the required energy storage capacity is <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>13</mn><mspace width="0.277778em"></mspace><mi>Wh</mi></mrow></semantics></math></inline-formula>, the necessary power output is less than <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>5</mn><mspace width="0.277778em"></mspace><mi>kW</mi></mrow></semantics></math></inline-formula> at any given time during the insult, and the required bandwidth for the controller is around <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>5</mn><mspace width="0.277778em"></mspace><mi>Hz</mi></mrow></semantics></math></inline-formula>. These specifications can be met by commercially available flywheel devices. This methodology can be extended to other energy storage devices to ensure that their specifications adequately address the requirements for HEMP mitigation.