Control Design for High-Side Blocking of E3 High-Altitude Electromagnetic Insults

This paper presents a novel approach for protecting transformers during an E3 HEMP insult as well as the associated technology-agnostic voltage, power, energy storage, and bandwidth requirements of various control laws. The mitigation is performed by placing a controlled voltage supply in series with the primary winding of a transformer. The controlled voltage supply is subjected to four control laws: an integral controller (capacitor), a linear quadratic regulator (LQR), a nonlinear energy storage optimal feedforward control law, and a Hamiltonian feedback control law. The research gap addressed is that most E3 mitigation discussions emphasize neutral-side blocking, whereas transmission-level (high-side) assets may offer a lower-upgrade pathway in some grids and require different actuator sizing and control structure. The results show that the Hamiltonian feedback control law performs the same as the energy storage optimized control law and requires the same specifications. Both of these control laws require less than 30 kV of control effort, 0 W of power, 0 kWh of energy storage, and 16 Hz of bandwidth. This suggests that the Hamiltonian feedback control law is an energy storage optimized feedback control law. These specifications should be considered bounds to the requirements, as power and energy storage requirements will change, depending on the efficiency of the actuator chosen to implement the control laws. These two controllers outperform the blocking capacitor and LQR solutions, despite having significantly less stringent specifications.