Study on High-Altitude Electromagnetic Pulse Protection Technology of Underground Nuclear Power Plant Generator

High-altitude electromagnetic pulse (HEMP) can produce Electromagnetic interference (EMI) on the generator system. Without a precise machine model, over-voltage on the stator winding of generator cannot be accurately evaluated, and this is a new challenge for the design of nuclear power plant generator system. Therefore, the paper establishes the motor model by considering multi-conductor transmission line, and employs this model to design a set of precautions. At first, the expression of HEMP and coupling channel of HEMP are performed to analyze magnitude and waveform of over-voltage caused by HEMP. Then, a novel stator winding model is developed which bases on the analysis for multi-conductor transmission line. This model is computationally efficient and the voltage of winding per turn under HEMP can be calculated fast and accurately via it. The proposed approach can be validated through a three-dimensional electromagnetic simulation software. Finally, couple of precautions are derived based on the existing lightning protection measures and the above analysis.