Computation of time-domain impulse-response from band-limited ship power distribution models using wavelet transformation

The impulse response of components and network interconnections within the power distribution system of an all-electric ship can be a useful tool for investigating certain fault conditions as well as common-mode current effects. Due to the large size of the ship compared to the wavelengths of the frequency of interest, time-domain measurement or simulation is a time-consuming process. Therefore, behavioral models described in the frequency domain, such as “Scattering” or S parameters, are often used to calculate the time domain impulse response. As simulated or measured scattering parameters are missing the DC and/or close to DC components, the calculated time domain response is an incomplete reconstruction and thus inaccurate. This paper addresses a novel recursive algorithm which is used to apply a continuous wavelet transform to the frequency data for calculating the time-domain impulse response of the ship power system precisely. The results show good agreement between the calculated impulse response using the S-parameter model reconstructed with the wavelet transform and a reference time-domain simulation.