How to use Haar wavelet decomposition to do sress analysis ??

Many Thanks in advance.

In an article I read about electric aircraft emergency power system, the stress analysis is performed using the Haar wavelet decomposition of the instantaneous power from each energy/power source.

The high frequency component of each power has a mean value of zero and the standard deviation of this component gives a good indication of how often the power source is solicited.

So, I think I need to calculate the high frequency component of my signal using the Haar wavelet decomposition, then calculate the standard deviation of this component. However most of the examples is about images stuff. What I have is the power signal of each power source with time.