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If the wind turbine output were now to be measured with an oscilloscope the waveform would look
much different. Notice the plot line is smooth and regular with no ripples – and that it is centered
at the average output of the rippled waves in the previous view. This is due to the voltage
smoothing effect of the capacitor.
Figure 7.6 - Oscilloscope plot of wind turbine DC voltage with a capacitor
Analysis:
If voltage were like water coming out of a hose in spurts, and not a continuous stream, a
capacitor acts like a water bucket with a hole in the bottom. As a water spurt enters the bucket it
temporarily fills the bucket with water. Then when the spurt ceases, the partially filled bucket
releases the water from the hole in the bottom. Repeating this spurt-stop sequence many times
over, water will drain from the hole in the bucket's bottom in a regular, uninterrupted manner.
Compare this water analogy many times faster using electricity and the reasons for a capacitor
(the water bucket) smoothing out the voltage begins to become clear.
Different values of capacitor are like larger and smaller water buckets. This is only one example
of a capacitor that can hold enough charge when the voltage is rising, then release that charge
when the voltage is falling, thus making the voltage a smooth, continuous value.
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