The working principle of UPS power supply for flywheel is to use vacuum magnetic coil to store energy and discharge. Similarly, according to the principle of energy conservation, when the kinetic energy of flywheel UPS drops to a certain degree, which is officially 85%, the diesel generator set is started. Therefore, the highest quality power supply of the so-called flywheel is equivalent to the power supply of the diesel generator set. What is high quality? As long as the harmonics and voltage fluctuations do not exceed 5%, it is called high quality.
Moreover, GenSTART (the starting unit of flywheel) needs 24V 1000A and 1000A to improve the success rate of starting the generator set. What concept? The principle of capacitor banks is well known. What is the capacitance of 1000A in parallel and series?
In fact, I personally think that the function of flywheel is only to provide a backup emergency with a large current. Finally, diesel generator sets are needed to maintain energy saving.