3) From a controller perspective, how does DC compare with AC?
For AC systems, the controllers must regulate AC current (three phase) and AC voltage (three phase), which impact AC real power and AC reactive power. AC system frequency must also be well maintained to avoid stability concerns within the electric grid. In DC systems, reactive power is not defined because DC current and DC voltage are always in phase, thus, power factor is also not defined. In a DC system, frequency does not exist. From this brief discussion, DC system control is less complex compared to AC.