A system comprising: a prime mover configured to rotate a shaft ; an independent speed variable frequency, ISVF, generator configured to convert torque from the shaft to an alternating current, AC, power signal , such that a frequency of the AC power signal is independent of a shaft speed of the shaft , wherein the ISVF generator has one or more pole pairs , and wherein an equivalent shaft frequency equals a shaft frequency of the shaft multiplied by a number of the pole pairs , characterized by further comprising: an AC bus having a lower frequency limit and an upper frequency limit ; and a generator control unit configured to: set a generator output frequency of the ISVF generator equal to the lower frequency limit when the equivalent shaft frequency is less than the lower frequency limit ; set the generator output frequency of the ISVF generator equal to the upper frequency limit when the equivalent shaft frequency is greater than the upper frequency limit ; and set the generator output frequency of the ISVF generator equal to the equivalent shaft frequency when the equivalent shaft frequency is greater than or equal to the lower frequency limit and less than or equal to the upper frequency limit . a prime mover configured to rotate a shaft ; an independent speed variable frequency, ISVF, generator configured to convert torque from the shaft to an alternating current, AC, power signal , such that a frequency of the AC power signal is independent of a shaft speed of the shaft , wherein the ISVF generator has one or more pole pairs , and wherein an equivalent shaft frequency equals a shaft frequency of the shaft multiplied by a number of the pole pairs , characterized by further comprising: an AC bus having a lower frequency limit and an upper frequency limit ; and a generator control unit configured to: set a generator output frequency of the ISVF generator equal to the lower frequency limit when the equivalent shaft frequency is less than the lower frequency limit ; set the generator output frequency of the ISVF generator equal to the upper frequency limit when the equivalent shaft frequency is greater than the upper frequency limit ; and set the generator output frequency of the ISVF generator equal to the equivalent shaft frequency when the equivalent shaft frequency is greater than or equal to the lower frequency limit and less than or equal to the upper frequency limit . an AC bus having a lower frequency limit and an upper frequency limit ; and a generator control unit configured to: set a generator output frequency of the ISVF generator equal to the lower frequency limit when the equivalent shaft frequency is less than the lower frequency limit ; set the generator output frequency of the ISVF generator equal to the upper frequency limit when the equivalent shaft frequency is greater than the upper frequency limit ; and set the generator output frequency of the ISVF generator equal to the equivalent shaft frequency when the equivalent shaft frequency is greater than or equal to the lower frequency limit and less than or equal to the upper frequency limit . set a generator output frequency of the ISVF generator equal to the lower frequency limit when the equivalent shaft frequency is less than the lower frequency limit ; set the generator output frequency of the ISVF generator equal to the upper frequency limit when the equivalent shaft frequency is greater than the upper frequency limit ; and set the generator output frequency of the ISVF generator equal to the equivalent shaft frequency when the equivalent shaft frequency is greater than or equal to the lower frequency limit and less than or equal to the upper frequency limit . <EOS>