A control and regulation system for use with a harmonic neutralization frequency changer system. In the generalized frequency changer system, a direct converter frequency changer is used to convert bulk power, but unwanted harmonics are introduced. Input and output power distortion is monitored by a control system, and groups of high performance inverters inject shunt/series harmonic currents/voltages into a specially designed transformer to neutralize the power distortion to a specific acceptable level. Two control strategies are used including one that is based on discrete narrow band harmonic regulation and another that is based on wide band harmonic control. Each of these control strategies can be used at the input and/or output of the frequency changer and can be injected using shunt-current and series-voltage schemes.