A novel approach to minimize line-current harmonics in interfacing renewable energy sources with 3-phase utility systems

An approach to interfacing renewable energy sources such as photovoltaic, wind-electric, and small hydroplants with three-phase utility systems is presented. By modulating the DC-link currents and then reinjecting the modulating currents on the AC side, distortion in the line currents can be reduced to be within the allowable limits. Other advantages include the capability to provide electrical isolation by means of high-frequency transformers and the potential for an overall low cost. With the presently available semiconductor switches such as insulated-gate bipolar transistors (IGBTs) and gate turn-off thyristors (GTOs), this approach can be used in a very wide range of voltage and power ratings in interfacing nearly all power electronics equipment to three-phase utility systems