Ancillary services of VSC interfaced energy sources - voltage harmonics compensation

With the envisaged high integration of distributed generation (DG), the use of their own technology to provide other services to the grid seems a practical option. The use of a PWM voltage source converter (VSC) to attenuate grid voltage harmonics, in the absence of measurement data at the grid side and lack of knowledge about the grid loads in close proximity, is investigated in this paper. The outer harmonic regulator is adaptive, in order to cope with the dynamic nature of the grid and modulation non-linearity. The grid voltage harmonics are extracted using least mean square (LMS) method, and the inner controller is a synchronous reference frame current controller. It has been shown through simulation that the controller is capable of attenuating the voltage harmonics to an acceptable limit. However, a direct current controller is recommended for better performance.