Patent ID: 8553434

Claim:
A method of controlling the grid-side current of a single-phase grid-connected converter having an LCL filter connected between an output of the converter and the grid, the method comprising the steps of: measuring, by a processor of a computing device, a grid voltage (v S ) and at least one signal in a group of signals consisting of a grid-side current (i 0 ), a converter-side current (i 1 ) and a capacitor voltage (v C0 ); estimating a fundamental component (v S,1 ) of the grid voltage (v S ); forming a grid-side current reference (i 0 *), a converter-side current reference (i 1 *) and a capacitor voltage reference (v C0 *) for the grid-side current of the LCL filter using the estimated fundamental component of the grid voltage (v S,1 ); forming estimates for any of the non-measured signals in said group of signals; forming a grid-side current difference term (ĩ 0 ), a converter-side current difference term (ĩ 1 ) and a capacitor voltage difference term ({tilde over (v)} C0 ) from the differences between references and the measured and/or estimated values of said signals; forming an injection term for damping the resonance of the LCL filter by using an active damping injection mechanism (ADI), in which the grid-side current difference term (ĩ 0 ), the converter-side current difference term (ĩ 1 ) and the capacitor voltage difference term ({tilde over (v)} C0 ) are used; forming an estimate of a harmonic distortion term ({circumflex over (φ)}) using the grid-side current difference term (ĩ 0 ); and controlling the output voltage (e) of the converter on the basis of the grid voltage, formed injection term and formed estimate of the harmonic distortion term ({circumflex over (φ)}) to produce a grid side (i 0 ) current corresponding to the current reference.