METHOD OF COMPENSATING PHASE ERROR CAUSED BY VARIATION OF POWER FREQUENCY OF SINGLE-PHASE GRID-CONNECTED INVERTER

摘要

The present invention relates to a method of compensating a phase error caused by variation of power frequency of a single-phase grid-connected inverter. Provided is a method of compensating a phase error caused by variation of power frequency of a single-phase grid-connected inverter. The method comprises: a first step of generating a virtual voltage with an APF through information of a grid voltage measured from a voltage sensor; and a second step of converting the virtual voltage and an actual voltage into a synchronous coordinate system d and q-axis voltage through coordinate conversion and then calculating a phase angle tracked by a SRF-PLL technique; and a third step of locating a integration section compensation algorithm at a rear end of the integrator of the synchronous coordinate system PI phase controller in the case that there is a pulsating component twice the synchronous coordinate system d-axis voltage, which is generated due to the difference between the cutoff frequency of the APF and the power supply frequency, depending on the fluctuation of the power frequency after the second step, compensating one cycle and two cycle through a section integrator with respect to a tracked phase angle, determining whether the average value outputted from the section integrator is stably obtained by transferring a selection switch or whether it is promptly obtained, compensating the error with the synchronous coordinate system PI controller with respect to the average value selected by the selection switch to reduce the pulsation component with respect to the variation of the power frequency, and then, distortion of the tracked phase angle, thereby remarkably enhancing the performance of single-phase grid-connected inverter.;COPYRIGHT KIPO 2017