| Popis: |
Phase locked loop (PLL) is an important part of the current-controlled grid-connected converter. Its job is to estimate the phase angle of the grid voltage. If the PLL is not robust, the grid-voltage distortion will lead to an error in the estimated phase leading to a degradable performance of the converter. In this paper, the effect of the PLL on the operation of a current-controlled voltage-source converter is examined. A PLL synthesis is proposed, to track the phase angle of the distorted grid voltage, and compared with a previously investigated PLL. The result found is that the proposed synthesis of the PLL is superior in case of grid voltage harmonics other than the 5th and the 7th orders. Moreover, the voltage amplitude oscillation has been reduced from 8% to 3%, with the proposed PLL, compared to 5% with the previously investigated PLL. |
