A Voltage Detection Method for the Voltage Ride-Through Operation of Renewable Energy Generation Systems Under Grid Voltage Distortion Conditions

This paper proposes a new voltage detection method to assist the low-voltage ride-through operation of grid-tied converters. In particular, it consists of one synchronous reference frame phase-locked-loop (SRF-PLL) and two voltage detection modules. The fast voltage detection module tracks maximum points or zero points of three-phase grid voltage waveforms to calculate the phase voltage amplitude. The accurate voltage detection module operated in parallel assumes an additional cascaded delayed signal cancellation block to filter out the possible low-order voltage harmonics and then employs the same operational principle as the fast voltage detection module to precisely derive the phase voltage amplitude. Coupling with the SRF-PLL, where the grid voltage amplitude before voltage sag or surge can be precisely calculated, the voltage variation ratios can then be derived in sequence. A progressive logic algorithm is designed to determine the converter control commands by fully considering the different voltage variation ratios derived at different time points. Doing so, the proposed method can assist the grid-tied converter to satisfy the grid voltage ride-through operation requirements under various grid voltage distortion conditions. Finally, validity and accuracy of the proposed method were verified by simulation and experimental results.