Power quality monitoring method

The invention discloses a power quality monitoring method. A FPGA is employed in the method to realize zero-crossing detection function and compared with traditional voltage-controlled oscillators, the method exhibits better real-time performance and following performance. On frequency measurement and sampling control, three-phase voltage signal is introduced as a standard of the frequency measurement and the sampling control so that, compared with one-phase voltage signal introduced as the standard, the method is more reliable and flexible; that software controls sample interval is as a supplement of hardware sampling control, so that sampling accuracy is improved; on algorithm input points, accuracy requirement of the algorithm and the calculated quantity are balanced; and under the condition that accuracy is guaranteed, calculated quantity is lessened, so that cost performance of the actual device is improved.