Improved DSOGI-PLL for synchronizing frequency detection of mine power grid voltage

In view of problems that there are frequency and phase errors in extracting voltage synchronization signals of DSOGI-PLL with multiple harmonics or DC bias in mine grid, an improved DSOGI-PLL was proposed to improve DSOGI-PLL from three aspects: frequency regulation, DC bias and harmonic detection.Frequency adaptive adjustment unit is constructed to automatically adjust resonant frequency of DSOGI-PLL through real-time monitoring of frequency change of mine power grid, so as to realize frequency adaptive function of DSOGI-PLL, which can improve accuracy of frequency detection and optimize dynamic response performance.Integral feedback compensation is applied to the second-order generalized integrator-quadrature signals generator(SOGI-QSG) to remove the influence of direct-current component on the test results.Cross feedback structure of multiple DSOGIs in parallel is proposed. In this structure, the input signal of each DSOGI does not contain harmonic components detected by other DSOGIs, which weakens influence of each harmonic component on each other. Matlab simulation results show that the improved DSOGI-PLL can complete accurate detection and tracking lock of frequency and phase angle of the grid voltage when the mine grid voltage has serious interference.