Application Of Minimum Beat Response Lowpass Filter In Grid Synchronization

With the development of smart grid,the synchronization between power grids becomes more and more important.To control the synchronization between power grids,it is necessary to obtain the grid information(usually the combination of frequency,phase and amplitude of grid voltage).According to the grid type,the grid synchronization can be divided into single-phase grid synchronization and three-phase grid synchronization.The commonly used synchronization methods are phase locked loop and frequency locked loop.Second order generalized integrator(sogi)is widely used in these power grid synchronization links.Usually,sogi obtains the estimated frequency of PLL / FLL to realize the function of frequency adaptation.However,due to the variation of grid voltage / phase,the estimated frequency will be distorted,which will be transmitted to the sogi module through the frequency adaptive link,so that the system will take a longer time to reach a stable state,which seriously affects the stability of the system.The minimum beat response refers to the time response that has the minimum overshoot and the ability to reach the steady-state response fluctuation range rapidly,and can keep within the fluctuation range continuously.The single-phase / three-phase PLL with sogi module usually has two feedback links: frequency feedback and phase feedback.In this paper,the low-pass filter with minimum beat response is cascaded in the frequency feedback branch to reduce the influence of power grid interference on sogi module through frequency feedback link,so as to improve the stability of the system,and the minimum beat response is cascaded in the frequency feedback link Pass filter can keep the original frequency self adaptability of the system to a great extent.