Research On Input Voltage Low Frequency Ripple Suppression Strategies For Two-stage Single-phase PV Grid-connected Inverter

Since the instantaneous output power of the inverter pulsates with the double-line frequency in the two-stage single-phase PV grid-connected system,the dc-link voltage contains double-line frequency ripple.Moreover,the double-line frequency pulsation can further transmit to the input side,which leads to the large double-line frequency ripple component contained in input voltage and the MPPT efficiency seriously reduced.Therefore,the low frequency ripple suppression strategies of input voltage for two-stage single-phase photovoltaic power generation system must be further studied.This paper established the mathematical model of input voltage ripple component analysis.Then,the basic way to suppress voltage ripple and four suppression strategies is pointed out.In addition,the standard of the input voltage DLF ripple suppression is also determined,and on that base,the robust suppression condition of the input voltage double-line frequency ripple is further discussed.Based on this,the parameters design method for four kinds of suppression strategies are given.As a result,the system has both robust stability and low frequency ripple robust rejection capability.Finally,the correctness and effectiveness of the theoretical analysis are verified by simulation and experiment results of a 300 W prototype.The research results show that the four input voltage double-line frequency ripple suppression strategies proposed in this paper can effectively suppress input voltage double-line frequency ripple.And taking the above strategies can make the double-line frequency ripple rate less than 5% under the entire working conditions,which can greatly improve the MPPT efficiency.