抑制电网背景谐波的变流器导纳重塑方法OACSTPCD

The background harmonic in grid voltage will produce harmonic current on grid-connected converter,and the frequency coupling characteristics of grid-connected converter will map new harmonic current components.In order to restrain the influence of background harmonics on grid connected current,this paper proposes an admittance remodeling method to improve the quality of grid connected current.First,the general form of the inner and outer loop admittance reshaping factors is constructed,and the grid connected converter is reconstructed into a symmetrical system in dq coordinate system to eliminate the frequency coupling characteristics of the converter and reduce the harmonic components of the grid connected current.Then,from the perspective of reducing harmonic content,the admittance remodeling factor is appropriately selected to improve the grid connected current quality by reducing the admittance value of the converter,which can eliminate the frequency coupling characteristics of the converter and suppress the background harmonics of the power grid.Furthermore,the decrease in the sequence admittance modulus of the converter makes it more difficult for the loop ratio curve formed by the converter and the grid impedance to surround(-1,0)point in the amplitude and phase plane,which is beneficial to the stability of the grid connected system.Simulation and experiment verify the feasibility and effectiveness of the proposed admittance remodeling method in improving the quality of the grid-connected current.