基于q轴阻抗重塑的并网逆变器稳定控制策略研究

随着可再生能源装机容量的增加,电网呈现出大电网阻抗的弱电网特性。通常逆变器通常通过锁相环(phase-locked loop,PLL)获得电网同步信息,为了抑制电网电压的背景谐波和幅值干扰,还需要进行电网电压前馈(grid voltage feedforward,GVF)控制。PLL和GVF引入的负面效应将导致逆变器在弱电网下不稳定。因此,本文提出了一个阻抗控制器,用于在低频段将q轴阻抗重塑为正电阻,解决了PLL和GVF造成的系统不稳定问题。

With the increasing installed capacity of renewable energy,the gridpresents characteristics of weak grids with large grid impedance.In general,the inverter often obtains grid synchronization information by the phase-locked loop(PLL)and to suppress thebackground harmonic and amplitude disturbance of grid voltage.the grid voltage feedforward(GVF)control is also needed.The negative effects introduced by PLL and GVF will cause the inverter to be unstable under the weak power grid.Therefore,this paper proposes an impedance controller for reshaping the q-axis impedance to positive resistance in the low frequency band,solving the problem of system instability caused by PLL and GVF.