弱电网下WAC控制LCL并网逆变器延时补偿策略

Delay Compensation Strategy for WAC Controlled LCL Grid-connected Inverter in Weak Grid

针对并网逆变装置中因LCL滤波器和数字控制延时产生的稳态误差、谐振和反向谐振尖峰问题,提出一种加权平均电流与补偿器相结合的控制策略。首先,建立加权平均电流并网逆变器数学模型,分析传统电流控制下电网阻抗和滤波器对系统影响,并采用加权平均电流降低系统阶数以减小稳态误差和抑制谐振。然后,分析由控制延时产生的反向谐振对系统影响和抑制反向谐振原理,通过合理设计所提出的补偿器参数以消除系统中的反向谐振尖峰。最后,通过建立仿真模型及搭建半实物仿真平台对所提控制策略进行验证,对比仿真与实验结果,验证了该策略的有效性。

Aimed at the problems caused by the filter and digital control delay in a grid-connected inverter device such as the steady-state errorand the resonance and reverseresonance spikesa control strategy which combines weighted aver⁃age current andlead compensator is proposed in this paper.First,amathematical model of the WAC controlledgrid-connected inverter is established,the influences of grid impedance and filter on the system are analyzed under the tradition⁃al current control,and weighted average current is introduced to reduce the order of the system,thuseliminating the steady-state error and suppressing the resonance.Second,the influences of reverse resonance generated by the control delay on the system and the principle of reverse resonance suppression are analyzed,and the parameters of the pro⁃posed compensator are rationally designed to eliminate the reverse resonance spike in the system gain.Finally,a simu⁃lation model andsemi-physical simulation platform are established to verify the proposed control strategy,and the com⁃parison between simulation and experimental resultsverifies its effectiveness.