弱电网下考虑数字控制延时的LCL并网逆变器改进WAC控制策略  

Improved WAC control strategy for LCL grid⁃connected inverters under weak grid considering digital control delay

作　　者：王新环[1,2] 姚冠宇 李元昊 WANG Xinhuan;YAO Guanyu;LI Yuanhao(School of Electrical Engineering and Automation,Henan Polytechnic University,Jiaozuo 454003,China;Henan Key Laboratory of Intelligent Detection and Control of Coal Mine Equipment,Jiaozuo 454003,China)

机构地区：[1]河南理工大学电气工程与自动化学院,河南焦作454003 [2]河南省煤矿装备智能检测与控制重点实验室,河南焦作454003

出　　处：《现代电子技术》2024年第13期108-116,共9页Modern Electronics Technique

基　　金：国家自然科学基金项目(U1804143)。

摘　　要：传统加权平均电流(WAC)控制方法因控制延时产生反向谐振峰而失去环路降阶特性,导致系统在弱电网下具有极大的失稳风险。文中首先分析了控制延时与弱电网共同影响下,传统WAC失去降阶特性导致系统失稳的问题,不再从环路降阶的角度而是在等效阻抗模型的基础上对系统输出阻抗进行失稳分析;然后在电压比例前馈的基础上,从增强谐波抗扰能力及稳定性入手,提出基于多二阶滤波器的电压前馈控制策略,对系统输出阻抗进行重塑,进而提升等效输出阻抗在中低频段的相位裕度,增强系统对电网阻抗宽范围变化的适应性。仿真及实验结果表明,该策略对弱电网阻抗宽范围变化具有较强的适应性,能够输出优良品质的入网电流。The traditional weighted average current(WAC)control method loses the loop step-down characteristics due to the inverse resonance peaks generated by the control delay,which leads to a great risk of system instability in case of weak grid.The paper firstly analyses the system destabilization caused by the loss of the order-degradation property of the conventional WAC under the influence of the control delay and weak grid.The destabilization of system output impedance is analyzed no longer in the perspective of loop step-down but on the basis of equivalent impedance model.And then,on the basis of voltage proportional feedforward,a voltage feedforward control strategy based on multiple second-order filters is proposed to reshape the system output impedance in the aspect of the enhancement of harmonic immunity and stability,which in turn improves the phase margin of the equivalent output impedance in the middle and low frequency bands,and strengthens the adaptability of the system to the wide-range changes of the grid impedance.Simulation and experimental results show that the proposed strategy has superior adaptability to the wide range of weak grid impedance variations,and is capable of outputting good-quality inlet currents.

关 键 词：并网逆变器 加权平均电流控制 数字控制延时 等效阻抗模型 多二阶滤波器 电压前馈控制策略 

分 类 号：TN709-34[电子电信—电路与系统]