弱电网下基于电容电压全前馈的LCL型并网逆变器稳定性控制  

Stability Control of LCL-type Grid-connected Inverter Based on Capacitor Voltage Full Feedforward Under Weak Grid Condition

作　　者：段晓宁 李萍[1] 赵峰[2] 陈硕[1] 王久和[1] DUAN Xiaoning;LI Ping;ZHAO Feng;CHEN Shuo;WANG Jiuhe(School of Automation,Beijing Information Science and Technology University,Beijing 100192,China;Institute of Electrical Engineering,Chinese Academy of Sciences,Beijing 100190,China)

机构地区：[1]北京信息科技大学自动化学院,北京100192 [2]中国科学院电工研究所,北京100190

出　　处：《高电压技术》2022年第6期2140-2151,共12页High Voltage Engineering

基　　金：国家自然科学基金(51777012;51907189);北京信息科技大学科研类分类发展重点研究培育项目(2021YJPY213)。

摘　　要：针对LCL型并网逆变器在弱电网条件下背景谐波影响并网电能质量,及电网阻抗波动易引发系统稳定性等问题,提出了基于LCL滤波器电容电压全前馈的并网电流延迟级联反馈控制策略。该控制策略在利用电容电压全前馈来抑制电网电压畸变对并网电流影响的前提下,引入并网电流纯延迟反馈环节以提高LCL型并网逆变器的相角稳定裕度,与此级联的比例延迟环节等效为有源阻尼,以提高LCL型并网逆变器的幅值稳定裕度,由此来适应弱电网下LCL滤波器谐振频率较宽范围的偏移。SIMULINK仿真与MT6020实验平台的试验结果表明:并网电流延迟级联反馈控制拓展了LCL型逆变系统在弱电网下谐振频率偏移的稳定范围,使得系统鲁棒性提高;与稳定性控制解耦的电容电压全前馈控制能够保障逆变器在电网电压畸变时,以并网电流正弦度高、谐波畸变率低、功率因数高的工况稳定运行。Under the condition of weak grids,background harmonics may impair the grid-connected power quality with the LCL-type grid-connected inverter,and this type inverter system instability can be easily caused by grid impedance fluctuation.Consequently,we put forward a grid-connected current delay cascade feedback control strategy based on full feedforward capacitor voltage of LCL filter.The capacitor voltage full feedforward is adopted to suppress the influence of grid voltage distortion on grid-connected current,a pure delay feedback link of the grid-connected current is introduced to improve the phase angle stability margin,and the proportional delay link cascaded with the pure delay is equivalent to active damping to improve the amplitude stability margin of the LCL grid-connected inverter.The above-mentioned methods work together to adapt the resonant frequency of the LCL filter to be shifted in a wide range under the weak grid conditions.The test results of SIMULINK simulation and MT6020 experimental platform show that the grid-connected current delay cascade feedback control expands the stable range of resonant frequency offset of the LCL-type grid-connected inverter system under the weak grid condition,and improves the robustness of the inverter system.When the grid voltage is distorted,the full feedforward of capacitor voltage decoupled from stability control ensures the stable operation of the inverter under the conditions of high sinusoidal degree of grid-connected current,low harmonic distortion rate and high power factor.

关 键 词：弱电网 电容电压全前馈 延迟级联反馈 相角裕度 幅值裕度 稳定性控制 

分 类 号：TM464[电气工程—电器]