弱电网下电网电压前馈控制分布式逆变系统的谐振阻尼特性分析  

Resonance Damping Characteristic Analysis of Distributed Inverter-based System with Grid Voltage Feed-forward Control in Weak Grid

作　　者：苗丽芳 王乐媛[1] 曹斌[1] 苏珂 王琪[1] MIAO Lifang;WANG Yueyuan;CAO Bin;SU Ke;WANG Qi(Inner Mongolia Electric Power Research Institute,Hohhot 010020,China)

机构地区：[1]内蒙古电力科学研究院,呼和浩特010020

出　　处：《高电压技术》2020年第10期3521-3529,共9页High Voltage Engineering

基　　金：内蒙古电力公司科技项目(2019-85)。

摘　　要：弱电网下电网电压前馈控制的实际电压前馈量包含电容电压信息,会影响分布式逆变系统(distributed inverter based system,DIBS)的谐振阻尼特性。考虑数字控制延迟,建立电网电压前馈电容电流反馈控制DIBS的数学模型。根据Mason规则对数学模型框图进行等效变换,得到控制环形成的等效虚拟阻抗,并进行阻抗特性分析。基于系统开环增益的Bode图,分析不存在数字控制延时和存在数字控制延时两种情况下电网电压前馈对DIBS谐振阻尼特性的影响。理论分析和仿真结果表明,两种情况下电网电压前馈会偏移谐振频率,数字控制延时一定程度上会改善电容电流反馈控制的谐振阻尼效果,提高系统稳定对电网阻抗变化的鲁棒性。Resonance damping characteristics of a distributed inverter-based system(DIBS)will be influenced by grid voltage feed-forward control in weak grid condition as the actual feed-forward component contains information of capacitor voltage.By taking the digital control delay into consideration,a mathematical model of grid voltage feed-forward and capacitor current feedback controlled DIBS is established.According to Mason rules,the equivalent virtual impedance formed by control loop is obtained through a set of equivalent transformation,and corresponding impedance characteristics are analyzed.Base on Bode diagrams of system open-loop gain,the influence of grid voltage feed-forward control on resonance damping characteristic of DIBS is fully discussed in the presence and absence of digital control delay.Theory analysis and simulation results show that grid voltage feed-forward can shift resonance frequency under the both conditions.In addition,the damping performance of capacitor-current feedback control can be improved,and the robustness of system stability against grid impedance variation with digital control delay can be Increased.

关 键 词：电网电压前馈 谐振阻尼特性 LCL逆变器 弱电网 数字控制延时 虚拟阻抗 

分 类 号：TM464[电气工程—电器]