单相并网逆变器新型奇次谐波重复控制策略

Novel Odd-harmonic Repetitive Control Scheme for Single-phase Grid-tied Inverters

奇次谐波重复控制(ORC)能够有效抑制单相并网逆变器系统低频奇数次谐波。然而,由于ORC内模固有的延时环节,其谐波抑制特性和动态性能仍需进一步改善。为此,提出了一种具有前馈通道的新型ORC(NORC),其在奇次谐波频率处具有更高的增益和更宽的谐振带宽。首先,在分析传统ORC内模的基础上,提出了具有前馈通道的NORC的内模;其次,分析了NORC的控制系统结构和稳定性,以及谐波抑制特性;接着以单相LCL型并网逆变器为例,给出了NORC的参数设计流程;最后,通过实验对比验证了所提NORC策略能够在电网频率波动时更有效的抑制奇数次谐波,并具有更快的动态响应速度。

Odd-harmonic repetitive control(ORC)can effectively suppress low-frequency odd-harmonic in single-phase grid-tied inverter system.However,due to the inherent delay link of the internal model of ORC,its harmonic suppression characteristics and dynamic performance still need to be further improved.For this purpose,a novel ORC(NORC)with a feedforward channel is proposed,which has a higher gain and a wider resonance bandwidth at the odd-harmonic frequencies.Firstly,based on the analysis of the internal model of traditional ORC,the internal model of NORC with feedforward channel is proposed.Secondly,the structure,stability,and harmonic suppression characteristics of NORC system are analyzed.Then,taking the single-phase LCL grid-connected inverter as an example,the parameters design process of NORC is given.Finally,the comparative experiment shows that the proposed NORC scheme can suppress odd-harmonic more effectively when the grid frequency fluctuates,and has a faster transient response speed.