摘要
弱电网下LCL滤波并网逆变器可能因系统开环截止频率附近的稳定裕度太低而引发入网电流谐波谐振等稳定性问题。基于上述考虑,以单相并网逆变器双闭环控制模型为例,揭示了弱电网下系统谐波谐振产生机理以及稳定裕度与滤波器谐振频率偏移之间的关系,推导了最小谐振频率偏移条件以及最小谐振频率偏移对电流控制器的影响。鉴于此,提出了一种弱电网下抑制谐振频率偏移的并网逆变器谐波谐振控制策略,并给出了该策略的详细实现方案和参数设计方法。相较于传统控制策略,所提控制策略可以有效抑制滤波器谐振频率偏移对系统中低频段动态性能的影响,而且不论是否考虑电网电压比例前馈环节,并网逆变器的等效输出阻抗增益均无明显变化,且高于传统控制策略的阻抗增益,系统鲁棒性得到保证。最后,仿真与实验结果验证了所提控制策略的有效性。
The LCL grid-connected inverter in a weak grid will cause stability problems such as grid-connected current harmonic resonance,which is caused by the low system stability margin near the open-loop cutoff frequency.It takes the dual closed-loop control model of a single-phase grid-connected inverter as an example.It not only reveals the mechanism of system harmonic resonance in weak power grid and the relationship between stability margin and filter resonance frequency deviation,but also deduces the minimum resonance frequency deviation condition and the influence of minimum resonance frequency deviation on the current controller.Therefore,a grid-connected inverter harmonic resonance control strategy for suppressing the resonant frequency deviation under weak grids is proposed,and the detailed implementation scheme and parameter design method of the strategy are given.Compared with the traditional control strategy,it can effectively suppress the influence of the resonant frequency shift of the filter on the dynamic performance of the system in the low frequency band.In addition,whether the grid voltage proportional feedforward link is considered,the equivalent output impedance gain of the inverter does not change significantly.The impedance gain is higher than the traditional control strategy,so the system robustness is guaranteed.Finally,simulation and experimental results verify the effectiveness of the proposed control strategy.
作者
杨明
杨杰
赵铁英
郑晨
韦延方
YANG Ming;YANG Jie;ZHAO Tie-ying;ZHENG Chen;WEI Yan-fang(School of Electrical Engineering and Automation,Henan Polytechnic University,Jiaozuo 454003,China;State Grid Henan Electric Power Research Institute,Zhengzhou 450052,China)
出处
《电机与控制学报》
EI
CSCD
北大核心
2021年第8期87-98,共12页
Electric Machines and Control
基金
国家自然科学基金(U1804143,61703144)
河南省矿山电力电子装置与控制创新型科技团队基金(CXTD2017085)。
关键词
弱电网
并网逆变器
谐波谐振
稳定裕度
最小谐振频率偏移
鲁棒性
weak grid
grid-connected inverter
harmonic resonance
stability margin
minimum resonance frequency deviation
robustness
