Robustness Improvement of Single-Phase Inverters Under Weak Grid Cases by Adding Grid Current Feedforward in Delay-Based Phase-Locked Loop
Robustness Improvement of Single-Phase Inverters Under Weak Grid Cases by Adding Grid Current Feedforward in Delay-Based Phase-Locked Loop
复制标题
通过在基于延迟的锁相环中添加电网电流前馈提高单相逆变器在弱电网情况下的鲁棒性
DOI：
10.1109/access.2020.2995624
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发表时间：
2020-05
期刊：
影响因子：
3.9
通讯作者：
Shaojun Xie
中科院分区：
文献类型：
--
作者：
Jinming Xu;Shenyiyang Bian;Qiang Qian;Hao Qian;Shaojun Xie
对于逆变器来说，电网同步通常需要锁相环(PLL)。通常，对于单相逆变器，可以使用基于正交信号产生器的PLL(例如，基于延迟的PLL)。然而，如果公共耦合点(PCC)处的电网表现出较大的电网阻抗，则逆变器可能无法正常工作，甚至可能不稳定。为了能在非常弱的网格中令人满意地工作，本研究旨在设计一种健壮的锁相环。首先，通过建立逆变器输出阻抗模型，考虑频率耦合效应，分析了典型延迟锁相环的稳定性，解释了性能下降的原因。然后，在分析不同PCC条件下锁相环模块的差异的基础上，讨论了具有电网电流前馈的鲁棒锁相环。与典型的锁相环相比，在弱网格情况下系统性能的改善主要归因于输出阻抗分子上的附加项，它是由所提出的锁相环的电流前馈引入的。为了保持较高的鲁棒性，控制参数的选择受到了重视。最后，选取比较波形验证了单相逆变器即使在电网阻抗较大的情况下也能很好地工作，而不需要电网阻抗估计。
For inverters, a phase-locked loop (PLL) is usually needed for the grid synchronization. Typically, for the single-phase inverters, the orthogonal-signal-generators based PLLs (e.g., delay-based PLL) can be used. However, if the grid at the point of common coupling (PCC) exhibits a large grid impedance, the inverter may not work well or even be unstable. In order to work satisfactorily in the very weak grid, this study aims to formulate a robust PLL. At first, by modeling the inverter output impedance and considering the frequency coupling effect, the stability of the typical delay-based PLL has been analyzed and the reason for the performance degradation has been explained. Then, based on analyzing the differences of PLL blocks under different PCC conditions, the robust PLL with the grid current feedforward is discussed. Compared with the typical PLL, the improvement of the system behaviors in the weak grid cases is mainly attributed to the extra term on the numerator of output impedance, which is introduced by the current feedforward of the proposed PLL. The selection of control parameters has been emphasized for maintaining the high robustness. At last, selected comparative waveforms have verified that the single-phase inverter can perform well even with the large grid impedance, without the grid impedance estimation.
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影响因子：
7.7
作者：
M. Karimi-Ghartemani
通讯作者：
M. Karimi-Ghartemani
DOI：
10.1109/jestpe.2019.2916002
发表时间：
2020-09
影响因子：
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