Impact of the Grid Impedance on the Single-Phase Grid-Tied Inverter Output Impedance Concerning the Frequency-Coupling Effect of the PLL

2019 ◽  
Author(s):  
Qiang Qian ◽  
Nini Zhong ◽  
Shaojun Xie ◽  
Jinming Xu ◽  
Binfeng Zhang
Keyword(s):  
Single Phase ◽  
Coupling Effect ◽  
Output Impedance ◽  
Grid Impedance ◽  
Frequency Coupling

Input Impedance Modeling of Single-Phase Voltage Source Rectifier With Consideration of FrequencyCoupling Effect

2020 ◽  
Author(s):  
Jianheng Lin ◽  
Mei Su ◽  
Yao Sun ◽  
Shiming Xie
Keyword(s):  
Input Impedance ◽  
Single Phase ◽  
Coupling Effect ◽  
Voltage Source ◽  
Phase Voltage ◽  
Impedance Model ◽  
Grid Impedance ◽  
Impedance Modeling ◽  
Frequency Coupling ◽  
Time Periodicity

Time-periodicity and non-linearity pose a challenge to the precise input impedance modeling of single-phase power converters. In this study, a precise input impedance model with measurability of the single-phase voltage source rectifier (VSR), which considers the frequency-coupling effect (FCE), is established. Meanwhile, it is revealed that the rectifier input impedance is dependent of the grid impedance. In the proposed modeling approach, only Laplace transform and frequencyshifting operation are required, which avoids the complicated convolution calculation in the frequency domain. In addition, the influence of grid impedance on the input impedance is studied. Simulations are conducted to verify the effectiveness of the proposed method. <br>

Output Impedance Modeling of Single-Phase Grid-Tied Inverters With Capturing the Frequency-Coupling Effect of PLL

2020 ◽  
Vol 35 (5) ◽  
pp. 5479-5495 ◽  
Author(s):  
Qiang Qian ◽  
Shaojun Xie ◽  
Jinming Xu ◽  
Kunshan Xu ◽  
Shenyiyang Bian ◽  
...  
Keyword(s):  
Single Phase ◽  
Coupling Effect ◽  
Output Impedance ◽  
Impedance Modeling ◽  
Frequency Coupling

scholarly journals Input Impedance Modeling of Single-Phase Voltage Source Rectifier With Consideration of FrequencyCoupling Effect

2020 ◽  
Author(s):  
Jianheng Lin ◽  
Mei Su ◽  
Yao Sun ◽  
Shiming Xie
Keyword(s):  
Input Impedance ◽  
Single Phase ◽  
Coupling Effect ◽  
Voltage Source ◽  
Phase Voltage ◽  
Impedance Model ◽  
Grid Impedance ◽  
Impedance Modeling ◽  
Frequency Coupling ◽  
Time Periodicity

Time-periodicity and non-linearity pose a challenge to the precise input impedance modeling of single-phase power converters. In this study, a precise input impedance model with measurability of the single-phase voltage source rectifier (VSR), which considers the frequency-coupling effect (FCE), is established. Meanwhile, it is revealed that the rectifier input impedance is dependent of the grid impedance. In the proposed modeling approach, only Laplace transform and frequencyshifting operation are required, which avoids the complicated convolution calculation in the frequency domain. In addition, the influence of grid impedance on the input impedance is studied. Simulations are conducted to verify the effectiveness of the proposed method. <br>

scholarly journals Adjusting output impedance using a PI controller to improve the stability of a single phase inverter under weak grid

2016 ◽  
Vol 1 (4) ◽  
pp. 50
Author(s):  
Jiao Jiao ◽  
R. Mark Nelms
Keyword(s):  
Single Phase ◽  
Pi Controller ◽  
Output Impedance ◽  
Weak Grid ◽  
Harmonic Reduction ◽  
Grid Impedance ◽  
Single Phase Inverter ◽  
Grid Connected Inverter ◽  
The Stability ◽  
Lc Filter

Explored in this paper is the grid impedance effect on the stability of a single-phase grid connected inverter with an LC filter based on an analysis of the inverter output impedance. For a single-phase grid connected inverter, a PI controller is often used to regulate the current injected into the grid. However, the control performance can be influenced when the inverter is connected to a weak grid. Also, the utility grid has background harmonic noise, which can make the injected current distorted. Therefore, analysis of the output impedance of a single-phase grid connected inverter is important for the robustness and stability of the system. By modeling the output impedance of inverter, it can be determined that the proportional gain and integral gain of the controller have an effect on the output impedance. Analytical results show that by adjusting the PI controller parameters, the ability for harmonic reduction and stability of the system can be improved. Simulation and experiments using a 1 kW single-phase grid connected inverter verify the effectiveness of the theoretical analysis.

scholarly journals Impedance Modeling and Stability Analysis of DFIG-Based Wind Energy Conversion System Considering Frequency Coupling

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3243
Author(s):  
Shaojian Song ◽  
Peichen Guan ◽  
Bin Liu ◽  
Yimin Lu ◽  
HuiHwang Goh
Keyword(s):  
Stability Analysis ◽  
Coupling Effect ◽  
Impedance Model ◽  
Wind Energy Conversion ◽  
Proposed Model ◽  
New Type ◽  
Impedance Modeling ◽  
Frequency Coupling ◽  
Bus Voltage ◽  
Voltage Dynamics

Impedance-based stability analysis is an effective method for addressing a new type of SSO accidents that have occurred in recent years, especially those caused by the control interaction between a DFIG and the power grid. However, the existing impedance modeling of DFIGs is mostly focused on a single converter, such as the GSC or RSC, and the influence between the RSC and GSC, as well as the frequency coupling effect inside the converter are usually overlooked, reducing the accuracy of DFIG stability analysis. Hence, the entire impedance is proposed in this paper for the DFIG-based WECS, taking coupling factors into account (e.g., DC bus voltage dynamics, asymmetric current regulation in the dq frame, and PLL). Numerical calculations and HIL simulations on RT-Lab were used to validate the proposed model. The results indicate that the entire impedance model with frequency coupling is more accurate, and it is capable of accurately predicting the system’s possible resonance points.

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