| 引用本文: | 毛玲,黄禹辰,赵晋斌,曾志伟.弱电网下并网逆变器锁相环正反馈效应抑制及稳定性分析[J].电力自动化设备,2025,45(7):121-128 |
| MAO Ling,HUANG Yuchen,ZHAO Jinbin,ZENG Zhiwei.PLL positive feedback effect suppression and stability analysis of grid-connected inverter under weak grid[J].Electric Power Automation Equipment,2025,45(7):121-128 |
|
| 摘要: |
| 电网阻抗与锁相环(PLL)之间的耦合会导致并网系统难以适应电网阻抗的宽范围变化。为此，通过构建dq域下计及电网阻抗影响的并网逆变器控制环路小信号模型，揭示弱电网下电网阻抗经由PLL引入的正反馈路径给并网逆变器系统的稳定性带来的不利影响。从削弱电网阻抗在PLL正反馈路径内发挥的作用出发，并基于PLL输出相位反馈思路补偿电网阻抗耦合项带来的不利影响，提出一种具备高鲁棒性的系统稳定性提升方法。理论分析结果表明，所提控制策略能够提升并网系统对PLL带宽及高电网阻抗的适应能力，甚至在极弱电网条件下仍具备一定的相位裕度。基于RT-LAB硬件在环实验验证了所提正反馈效应抑制控制策略的有效性。 |
| 关键词: 弱电网 并网逆变器 锁相环 正反馈效应 鲁棒性 稳定性 |
| DOI：10.16081/j.epae.202501005 |
| 分类号:TM464 |
| 基金项目:国家自然科学基金资助项目(52177184) |
|
| PLL positive feedback effect suppression and stability analysis of grid-connected inverter under weak grid |
|
MAO Ling1, HUANG Yuchen1, ZHAO Jinbin2, ZENG Zhiwei1
|
|
1.College of Electrical Engineering, Shanghai University of Electric Power, Shanghai 200090, China;2.Offshore Wind Power Research Institute, Shanghai University of Electric Power, Shanghai 200090, China
|
| Abstract: |
| The coupling between grid impedance and phase locked loop(PLL) makes it difficult for the grid-connected system to adapt to the wide range variation of grid impedance. In view of this, by constructing a small-signal model of the grid-connected inverter control loop in the dq domain considering the influence of grid impedance, the adverse effect of the positive feedback path introduced by the grid impedance through PLL under the weak grid on the stability of the grid-connected inverter system is revealed. Starting from weakening the role of power grid impedance in the PLL positive feedback path, and based on the idea of PLL output phase feedback to compensate for the adverse effect caused by the grid impedance coupling term, a system stability improvement method with high robustness is proposed. Theoretical analysis results show that the proposed control strategy can enhance the adaptability of the grid-connected system to PLL bandwidth and high grid impedance, and it still has a certain phase margin even under extremely weak grid conditions. The effectiveness of the proposed positive feedback effect suppression control strategy is verified based on the RT-LAB hardware-in-the-loop experiment. |
| Key words: weak grid grid-connected inverters phase locked loop positive feedback effect robustness stability |
