| 引用本文: | 洪镇堃,占萌.构网型变流器并网系统在强弱电网下的分岔分析[J].电力自动化设备,2023,43(9):27-32，54. |
| HONG Zhenkun,ZHAN Meng.Bifurcation analysis of grid-forming converter system connected with stiff or weak AC grids[J].Electric Power Automation Equipment,2023,43(9):27-32，54. |
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| 摘要: |
| 构网型变流器并网系统在强弱电网下均存在稳定性问题，但这2类稳定性问题之间的联系并不清晰。为此，基于分岔理论揭示了这2类稳定性问题之间的非线性动力学关系和过渡过程的物理图像。首先根据所建模型，对这2类稳定性问题的动力学响应进行分岔分析，得出系统在弱电网下会发生鞍结点分岔，在强电网下会依次发生霍普夫分岔、倍周期分岔并通向混沌。其次基于时间尺度理论进行模型降阶，然后通过小扰动和大扰动分析确定端电压控制是导致强弱电网下系统动力学行为差异的关键因素。之后运用复转矩法进一步揭示了端电压控制会导致系统在强弱电网下分别因阻尼转矩不足和同步转矩不足而失稳。最后通过多机仿真证实了多机系统也存在类似的强电网失稳问题。 |
| 关键词: 构网型变流器 电网强度 端电压控制 分岔分析 复转矩法 |
| DOI：10.16081/j.epae.202308015 |
| 分类号: |
| 基金项目:国家自然科学基金企业创新发展联合基金资助项目(U22B6008)；国家自然科学基金面上项目(12075091) |
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| Bifurcation analysis of grid-forming converter system connected with stiff or weak AC grids |
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HONG Zhenkun, ZHAN Meng
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State Key Laboratory of Advanced Electromagnetic Engineering and Technology, School of Electrical and Electronic Engineering, Hubei Electric Power Security and High Efficiency Key Laboratory, Huazhong University of Science and Technology, Wuhan 430074, China
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| Abstract: |
| The stability problems exist in the grid-forming converter system connected with stiff or weak grid, but their relation is unclear. The nonlinear dynamic relation between these two types of stability problems and the physical image of the transition process are revealed based on the bifurcation theory. Firstly, based on the model established, bifurcation analysis of the dynamic response between these two types of stability problems is carried out. It is found that saddle-node bifurcation occurs in weak grid, and Hopf bifurcation, period doubling bifurcation, transition to chaos, and chaos collapse occur successively in stiff grid. Next, the model is reduced based on the time scale theory. Then, by the small disturbance and large disturbance analysis, it is obtained that the terminal voltage control is the major cause of the dynamic behavior differences in stiff and weak grids. Furthermore, the complex torque is utilized to further reveal that the terminal voltage control will cause the stiff-and weak-grid instability due to insufficient damping torque and insufficient synchronizing torque, respectively. Finally, multi-machine simulations are performed to show similar instability issues in stiff grid. |
| Key words: grid-forming converter grid strength terminal voltage control bifurcation analysis complex torque method |
