Journal of Power Electronics

The Korean Institute of Power Electronics (전력전자학회)
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Small-signal stability of AC/DC capacity and MMC controller voltage loop dominated systems

  • Received : 2022.05.17
  • Accepted : 2023.02.27
  • Published : 2023.09.20
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Abstract

The stability of an MMC AC/DC hybrid system shows differences with changes in its operating state. However, the time domain analysis method cannot quantitatively evaluate the dynamic characteristics of the system. In this paper, a small-signal model of an MMC AC/DC hybrid system is established to analyze the system stability under continuous changes of the parameters. First, the dynamic characteristics of the small-signal model and the time-domain simulation model are compared to verify the accuracy of the small-signal model. Second, the dynamic stability of the MMC under four typical operating states is analyzed, and the influences of the AC system capacity and impedance angle on the stability domain of the system are evaluated. Then, the modal analysis method is used to solve the dominant mode and participation factor of the critically stable system. In addition, the oscillation characteristics of the system are solved. Finally, the variation trend of the system stability dominated by the controller parameters and DC capacity is obtained. The obtained results show that the controller parameters of the MMC do not contribute to the system oscillation characteristics. The selection of the AC/DC capacity leads to differences in system stability. Under PV control, the MMC AC/DC hybrid system presents stronger stability, and the system is easily affected by low-frequency oscillation.

Keywords

Acknowledgement

This work was supported by State Grid Corporation of China Science and Technology Project "Research on Dynamic Stability of MMC AC/DC Hybrid System".

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