Summary: | Modular multi-level converter (MMC)-based multi-terminal dc (MTDC) grid (abbreviated as MMC-MTDC) is promising in the integration and transmission of bulk renewable energy. This paper analyzes the transient characteristic of large-scale power systems with the MMC-MTDC. First, the transient stability-electromagnetic transient (TS-EMT) model of the system is established. The corresponding simulation flowchart is also presented, where the MMC-MTDC grid dynamics are calculated by EMT simulation and the ac grid is simulated by the TS program. Second, based on the mathematical model of the MMC-MTDC grid, the transient characteristics during various faults are analyzed. Third, it analyzes the influences of the controller parameters on the transient characteristics. Test results on the North-China power system with Zhangbei MTDC verifies the correctness of the transient characteristic analyses.
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