Abstract: The section power loss (SPL) of modular multilevel converter (MMC) refers to the abnormal disconnection of the ac transmission lines linked with the MMC. This article proposes the analytical calculation method of SPL overvoltage. The suppression methods based on the control strategy and the control parameters of SPL are presented in this article. Furthermore, considering the capacitor effect of the long transmission lines, the calculation method of remote region SPL voltage is proposed. Finally, the Zhangbei MMC DC grid model is established in PSCAD/EMTDC. All the research results have been validated with three main conclusions: Power surplus and control system saturation are the primary reasons of SPL overvoltage; The SPL overvoltage can be reduced by the coordinate control method and the optimization of control system parameters; The SPL overvoltage of remote region rises drastically for the no-load long transmission line capacitor effect.