An active protection strategy for bulk-power modular multilevel converter based on thermal balancing control

• The allowable junction temperature distribution band and the submodule input priority are introduced in this paper, and an active protection strategy for bulk-power modular multilevel converter based on thermal balancing control, which is beneficial to extend the lifetime of power devices. • The proposed control method eliminates dependency on sorting algorithms, both the computationalcomplexity and execution time and are substantial reduced compared to the existing methods. • The proposed method can be dynamically adjusted in real time according to the operating conditions of the system, and has strong applicability in practical engineering. The thermal of power devices in the submodules of the modular multilevel converter are imbalance, which is more serious under capacitor deterioration, threatening the safety of the MMC. In order to address the above issues, an active protection strategy based on thermal balancing control without sorting algorithm is proposed in this paper. The relationship between the power device junction temperature changes and the SM states is analyzed in detail, and the SM input priority and the allowable junction temperature distribution band are introduced. The power device junction temperatures are balanced under different SM capacitor parameters, which is beneficial for extending the lifetime of power devices. Meanwhile, the switching frequency of power devices and system control complexity are also significantly reduced, which is more conducive to practical application in engineering. The performance of the proposed method is also detailed compared with the existing methods. The proposed active protection strategy is evaluated through the PLECS blockset simulation model integrated into MATLAB/Simulink and the detailed single SM experiment platform.