Optimal Design of Ranking Frequency for Modular Multilevel Converter

doi:10.3969/j.issn.1000－7229.2017.11.004

Abstract

Abstract: ABSTRACT： Modular multilevel converter (MMC) has been widely used due to its typical advantages, and the sort algorithm of voltage capacitor balancing in MMC sub-modules has been a hot issue nowadays. The optimization of most voltage balancing algorithm is mainly aimed to reduce the time and computing complexity and its switching frequency at present. This paper analyzes the renewal process and wave principle of the capacitor voltage in MMC sub-modules, and deduces the calculation method of the minimum ranking frequency of voltage balancing algorithm. The influence of the ranking frequency on the voltage balancing effect is studied by simulation, and the ranking frequency is optimized according to the simulation results. Finally, taking Xiamen Project as an example, this paper constructs the model in PSCAD/EMTDC for simulation, to verify the correctness of the proposed optimized design scheme. The simulation results show that the proposed ranking algorithm optimization algorithm has good voltage balancing effect, which can reduce half of the switching frequency of the device compared with the traditional time sorting method and can reduce the computational complexity of the overall average time at the same time.

Key words: KEYWORDS： modular multilevel converter (MMC), nearest level modulation, voltage capacitor balancing, ranking algorithm, switching frequency

CLC Number:

TM 77

GAO Guanlun, LI Gengyin. Optimal Design of Ranking Frequency for Modular Multilevel Converter[J]. Electric Power Construction, 2017, 38(11): 26-.

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