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A Low-Computation Indirect Model Predictive Control for Modular Multilevel Converters
Ma, Wenzhong,Sun, Peng,Zhou, Guanyu,Sailijiang, Gulipali,Zhang, Ziang,Liu, Yong The Korean Institute of Power Electronics 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.2
The modular multilevel converter (MMC) has become a promising topology for high-voltage direct current (HVDC) transmission systems. To control a MMC system properly, the ac-side current, circulating current and submodule (SM) capacitor voltage are taken into consideration. This paper proposes a low-computation indirect model predictive control (IMPC) strategy that takes advantages of the conventional MPC and has no weighting factors. The cost function and duty cycle are introduced to minimize the tracking error of the ac-side current and to eliminate the circulating current. An optimized merge sort (OMS) algorithm is applied to keep the SM capacitor voltages balanced. The proposed IMPC strategy effectively reduces the controller complexity and computational burden. In this paper, a discrete-time mathematical model of a MMC system is developed and the duty ratio of switching state is designed. In addition, a simulation of an eleven-level MMC system based on MATLAB/Simulink and a five-level experimental setup are built to evaluate the feasibility and performance of the proposed low-computation IMPC strategy.
A Low-Computation Indirect Model Predictive Control for Modular Multilevel Converters
Wenzhong Ma,Peng Sun,Guanyu Zhou,Gulipali Sailijiang,Ziang Zhang,Yong Liu 전력전자학회 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.2
The modular multilevel converter (MMC) has become a promising topology for high-voltage direct current (HVDC) transmission systems. To control a MMC system properly, the ac-side current, circulating current and submodule (SM) capacitor voltage are taken into consideration. This paper proposes a low-computation indirect model predictive control (IMPC) strategy that takes advantages of the conventional MPC and has no weighting factors. The cost function and duty cycle are introduced to minimize the tracking error of the ac-side current and to eliminate the circulating current. An optimized merge sort (OMS) algorithm is applied to keep the SM capacitor voltages balanced. The proposed IMPC strategy effectively reduces the controller complexity and computational burden. In this paper, a discrete-time mathematical model of a MMC system is developed and the duty ratio of switching state is designed. In addition, a simulation of an eleven-level MMC system based on MATLAB/Simulink and a five-level experimental setup are built to evaluate the feasibility and performance of the proposed low-computation IMPC strategy.
Yu Zou,Wenzhong Hu,Kun Ma,Mixia Tian 한국식품과학회 2015 Food Science and Biotechnology Vol.24 No.1
Fractions I and II from Auricularia auricula fruiting body (AAFB) melanin were separated using Sephadex G-100 column chromatography and their physicochemical properties and antioxidant activities were investigated. Molecular mass values of the fractions were 384 and 47 kDa, respectively. Fraction I exhibited lower L*, a*, and b* values than AAFB melanin and fraction II. AAFB melanin and fractions possessed the same solubility and spectroscopic properties, which were similar to the properties of other melanin. Elemental composition analysis revealed that the main component of AAFB melanin and fractions was pheomelanin. AAFB melanin and fractions, particularly fraction II, exhibited strong antioxidant activities based on Fe2+-chelating, DPPH radical scavenging, and superoxide radical scavenging activities.