A side‐effect‐free method of reducing capacitance requirement for modular multilevel converters

The concept of high-voltage DC transmission using a multiterminal configuration is presently a central topic of research and investment due to rekindled interest in renewable energy resource integration. Moreover, great attention is given to fault analysis, which leads to the necessity of developing proper tools that enable proficient dynamic simulations. This paper leverages models and control system design techniques and demonstrates their appropriateness for scenarios in which faults are applied. Furthermore, this paper relies on full-bridge submodule topologies in order to underline the increase in resilience that such a configuration brings to the multiterminal DC network, after an unexpected disturbance. Therefore, strong focus is given to fault response, considering that converters use a full-bridge topology and that overhead power lines connect the terminals.

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An Accurate Accelerated Steady-State Model For Modular Multilevel Converters With Very High Voltage Levels

2020 IEEE Industry Applications Society Annual Meeting ◽

10.1109/ias44978.2020.9334761 ◽

2020 ◽

Author(s):

Ramadhani Kurniawan Subroto ◽

Yi Chun Chen ◽

Kuo Lung Lian ◽

Chia Chi Chu

Keyword(s):

Steady State ◽

High Voltage ◽

State Model ◽

Multilevel Converters ◽

Steady State Model ◽

Modular Multilevel Converters ◽

Very High

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Lifetime and reliability improvements in modular multilevel converters using controlled circulating current

Journal of Power Electronics ◽

10.1007/s43236-021-00297-7 ◽

2021 ◽

Author(s):

Nasiru B. Kadandani ◽

Mohamed Dahidah ◽

Salaheddine Ethni ◽

Musbahu Muhammad

Keyword(s):

Control Method ◽

Semiconductor Devices ◽

Junction Temperature ◽

Multilevel Converters ◽

Control Approach ◽

Circulating Current ◽

Inherent Feature ◽

Modular Multilevel Converters ◽

Current Loading ◽

Laboratory Prototype

AbstractCirculating current has been an inherent feature of modular multilevel converters (MMC), which results in second-order harmonics on the arms currents. If not properly controlled, the circulating current can affect the lifetime and reliability of a converter by increasing the current loading, loss distribution, and junction temperature of its semiconductor devices. This paper proposes controlled circulating current injection as a means of improving the lifetime and reliability of an MMC. The proposed method involves modifying the reference modulating signals of the converter arms to include the controlled differential voltage as an offset. The junction temperature of the semiconductor devices obtained from an electro-thermal simulation is processed to deduce the lifetime and reliability of the converter. The obtained results are benchmarked against a case where the control method is not incorporated. The incorporation of the proposed control method results in a 68.25% increase in the expected lifetime of the converter and a 3.06% increase on its reliability index. Experimental results of a scaled down laboratory prototype validate the effectiveness of the proposed control approach.

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