A Modular Multilevel Converter with Boosting, Self-Balancing, and Scaling Capabilities for High- Voltage Transformerless PV Applications

2018 ◽  
Author(s):  
Hossein Khoun Jahan ◽  
Mehdi Abapour ◽  
Kazem Zare ◽  
Seyed Hossein Hosseini ◽  
Yongheng Yang ◽  
...  
Keyword(s):  
High Voltage ◽  
Modular Multilevel Converter ◽  
Multilevel Converter

scholarly journals Novel Enhanced Modular Multilevel Converter for High-Voltage Direct Current Transmission Systems

Energies ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2257
Author(s):  
Dimitrios Vozikis ◽  
Fahad Alsokhiry ◽  
Grain Philip Adam ◽  
Yusuf Al-Turki
Keyword(s):  
High Voltage ◽  
Low Voltage ◽  
Modular Multilevel Converter ◽  
Multilevel Converter ◽  
Medium Voltage ◽  
High Voltage Direct Current ◽  
Current Transmission ◽  
The Cost ◽  
Voltage Harmonics ◽  
Chain Links

This paper proposes an enhanced modular multilevel converter as an alternative to the conventional half-bridge modular multilevel converter that employs a reduced number of medium-voltage cells, with the aim of improving waveforms quality in its AC and DC sides. Each enhanced modular multilevel converter arm consists of high-voltage and low-voltage chain-links. The enhanced modular multilevel converter uses the high-voltage chain-links based on medium-voltage half-bridge cells to synthesize the fundamental voltage using nearest level modulation. Although the low-voltage chain-links filter out the voltage harmonics from the voltage generated by the high-voltage chain-links, which are rough and stepped approximations of the fundamental voltage, the enhanced modular multilevel converter uses the nested multilevel concept to dramatically increase the number of voltage levels per phase compared to half-bridge modular multilevel converter. The aforementioned improvements are achieved at the cost of a small increase in semiconductor losses. Detailed simulations conducted in EMPT-RV and experimental results confirm the validity of the proposed converter.

scholarly journals Energy balancing in modular multilevel converter systems

2017 ◽  
Vol 65 (5) ◽  
pp. 685-694
Author(s):  
P. Blaszczyk ◽  
K. Koska ◽  
P. Klimczak
Keyword(s):  
Control System ◽  
High Voltage ◽  
High Power ◽  
Power Converter ◽  
Modular Multilevel Converter ◽  
Energy Balancing ◽  
Multilevel Converter ◽  
Test Setup ◽  
Clear View ◽  
Hierarchical Levels

Abstract The modular multilevel converter (MMC) is a well-known solution for medium and high voltage high power converter systems. This paper deals with energy balancing of MMCs. The analysis includes multi-converter systems. In order to provide clear view, the MMC control system is divided into hierarchical levels. Details of control and balancing methods are discussed for each level separately. Finally, experimental results, based on multi-converter test setup, are presented.

scholarly journals Enhanced Fault Current-Limiting Circuit Design for a DC Fault in a Modular Multilevel Converter-Based High-Voltage Direct Current System

2019 ◽  
Vol 9 (8) ◽  
pp. 1661 ◽  
Author(s):  
Kaipei Liu ◽  
Qing Huai ◽  
Liang Qin ◽  
Shu Zhu ◽  
Xiaobing Liao ◽  
...  
Keyword(s):  
High Voltage ◽  
Direct Current ◽  
Parameter Determination ◽  
Fault Current ◽  
Modular Multilevel Converter ◽  
Multilevel Converter ◽  
Hvdc System ◽  
High Voltage Direct Current ◽  
Operation Speed ◽  
Current Limiting

The main weakness of the half-bridge modular multilevel converter-based high-voltage direct current (MMC-HVDC) system lies in its immature solution to extremely high current under direct current (DC) line fault. The development of the direct current circuit breaker (DCCB) remains constrained in terms of interruption capacity and operation speed. Therefore, it is essential to limit fault current in the MMC-HVDC system. An enhanced fault current-limiting circuit (EFCLC) is proposed on the basis of fault current study to restrict fault current under DC pole-to-pole fault. Specifically, the EFCLC consists of fault current-limiting inductance L F C L and energy dissipation resistance R F C L in parallel with surge arrestor. L F C L reduces the fault current rising speed, together with arm inductance and smoothing reactor. However, in contrast to arm inductance and smoothing reactor, L F C L will be bypassed via parallel-connected thyristors after blocking converter to prevent the effect on fault interruption speed. R F C L shares the stress on energy absorption device (metal oxide arrester) to facilitate fault interruption. The DCCB requirement in interruption capacity and breaking speed can be satisfied effortlessly through the EFCLC. The working principle and parameter determination of the EFCLC are presented in detail, and its effectiveness is verified by simulation in RT-LAB and MATLAB software platforms.

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