Hierarchical control system of modular multilevel converter used in high-voltage direct current transmission

2014 ◽  
Author(s):  
Boran Fan ◽  
Kui Wang ◽  
Zedong Zheng ◽  
Yongdong Li ◽  
Xiaokun Wu
Keyword(s):  
Control System ◽  
High Voltage ◽  
Direct Current ◽  
Hierarchical Control ◽  
Modular Multilevel Converter ◽  
Multilevel Converter ◽  
High Voltage Direct Current ◽  
Current Transmission

scholarly journals Fault Characteristics and Control Strategies of Multiterminal High Voltage Direct Current Transmission Based on Modular Multilevel Converter

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Fei Chang ◽  
Zhongping Yang ◽  
Yi Wang ◽  
Fei Lin ◽  
Shihui Liu
Keyword(s):  
High Voltage ◽  
Direct Current ◽  
Wind Farm ◽  
Control Strategies ◽  
Voltage Source ◽  
Voltage Source Converter ◽  
Modular Multilevel Converter ◽  
Multilevel Converter ◽  
High Voltage Direct Current ◽  
Current Transmission

The modular multilevel converter (MMC) is an emerging voltage source converter topology suitable for multiterminal high voltage direct current transmission based on modular multilevel converter (MMC-MTDC). This paper presents fault characteristics of MMC-MTDC including submodule fault, DC line fault, and fault ride-through of wind farm integration. Meanwhile, the corresponding protection strategies are proposed. The correctness and effectiveness of the control strategies are verified by establishing a three-terminal MMC-MTDC system under the PSCAD/EMTDC electromagnetic transient simulation environment.

scholarly journals Electromechanical Transient Modeling of Line Commutated Converter-Modular Multilevel Converter-Based Hybrid Multi-Terminal High Voltage Direct Current Transmission Systems

Energies ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 2102 ◽  
Author(s):  
Liang Xiao ◽  
Yan Li ◽  
Huangqing Xiao ◽  
Zheren Zhang ◽  
Zheng Xu
Keyword(s):  
High Voltage ◽  
Direct Current ◽  
Power Flow ◽  
Large Scale ◽  
Transient Stability ◽  
Modular Multilevel Converter ◽  
Multilevel Converter ◽  
Hvdc System ◽  
High Voltage Direct Current ◽  
Current Transmission

A method for electromechanical modeling of line commutated converter (LCC)-modular multilevel converter (MMC)-based hybrid multi-terminal High Voltage Direct Current Transmission (HVDC) systems for large-scale power system transient stability study is proposed. Firstly, the general idea of modeling the LCC-MMC hybrid multi-terminal HVDC system is presented, then the AC-side and DC-side models of the LCC/MMC are established. Different from the conventional first-order DC-side model of the MMC, an improved second-order DC-side model of the MMC is established. Besides considering the firing angle limit of the LCC, a sequential power flow algorithm is proposed for the initialization of LCC-MMC hybrid multi-terminal HVDC system. Lastly, simulations of small scale and large scale power systems embedded with a three-terminal LCC-MMC hybrid HVDC system are performed on the electromechanical simulation platform PSS/E. It is demonstrated that if the firing angle limit is not considered, the accuracy of the power flow solutions will be greatly affected. Steady state calculation and dynamic simulation show that the developed LCC-MMC hybrid MTDC model is accurate enough for electromechanical transient stability studies of large-scale AC/DC system.

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.

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