scholarly journals A Novel Protection and Location Scheme for Pole-to-Pole Fault in MMC-MVDC Distribution Grid

Energies ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 2076 ◽  
Author(s):  
Yu Zeng ◽  
Guibin Zou ◽  
Xiuyan Wei ◽  
Chenjun Sun ◽  
Lingtong Jiang
Keyword(s):  
Frequency Band ◽  
Characteristic Frequency ◽  
High Accuracy ◽  
Modular Multilevel Converter ◽  
Protection Device ◽  
Distribution Grid ◽  
Multilevel Converter ◽  
Medium Voltage ◽  
Identification Criterion ◽  
S Transform

Nowadays, the efficient and reliable protection and location schemes for MMC-MVDC (Modular Multilevel Converter-Medium Voltage Direct Current) grid are few. This paper is the first to propose a scheme to not only protect the feeders and the busbar, but locate the segments in MMC-MVDC grid. To improve the reliability, this paper analyzes the transient characteristics of the pole-to-pole fault and then obtains the characteristic frequency band. Based on S-transform, STCFB (S-transform characteristic frequency band) Phase of fault component is utilized to construct the identification criterion for faulty feeder and faulty segment. The whole scheme can be divided into three steps, namely, protection starting criterion, faulty feeder and busbar protection criterion, and faulty segment location criterion. Firstly, the current gradient method is utilized to quickly detect the fault and start the protection device. Secondly, the non-unit protection criterion on busbar and feeders is proposed according to STCFB Phase of the voltage and current fault component. Thirdly, according to the STCFB Phase on both sides of the feeder segment, the faulty segment can be located. A radial MMC-MVDC distribution network model was built in PSCAD/EMTDC software to evaluate the performance of the protection and location method. Simulation results for different cases demonstrate that the proposed scheme has high accuracy, good adaptability and reliability.

Modular Multilevel Converter Synthetic Inertia-Based Frequency Support for Medium-Voltage Microgrids

2019 ◽  
Vol 66 (11) ◽  
pp. 8992-9002 ◽  
Author(s):  
Shunfeng Yang ◽  
Jingyang Fang ◽  
Yi Tang ◽  
Huan Qiu ◽  
Chaoyu Dong ◽  
...  
Keyword(s):  
Modular Multilevel Converter ◽  
Multilevel Converter ◽  
Medium Voltage

scholarly journals Series Active Filter Design Based on Asymmetric Hybrid Modular Multilevel Converter for Traction System

Electronics ◽  
2018 ◽  
Vol 7 (8) ◽  
pp. 134 ◽  
Author(s):  
Muhammad Ali ◽  
Muhammad Khan ◽  
Jianming Xu ◽  
Muhammad Faiz ◽  
Yaqoob Ali ◽  
...  
Keyword(s):  
Low Voltage ◽  
Filter Design ◽  
Switching Frequency ◽  
Modular Multilevel Converter ◽  
Multilevel Converter ◽  
Medium Voltage ◽  
Converter Topologies ◽  
Asymmetric Hybrid ◽  
Simulation Results ◽  
Traction System

This paper presents a comparative analysis of a new topology based on an asymmetric hybrid modular multilevel converter (AHMMC) with recently proposed multilevel converter topologies. The analysis is based on various parameters for medium voltage-high power electric traction system. Among recently proposed topologies, few converters have been analysed through simulation results. In addition, the study investigates AHMMC converter which is a cascade arrangement of H-bridge with five-level cascaded converter module (FCCM) in more detail. The key features of the proposed AHMMC includes: reduced switch losses by minimizing the switching frequency as well as the components count, and improved power factor with minimum harmonic distortion. Extensive simulation results and low voltage laboratory prototype validates the working principle of the proposed converter topology. Furthermore, the paper concludes with the comparison factors evaluation of the discussed converter topologies for medium voltage traction applications.

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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