scholarly journals Improved hybrid modular multilevel converters with dc short-circuit fault ride-through capacity

2019 ◽  
Vol 2019 (16) ◽  
pp. 1194-1198
Author(s):  
Yuhang Lei ◽  
Gangquan Si ◽  
Jianwei Zhu ◽  
Yanbing Zhang
Keyword(s):  
Short Circuit ◽  
Multilevel Converters ◽  
Fault Ride Through ◽  
Modular Multilevel Converters ◽  
Short Circuit Fault

Research on fault clearing scheme for half-bridge modular multilevel converters high voltage DC based on overhead transmission lines

2020 ◽  
Vol 22 (1) ◽  
pp. 61-72
Author(s):  
Jingru Zhang ◽  
Baina He ◽  
Xingmin He ◽  
Yanchen Dong ◽  
Renzhuo Jiang
Keyword(s):  
High Voltage ◽  
Transmission Lines ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Circuit Breakers ◽  
Multilevel Converters ◽  
Modular Multilevel Converters ◽  
Clearing Time ◽  
The Impact ◽  
Short Circuit Fault

Abstract When a short-circuit fault occurs on the transmission lines of high voltage DC transmission system based on modular multilevel converters, the fault cannot be cleared by adjusting the converter control system, which results in longer recovery time. Aiming at the problem above, a fault self-clearing scheme based on the fault clearing module for the half-bridge converter station is proposed. Combined with the actual operating status of the flexible DC transmission project, centralized parameter models are utilized to analyze the fault self-clearing mechanism. Besides, the impact of the discharge branch on the fault clearing effect is studied in depth to provide a design consideration for the fault clearing module and improve the comprehensive benefits of the proposed scheme. PSCAD/EMTDC simulation results show that the introduction of the fault clearing module in the half-bridge converter station can effectively suppress the fault short-circuit current and shorten the fault clearing time. In addition, circuit breakers on both sides of the line do not need to be tripped, providing a reliable guarantee for the subsequent adaptive restart process.

scholarly journals A DC Short-Circuit Fault Ride Through Strategy of MMC-HVDC Based on the Cascaded Star Converter

Energies ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 2079 ◽  
Author(s):  
Yingjie Wang ◽  
Bo Yang ◽  
Huifang Zuo ◽  
Haiyuan Liu ◽  
Haohao Yan
Keyword(s):  
Control Method ◽  
Short Circuit ◽  
Normal Operation ◽  
Zero Crossing ◽  
High Voltage Direct Current ◽  
Fault Ride Through ◽  
Power Load ◽  
Constant Power Load ◽  
Short Circuit Fault ◽  
Balancing Control

A modular multilevel converter based high voltage direct current (MMC-HVDC) with DC fault self-clearing is adopted to deal with the DC short-circuit fault. However, the constant power load characteristic of the sub-modules causes capacitor voltages to diverge and the converter to go out of hot standby. To address this problem, a novel DC short-circuit fault ride through strategy is proposed. According to the polarities of grid voltages, the working or blockage of the upper and lower bridge arms is chosen according to six sections to obtain a cascaded star converter. The capacitor voltages of MMC sub-modules are maintained and balanced through the control similar to the cascaded star converter. Moreover, in order not to change zero crossing, a cluster balancing control method by scaling the amplitudes of the modulated waves is proposed to balance the capacitor voltages between phase clusters. The strategy also achieves the DC Bus line-to-line equipotential and no fault current generated. With the switches of two modes (normal operation and fault ride through operation) after the fault is cleared, the power transfer of MMC-HVDC can be recovered quickly. Finally, the effectiveness of the proposed fault ride through strategy is demonstrated on the 21-level MMC-HVDC simulation model in PSCAD/EMTDC.

scholarly journals A Hybrid MMC Topology with dc Fault Ride-Through Capability for MTDC Transmission System

2015 ◽  
Vol 2015 ◽  
pp. 1-11
Author(s):  
Xinhan Meng ◽  
Ke-Jun Li ◽  
Zhuodi Wang ◽  
Wenning Yan ◽  
Jianguo Zhao
Keyword(s):  
Short Circuit ◽  
Harmonic Distortion ◽  
Transmission System ◽  
Simulation Software ◽  
Power System Simulation ◽  
Multilevel Converter ◽  
Harmonic Content ◽  
Dc Fault ◽  
Fault Ride Through ◽  
Short Circuit Fault

This paper proposes a hybrid modular multilevel converter (MMC) topology based on mismatched-cascade mechanism. The blocking conditions of different submodule (SM) structures under dc fault are analyzed and a series double submodule is presented. With series-double submodules and mismatched-cascade submodules, the proposed hybrid MMC can ride-through the dc side short-circuit fault and provide an output voltage with the feature of low harmonic content. This hybrid MMC topology can be used in the VSC based multiterminal dc (VSC-MTDC) transmission system. The dc fault ride-through properties of the new structure and the total harmonic distortion (THD) are analyzed compared with the previous full-bridge and clamp-double architectures. An appropriate fault blocking procedure is presented, and a typical four-terminal dc transmission simulation system is given in the power system simulation software. Finally, simulation of steady-state and dc bipolar short-circuit fault verifies that the MTDC system based on this new hybrid MMC topology is stabilized and can block the dc fault and return the nonfault parts to normal.

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