The analysis and experiment of dc-link short-circuit of modular multilevel converter based high voltage direct current system

Author(s):  
Zhandong Sun ◽  
Fanqiang Gao ◽  
Zixin Li ◽  
Yongjie Luo ◽  
Ping Wang ◽  
...  
2019 ◽  
Vol 9 (8) ◽  
pp. 1661 ◽  
Author(s):  
Kaipei Liu ◽  
Qing Huai ◽  
Liang Qin ◽  
Shu Zhu ◽  
Xiaobing Liao ◽  
...  

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.


Electronics ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 993
Author(s):  
Yun-Gi Kwak ◽  
Feel-Soon Kang ◽  
Sung-Geun Song

Clamped-single submodule (CSSM) has DC short circuit current protection function to improve the safety and stability of high voltage, direct current (HVDC) system. In order to carry out the protection, it needs an additional number of insulated gate bipolar transistors (IGBTs) and diodes compared to the conventional half-bridge submodule (HBSM). In general, the failure rate tends to increase in proportion to the number of circuit components. Also, complex operation of the submodule may increase the failure rate, so accurate reliability analysis considering these points is required to apply CSSM in a practical HVDC system. We estimate the failure rate and the mean time between failures (MTBF) of CSSM using a fault tree. Fault-tree analysis (FTA) is possible to analyze the failure rate more accurately than the prior part count failure analysis (PCA) that considers only the number of parts, the type of parts, and the connection status of each circuit component. To provide guidelines for submodule selection under various conditions, we compare the economic cost of a CSSM with HBSM, FBSM, and clamped-double submodule (CDSM), and analyze the failure rate according to the voltage margin of the parts.


Author(s):  
Araitz Iturregi ◽  
Agurtzane Etxegarai ◽  
D. Marene Larruskain ◽  
Pablo Eguia ◽  
Oihane Abarrategui

Goi-tentsioko korronte zuzeneko (ingelesez, High Voltage Direct Current HVDC) garraio-sistemak gero eta garrantzitsuagoak dira sistema elektrikoan, onura ekonomiko eta teknikoak direla eta. Hala ere, akatsen bat gertatzen denean, korrontea eteteak oraindik ere erronka izaten jarraitzen du HVDC sareetan. Desiragarriak ez diren korronteak eteteko, korronte zuzeneko etengailuak erabil daitezke, baina horien gaitasuna mugatua da. Egoera hala izanik, akats-korronteen mugagailuak (ingelesez, Fault Current Limiter FCL) dira proposamenik egokiena akats-korronteak maneiagarriagoak diren balioetara txikitzeko; hartara, sistema elektrikoaren garraio-ahalmena handitu daiteke, ekipamendua aldatu beharrik gabe. Sarean aldez aurretik legokeen ekipamendua gai izango litzateke korronte berriak kudeatzeko eta sistema era eraginkorrean babesteko FCLen erabilpenaz. Artikulu honetan, FCL tresnen ezaugarri orokorrak eta sailkapena aurkezten dira. Ondoren, egoera solidoko FCLa erabili da maila anizkoitzeko bihurgailudun (ingelesez, Modular Multilevel Converter MMC) VSC-HVDC (ingelesez, Voltage Source Converter) sistema batean, eta horren jokaera azaltzen da simulazio bidez.


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