scholarly journals Assessment of Appropriate MMC Topology Considering DC Fault Handling Performance of Fault Protection Devices

2018 ◽  
Vol 8 (10) ◽  
pp. 1834 ◽  
Author(s):  
Ho-Yun Lee ◽  
Mansoor Asif ◽  
Kyu-Hoon Park ◽  
Bang-Wook Lee

The eventual goal of high-voltage direct-voltage (HVDC) systems is to implement HVDC grids. The modular multilevel converter (MMC) has been identified as the best candidate for the realization of an HVDC grid by eliminating the shortcomings of conventional voltage source converter (VSC) technology. The related research has focused on efficient control schemes, new MMC topologies, and operational characteristics of an MMC in a DC grid, but there is little understanding about the fault handling capability of two mainstream MMC topologies, i.e., half bridge (HB) and full bridge (FB) MMCs in combination with an adequate protection device. Contrary to the existing research where the fault location is usually fixed (center of the line), this paper considered a variable fault location on the DC line, so as to compare the fault interruption time and maximum fault current magnitude. From the point of view of fault interruption, AC and DC side transient analyses were performed for both MMC topologies to suggest the appropriate topology. The simulation result confirmed that the fault handling performance of an HB-MMC with a DC circuit breaker is superior due to the smaller fault current magnitude, faster interruption time, lower overvoltage magnitude, and lesser stresses on the insulation of the DC grid.

Energies ◽  
2019 ◽  
Vol 12 (12) ◽  
pp. 2388 ◽  
Author(s):  
Muhammad Ahmad ◽  
Zhixin Wang

The direct current circuit breakers are considered a promising option to protect the transmission line against commonly appearing line-to-ground fault. However, the challenges of losses in the nonoperational stage, escalation of response against fault current, and large fault current handling capability remain the debatable issues for direct current circuit breakers. This paper introduces a novel topology of the hybrid circuit breaker with fault-current-limiting characteristics, which contains three branches: the main branch, fault-current-limiting branch, and energy absorption branch. The main branch includes a mechanical switch, breaker impedance, and bidirectional power electronics switches. In the fault-current-limiting branch, a fault-current-limiting circuit is introduced which contains n numbers of bidirectional switches and current-limiting inductors, which are connected in series to make the design modular in nature. During the normal working stage, the current flows through the main branch of the breaker. Once a fault in the system is confirmed, the fault current is transferred to the fault-current-limiting branch. At this stage, the intensity of the fault current is reduced significantly using the fault-current-limiting circuit, and finally, the residual current is shifted to the energy absorption branch. The working principle, design considerations, and parametric analysis concerning the design of hybrid circuit breakers are incorporated in this paper. The performance of the proposed breaker is evaluated using a three-terminal voltage-source converter-based high-voltage direct current transmission network; for this purpose, a PSCAD/EMTDC simulation tool is used. The performance of the proposed breaker is also compared with other topologies. The comparative analysis shows that the proposed breaker is a good alternative considering high fault current interruption requirements, response time against fault current, and power losses.


2017 ◽  
Vol 2017 ◽  
pp. 1-12
Author(s):  
Lei Chen ◽  
Hongkun Chen ◽  
Jun Yang ◽  
Huiwen He

Considering the rapid development of high temperature superconducting (HTS) materials, superconducting power applications have attracted more and more attention in the power industry, particularly for electrical systems including renewable energy. This paper conducts experimental tests on a voltage compensation type active superconducting fault current limiter (SFCL) prototype and explores the SFCL’s application in a permanent-magnet synchronous generator- (PMSG-) based wind turbine system. The SFCL prototype is composed of a three-phase air-core superconducting transformer and a voltage source converter (VSC) integrated with supercapacitor energy storage. According to the commissioning test and the current-limiting test, the SFCL prototype can automatically suppress the fault current and offer a highly controlled compensation voltage in series with the 132 V electrical test system. To expand the application of the active SFCL in a 10 kW class PMSG-based wind turbine system, digital simulations under different fault cases are performed in MATLAB/Simulink. From the demonstrated simulation results, using the active SFCL can help to maintain the power balance, mitigate the voltage-current fluctuation, and improve the wind energy efficiency. The active SFCL can be regarded as a feasible solution to assist the PMSG-based wind turbine system to achieve low-voltage ride-through (LVRT) operation.


2019 ◽  
Vol 9 (17) ◽  
pp. 3513 ◽  
Author(s):  
Mohammed Alhasheem ◽  
Frede Blaabjerg ◽  
Pooya Davari

Finite control set model predictive control (FCS-MPC) methods in different power electronic applications are gaining considerable attention due to their simplicity and fast dynamics. This paper introduces an assessment of the two-level three-phase voltage source converter (2L-VSC) utilizing different MPC schemes with and without a modulation stage. In order to perform such a comparative evaluation, 2L-VSC efficiency and total harmonics distortion of the voltage (THDv) have been investigated, when considering a linear load. The results demonstrate the performance of different MPC algorithms through an experimental verification on a Danfoss converter, and a set of analyses have been studied using the PLECS and MATLAB/SIMULINK together. It can be concluded that a comparable performance is achieved by using conventional MPC (CMPC), improved MPC (IMPC), periodic MPC (PMPC), and MPC scheme with modulator (M 2 PC) controllers. The assessment is critical to classify the strategies as mentioned earlier according to their efficiency. Furthermore, it gives a thorough point of view on which algorithm is suitable for the grid-forming applications.


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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