A New Hybrid Submodule for MMC with DC Fault Ride-Through Capability

Modular multilevel converter (MMC) has become the most prominent topology for high voltage direct current (HVDC) applications due to its modularity, lower losses, less filtering requirements and flexible controllability. However, MMC still lacks in terms of efficiency and fault tolerant capability compared to the line commutated converters (LCC) based HVDC systems. This paper proposes a thyristor bypassed fault tolerant half bridge submodule (TBFT-HBSM) for MMC to achieve high efficiency as that in LCC while retaining DC fault tolerant capability and controllability. The lower switch of conventional HBSMs is replaced by anti-parallel thyristor switches to reduce the overall conduction losses of the converter. A new control algorithm has been proposed to balance the arm voltages. Moreover, loss analysis of proposed submodule (SM) is carried out and its efficiency compared with existing SM topologies. Simulation as well as experimental studies are carried out to verify the effectiveness of the proposed SM structure and its control.

[1]  Rainer Marquardt,et al.  An innovative modular multilevel converter topology suitable for a wide power range , 2003, 2003 IEEE Bologna Power Tech Conference Proceedings,.

[2]  Rong Zeng,et al.  Design and Operation of a Hybrid Modular Multilevel Converter , 2015, IEEE Transactions on Power Electronics.

[3]  Remus Teodorescu,et al.  Design, Control, and Application of Modular Multilevel Converters for HVDC Transmission Systems , 2016 .

[4]  Wenhua Liu,et al.  Protection of Nonpermanent Faults on DC Overhead Lines in MMC-Based HVDC Systems , 2013, IEEE Transactions on Power Delivery.

[5]  Dragan Jovcic,et al.  LCL and L-VSC Converters With DC Fault Current-Limiting Property and Minimal Power Losses , 2014 .

[6]  Maryam Saeedifard,et al.  Hybrid Design of Modular Multilevel Converters for HVDC Systems Based on Various Submodule Circuits , 2015, IEEE Transactions on Power Delivery.

[7]  L.G. Franquelo,et al.  The age of multilevel converters arrives , 2008, IEEE Industrial Electronics Magazine.

[8]  Phil S. Jones,et al.  Calculation of power losses for MMC-based VSC HVDC stations , 2013, 2013 15th European Conference on Power Electronics and Applications (EPE).

[9]  Soteris Poyiadjis.  A New Cell Bypass Arrangement and Control for Modular Multilevel Converters based on Thyristor Forced Commutation Circuit , 2017 .

[10]  Konstantin Vershinin,et al.  Thyristor-Bypassed Submodule Power-Groups for Achieving High-Efficiency, DC Fault Tolerant Multilevel VSCs , 2018, IEEE Transactions on Power Delivery.

[11]  Stephen J. Finney,et al.  Thyristor based modular multilevel converter with active full-bridge chain-link for forced commutation , 2016, 2016 IEEE 17th Workshop on Control and Modeling for Power Electronics (COMPEL).

[12]  Alireza Nami,et al.  Modular Multilevel Converters for HVDC Applications: Review on Converter Cells and Functionalities , 2015, IEEE Transactions on Power Electronics.

[13]  Jae-Do Park,et al.  VSC-HVDC system protection: A review of current methods , 2011, 2011 IEEE/PES Power Systems Conference and Exposition.