Coordination of Mechanical DCCBs and Temporary Blocking of Half Bridge MMC

This paper proposes a dc grid protection strategy based on temporary MMC blocking in combination with mechanical DCCBs on dc lines. MMCs are blocked for only a short period of time while DCCBs operate and resume operation afterwards. A comparison is made with a protection strategy in which MMC blocking is avoided. The study analyses the impact of dc faults on dc power flow, ac system, DCCB dimensioning and MMC’s antiparallel diodes. Operation is demonstrated on a point-to-point HVDC and a three-terminal dc grid, also using thermal model of MMC’s IGBT module. Main benefits of the proposed strategy are simplicity and low protection system cost. On the downside, antiparallel diodes are exposed to greater current and thermal stress.

[1]  Dragan Jovcic,et al.  DC Transmission Grid With Low-Speed Protection Using Mechanical DC Circuit Breakers , 2015, IEEE Transactions on Power Delivery.

[2]  Bertrand Raison,et al.  Full-selective protection strategy for MTDC grids based on R-type superconducting FCLs and mechanical DC circuit breakers , 2016 .

[3]  Dirk Van Hertem,et al.  Impact of DC grid contingencies on AC system stability , 2017 .

[4]  Bertrand Raison,et al.  Technical and Economic Analysis of the R-Type SFCL for HVDC Grids Protection , 2017, IEEE Transactions on Applied Superconductivity.

[5]  Ashley Plumpton,et al.  Design and Characterisation of Optimised Protective Thyristors for VSC Systems , 2016 .

[6]  T. Eriksson,et al.  A low loss mechanical HVDC breaker for HVDC Grid applications , 2014 .

[7]  Wenyuan Wang,et al.  Impact of DC Breaker Systems on Multiterminal VSC-HVDC Stability , 2016, IEEE Transactions on Power Delivery.

[8]  Dragan Jovcic,et al.  Low-Energy Protection System for DC Grids Based on Full-Bridge MMC Converters , 2018, IEEE Transactions on Power Delivery.

[9]  Athula D. Rajapakse,et al.  Fault Detection and Interruption in an Earthed HVDC Grid Using ROCOV and Hybrid DC Breakers , 2015, IEEE Transactions on Power Delivery.

[10]  Dragan Jovcic,et al.  Capacitive Element for Limiting VSC Fault Current in DC Grids , 2018, 2018 IEEE Power & Energy Society General Meeting (PESGM).

[11]  Ahmed M. Massoud,et al.  A Switched-Capacitor Submodule for Modular Multilevel HVDC Converters With DC-Fault Blocking Capability and a Reduced Number of Sensors , 2016, IEEE Transactions on Power Delivery.

[12]  Dragan Jovcic,et al.  High Voltage Direct Current Transmission: Converters, Systems and DC Grids , 2015 .

[13]  Oliver Cwikowski,et al.  Operating DC Circuit Breakers With MMC , 2018, IEEE Transactions on Power Delivery.

[14]  K. Kamei,et al.  HVDC Circuit Breakers for HVDC Grid Applications , 2015 .

[15]  Jörg Dorn,et al.  System integration aspects of DC circuit breakers , 2016 .

[16]  Dragan Jovcic,et al.  Coordination of MMC converter protection and DC line protection in DC grids , 2016, 2016 IEEE Power and Energy Society General Meeting (PESGM).