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B4-76 DC-DC converters in HVDC Grids and for connections to HVDC systems

It is accepted that DC-DC will play an important role in DC grids but the exact functions, performance requirements and applications are not clear. DC-DC converters will be essential in transforming DC voltage but they also may have other functions. As an example, many DC-DC converters can work as DC circuit breakers and fault current limiters. In particular DC-DC converters provide alternative solutions for some DC grid topologies and more work is required to understand how to exploit DC-DC converters in developing/simplifying DC grid protection and control. DC-DC converters might facilitate power exchange between different DC topologies, i.e. monopolar and/or bipolar systems. They could meet other requirements like power control, voltage control, regulation of DC harmonics, energization and start up, and integration of wide range of existing DC systems.

The objectives of the WG are to:

1. Confirm the feasibility of high power DC-DC converters and provide basic technical characteristics in terms of DC configurations (monopole, bipole, symmetric/asymmetric, isolated/non-isolated) and power/voltage ranges.

2. Identify the role and need for DC-DC converters in DC Grids.

3. Evaluate the applications for DC-DC converters in interconnecting HV and MV DC systems.

4. Identify benefits of DC-DC converters in applications of tapping on HVDC

The working group will review principal technology concepts like: non-isolated converters, isolated dual-active-bridge, DC-DC auto-transformers, high/low stepping ratios, multiport converters and others. The performance indicators will be studied, including range/variation of DC-DC stepping ratios, efficiency, DC fault isolation capability and power flow control. The power reversal capability will have important implications on the DC-DC technology costs and losses. In particular this WG will provide guidelines on the power reversal options (DC voltage or DC current reversal) and link these options with DC-DC technologies. It is not the intention to delve in depth in DC-DC technologies (particularly not MV DC-DC concepts), but rather to collate knowledge on accepted technologies and to establish a platform for further developments. Some attention will also be given to DC-DC modelling methods.

Terms of Reference (pdf, 139kB)

WG members:

NAMEGIVEN NAMECOUNTRY CODE
JovcicDraganGB
Gomis OriolES
Yang PaulFR
SaeedifardMaryamUS
Adapa RamUS
Zhang PengUS
Trainer DavidGB
Yao LiangzhongCN
Kunpeng ZhaCN
TaffeseAbelNO
Kish  GregoryCA
DarbandiArashCA
Woodford DennisCA
AzarRamyCA
IravaniRezaCA
JamshidifarAliGB
Ferrer RicardES
GuillaudFerrerFr
Junyent-FerreAdriaGB
BongiornoMassimoSE
Takushi JimichiJP
Kuroda KazuhiroJP
NaimiAlirezaSE
RentschlerAlexanderDE
DworakowskiPiotrFR
GuillaudXavierFR
JordanPhilipIE