This paper presents the detailed description of DC/DC operation for reliable grid integration of renewable energy into HVDC grid, under normal operation and different fault conditions. The DC/DC uses the isolated dual-active-bridge DC/DC converter based on MMC (Modular Multilevel Converter) technology. Within the MMC DC/DC converter, an optimal efficiency control strategy to achieve minimal inner current magnitude and fast control for the full power range is proposed. At grid level, the 3-level cascaded current controller design achieves reliable power transfer and grid voltage control. Under normal grid operating conditions, the tie line DC/DC converter enables flexible power exchange between interconnected HVDC links. During fault conditions, the proposed DC/DC cascaded current controller limits the converter currents. The DC/DC converter will therefore function differently, either in power control mode or voltage control mode, for a proper post-fault grid management without grid-wide communication. The validity of the proposed DC/DC control is verified using a 4-terminal DC system with a large wind farm on a detailed PSCAD model for both normal and fault conditions.
|Title of host publication||2016 IEEE 8th International Power Electronics and Motion Control Conference, IPEMC-ECCE Asia 2016|
|Publisher||Institute of Electrical and Electronics Engineers Inc.|
|Number of pages||7|
|Publication status||Published - 13 Jul 2016|
|Event||8th IEEE International Power Electronics and Motion Control Conference, IPEMC-ECCE Asia 2016 - Hefei, China|
Duration: 22 May 2016 → 26 May 2016
|Conference||8th IEEE International Power Electronics and Motion Control Conference, IPEMC-ECCE Asia 2016|
|Period||22/05/16 → 26/05/16|
Bibliographical noteThis study is sponsored by the Engineering and Physical Sciences Research Council (EPSRC) grant no EP/K006428/1, 2013.
- DC-DC power converters
- HVDC transmission
- power system protection
- power system simulation
- wind energy