TY - JOUR
T1 - Balancing of submodule capacitor voltage of hybrid modular multilevel converter under DC-Bus voltage variation of HVDC System
AU - Lee, Joon Hee
AU - Jung, Jae Jung
AU - Sul, Seung Ki
N1 - Publisher Copyright:
© 1986-2012 IEEE.
PY - 2019/11
Y1 - 2019/11
N2 - A hybrid modular multilevel converter (MMC) consists of both half-bridge submodule (HBSM) and full-bridge submodule (FBSM) in each arm. It has several advantages over other MMC topologies, such as low system loss, reduced cost of the system, but still maintains fault ride-through capability against a solid dc-side fault. However, the hybrid MMC may have a difficulty of submodule (SM) voltage balancing under variation of its dc-bus voltage. Since the voltage unbalance of SMs results in SM capacitor overvoltage and low reliability of the system, the voltage of SMs, which can be also represented as energy of SMs, should be balanced at all time. In this paper, to extend the narrow adjustable range of dc-bus voltage due to the voltage/energy unbalance, new feedback and feedforward energy balancing controllers with revised sorting algorithm are proposed. The feedback control ensures the zero steady-state error, while the feedforward control provides fast dynamic response in the energy balancing control. By applying the proposed control scheme, the hybrid MMC can keep the voltage balance between HBSMs and FBSMs in wider range of dc-bus voltage. The full-scale computer simulation results and down-scale experimental results demonstrate the validity of the proposed control scheme.
AB - A hybrid modular multilevel converter (MMC) consists of both half-bridge submodule (HBSM) and full-bridge submodule (FBSM) in each arm. It has several advantages over other MMC topologies, such as low system loss, reduced cost of the system, but still maintains fault ride-through capability against a solid dc-side fault. However, the hybrid MMC may have a difficulty of submodule (SM) voltage balancing under variation of its dc-bus voltage. Since the voltage unbalance of SMs results in SM capacitor overvoltage and low reliability of the system, the voltage of SMs, which can be also represented as energy of SMs, should be balanced at all time. In this paper, to extend the narrow adjustable range of dc-bus voltage due to the voltage/energy unbalance, new feedback and feedforward energy balancing controllers with revised sorting algorithm are proposed. The feedback control ensures the zero steady-state error, while the feedforward control provides fast dynamic response in the energy balancing control. By applying the proposed control scheme, the hybrid MMC can keep the voltage balance between HBSMs and FBSMs in wider range of dc-bus voltage. The full-scale computer simulation results and down-scale experimental results demonstrate the validity of the proposed control scheme.
KW - Feedforward control
KW - hybrid high voltage direct current (HVDC)
KW - hybrid modular multilevel converter (MMC)
KW - submodule (SM) balancing
UR - http://www.scopus.com/inward/record.url?scp=85065818179&partnerID=8YFLogxK
U2 - 10.1109/TPEL.2019.2896336
DO - 10.1109/TPEL.2019.2896336
M3 - Article
AN - SCOPUS:85065818179
SN - 0885-8993
VL - 34
SP - 10458
EP - 10470
JO - IEEE Transactions on Power Electronics
JF - IEEE Transactions on Power Electronics
IS - 11
M1 - 8630082
ER -