| Title |
Enhancement of Cell Voltage Balancing Control by Zero Sequence Current Injection in a Cascaded H-Bridge STATCOM |
| Authors |
Byung-Ki Kwon ; Seung-Ki Jung ; Tae-Hyeong Kim |
| DOI |
10.6113/TKPE/2015.20.4.321 |
| Keywords |
STATCOM; DC Voltage unbalance; Cell voltage balancing; Reactive power component current; Zero sequence current |
| Abstract |
The static synchronous compensator (STATCOM) of cascaded H-bridge configuration accompanying multiple separate DC sides is inherently subject to the problem of uneven DC voltages. These DC voltages in one leg can be controlled by adjusting the AC-side output voltage of each cell inverter, which is proportional to the active power. However, when the phase current is extremely small, large AC-side voltage is required to generate the active power to balance the cell voltages. In this study, an alternative zero-sequence current injection method is proposed, which facilitates effective cell balancing controllers at no load, and has no effect on the power grid because the injected zero sequence current only flows within the STATCOM delta circuit. The performance of the proposed method is verified through simulation and experiments. |