Abstract
This paper presents a three-phase transformerless structure of modular multilevel converters based on cascaded pulsewidth-modulated chopper cells in medium-voltage D-STATCOM application. It is suggested for installation on unbalanced medium-voltage power-supply systems to achieve higher performance in improving power quality. This paper proposes a new control strategy based on power-flow analysis with a focus on dc capacitor voltage control that is insulated from the source voltage fault. This control strategy enables the D-STATCOM system to compensate unbalanced nonlinear load even under asymmetrical grid fault conditions and it has no limitations on the cascaded number. Experimental results obtained from a 60-V 3-kVA downscaled prototype verify that this D-STATCOM system performs satisfactory, not only compensating for unbalanced nonlinear load but also keeping the capacitor voltages maintained at the given value even in unbalanced power systems.
| Original language | English |
|---|---|
| Article number | 6594905 |
| Pages (from-to) | 2030-2038 |
| Number of pages | 9 |
| Journal | IEEE Transactions on Power Delivery |
| Volume | 28 |
| Issue number | 4 |
| DOIs | |
| State | Published - 2013 |
Keywords
- D-STATCOM
- DC voltage control
- Modular multilevel converter (MMC)
- compensating unbalanced nonlinear load