Abstract
A high-voltage direct current (HVDC) transmission system based on three-level flying capacitor (FC) multilevel converters with hybrid pulse-width modulation (PWM) is presented in this paper. Selective harmonic elimination PWM (SHE-PWM) is used during normal operating conditions and is switched to phase-shifted sinusoidal PWM (PS-SPWM) during an asymmetric network fault. The generation of the switching patterns under SHE-PWM control for each power device is described taking into account the natural balancing of the FC voltages. A new and simple control method for balancing the FC voltages when using SHE-PWM is proposed which is based on the small change of the firing angle according to the polarity of the load current. The FC voltage ripple under SHE-PWM control is estimated and compared to that under PS-SPWM. A method to implement the proposed hybrid PWM with capacitor voltage balancing is also provided. Simulation studies on a 300-MW/plusmn150 kV voltage-source converter transmission system are presented to confirm the satisfactory performance of the proposed system under active and reactive power variations and single-phase fault conditions.
| Original language | English |
|---|---|
| Pages (from-to) | 693-702 |
| Number of pages | 10 |
| Journal | IEEE Transactions on Power Delivery |
| Volume | 22 |
| Issue number | 1 |
| DOIs | |
| Publication status | Published - Jan 2007 |
Keywords
- capacitors
- control systems
- voltage control
- power conversion
- power generation