| Abstract |
The well-known voltage-source inverter can be used as a compensator for fundamental reactive power. Compared to conventional static compensators the reactive components of the circuit are much smaller, which means less cost and less room. To reach the lower limit of a reasonable power level for a static compensator, the inverter has to be equipped with large GTOs. Therefore a very low switching frequency of some 100Hz has to be accepted. Two specific problems which arise in this situation are discussed in this paper: an adequate PWM and a controller which is able to handle a system with tendency to oscillate. It is shown that an improved optimization of switching angles helps to keep harmonics of the line-currents at a low level. Further on, a state controller is discussed, which Iets the compensator appear as a fast controllable reactive current source. The simulation results have been verified with a laboratory model on reduced scale. |
