| Abstract |
This paper presents the comparison between two power converter topologies to feed a superconducting coil in a SMES (Superconducting Magnet Energy Storage) system. The two converters are a 6 and a 12 pulse GTO current converters, both controlled in PWM mode with a low switching frequency. This allows a fast adjustment of both active and reactive power and a 4-quadrant (P,Q) operation. The analysis has been carried out by using EMTP (Electromagnetic Transient Program) simulation results. The comparison criteria between both topologies has been based on the following considerations: AC current line harmonics, minimum GTO on-time, superconducting coil voltage ripple, active and reactive power capabilities and transient response. Based on the results of this paper a 500 kW power converter is being constructed as a part of a 1 MJ SMES system to carry out experimental studies in network stabilization. The PWM strategy has been implemented in the converters by means of a very fast DSP, in order to compute on-line the switching angles for any modulation index. |
