Improvised Power Quality in a Solid State Transformer for Sharing Comprehensive Load using Soft Computing Techniques

Solid State Transformers are power electronic devices based intelligent transformer systems. They operate at very high frequency. For the same power rating, compared to the conventional transformers, these SSTs are smaller in size, as they operate at this high frequency level. SSTs are realized as single stage, dual stage and three stage topologies. In this research work, three stage topology is considered for analysis. The three stages of STT include an input stage with AC to DC conversion, intermediate stage with DC to DC converter as Dual Active Bridge (DAB) and an inverter at the output stage with DC to AC conversion. Conventional three stage SST suffer from drawbacks viz. reduced power factor and increased THD levels. To overcome these drawbacks a modified three stage SST with dual secondary winding has been suggested The simulation model of the proposed modified three stage DAB SST has been developed and simulated for various load conditions. Simulation studies have been carried out to study the bidirectional power flow capability of the proposed scheme of interest. These proposed SST systems are designed based on fuzzy logic and ANN techniques. The fuzzy SST system utilizes voltage error and change in voltage error and produced the desired change in switching frequency of the input inverter of DAB. The ANN system utilizes only the voltage error and produces the desired change in frequency. However, these systems found to produce over compensation.