Design and realization of a solid-state transformer for smart grids

Smart power distribution systems have emerged as potential solutions to fulfill the rising demand for energy in developed nations. Smart grids have become increasingly common, but this has led to a number of power quality problems, including distorted current and voltage harmonics, instantaneous voltage changes , failures, and isolation breakdowns. Solid-state transformers, commonly referred to as smart transformers, provide prospective solutions to enhance power quality in smart grids in order to deal with these issues. Numerous advantages are provided by these transformers, including increased grid dependability, greater energy economy, control over power flow, voltage management, bidirectional power flow, fault current limiting, harmonic blocking, and galvanic isolation. In this thesis, a solid-state transformer (SST) model with three level (AC-DC-DC-AC) and a power management scheme tailored for solar photovoltaic (PV) power plants connected with smart grids are presented. The isolated bidirectional converter, inverter, and rectifier in the suggested topology all have soft-switching components. This offers great efficiency, low electromagnetic interference (EMI), reduced conduction losses, zero-voltage switching for converters, and zero-current switching for electrical auxiliary systems, among other advantages. The thesis also describes the SST's operating tactics, such as voltage and current management between converters and pulse-width modulation (PWM) control. To create a solid-state transformer with a power of 10 kVA, a medium-voltage (MV) high-frequency transformer is used. The enhanced control technique enables SST to achieve an outstanding conversion efficiency of 96.7% despite the solar power plant's variable power generating conditions, according to experimental results. The transformer's ability to withstand a dv/dt ratio of 6.8 kV/us is confirmed by experimental findings at a load current of 344 Vac and 10.4 A. The suggested bidirectional smart transformer's dynamic and experimental findings show how well they work to mitigate power quality issues in photovoltaic integration-based smart power distribution systems.