Indirect Front-End Smart Transformer with Reactive Power Management

摘要

Smart Transformers (STs) are an application of Solid-State Transformers (SSTs) which, among others, feature voltage regulation through reactive power flow control. Several topologies, including Direct Solid-State Transformers have been reported. These configurations show a reduced number of conversion stages, however, are limited for reactive power control. A transcendental characteristic that STs present is the Medium Voltage (MV)-side reactive power control which can lead to control the MV profile. For this reason, in this paper, an Indirect Front-end smart transformer with reactive power management is presented. A control scheme is proposed, considering the PQ Theory and a Power Factor (PF) correction scheme. The proposal permits to define the desired PF and then generate a current reference to handle the reactive power at the MV-side for a Dual-Active-Bridge (DAB) converter in a smart transformer application; this allows the converter to maintain the Low Voltage (LV) side output regulated while modifying the ac input current waveform at MV-side. A simulation is presented to corroborate the proposal.