A Unified Power Flow Controller Using A Power Electronics Integrated Transformer

This paper investigates the Custom Power Active Transformer (CPAT)’s capability to provide UPFC services which includes power flow control, reactive power compensation, voltage regulation and harmonics elimination. CPAT is a power electronics integrated transformer which provides services to the grid through its auxiliary windings. The CPAT structure integrates three single-phase transformers into one shunt-series combining transformer. This integration empowers a sub-station with the capability of dynamically regulating the terminal voltage and current of a transformer through isolated power electronics converters. Simulations of the CPAT-UPFC with a stiff grid and a 5-bus power system demonstrates its functionality as an inter-bus coupling transformer that provides the required grid services. Moreover, the impact of the CPAT-UPFC during load perturbations on the power system is investigated to further validate its transient and steady-state response.