An Integrated Multifunctional Soft Open Point with Switch Multiplexing for Low Voltage Distribution Networks

This paper presents an integrated three-phase AC-DC-AC topology with reduced active switch count, designed as a multifunctional soft open point (SOP) for low voltage distribution networks. The proposed topology enables voltage regulation, power flow control and power quality improvement, thereby enhancing the flexibility of low voltage distribution networks. The topology contains a single-stage AC-DC converter and three floating modules. The single-stage AC-DC converter integrates a shunt active front end (AFE) and resonant DC-DC converters for three phases into one stage. This single-stage AC-DC converter performs the low-frequency grid-current exchange and generates the high-frequency pulsating voltage for the compact transformer of the isolation stage. The frequency-selective integration reduces the switch count for a more compacted design. The series floating modules are directly inserted into the grid lines, where they can inject a voltage along the lines. Due to the low impedance of the grid, the series modules can exclusively use low-voltage components.