Low-voltage Compensation of Distribution Networks Based on A Hybrid UPQC with Single and Three-phase Converters

For remote distribution networks, low voltage is prevalent, which seriously affects the normal use of electricity. Aiming at solving the voltage sag/dip problems in 10.5 kV distribution networks, a hybrid UPQC with a shunt single-phase rectifier and a series three-phase inverter is proposed in this paper. The shunt single-phase rectifier is connected to the feeder lines with the highest and lowest voltage phases to supply enough energy to the series inverter, and the three-phase inverter compensates the voltage deviation by injecting active power through a series transformer, such that the voltage sag/dip problems can be mitigated. The control strategies of the two converters are designed in detail in this paper. Compared with the traditional UPQC with two three-phase converters, the proposed method has the advantage of simpler control methods and lower cost. Finally, the proposed method is verified through MATLAB/Simulink model.