Practical approaches and novel control schemes for a three-phase three-wire series-parallel compensated universal power quality conditioner

Three-phase three-wire series-parallel compensated universal power quality conditioner based on two voltage-source converters controlled separately by two digital signal processors is discussed at length. Different from those popular active power filters, the series voltage-source converter is controlled as a fundamental sinusoidal current source in phase with the utility, while the parallel voltage-source converter is controlled as a fundamental sinusoidal voltage source with constant voltage and constant frequency. These novel control schemes and some practical approaches are both verified by detailed experiment results. It is shown that the total harmonic distortion values of input current and output voltage are both less than 5% with almost unity input power factor, even in the case of distorted utility and feeding reactive and nonlinear loads.