Validation of a Constant DC-Capacitor Voltage Control Strategy for a Four-Leg Active Power-Line Conditioner: A Simulation and Experimental Study

This study demonstrates that a proportional-integral (PI) controller in the constant DC-capacitor voltage control (CDCVC) block of a four-leg active power-line conditioner (APLC) in three-phase four-wire distribution feeders (TPFWDFs) accurately calculates the root-mean-square (RMS) value of the fundamental active currents in the feeder currents, using simulation and experimental results. The accuracy of the RMS value calculated by the PI controller in the CDCVC block is crucial because the reference signals for the source currents are calculated using the RMS value calculated in a previously proposed CDCVC-based strategy for the four-leg APLC in TPFWDFs. In this study, the previously proposed CDCVC-based strategy is modified by adding an algorithm for calculating the fundamental active currents in the feeder currents. The basic principle of the modified CDCVC-based strategy is discussed in detail and confirmed by digital computer simulations using a power electronics simulator (PSIM). A scaled-down experimental set-up is developed and examined. The simulation and experimental results demonstrate that the PI controller in the CDCVC block of the four-leg APLC accurately calculates the RMS value of the fundamental active currents in the load currents. Therefore, it is concluded that the previously proposed CDCVC-based strategy for a four-leg APLC is applicable to the four-leg APLCs in practical TPFWDFs.