Control Strategy for a Four-Wire T-Type qZSI based PV System to Support Grids with Unbalanced Non-Linear Loads

The existence of a high number of prosumers (producers and consumers) can affect positively the distribution grids through ancillary services. Usually prosumers use the generated energy from single and three-phase PV systems. However, since low voltage grids are normally affected by unbalanced loads, the use of a four-leg converter connected to a PV system can improve the power quality in these grids. Thus, this work will present a study in which a multilevel T-Type qZS-based PV system is used to support the grid with unbalanced non-linear loads. A control strategy able to deal with different conditions, such as, the existence of reactive power and/or harmonics in the grid is also proposed. To analyze the impact of the proposed system several simulation tests are presented. The results show a positive impact on the grid regarding this system.