Flexible Unbalanced Compensation of Three-Phase Distribution System Using Single-Phase Distributed Generation Inverters

In this paper, flexible compensation of negative and zero sequences current in three-phase distribution power system by using single-phase distributed generations (DGs) smart inverters is proposed. In the proposed control strategy, power factors of the DGs are controlled without modifying the active powers production. The instantaneous power analysis from single-phase perspective is developed and used to achieve the objective function for negative and zero sequences current compensation. In the proposed strategy, voltage regulation of three phases and available reactive powers of the single-phase DGs are considered as constraints of compensation problem. The developed objective function subjected to the constraints is minimized on-line by using Karush-Kuhn-Tucker optimization method. After determining the required reactive power in each phase, this power demand is shared among DGs in that phase based on their available power ratings. In this paper, comprehensive studies on the effects of voltages regulation and DGs available reactive power ratings on the proposed control strategy are conducted. An IEEE 13-node test system with seven integrated single-phase DGs has been adopted for case studies.