Four-leg Voltage Source Inverter for Voltage and Current Balancing of Distribution Transformer with Distributed Generations

This paper is dealing with innovative control strategy of a four-leg voltage source inverter (FLVSI) which is implemented in unbalanced condition. The proposed method is aimed to maintain the balancing of voltage and current distribution system due to unbalance capacity of DG connection and unbalanced load. These unbalance condition can affect the transformer performance which is essentially designed to supply a balanced voltage. For solving the problem, the unbalance voltage and current transformer signals are decomposed to its symmetrical components: positive, negative, and zero sequence. Each results of the decomposition are transformed into a synchronous reference frame (dq coordinate) and controlled by ANFIS controller. Based on the simulation results with Matlab/Simulink, current unbalance of transformer is decreased from 48.44% to 15.15% and voltage unbalance is decreased from 5.09% to 2.46%.