Voltage unbalance treatment for distribution network with massively connected distributed generators

Large scale interconnection of single-phase distributed generation (DG) with utility distribution grid can cause current unbalances resulting in voltage unbalances. The methods of Newton-Raphson and Gauss-Seidel are generally used for power flow´s calculation. However, these methods are sometimes complex and their convergences may be long. The iterative process of Newton-Raphson method, using the admittances matrix is practically independent of bus bars number. The calculation´s time of Gauss-Seidel method increases almost proportionally with the bus bars. In addition, the calculation´s time of the Jacobien´s matrix and each iterative process are considerably long for the Newton-Raphson method. In this paper, a method based on the impedance order reduction and identification of the power flow´s direction is presented. Analytical and simulation studies were performed in order to validate the accuracy of the proposed method. For an application network model, the voltage unbalances are calculated. The results are compared with those of two commercial softwares.