Paper Title
Flexible D-STATCOM to Mitigate Voltage Sags Under Unbalanced Faults and Islanded Fault Condition

This paper proposes a flexible D-STATCOM (Distribution Static Compensator) and its new controller system, that be able to mitigate both unbalanced faults and fault under islanded condition and operate as a Distribution Generator (DG), when it supplies power to sensitive loads while the main utility source is disconnected (i.e., it is under islanded operating condition). Thus D-STATCOM operates same as flexible DG (FDG) and consequently, it is called Flexible DSTATCOM (FDSTATCOM). In this paper, the 12-pulse FD-STATCOM configuration with IGBT is designed and the graphic based models of the FD-STATCOM are developed using the MATLAB/ Simulink program. The performance of FD-STATCOM is to mitigate voltage sag problems and to improve distribution system performance under unbalance faults such as L-L & D-L-G faults and supplies power to sensitive loads under islanding condition. The reliability and robustness of the control schemes in the system response to the voltage disturbances caused by faults under islanded operating condition are obviously proved in the simulation results. Keywords— FD-STATCOM, Voltage Sags, Islanding Condition, Test System.