INVERTER BASED DISTRIBUTED GENERATION PROTECTION SCHEME USING BRIDGE TYPE FAULT CURRENT LIMITER

Abstract

Power systems are becoming more vulnerable to different faults due to high penetration of various renewable energy based distributed generators known as inverter based distributed generator (IBDG). It has become a great challenge to keep the system stable and to keep the fault current at a manageable range during a short circuit fault. High fault current insists system designer to install high rated protection equipments which increases the overall cost of the system. While connecting an IBDG system to the grid, it’s protection scheme must be considered because of this fault current problem. In this work, a bridge type fault current limiter (BFCL) with a proper control of the whole system has been proposed as a solution to the high fault current problems of IBDG systems. The BFCL is connected to the AC side of IBDG system and a proper controller is designed and implemented to control the reactance of BFCL. Voltage at point of common coupling (PCC) is used as input to the BFCL activation controller. Outer controller loop is proposed to control the DC link voltage of IBDG whereas an inner current controller is designed to control the power exchange between AC and DC side of IBDG. Both the balanced and unbalanced faults are applied in the AC side of the IBDG system to demonstrate the effectiveness of the proposed controller. Finally the proposed strategy is compared with series dynamic braking resistor (SDBR) and conventional method to see the effectiveness of the proposed strategy.