DETECTING POWER GRID SYNCHRONIZATION FAILURE ON SENSING OUT OF RANGE FREQUENCY OR VOLTAGE

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This paper presents the development of a microcontroller based islanding detection for grid connected inverter with very simple under/over voltage and under/over frequency islanding detection algorithms. The system is based on a microcontroller from Atmel 8051 family. The microcontroller monitors the under/over voltage and under/over frequency from utility grid and the processed value of voltage and frequency for turning ON/OFF the relay between a grid connected inverter and the utility grid. The project would alternatively use a variable frequency generator using 555timer for changing the frequency while a standard variac shall be used to vary the input voltage for achieving the test conditions as stated above.