Implementation of Anti-Islanding Scheme for Grid Connected Inverter using ATmega328

Abstract

The phenomenon of unintentional islanding due to the distributed generation resources is undesirable. It has potential safety hazards to the utility workers; may damage the DGs, power supply utilities and the consumer load. An anti-islanding scheme which detects the islanding and clears it within 2 seconds is to be developed. This scheme is developed for single phase grid connected inverter. The converter topology has been proposed for the anti-islanding scheme which is to be simulated and later comparing with the hardware results.

An anti-islanding scheme to be developed has to meet the established IEEE standard 1547-2003 and 929-2000, set for the inter connection of distributed resources with the electrical power system. The proposed scheme uses an active method and maintains high power quality by using a combination of periodic current magnitude and AFD (active frequency drift) method. The proposed scheme also maintains lower THD of output current. The scheme is developed and simulated in PSIM software with the parameters for the circuit decided and designed accordingly.

The proposed scheme has to be implemented and fabricated in hardware by modelling the H-bridge inverter using MOSFETs. The gate driver circuit has to be prepared by using microcontroller ATmega328 for the SPWM of the inverter. The proposed anti-islanding scheme is also to be implemented by using ATmega328. The algorithm is to be developed for a single phase inverter using ATmega328 and real time tests are to be carried out.