An effective passive islanding detection method for PV single-phase grid-connected inverter

• Low cost passive islanding is developed for single phase grid connected inverter.
• Drastically improved disconnection time in the proposed method for single phase inverter.
• Low cost, effective and minimal of external components are the forte for this method.
• Effectively detect islanding for different loads, inverter output powers and quality factors.

This paper presented a low cost and effective passive islanding detection method for single-phase photovoltaic grid-connected inverters. An analog circuit for over/under voltage protection is developed to ensure fast detection and no delay to system. An under/over frequency circuit is also developed, for accurate and fast frequency detection with minimal external components. A new algorithm is developed in a low-cost PIC18F4550. An improved disconnection time in the proposed method compared with that in the previously developed method is an attractive solution for single phase grid connected inverters. The low cost, effective and minimal external component count are the advantages. A prototype is developed and tested to demonstrate the performance and feasibility of the proposed method. The experiment results verified that the proposed islanding detection method able to detect islanding operation effectively under various load types, inverter output powers and quality factors.