An anti-islanding method for voltage controlled VSI

Islanding detection methods have been widely applied and thought for current-controlled voltage source inverters, as in case of photovoltaic inverters. However, some considerations have to be taken into account when anti-islanding detection strategies are applied on voltage controlled-voltage source inverters, for example in case of using AC droop control. This paper shows different issues when anti-islanding algorithms based on the voltage and frequency displacements are used in voltage-controlled inverters. The impedance measurement of the point of common coupling is presented as a mechanism to achieve the islanding detection. An anti-islanding method for voltage-controlled voltage source inverters is proposed, and the suitable frequencies to be used are analysed. The concept of frequency detection band is defined allowing the impedance measurement to improve its behaviour towards resonant and non-resonant loads.