Modeling of islanding detection by sensing jump change of harmonic voltage at PCC by the combination of a narrow band-pass filter and wavelet analysis

This paper presents a full code-based implementation of islanding detection using a narrow band-pass filter together with a wavelet filter in Simulink environment. Topology of local distribution generation is modeled by a grid-tied inverter with LCL filter. Proportional resonant controller is adopted to control the inverter. Narrow band-pass filter has been designed to effectively extract fundamental component of all signals. Islanding occurrence has been simulated by the opening of a breaker and its detection has been implemented by two methods, one being based on detecting specific harmonic voltage change at the point of common coupling before and after islanding by using a narrow band pass filter, and the other being based on a wavelet filter which detects a jump change of a band of harmonic voltage. All of these are implemented using code in Simulink environment. The advantage and disadvantages of these two methods are compared. It is found that the wavelet is more capable of producing more consistent results after islanding occurrence but it may cause mal-operation at start-up. By combining the narrow-band pass filtering and wavelet approaches, one can reach error-free islanding detection and protection.