DEVICE AND METHOD FOR DETECTING ISLANDING OF DISTRIBUTED GENERATION SYSTEM INTERCONNECTED WITH UTILITY GRID

摘要

independently from the operation detecting device of the grid-connected power distribution system according to an embodiment of the present invention is a distributed power receives the voltage and current to the first input signal, receives the input voltage and current from the power system to the second input signal, a fast Fourier transform (FFT for each of said first input signal and the second input signal: Fast fast Fourier transform unit performs a Fourier Transform) to output the first and second harmonic frequency components; Harmonic extraction unit extracting harmonic components by removing the pure switching frequency components and the fundamental frequency component from each of the first and second harmonic frequency components; Equation of state for creating a virtual operating section of the grid voltage component to configure the state equation using the extracted harmonic components; Any time for extracting the power spectrum density by calculating the correlation time of the virtual grid voltage component; Detecting the maximum value of the power spectral density compared with the predetermined threshold value (Threshold Level) and, if the comparison is less than the reference value the maximum value, the dispersion comprises a peak power detection unit for recognition to be the islanding state. ;