Patent ID: 8095326

Claim:
A method to predict a state of a power system with a computing device, comprising the steps of using the computing device to perform a Fast Fourier Transform on measured samples of a periodic waveform signal in order for the computing device to determine a frequency spectrum of the periodic waveform signal, where the computing device derives the periodic waveform signal from at least one measurable electric quantity of the power system and is representative of the state of the power system, the computing device performing the following steps: determining frequencies and related complex amplitudes at selected peaks in the frequency spectrum and storing the frequencies and amplitudes together with a time stamp in a storage device connected to the computing device, determining and storing one or more predicted values of the periodic waveform signal (φ) in the time domain at one or more prediction times by calculating a sum of sinusoidal signals at the corresponding prediction times, each of the sinusoidal signals based on one of the determined frequencies and its related complex amplitude and the time stamp, comparing each of the one or more predicted values with a measured value derived from a measurement of the at least one electric quantity of the power system, where the one or more prediction times each equal to a point in time when the corresponding measurement was taken, and generating a notification based on a change in the state of the power system if a select number of differences between the one or more predicted values and the corresponding measured values each exceed a predetermined limit.