A composite fitting algorithm based on Sine function and a polynomial

Sine function is often used to fit the alternating current or voltage signal. However, affected by the physical characteristics of practical systems, there is always distinct difference between the waveform of a practical signal and that of a standard Sine function, which will bring a great fitting error. A composite fitting algorithm based on Sine function and a polynomial has been proposed. Sine function is used to fit the sinusoidal component of a practical signal. A polynomial is used to fit the other component. This will greatly reduce the fitting error. The proposed algorithm has been used to fit a practical alternating current signal. The results showed that the proposed algorithm can accurately fit the signal. The fitting error is less than that achieved by fitting with a Sine function merely. In addition, the algorithm is simple, rapid, and robust.