Algorithm of MICA for analyzing harmonics in power system

Taking the rectangular window as an example, the summation in the expression of discrete Fourier transform (DFT) is solved out by the integral operation. The obtained expression is used to interpret directly the long-range leakage and short-range leakage effects in the spectrum analysis under the asynchronous sampling. Being different from applying the window with better spectrum characteristic to reduce the long-range leakage, a new method, named multi-spectrum-line interpolation correction algorithm (MICA), is presented to correct both kinds of leakage. Under the conditions that the long-range leakage effect is neglected or considered, the differences between MICA and the existing windowed interpolation algorithm are analyzed, which indicates the existing algorithm is a special case of MICA and MICA has a wider application. Using three different kinds of algorithm to calculate the parameters of a signal with inter-harmonic, the simulation results show that the accuracy of MICA is very high. For the signal with Gaussian noise, MICA has a good anti-interference capacity.