Abstract: Due to its high power, the grid accessing of large Emergency Power Supply (EPS) would cause the fluctuation and flicker of the voltage, which have to be detected and controlled. This paper analyzed and compared some current detection algorithms and proposed a new algorithm for detecting voltage wave elimination of matrix type. In MATLAB, the newly proposed algorithm is analyzed through simulation. The simulation result shows that this algorithm can effectively detect the voltage fluctuation and flicker. It gets rid of not only the filter in traditional algorithm but also the influence of direct current component and doubling frequency component. The superiority of this algorithm can be better embodied when it is applied in multi-frequency signals. The calculation of this new algorithm is simple and fast. The final data is relatively fewer and can be easily realized in DSP, which greatly and effectively improves the real-time detection of large EPS voltage wave.