Fast Fitting Of Power System Fault Signals Based On Prony's Method

It is especially important to extract the useful steady component and transient ones from the fault signal fast and exactly for protection principle development and enhancement of the relay action speed and reliability. But the fundamental component of the fault signal can't be obtained in one cycle (20 ms) using the conventional algorithms such as the Fourier Algorithm and the Least Squares Algorithm, which needs to filter the aperiodic components and high frequency transient components. As a consequently, the relay equipment can't behave reliable in one cycle during the actual application. In this paper, Prony's method is applied to the fault signal's analysis and processing, the fault signal is presented using a linear combination of fundamental component, some exponentially damped aperiodic components and high-frequency ones. The aim of the study is to exact the fundamental component and transient signal exactly using the half-cycle fault signal, in order to reduce the time of the relay behavior.According to the relevant references the reason and features of the fault quantities are described, the development and present situation of protection algorithms are surveyed and the inherent drawbacks of the prior algorithms. And consequently, Prony's method is introduced. The principles, application method, fitting indexes of Prony's method are discussed in detail. The parameters of the fitting order, the window length of the data and the sample interval are analyzed in detail, as long as the selection reasonability of these parameters. The influence of the noise and nonlinear of the parameter to Prony's method is discussed. An integral power system is built using simulation tool EMTP-ATP. Both the theoretical analysis and simulation results show that the steady and transient components can be extracted effectively in the half cycle after fault using the Prony's method.In this paper, a new method of extracting fault characteristics using Prony's method which is suitable for the transient signals analysis is provided. Both the theoretical analysis and simulation results show that the method has satisfactory reliability and effectiveness. The study fruits have important theory significance and practical values in the study domain of microprocessor based protections. Since the computation is complex, it is difficult to finish in half a cycle after the fault occurrence in actual application. It is needed to improve the prony's method and reduce the computation, so the relay equipment could behave in half a cycle reliable in actual application.