Study Of Adaptive Algorithms And Transient Characteristic Quantities Algorithm Of Microprocessor Based Protections

Along with the deepening of study and the development of microprocessors, high speed data acquisition technique and digital dealing technique, it is a general trend that the transient signals are used by microprocessor based protections to realize high speed, none delay time or short delay time and adaptation of the protections' operation. In order to be suited for the trend, the algorithms of microprocessor based protections must be adjusted. Based on the above, the adaptive algorithm and the one of transient characteristic quantity are studied in the thesis.An adaptive window length algorithm based on the differential equation is presented in the thesis to improve the high frequency property of differential equation. The window length is adaptive to high frequency content of the transient signals after fault occurring. When high frequency content of the transient signals is high, this algorithm can acquire a long window length. Otherwise a short window length is obtained. The study fruits show that the presented algorithm not only possesses excellent performance, but also converge rapidly. It is suitable for EHV transmission line protections.The accurate algorithm of adapting to power swing, presented in this thesis, applies full-cycle Fourier algorithm and difference one as a digit filter, firstly calculates the frequency and then reckons at the corresponding frequency. Because the calculation of follows always the change of the system frequency and adapts to the process of power swing, the calculating result of is convergent and high accurate. Thus, the time of detecting three-phases short-circuit in the course of power swing is shorten when is used as an identifying element of power swing simultaneously with three-phases short-circuit fault. Simulation analysis proves the correctness and effectiveness of this algorithm.In this thesis, a new method of choosing phase-to-ground fault line in distribution networks using transient characteristic quantities is presented. Through constructing transient zero sequence currents' analysis signals and the wavelet packets transform of analysis signals, the transient characteristic quantities in suitable frequency band are extracted. According to the definite criterions to choosing the fault line. Both theoretical analysis and simulation results show that the method has satisfactory reliability and sensitivity.The study fruits of this thesis are possessed of breakthrough and creation in the adaptive algorithms and the transient characteristic quantity algorithm. These fruits have important theory significance and practical values in the study domain of microprocessor based protections.