Study Of Fault Analysis Algorithm In Power System Based On Phase Component

The fault analysis method of power system has been the interesting field of study for years, and it plays an important role in design of power system, fault analysis, and the setting and switching analysis of power system relays. During the 100 years' development of power system the symmetrical components method and the phase components method were proposed. And now they are the two basic methods in power system fault analysis.Definitely the symmetrical components is wildly used now, however, there are also many papers about the phase components method. The phase components are external existing compared with the symmetrical component. So the method based on phase components is able to represent the true system exactly and is more understandable.The traditional fault analysis method based on symmetrical components is not suited for analyzing the power system with unsymmetrical parameters. This paper proposes a new algorithm, which is suitable for the analysis of various complex faults in both balanced and unbalanced electrical power system. First, an equation is developed on the base of phase components and multi-port network theory and the relation between the elements in the multi-port impedance matrix and the multi-port node impedances is developed according to the physical meaning. Then, an equation of the general fault boundary condition is developed on the base of general form of faults. Finally, a mathematical model is developed with the aforesaid two equations that can be used to analyze all kinds of simple faults and complicated faults, including faults with various fault impedances. The effectiveness of the proposed method has been verified by using simulation studies and by comparing the results with those obtained from the EMTP simulation. In summary, the proposed method is a general-purpose and flexible method for analyzing the faulted power system with unsymmetrical parameters.The method based on phase components needs much more calculation than the symmetrical components method. So in this paper the power system admittance matrix is transformed by the matrix transformation to make the traditional phase components more efficient and the impedance matrix is presented as the inverse of the transformed admittance matrix. And then the multi-port theory and the relation between the elements in the multi-port impedance matrix and the multi-port node impedances is developed.Along with the development of the power system, the double-circuit lines become more and more common. And the system with double-circuit lines is mostly unsymmetrical. This paper studies the double-circuit lines and uses the phase components method to analyze the double-circuit lines.When analyzing the double-circuit lines the mutually coupled lines would have independent sources at one or two ends respectively. To fit for every topologies of double-circuit lines the two buses on each end are looked as two three-phase nodes respectively when the system node impedance equation is made, while they are looked as a six-phase node when the multi-port is made. On double-circuit lines the relation between the elements in the six-phase multi-port impedance matrix and the six-phase multi-port node impedances is developed. Then a common mathematical model for computer is developed with boundary equations that can be used to analyze all kinds of faults on double-circuit lines. The effectiveness of the proposed method has been verified by using simulation studies and by comparing the results with those obtained from the EMTP simulation. In summary, the proposed algorithm is a general-purpose and flexible method for analyzing the arbitrary complicated faults of inherently unbalanced power system.