Wide-band Fractional Modeling Of Cable And Application Research

As a major power transmission equipment, power cable is second only to overhead line. In recent years, China has seen a rapid growth of its power industry. Under this kind of situation, ultra high voltage(UHV) and extra high voltage(EHV) transmission projects, long distance transmission projects and submarine cable projects are all calling for a further study on power cable. So establishing an accurate cable model is of great significance to the practical application, mornitoring and failure of power cable. This paper focuses on single core coaxial cable. A new wide-band fractional model of cable is aroused considering the transient overvoltage in power system and the fractional characteristics of cable with skin effect. In this paper, the calculation method of cable impedance matrix is improved, so that the complicated impedance calculation formula on complex frequency domain can be transferred into time domain differential equations with inverse Laplace transform, when fractional characteristic can be reflected as well. The accuracy of the matrix parameters can meet the demands of engineering. Weighted residual method has the highest accuracy among finite element methods; fractional order calculation involves the quantities of the whole time interval, and matrix method can be an ideal tool. Taking advantage of which, the cable equations can be discretized with weighted residual method spacially and matrix method temporally. Then the time domain model of cable can be achieved.