电缆线路中操作过电压主导频率的确定方法

Accuracy of cable parameters is very important for electromagnetic simulation research. To improve the consistency of the transient overvoltage in power cables simulated in EMTP with that in practice, the paper proposed a method for determination of the calculation frequency for cables. Firstly, equations for dominant frequency calculation of single-phase pure line and hybrid line were obtained based on distributed-parameter theory. By adjusting boundary conditions, the effect of source impedance could be considered. Then, according to eigenvalue transformation and Fortescue transformation, dominant modes of pure cable and hybrid cable-overhead line were determined. Further, by substituting the parameters of the dominant mode derived from the parameters in the phase domain, the relationship between the dominant frequency and the calculation frequency could be obtained. According to equivalence of these two kind of frequencies, the value of the calculation frequency could be determined. For cables and hybrid lines, simulation results revealed that the dominant frequency showed great agreement with the calculation frequency of parameters. Therefore, accuracy and feasibility of the proposed method were verified.