抄録
The present paper proposes a method for analyzing lightning surge overvoltages at a substation using steady-state solution. A lightning current is assumed to be periodic so that it is represented by Fourier series. Then, the frequency responses of the line and substation impedances seeing from the substation entrance and of the steady-state solution of the open-end line voltage when the substation is deleted are obtained easily. The steady-state voltage at the substation entrance is evaluated from the above frequency responses applying Thevenen's theorem. The transient voltage is given as the sum of Fourier series of the steady-state voltage. The calculated results of lightning surge overvoltages by the proposed method agree reasonably with the transient solutions calculated by the EMTP, and the computation time and memory are far smaller.
For the proposed method evaluates a lightning surge overvoltage only by a steady-state solution, the method has an advantage to be able to estimate easily the effect of circuit parameters of a substation applying an alternating current theory. Therefore, the method might be quite useful to study the relation between bus length and an overvoltage generated, estimation of an optimum position of arrester installation, and so on.
