Modified travelling-wave techniques to solve electrical transients on lumped and distributed constant circuits. Refraction-coefficient method

The paper describes a newly developed travelling-wave technique, the `refraction-coefficient method¿, to solve electrical transients on complicated lumped constant circuits connected to distributed lines. Travelling waves on distributed constants are calculated with the ordinary refraction coefficients, and travelling waves on lumped constants are dealt with by the modified refraction coefficients of the new method. The new method makes it possible to solve complicated lumped constant circuits, which have been regarded as almost impossible to handle by the travelling-wave technique. Typical applications are shown for overvoltages due to a lightning stroke on a line connected to a complicated lumped constant circuit, and for switching surges due to energisation of a line, followed by a line fault and de-energisation. As is illustrated by the applications, the computation time needed by the new technique is considerably less than that required by the existing methods, and the accuracy is also very high.