| Popis: |
This thesis addresses the problem of calculating and utilizing the voltage and current transients that may occur in underground residential distribution (URD) systems. A computational model for such systems is proposed and evaluated by comparisons to experimental results. The propagation characteristics of standard URD cables are complex but central to the computational model. The specific objective of this study was to determine whether a relatively simple approximation for the cable propagation constant is accurate enough that, when incorporated into the computational model for the transients resulting from a fault in the system, the resulting fault transient can be utilized to locate the fault. The conclusion is that over a frequency range of approximately 0.1 to 10 MHz, the computational model does provide a useful description of the transients. The approximation for the cable propagation constant does seem to provide adequate information about the variation with frequency of the phase constant and the attenuation constant when plausible ad hoc values of the parameters are included. The computational model is simple and quick to evaluate. It is based on standard lattice diagram analysis of the multiple reflections in the system. The model provides an approximation to the impulse response of the system, when the impulse is applied at various positions in the system. |
