32.4 : 输电线路:暂态运行

Electrical signals on a line face resistance and conductance, causing attenuation.

In a single-phase two-wire circuit, incorporating constant series resistance and shunt conductance alters the voltage and current equations, which can be solved using the Laplace transform and propagation constant.

For distortionless lines, where the ratio of resistance to inductance equals the ratio of conductance to capacitance, the equations are rewritten using delta and sigma, describing forward and backward traveling waves with consistent attenuation.

For sinusoidal steady-state waves, the propagation constant is revised.

Lossless lines, with zero resistance and conductance, experience no attenuation, allowing waves to travel at constant speed.

Power losses occur due to circuit resistance and conductance.

Resistance causes losses due to current flow, while conductance losses are linked to voltage across conductors, primarily from insulator leakage, corona effects, and dielectric losses in cables.

Overvoltage results from lightning, switching surges, or power frequency overvoltage, exceeding the circuit's voltage limit.