6. Conclusion

To complete this article devoted to elements of line theory, it seems worthwhile to conclude with four academic problems that extend and deepen the scope of the preceding formalisms.

The first problem concerns the treatment of transmission lines connected to loads with non-linear behavior. It should be noted that the difficult question of non-linear operation can be elucidated fairly well by calculating the currents and voltages developed on a line loaded by a diode or by a resistor varying cyclically over time. In the first configuration, we try to evaluate the resonance conditions of the line subjected to harmonic signals. In the second, we investigate the current and voltage spectrum of the line supplied by a DC voltage source. This apparently simple academic problem is related to the electromagnetic disturbances produced by energy converters on power grids....