Simulation Study of the Consequences of Electromagnetic Waves on High-Voltage AC Power Transmissin Lines Using Numerical Methods

When alternating current power transmission lines exceed a certain length, the electrical parameters become highly dependent on distance and frequency. Under these conditions, the lines behave like electromagnetic waveguides, generating significant capacitive and inductive effects. The propagation of these waves leads to phenomena such as no-load overvoltages Ferranti effect, reactive power losses, harmonic currents in the neutral conductor, transformer saturation, and nuisance tripping of protection systems. These disturbances can also affect electronic control circuits and, to a lesser extent, pose health risks to workers exposed to intense electromagnetic fields, this aspect is considered outside the scope of the analysis of this article. Controlling these phenomena is crucial for maintaining the quality and stability of the transmitted power, which poses a significant challenge for modern electrical grids. The objective of this work is to simulate and study the consequences of electromagnetic wave propagation in a long-distance, high-voltage alternating current transmission line and to propose strategies for reducing no-load overvoltages. To this end, two complementary approaches are investigated, an analytical approach based on classical telegraph equations, derived from Maxwell’s equations, and a numerical approach based on the FDTD method, widely used to solve nonlinear transient phenomena. The long-distance, high-voltage AC transmission line was modelled by an equivalent passive two-port network, while Kirchhoff’s laws and Ohm’s law were used to optimise the representation of disturbances. The distributed insertion of series capacitors and shunt inductors was also studied as a solution for reducing capacitive current. The two-dimensional simulations performed show that the analytical and numerical approaches used provide consistent and satisfactory results, allowing for a better understanding and prediction of the occurrence of overvoltages over long distances.