Análise das características de propagação e de transitórios eletromagnéticos em cabos subterrâneos instalados em tubos não metálicos no contexto de parques eólicos

Abstract

The construction of wind farms has grown significantly in recent years, becoming a promising source of renewable energy in the global energy transition scenario. In this context, different cable configurations are employed both for transmitting the generated energy and for interconnecting the grounding systems of adjacent wind turbines, as well as for the equipotentialization of the wind farms, with the aim to mitigate lightning overvoltages and their impacts. For these purposes, underground cables have been widely used, in configurations that involve directly buried cables and pipe-type cables, often made of non-metallic materials. For the latter configuration, there is no analytical formulation in the literature for calculation of impedance and admittance parameters. Accordingly, this study proposes a hybrid methodology combining closed-form expressions and the finite element method to characterize typical cable arrangements in wind farms. Four configurations are evaluated, involving medium-voltage cables directly buried and cables placed within high-density polyethylene pipes, as well as their variations that include a grounding conductor directly buried or within the pipes. These configurations are assessed in terms of their propagation characteristics in the modal domain and their transient response. Results indicate that pipe-type configurations generally have lower attenuation and higher propagation velocities of voltage and current waves, leading to transient responses with higher overvoltage magnitudes compared to directly buried cables configurations. This behavior highlights the importance of accurately modeling the cable configurations to properly assess the impact of lightning overvoltages on wind farm networks and wind turbine grounding systems.