Calculation of Lightning-Induced Voltages and Currents on the Transformers Courtyard of Tucurui Hydroelectric Generation Plant Using the Finite-Difference Time-Domain Method

In this work, voltages and currents induced due to lightning occurrence on the transformers' courtyard of Tucurui hydroelectric generation plant are calculated by employing the Finite-Difference Time-Domain method. The transient functions are obtained for 500 kV-transmission lines at the output of the power plant. In order to the simulations become viable from the computational point of view, it was necessary to use parallel processing for dividing the analysis region into 24 subdomains (24 computer cores were used). The simulated problem in this work consists on an 1 kA-lightning stroke on phase A of the output transmission system of the Tucurui's plant. In this work, induced voltages between the phase A of the line and the following reference points were obtained: a) the courtyard grounding mesh for voltage transformers, b) ground grid in the first floor concrete, c) rock (basalt) surface at the base of the plant, d) the soil's layer and water surfaces. Transient voltages induced between the phases A, B and V of the transmission line are also analyzed. These data are important because the electrical system is based on voltage differences between phases. It is also noticed that, in this case, the maximum induced voltage between phases A and B is approximately 157.9 kV/kA. It is also performed a study regarding voltage supportability for line insulators on the structure.