Methods based on both time (t)-domain and frequency (f)-domain have been used for electromagnetic transient (EMT) analysis using both circuit-theory and field-theory approaches. Methods based on circuit theory are fast and convenient but may become inapplicable to many engineering problems due to simplifications such as the transverse electromagnetic assumptions. Moreover, t-domain-based techniques rely on approximate methods to account for frequency dependence, which is an essential characteristic of electric conductors, equipment and soil environment. In this paper, f-domain solutions obtained from the method of moments (MoM) discretization of the electric field integral equation (EFIE) are converted to t-domain using the numerical Laplace transform (NLT) by means of post-processing. This circumvents the need to formulate the EFIE and MoM based on the complex frequency which would be required for their application to conventional NLT. Hence, existing MoM implementations can be used to perform a full-wave 3-D EMT analysis for a wide range of power system applications. Examples include energizations of 3-D power system networks with fast and non-vanishing excitations such as step functions, as well as modeling non-linear elements using the piecewise linear approximation. Results from experimental measurements, finite-difference t-domain method, and EMT-type software confirm the validity of the proposed method for power system transients in the range of microseconds down to nanoseconds.

Published in: IEEE Transactions on Power Delivery

Power stations have a very complex electromagnetic environment. The situation is typically worse in an HVDC converter station, because the electromagnetic field (EMF) levels are more severe in proximity to HVDC equipment. Therefore, it is very important to address electromagnetic compatibility (EMC) issues and compliance in the design and operation of HVDC converter stations. This article analyses and discusses in detail HVDC convertor station EMC concerns by focusing on three aspects of the overall design process: analysis method, computer model simulation and EMF calculation. The main purpose of this work is to evaluate the impact of the HVDC station electromagnetic environment on personnel safety and specific equipment by examining the electromagnetic field of the entire converter station under various operating conditions. The analysis methods and procedures introduced in this article can provide guidance and reference for similar EMC analysis and design of offshore and onshore AC/DC converter stations.

Published in: 2021 4th International Conference on Energy, Electrical and Power Engineering (CEEPE)

Improvement of transmission line tower grounding is of particular importance for the line service quality. The tower transient impedance is a key parameter for the prediction and estimation of transmission line performance under abnormal conditions including lightning strikes. In this paper we compare the impulse impedance to the low frequency resistance of the tower by evaluating their respective effects on back-flashovers estimation. Based on real-case scenarios of grounding system configurations the critical current is computed and analysed to estimate the gain in the tower-footing grounding system design.

Published in: 2021 35th International Conference on Lightning Protection (ICLP) and XVI International Symposium on Lightning Protection (SIPDA)

Analysis of transmission lines backflashovers is of particular importance for the service quality. The tower surge impedance is a key parameter for the prediction and estimation of backflashovers. In this paper we introduce a new multi-region soil model to take into account soil model variations along a transmission line while using a global full-wave modelling approach. This new capability focuses on the transient behavior of the whole system to assess backflashover occurrences along the transmission line.

Published in: 2021 35th International Conference on Lightning Protection (ICLP) and XVI International Symposium on Lightning Protection (SIPDA)