Non-uniform lines – review of the theory and measured / simulation examples

• Published in: Electric power systems research 2020-11, Vol.188, p.106514, Article 106514
• Main Authors: Ametani, A., Yamamoto, K., Triruttanapiruk, N.
• Format: Article
• Language: English
• Subjects: Circuit protection; Circuits; Computation; Electric power lines; EMTP; FDTD; Finite difference time domain method; Frequency domain analysis; Homogeneous/non-homogeneous line; Measured result; Non-uniform line; Simulation; Wire
• ISSN: 0378-7796; 1873-2046
• DOI: 10.1016/j.epsr.2020.106514

•Existing theories of non-homogeneous lines and discussing problems are reviewed.•Characteristics of non-uniform lines are demonstrated based on measured and FDTD computed results.•The limit of a circuit-theory based approach (EMTP) to deal with non-uniform lines is reviewed based on measured results, FDTD and EMTP simulation results. This paper reviews existing theories dealing with non-uniform lines both in time domain and in frequency domain. Some papers discussed a non-homogeneous line composed of cascaded homogeneous lines. The theory in the papers neglected lead wires between the cascaded lines. This is mathematically permissible, but physically impossible and thus the theory result in an in-accurate or erroneous solution of the non-homogeneous line. The lead wires are non-uniform because the geometrical configuration at the sending end of the lead wires, i.e. the first homogeneous line, differs from that at the receiving end, i.e. the next homogeneous line. Measured results in time and frequency domains and FDTD computed results are demonstrated for the non-uniform line characteristics. Finally, approximate calculations by a circuit-theory based approach including EMTP are compared with the measured and FDTD computed results, and the limit of the circuit-theory approach is explained.