Per-unit Length Parameters Research Articles

Realistic modeling of the grounding system transient behavior with frequency dependence

For better protection of electrical networks, modeling the transient behavior of grounding systems is now fundamental before the realization step. In this work we propose a new modeling approach which permits a quick and efficient analysis of the grounding systems.In the proposed approach we solve the transmission lines equations using the Finites Differences (FD) taking into account the different electromagnetic couplings that occur during the spatial discretization of the grounding electrodes. To achieve this objective we complete the general transmission lines equations by introducing the coupling terms between the different parts of the grounding system and we calculate the self and mutual per-unit length parameters according to the geometrical position of the elements (cells). We therefore use rather the term non-uniform Transmission Lines (nuTL). This new modeling offers the advantages of calculating in a single step the currents and voltages at all the points of a grounding system, also taking into account the frequency dependence. Compared to already existing full-wave electromagnetic models our modeling is realistic because its numerical implementation is simple, retains good precision and the calculation times are much reduced.

MTL-Based Analysis to Distinguish High-Frequency Behavior of Interleaved Windings in Power Transformers

An elaborate method to analyze the high-frequency behavior of transformer windings by means of the multiconductor transmission line (MTL) method is presented. A procedure for the evaluation of per-unit length parameters for transformer windings (TWs) is enumerated, which is not available in existing literature on the subject. A full-length detailed solution of the MTL method for TW is also demonstrated. A comparison of this method with the conventional circuit approach is illustrated wherever necessary. The analysis of two types of commonly used interleaved windings is performed in this paper. It is also inferred from experimental results that a conventional low-voltage impulse test is insufficient to make a distinction between the two windings. As far as interwinding oscillations at high-frequency excitations are concerned, it also proved by the MTL analysis that one type is better than the other.

TRANSIENT RESPONSE CHARACTERIZATION OF THE HIGH-SPEED INTERCONNECTION RLCG-MODEL FOR THE SIGNAL INTEGRITY ANALYSIS

This paper is devoted on the characterization method of RF/digital PCB interconnections for the prediction of the high- speed signal transient responses. The introduced method is based on the use of the interconnection line RLCG-model. Theoretical formulae enabling the extraction of the electrical per-unit length parameters R, L, C and G in function of the interconnection line physical characteristics (width, length, metal conductivity, dielectric permittivity ...) are established. Then, by considering the second order approximation of the interconnection RLCG-model transfer matrix, the calculation process of the transient responses from the interconnection system transfer function is originally established. To demonstrate the relevance of the proposed model, microwave- digital interconnection structure comprised of millimetre microstrip line driven and loaded by logic gates which are respectively modelled by their input and output impedances was considered. Then, comparisons between the SPICE-computation results and those obtained from the proposed analytical model implemented in Matlab were made. As results, by considering a periodical square microwave-digital excitation signal with 2Gbits/s rate, transient responses which are very well- correlated to the SPICE-results and showing the degradation of the tested signal fldelity are observed. The numerical computations conflrm that the proposed modelling method enables also to evaluate accurately the transient signal parameters as the rise-/fall-times and the 50% propagation delay in very less computation time. For this reason, this analytical-numerical modelling method is potentially interesting for the analysis of the signal integrity which propagates

Modeling Issues and Performance Analysis of High-Speed Interconnects Based on a Bundle of SWCNT

The effects of the uncertainties associated with the transverse pattern of carbon nanotubes (CNTs) of the conducting type in a semiglobal interconnect based on a densely packed CNT bundle are investigated. The effectiveness of the insertion of a variable number of repeaters along the interconnect and the influence of the contact resistances between CNTs and external circuitry are also studied. The numerical computations are performed by using a multiconductor transmission line model in which the per-unit length parameters are accurately derived from a macroscopic fluidlike description of the conduction phenomena in CNTs.

An Engineering Model for Transient Analysis of Grounding System Under Lightning Strikes: Nonuniform Transmission-Line Approach

A nonuniform transmission line approach is adopted in this paper for modeling the transient behavior of different types of grounding systems under lightning strikes in time domain by solving Telegrapher's equations based on finite-difference time-domain (FDTD) technique. Electromagnetic couplings between different parts of the grounding wires are included using effective per-unit length parameters (l, c, and g), which are space and time dependent. The present model can predict both the effective length and the transient voltage of grounding electrodes accurately, while, an uniform transmission line approach with electrode length dependent per-unit length parameters fails to predict the same. Unlike the circuit theory approach , the present model is capable of predicting accurately the surge propagation delay in the large grounding system. The simulation results for buried horizontal wires and grounding grids based on the present model are in good agreement with that of the circuit and electromagnetic field approaches , . From an engineering point of view, the model presented in this paper is sufficiently accurate, time efficient, and easy to apply.

On Nonuniform Distributed ParameterZ-Y-KZNetworks

The physical shape of nonuniform distributed parameter (NUDP) Z—Y—KZ structure may be changed, if the patterns of variation of the per-unit-length (PUL) parameters of a given NUDP Z—Y—KZ structure are mutually interchanged. Expressions for the two-port four-terminal matrix parameter functions (MPF's) for the new NUDP Z—Y—KZ structure are derived and their relationships with those of the known Z—Y—KZ network are evaluated. A theorem is formulated on the basis of the results yielded by the mutual interchange of the patterns of variation of the PUL parameters of the NUDP Z—Y—KZ structure.