Electromagnetic transient programs (EMTPs) are widely used for simulating electromagnetic transient in power systems. With the increasing interest in integrated energy system (IES), it would be beneficial to extend th...
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Electromagnetic transient programs (EMTPs) are widely used for simulating electromagnetic transient in power systems. With the increasing interest in integrated energy system (IES), it would be beneficial to extend the scope of EMTP-type application to multi-physics transients in integrated electrical and gas networks. An efficient and accurate model of gas pipeline is proposed in EMTP for the simulation of pneumatic transients. The pipeline is split into a number of segments using spatial discretization. Analogies between pneumatic and electric quantities, such as flow and pressure, current, and voltage, are used to create a circuit representation of pipe segment. The pipeline is represented by a distributed-element model. In order to enhance the computational efficiency, the nodal equation for pipeline model is reformulated. The pipeline model appears as a two-port Norton equivalent with constant admittances. Case studies are performed to demonstrate the accuracy and efficiency of the proposed pipeline model. The implementation of the proposed pipeline model in the EMTP-type program power systems computer aided design (PSCAD) enables the analysis of diverse transients in integrated electrical and gas systems (IEGSs).
Constitutive modeling of cyclic relaxation and ratcheting (cumulative inelastic deformation) is developed on the basis of the distributed-element model (DEM). Although the original DEM is capable of describing general...
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Constitutive modeling of cyclic relaxation and ratcheting (cumulative inelastic deformation) is developed on the basis of the distributed-element model (DEM). Although the original DEM is capable of describing general, elastic-plastic behavior for cyclically stabilized materials, it has the inadequacy of not being able to account for the effect of cyclic relaxation and ratcheting. By introducing the nonlinear kinematic hardening rule proposed by Armstrong and Frederick into element behavior of the DEM, the model becomes effective in characterizing the behavior of cyclic relaxation and ratcheting. Validation of the modified DEM is conducted by simulating cyclic behavior of various metal materials, including CS 1018, heat-treated rail steel, and Grade 60 steel. The results show that the modified DEM demonstrates realistic behavior of materials in both uniaxial and biaxial cyclic relaxation and ratcheting. Furthermore, detailed investigation of element behavior in the model provides us with additional insight into complex behavior and characteristics of materials in cyclic relaxation and ratcheting. (c) 2007 Elsevier Inc. All rights reserved.
This study considers extension of the distributed-element model to account for the deformation-induced anisotropy demonstrated in subsequent yield surfaces. By modifying the shape parameter of the strength-distributio...
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This study considers extension of the distributed-element model to account for the deformation-induced anisotropy demonstrated in subsequent yield surfaces. By modifying the shape parameter of the strength-distribution function in the model as a function of the accumulated plastic deformation and the preloading direction, the DEM is able to account appropriately for major features of the subsequent yield surfaces demonstrated by real materials under proportional loading. The proposed modeling technique is confirmed by performing numerical simulations and comparing with experimental results available in the literature. (C) 2002 Elsevier Science Ltd. All rights reserved.
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