Electro-thermal Load Research Articles

Comprehensive energy system planning with a focus on electric-thermal load correlations

Abstract Deepening research on electrothermal integrated energy systems has heightened the coupling between electric power and thermal systems. Accurate electrothermal load scenario modeling and thorough consideration of their interdependencies are crucial for effective planning and scheduling. The traditional method of generating scenarios cannot fully reflect the full complexity of the original power load. To address this, our paper introduces an enhanced clustering approach. Employing the Frank-Copula function to express the correlation between electric and thermal loads, we optimize the clustering and scene reduction sequence, yielding correlated typical electric and thermal load datasets. These refined load profiles serve as the foundation for comprehensive planning and analysis of the integrated energy system.

Three-Dimensional Thermoelasticity Analysis of Viscoelastic FGM Plate Embedded in Piezoelectric Layers under Thermal Load

Due to the high importance of viscoelastic materials in modern industrial applications, besides the intensive popularity of piezoelectric smart structures, analyzing their thermoelastic response in extreme temperature conditions inevitably becomes very important. Accordingly, this research explores the thermoviscoelastic response of sandwich plates made of a functionally-graded Boltzmann viscoelastic core and two surrounding piezoelectric face-layers subjected to electrothermal load in the platform of three-dimensional elasticity theory. The relaxation modulus of the FG viscoelastic layer across the thickness follows the power law model. the plate’s governing equations are expressed in the Laplace domain to handle mathematical complications corresponding to the sandwich plate with a viscoelastic core. Then, the state-space method, combined with Fourier expansion, is utilized to extract the plate response precisely. Finally, the obtained solution is converted to the time domain using the inverse Laplace technique. Verification of the present formulation is compared with those reported in the published papers. Finally, the influences of plate dimension, temperature gradient, and relaxation time constant on the bending response of the above-mentioned sandwich plate are examined. As an interesting finding, it is revealed that increasing the length-to-thickness ratio leads to a decrease in deflections and an increase in stresses.

The effectiveness of decentralised electro-thermal load shifting strategies in low voltage network violation management

The IPCC 1.5 °C report highlights the need to reduce UK carbon emissions by 80% 2050, and so it is essential to examine the routes that could be taken to achieve this goal. Replacement of traditional boiler systems with heat pumps (using electricity from clean sources) in residences may aid decarbonization of the energy sector. However, typical LV distribution networks are not designed to carry the increased loads will result from this change, and so it is necessary to explore strategies to mitigate any adverse effects of such loads.In this study, we examine the effect of air source heat pumps on voltage and thermal violations experienced by a typical UK LV network. The effect of decentralized heating system operational strategies (pre-heating, thermostat setback, and space heat buffering) on results is then investigated. Finally, the sensitivity of results to external temperature, network topology, and building fabric standard are examined.It is found that no mixture of strategies is sufficient to significantly improve localized voltage conditions at remote/branch points on LV feeders, as a result of the much greater sensitivity of branch node voltages to power demand of localized loads. Even where EN 50160 voltage standards are applied, elimination of violations is rarely possible.

A smoothly tunable shape memory metamaterial with adaptive bandgaps for ultra-wide frequency spectrum vibration control

This article presents a smoothly tunable shape memory elastic metamaterial with adaptive bandgaps enabling the broadband frequency vibration control. The underlying bandgap-tuning mechanism arises from the reversible large deformation induced by shape memory alloy (SMA) element under electro-thermal loads, through which, various microstructural shape morphing could be achieved. Via delicately designing the unit cell, the numerically obtained band structures and effective medium properties display a successful attainment of the vibration stop-passing band formation and smoothly controllable two-way tuning phenomenon for a series of transitional and intermediate status. The overall controllable frequency scope could be shifted over an ultra-wide band. Subsequently, a systematic parametric study is carried out to unfold the bandgap-adjusting patterns by altering the apparent structural stiffness and the SMA elastic modulus, individually. The finite element harmonic analysis of a metamaterial unit-cell-chain model is further investigated to verify the effectiveness of vibration suppression and the variability of the stopband region from the frequency spectra and the equivalent stresses images. Finally, the experimental demonstration is performed to validate the numerical predication from a practical perspective. The proposed design may possess enabling application potentials for future active vibration control and noise isolation in engineering facilities.

Comparative analysis of deflection in a bimetal

A Bimetal is a combination of two different metals, which is employed in electrical appliances as a circuit breaker to prevent the overflow of current. The primary objective of this work is to examine the deflection produced in the bimetal component, due to electro-thermal load induced when the current flows through it. Copper and stainless steel are the most widely used metals having different coefficient of linear thermal expansion were taken as a bimetal composition and the same has been compared with Stainless steel and Aluminum. Modeling and analysis of the bimetal component, with different amperes, has been done using ANSYS and resulted stainless steel - Aluminium combination were shown higher deflection during the Analysis.

A scalable pressure sensor based on an electrothermally and electrostatically operated resonator

We present a pressure sensor based on the convective cooling of the air surrounding an electrothermally heated resonant bridge. Unlike conventional pressure sensors that rely on diaphragm deformation in response to pressure, the sensor does not require diaphragms of the large surface area, and hence is scalable and can be realized even at the nanoscale. The concept is demonstrated using both straight and arch microbeam resonators driven and sensed electrostatically. The change in the surrounding pressure is shown to be accurately tracked by monitoring the change in the resonance frequency of the structure. The sensitivity of the sensor, which is controllable by the applied electrothermal load, is shown near 57 811 ppm/mbar for a pressure range from 1 to 10 Torr. We show that a straight beam operated near the buckling threshold leads to the maximum sensitivity of the device. The experimental data and simulation results, based on a multi-physics finite element model, demonstrate the feasibility and simplicity of the pressure sensor.

Crack Propagation Modeling in Silicon: A Comprehensive Thermomechanical Finite-Element Model Approach for Power Devices

Wafer handling during the manufacturing process introduces microcracks and flaws at the wafer edge. This paper aims at determining whether an initial crack would be able to propagate through the silicon active region of power devices when it is subjected to high electrothermal loads during operating conditions or accelerated thermal cycling tests. Failure analysis performed on these power devices has revealed some typical propagation paths. The most critical crack propagation cases (or paths) were determined by finite-element model simulations. The energy release rate has been calculated for different crack lengths, locations, or thermal loads, and then compared with the silicon critical energy release rate. Hence, different critical crack lengths have been determined. The effect of dice design, temperature, or mechanical properties of the materials on crack thresholds has been also investigated.

Static analysis for functionally graded piezoelectric actuators or sensors under a combined electro-thermal load

Based on the theory of piezoelasticity, a functionally graded piezoelectric sandwich cantilever under an applied electric field and/or a heat load is studied. All materials may be arbitrary functional gradients in the thickness direction. The static solution for the mentioned problems is presented by the Airy stress function method. As a special case, assuming that the material composition varies continuously in the direction of the thickness according to a power law distribution, a comprehensive parametric study is conducted to show the influence of electromechanical coupling (EMC), functionally graded index, temperature change and thickness ratio on the bending behavior of actuators or sensors. The distribution of electric field or normal stress in present FGPM actuators is continuous along the thickness, which overcomes the problem in traditional layered actuators. The solution facilitates the design optimization for different piezoelectric actuators and has another potential application for material parameter identification.

Nonlinear Zigzag Theory for Buckling of Hybrid Piezoelectric Rectangular Beams under Electrothermomechanical Loads

A new efficient electromechanically coupled geometrically nonlinear (of von Karman type) zigzag theory is developed for buckling analysis of hybrid piezoelectric beams, under electrothermomechanical loads. The thermal and potential fields are approximated as piecewise linear in sublayers. The deflection is approximated as piecewise quadratic to explicitly account for the transverse normal strain due to thermal and electric fields. The longitudinal displacement is approximated as a combination of third order global variation and a layerwise linear variation. The shear continuity conditions at the layer interfaces and the shear traction-free conditions at the top and bottom are used to formulate the theory in terms of three primary displacement variables. The governing coupled nonlinear field equations and boundary conditions are derived using a variational principle. Analytical solutions for buckling of symmetrically laminated simply supported beams under electrothermal loads are obtained for comparing the...

Repetitive inductive storage supply for an ETC tank gun

A laboratory repetitive inductive storage power supply (ISPS) for the ignition of an electrothermal-chemical (ETC) gun is described. It is designed for delivering to an electrothermal load an energy of 400 kJ in a shot under the assumption that this energy suffices for an effective ignition of advanced consolidated propellants accounting for temperature compensation. The ISPS is battery-based. The battery has a peak power of 5 MW and is able to charge a cylindrical coil to 700 kJ. Fringe fields of the coil with and without ferromagnetic screens in static and transient conditions are analyzed using numerical simulation. A conclusion is drawn that a screen of reasonable weight cannot reduce the stray field below a susceptibility level of electronic devices that should be shielded individually. A hybrid repetitive opening switch (OS) rated 50 kA, 4 kV, 70 /spl mu/s breaking time is described. A commercial vacuum circuit breaker serves as the first stage. At a desired moment, it is opened, and the current is transferred to the second stage, which is an integrated gate-commutated thyristor (IGCT) that finally breaks the current. The IGCT turnoff is assisted by an inverse current injection into the second stage. The main benefit of this technique is a dramatic reduction (by a factor of ten) in the quantity of semiconductor devices in the second stage. The OS design, assisted by PSpice simulations coupled with field analysis of nonlinear magnetic components is described. Test results are presented. Overall, this work supports an earlier conclusion that an 0.5-MJ ISPS, capable of delivering the first round of an eight-shot burst in 0.3 s, will occupy 0.6 m/sup 3/ net volume and weigh 1000 kg.

Features of the relaxation polarization of a polar dielectric under conditions of large electrothermal loads

In a polar dielectric occurring under the conditions of large electrothermal loads, it is necessary to take into account the temperature dependence of the conductivity γ(T) and complex permittivity $$\overset{\lower0.5em\hbox{$\smash{\scriptscriptstyle\smile}$}}{l} $$ . An allowance for this circumstance in the simplest model of the Debye relaxation polarization leads to deviation of the e″=f(e′) curve from the well-known Cole-Cole semicircle. Exact solutions of the model problems for a flat capacitor are presented for the cases when the temperature gradient is caused by an external source and by relaxation losses in the dielectric material.

Design and testing of a 5 MW battery-based inductive power supply

A 5 MW battery-based inductive power supply (IFS) was designed and tested. The battery consisted of 636 low-resistance, sealed, lead-acid batteries organized in strings that are connected to busbars via small-size contactors. A vacuum breaker serves as a closing switch, while an explosively driven opening switch interrupts the circuit, transferring the coil current to the load. In case of load malfunction, the energy stored in the coil is dumped into a dissipative load. The systems for control and measurement are decoupled from the high-current carrying conductors. In this paper, optimization of the battery-coil matching is discussed. The current sharing between the strings is analyzed. IFS parasitic inductance for different arrangements was calculated and reduced by careful design to 4 /spl mu/H. PSpice simulations of the IFS accounting for nonlinearity in the components are presented. Main components, such as batteries, contactors, and protective equipment were tested under high current conditions. The IFS was evaluated both with a resistive and an electro-thermal load with stored energy up to 0.5 MJ. Power amplification of 100 was obtained. It was found that the experimental results agree closely with calculations, and the IFS performs according to the design specifications. Methods of developing a more compact IFS using advanced battery technology are analyzed.

Frequency effects in a pancake coil

An aluminum pancake coil is designed to amplify pulsed power in the range of 100-MW to a 100-m/spl Omega/ electro-thermal load. For the tradeoff between the coil energy density limit and energy discharge efficiency, the frequency dependence of its current and magnetic field distributions is calculated in the range of DC to 1 kHz. Near DC magnetic field measurements are compared to the calculated results. Energy efficiency of about 85% has been measured for the discharge of 1.6 kA from the coil to a linear resistive load in the range of 40-400 m/spl Omega/.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

52 megajoule electric gun test facility

The Electric Armaments Division at the US Army Armament Research, Development and Engineering Center has constructed an advanced, high-energy, electric gun test facility. A 52 MJ, capacitor-based, pulsed power supply, consisting of 16 individual 3.25 MJ modules, has been installed. Pulse forming networks have been designed to provide appropriate pulses for both electrothermal (ET) and electromagnetic (EM) railgun loads. A 120 mm ET launch fixture has been installed and a 90 mm EM railgun is to be installed in summer 1992. A 900 ft/sup 2/ control and data acquisition center is installed. The layout of the facility, design of the pulse power supply, and configuration of the diagnostic systems are discussed. >

Inductive programmed generator for electrothermal guns

A three-stage generator experimental circuit for current multiplication has been designed and tested with semiconductor switches and a resistive load. The inductors are charged from a capacitor bank at 500 A and store 0.6 kJ. The load current is amplified and shaped through the timing of the switch operation. With commercially available single GTO (gate-turn-off thyristor) switches, current in the range of several kA has been achieved. A simulation program has been constructed for the experimental circuit, and the equations of a simplified circuit coupled to an electrothermal load have been solved analytically. Based on these calculations, a conceptual design is given for a 1 MJ system. >