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Electronic load-bank circuit provides pulsed or continuous low-resistance load to imitate effect of short circuit on Ni/H2 or other electrochemical power cells. Includes safety/warning feature and taps for measurement of cell-output voltage and current.
A LabVIEW-language computer program enables monitoring and control of a Transistor Devices, Inc., Dynaload WCL232 (or equivalent) electronic load via an RS-232 serial communication link between the electronic load and a remote personal computer. (The electronic load can operate at constant voltage, current, power consumption, or resistance.) The program generates a graphical user interface (GUI) at the computer that looks and acts like the front panel of the electronic load. Once the electronic load has been placed in remote-control mode, this program first queries the electronic load for the present values of all its operational and limit settings, and then drops into a cycle in which it reports the instantaneous voltage, current, and power values in displays that resemble those on the electronic load while monitoring the GUI images of pushbuttons for control actions by the user. By means of the pushbutton images and associated prompts, the user can perform such operations as changing limit values, the operating mode, or the set point. The benefit of this software is that it relieves the user of the need to learn one method for operating the electronic load locally and another method for operating it remotely via a personal computer.
The influx of non-linear power electronic loads into the distribution network has the potential to disrupt the existing distribution transformer operations. They were not designed to mediate the excessive heating losses generated from the harmonics. To have a good understanding of current standing challenges, a knowledge of the generation and load mix as well as the current harmonic estimations are essential for designing transformers and evaluating their performance. In this paper, we investigate a mixture of essential power electronic loads for a household designed in PSCAD/EMTdc and their potential impacts on transformer eddy current losses and derating using harmonic analysis. Our findings reveal that in the presence of high power electronic loads (especially third harmonics), increasing PV generation may worsen transformer degradation. However, with a low amount of power electronic loads, additional PV generation helps to reduce the harmonic content in the current and improve transformer performance.
Adjustable electronic load in solar-cell-array test instrument uses ten power MOSFET's and eight resistors. Two gate-control voltages adjusting load are derived from single, manually-operated, ganged potentiometer control. Third adjustable resistor adjusts relative turn-on points of two groups of transistors.
The prevalence of power electronics in the bulk power system is increasing rapidly in both the generation and consumption of electricity. This work focuses on the effect of changing load composition - specifically the transition from single phase air conditioner motors to power electronics backed air conditioners - on power system stability. Various transmission and generation contingency events for the Western Interconnection were simulated using Positive Sequence Load Flow software and planning models from the Western Electricity Coordinating Council. In general, an increased proportion of power electronic load leads to more instability. For some specific faults resulting in fault-induced delayed voltage recovery, transitioning to higher proportions of power electronic loads helps expedite system recovery. These results demonstrate that load composition should be examined in conjunction with generation composition when evaluating system stability.
The free-piston Stirling convertor end-to-end modeling effort at the NASA Glenn Research Center has produced a software-based test bed in which free-piston Stirling convertors can be simulated and evaluated. The simulation model includes all the components of the convertor: the Stirling cycle engine, heat source, linear alternator, controller, and load. So far, it has been used in evaluating the performance of electronic controller designs. Three different controller design concepts were simulated using the model: 1) Controllers with parasitic direct current loading. 2) Controllers with parasitic alternating current loading. 3) Controllers that maintain a reference current. The free-piston Stirling convertor is an electromechanical device that operates at resonance. It is the function of the electronic load controller to ensure that the electrical load seen by the machine is always great enough to keep the amplitude of the piston and alternator oscillation at the rated value. This is done by regulating the load on the output bus. The controller monitors the instantaneous voltage, regulating it by switching loads called parasitic loads onto the bus whenever the bus voltage is too high and removing them whenever the voltage is too low. In the first type of controller, the monitor-ing and switching are done on the direct-current (dc) bus. In the second type, the alternating current bus is used. The model allows designers to test a controller concept before investing time in hardware. The simulation code used to develop the model also offers detailed models of digital and analog electronic components so that the resulting designs are realistic enough to translate directly into hardware circuits.
Instrument tests various electric power generating devices by connecting the devices to the input of the load and comparing their outputs with a reference voltage. The load automatically adjusts until voltage output of the power generating device matches the reference.
Variable load has very fast response under wide range of simulated dynamic operating conditions, and can accept inputs up to 1000 watts. Many types of signals may be applied to load. Variable pulse generator and flip-flop produce rectangular waveform. Other signals include steady state step and single pulse.
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Electronically variable linear resistive load circuit synthesized by use of analog components to control conductance of power metal oxide/semiconductor field-effect transistors, MOSFET's. Circuit has modular configuration, in which single controller drives parallel load units. A 3-kW load module that exhibits submicrosecond response time with respect to control signal demonstrated.
Electron bombardment produced clustered displacements, paired vacancies and interstitial atoms in Si, discussing possible mechanism for developing defects
Over the past decades, the increasing penetration of distributed energy resources (DERs) has dramatically changed the power load composition in the distribution networks. The traditional static and dynamic load models can hardly capture the dynamic behavior of modern loads especially for fault-induced delayed voltage recovery (FIDVR) events. Thus, a more comprehensive composite load model with combination of static load, different types of induction motors, single-phase A/C motor, electronic load and DERs has been proposed by Western Electricity Coordinating Council (WECC). However, due to the large number of parameters and model complexity, the WECC composite load model (WECC CMLD) raises new challenges to power system studies. To overcome these challenges, in this paper, a cutting-edge parameter reduction (PR) approach for WECC CMLD based on active subspace method (ASM) is proposed. Firstly, the WECC CMLD is parameterized in a discrete-time manner for the application of the proposed method. Then, parameter sensitivities are calculated by discovering the active subspace, which is a lower-dimensional linear subspace of the parameter space of WECC CMLD in which the dynamic response is most sensitive. The interdependency among parameters can be taken into consideration by our approach. Finally, the numerical experiments validate the effectiveness and advantages of the proposed approach for WECC CMLD model.
Electronic load pulser uses silicon-controlled rectifier (SCR) and timer to open and close circuit periodically. It replaces a motor-driven mechanical switch, which causes sparks and is unsafe in hazardous environments. Device should find applications in chemical petroleum, and transportation industries.
With the increasing penetration of electronic loads and distributed energy resources, conventional load models cannot capture their dynamics. Therefore, a new comprehensive composite load model is developed by Western Electricity Coordinating Council (WECC). However, this model is a complex high-order non-linear system with multi-time-scale property, which poses challenges on power system studies with heavy computational burden. In order to reduce the model complexity, the authors firstly develop a large-signal order reduction (LSOR) method using singular perturbation theory. In this method, the fast dynamics are integrated into the slow ones to preserve transient characteristics of the former. Then, accuracy assessment conditions are proposed and embedded into the LSOR to improve and guarantee the accuracy of reduced-order model. Finally, the reduced-order WECC composite load model is derived by using the proposed algorithm. Overall, simulation results show that the reduced-order large-signal model significantly alleviates the computational burden while maintaining similar dynamic responses as the original composite load model.
Grid-forming wind turbines must be able to re-energize transmission branches, motor loads, unbalanced loads, and power electronics loads following a blackout. Further, they must ride through faults that can arise during restoration. To tackle these challenges, this paper sets forth a grid-forming control strategy for wind turbines using doubly-fed induction generators (DFIGs). In particular, a special set of feedforward control loops are engineered to mitigate the impacts of restoration transients as well as symmetrical and asymmetrical faults on the regulation of DFIG rotor currents and stator voltages. This paper also leverages two-axis anti-windup regulators to bound two-axis voltage and current commands within ratings. As a result, the controller performance is demonstrated via a high-fidelity simulation model of a notional wind-dominant grid.
By loading the wiggler cavity of an FEL with hydrogen gas, it is possible to tune the FEL to below 130 nm, just above the electronic resonance of molecular hydrogen. The change in wavelength results from the refractive index of the gas, which alters the phase velocity of the wave and so modifies the synchronism condition. Using the parameters of the wiggler on the beamline of the Stanford Superconducting Accelerataor, this FEL can be tuned from 500 to 130 nm with a pressure ranging from 0 to 55 torr. The calculated electronic gain varies between 5.6 and 11 percent over this wavelength interval, comparable to the gain in vacuum.
Second harmonic generation (SHG), a laser-based surface technique, was used to characterize near-surface defect evolution associated with mechanical deformation in 2024-T3 aluminum due to tensile loads. Electron backscatter diffraction (EBSD) measurements were also performed to determine the geometrically necessary dislocation density before and after tensile deformation. Comparison of the EBSD and SHG results found that dislocation density and SHG signal are inversely proportional; tensile deformation in the plastic regime led to an increase in dislocation density and a decrease in SHG response. A similar trend was seen in the SHG results on as-received (unpolished) Al samples; SHG response decreases with extent of plastic deformation. Furthermore, this study suggests that SHG has potential as a nondestructive evaluation technique.