Vehicle electrification presents a great opportunity to reduce transportation greenhouse gas emissions. The greater use of plug-in electric vehicles (PEVs), however, puts stress on local distribution networks. This paper presents an optimal PEV charging control method integrated with utility demand response (DR) signals to mitigate the impact of PEV charging to several aspects of a grid, including load surge, distribution accumulative voltage deviation, and transformer aging. To build a realistic PEV charging load model, the results of National Household Travel Survey (NHTS) have been analyzed and a stochastic PEV charging model has been defined based on survey results. The residential distribution grid contains 120 houses and is modeled in GridLAB-D. Co-simulation is performed using Matlab and GridLAB-D to enable the optimal control algorithm in Matlab to control PEV charging loads in the residential grid modeled in GridLAB-D. Simulation results demonstrate the effectiveness of the proposed optimal charging control method in mitigating the negative impacts of PEV charging on the residential grid.
The electrification of vehicles has caused a great change in the characteristics of noise, vibration and harshness. A rangeextended electric vehicle has complicated noise and vibration problems because it behaves both like a traditional vehicle and like a battery electric vehicle as well as having its own specific noise, vibration and harshness properties. Therefore, increasing attention should be paid to these issues. This paper is intended as a contribution to the current research on the noise, vibration and harshness of a range-extended electric vehicle. The electric driveline, the auxiliary power unit and the accessories, including the power steering pump, the electric vacuum pump and the air conditioner compressor, are tested and their noise, vibration and harshness performances are analysed. The results indicate that the highfrequency noise of the electric driveline and the vibrations of the auxiliary power unit and the air conditioner compressor are crucial noise, vibration and harshness issues of a range-extended electric vehicle. Some improvement methods are implemented or proposed for better comfort in the passenger compartment. Application of a material which is sound insulating and sound absorbing proved to be an effective countermeasure. The design and refinement of a vibration isolation system for the auxiliary power unit and the air conditioner compressor are of great importance. A reduction in the low-frequency torsional resonance of the auxiliary power unit shaft during a start-stop process is a new problem compared with that of a conventional engine. It is necessary to find a well-balanced compromise between the expected acoustic feedback and the power demand.
Summary This paper presents a generalized Nash equilibrium problem (GNEP) approach for the management of plug‐in electric vehicle (PEV) charging activities in a distribution network. The PEV charging pricing signal is designed to reflect the distribution network operational cost. The charging strategy of individual PEVs is allowed to respond price tariff to minimize its charging cost, while must also consider the charging requirement and grid facility constraints, such as vehicle on board charger, distribution node, and substation power limits. With this approach, the selected charging strategies are near socially optimal solutions under physical constraints. The PEV charging GNEP is reformulated by Nikaido‐Isoda function, which converts a distributed decision‐making problem to a constrained optimization problem. Due to the non‐differentiability of individual objective functions in the GNEP, relaxation algorithm is employed for searching optimal solutions in an iteration process. To adapt to the uncertainty and randomness of PEV fleet and grid load dynamics, the PEV charging management algorithm updates the GNEP when there are newly connected/disconnected PEVs or the load variation in the distribution network exceeds a predefined value. To validate the presented method, two use cases are defined. Simulation results of these two use cases verify the effectiveness of this method in both regulating the PEV charging activities and achieving PEV charging customers' objectives. The effect of customer participation rate on the performance of the presented control scheme is also analyzed.
In recent years, sand production has been frequently observed in offshore weakly consolidated sandstone reservoirs. Permeability changes due to sand migration seriously affect the confidence in well test interpretation, production forecasts, and oilfield development plan schedules. The purpose of this paper is to propose a comprehensive model of coupled sand migration, stress sensitivity, and high viscosity oil and to study the effect of sand production induced permeability zoning on transient pressure behavior by combining discrete boundary and discrete wellbore with the boundary element method. In this two-zone composite model, the reservoir can be divided into the inner zone with the improved permeability due to sand migration and the outer zone with initial reservoir permeability. The multifactor effects of stress-sensitive, highly viscous oil, sand migration, and horizontal well are included in this model. Thus, the seepage equation presents a highly nonlinear and difficult to obtain an accurate analytical solution. In this paper, the boundary element method (BEM) is introduced to separate the boundary and wellbore, and the semianalytical solution of the hybrid model is obtained. The comparative analysis of measured pressure curve fitting from a horizontal well, located in the eastern of the South China Sea, proves that this comprehensive model can be used for pressure transient analysis of the weakly consolidated sandstone reservoir. The flow regime analysis indicates that a two-zone composite system may develop seven flow regimes: the wellbore storage stage, early-time radial stage, first transition stage, inner linear stage, inner pseudoradial flow, transition flow from the inner area to the outer area, and outer pseudoradial flow. Sensitivity analysis indicates that the smaller the sand production radius, the shorter the duration of the transition flow from the inner to the outer zone, which suggests the well is mainly affected by the outer boundary in the later period. The larger the permeability ratio, the higher the pressure curves may move up.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.