Journal articles on the topic 'Grid sensitivity'
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1
Somayajula, Gopichand, and James E. Bernard. "Grid sensitivity analysis." Finite Elements in Analysis and Design 7, no. 4 (February 1991): 307–15. http://dx.doi.org/10.1016/0168-874x(91)90046-2.
2
Lian, Shuai, Bintang Li, Jianbo Wang, and Rui Jiang. "On-line Update Method for the Sensitivity Consistency Model of Interconnected Power Grid Based on Electric Power Big Data." E3S Web of Conferences 256 (2021): 01014. http://dx.doi.org/10.1051/e3sconf/202125601014.
Abstract:
Real-time fast calculation of the power flow of the interconnected power grid is an important guarantee for the reliable operation of the interconnected power grid. The topology of the interconnected power grid is complex, and the calculation of the power flow of the whole network is large and timeconsuming. The sensitivity equivalent model can effectively simplify the interconnected power grid and shorten the time of the power flow calculation of the whole network. The operating state of the power grid is constantly changing. In order to ensure the accuracy of the power flow calculation results, it is necessary to update the uniform sensitivity equivalent model in real time. Due to factors such as the vertical management system between the interconnected power grids and the principle of commercial confidentiality, it is difficult to share information between interconnected power grids in real time, and the sensitivity equivalent model cannot be updated in real time, resulting in too much error in the calculation results and no reference value. To solve this problem, this paper proposes an online update method for the sensitivity equivalent model of the interconnected power grid based on power big data to solve the problem of excessive power flow calculation errors caused by the untimely update of the equivalent model parameters, and to ensure the operational reliability of the interconnected power grid.
3
Guba, O., M. A. Taylor, P. A. Ullrich, J. R. Overfelt, and M. N. Levy. "The spectral element method on variable resolution grids: evaluating grid sensitivity and resolution-aware numerical viscosity." Geoscientific Model Development Discussions 7, no. 3 (June 25, 2014): 4081–117. http://dx.doi.org/10.5194/gmdd-7-4081-2014.
Abstract:
Abstract. We evaluate the performance of the Community Atmosphere Model's (CAM) spectral element method on variable resolution grids using the shallow water equations in spherical geometry. We configure the method as it is used in CAM, with dissipation of grid scale variance implemented using hyperviscosity. Hyperviscosity is highly scale selective and grid independent, but does require a resolution dependent coefficient. For the spectral element method with variable resolution grids and highly distorted elements, we obtain the best results if we introduce a tensor-based hyperviscosity with tensor coefficients tied to the eigenvalues of the local element metric tensor. The tensor hyperviscosity is constructed so that for regions of uniform resolution it matches the traditional constant coefficient hyperviscsosity. With the tensor hyperviscosity the large scale solution is almost completely unaffected by the presence of grid refinement. This later point is important for climate applications where long term climatological averages can be imprinted by stationary inhomogeneities in the truncation error. We also evaluate the robustness of the approach with respect to grid quality by considering unstructured conforming quadrilateral grids generated with a well-known grid-generating toolkit and grids generated by SQuadGen, a new open source alternative which produces lower valence nodes.
4
Buzzard, Gregery T., and Dongbin Xiu. "Variance-Based Global Sensitivity Analysis via Sparse-Grid Interpolation and Cubature." Communications in Computational Physics 9, no. 3 (March 2011): 542–67. http://dx.doi.org/10.4208/cicp.230909.160310s.
Abstract:
AbstractThe stochastic collocation method using sparse grids has become a popular choice for performing stochastic computations in high dimensional (random) parameter space. In addition to providing highly accurate stochastic solutions, the sparse grid collocation results naturally contain sensitivity information with respect to the input random parameters. In this paper, we use the sparse grid interpolation and cubature methods of Smolyak together with combinatorial analysis to give a computationally efficient method for computing the global sensitivity values of Sobol’. This method allows for approximation of all main effect and total effect values from evaluation of f on a single set of sparse grids. We discuss convergence of this method, apply it to several test cases and compare to existing methods. As a result which may be of independent interest, we recover an explicit formula for evaluating a Lagrange basis interpolating polynomial associated with the Chebyshev extrema. This allows one to manipulate the sparse grid collocation results in a highly efficient manner.
5
Guba, O., M. A. Taylor, P. A. Ullrich, J. R. Overfelt, and M. N. Levy. "The spectral element method (SEM) on variable-resolution grids: evaluating grid sensitivity and resolution-aware numerical viscosity." Geoscientific Model Development 7, no. 6 (November 27, 2014): 2803–16. http://dx.doi.org/10.5194/gmd-7-2803-2014.
Abstract:
Abstract. We evaluate the performance of the Community Atmosphere Model's (CAM) spectral element method on variable-resolution grids using the shallow-water equations in spherical geometry. We configure the method as it is used in CAM, with dissipation of grid scale variance, implemented using hyperviscosity. Hyperviscosity is highly scale selective and grid independent, but does require a resolution-dependent coefficient. For the spectral element method with variable-resolution grids and highly distorted elements, we obtain the best results if we introduce a tensor-based hyperviscosity with tensor coefficients tied to the eigenvalues of the local element metric tensor. The tensor hyperviscosity is constructed so that, for regions of uniform resolution, it matches the traditional constant-coefficient hyperviscosity. With the tensor hyperviscosity, the large-scale solution is almost completely unaffected by the presence of grid refinement. This later point is important for climate applications in which long term climatological averages can be imprinted by stationary inhomogeneities in the truncation error. We also evaluate the robustness of the approach with respect to grid quality by considering unstructured conforming quadrilateral grids generated with a well-known grid-generating toolkit and grids generated by SQuadGen, a new open source alternative which produces lower valence nodes.
6
Mo, Yixiang, Jianfeng Tang, Zhongkai Fan, Tao Hu, Fen Lin, Ruomei Xie, Shuai Yuan, Shuaibin Liu, Hongzhi Yuan, and Yanliang Tan. "Design of multi-layer grid in a giant electrostatic collection vessel of ultra-high sensitivity radon monitor." Journal of Instrumentation 17, no. 07 (July 1, 2022): T07011. http://dx.doi.org/10.1088/1748-0221/17/07/t07011.
Abstract:
Abstract Developing an ultra-high sensitivity electrostatic collection radon monitor benefits the scientific experiments of China Jinping Underground Laboratory. Here, a one cubic meter electrostatic collection vessel with a multi-layer hemispherical metal grid was designed to increase the collection efficiency of positively charged Po-218 ions. The 3D model of the giant electrostatic collection vessel was constructed using the COMSOL Multiphysics simulation software, and the potential and electric field distributions in the vessel were simulated. Numerical simulation results were obtained according to the different radii and voltages applied to the grid. The electric field between the vessel wall and grid, between two grids, and between the grid and surface of the PIPS detector must be set uniformly to reduce the collection time of the positively charged Po-218 ions. Simulation results showed that setting a charged metal grid in the vessel can optimize the electric field distribution, and setting a two-layer charged metal grid in the giant vessel can further increase the cost performance. The average collection times of the electrostatic collection vessel with the two-layer grid along the vertical and oblique lines approximately 15% and 13% of that without the grid. The rates of positively charged Po-218 ions that could pass through the one and two-layer metal grids were 86.78% and 50%. Optimizing the electric field can greatly increase the sensitivity of radon monitors and reduce the humidity restrictions.
7
Luhtala, Roni, Henrik Alenius, and Tomi Roinila. "Practical Implementation of Adaptive SRF-PLL for Three-Phase Inverters Based on Sensitivity Function and Real-Time Grid-Impedance Measurements." Energies 13, no. 5 (March 4, 2020): 1173. http://dx.doi.org/10.3390/en13051173.
Abstract:
Rapidly increasing demand for renewable energy has created a need for the photovoltaic and wind farms to be placed in various locations that have diverse and possibly time-variant grid conditions. A mismatch between the grid impedance and output admittance of an inverter causes impedance-based stability issues, which appear as power quality problems and poor transient performance. Grid synchronization with phase-locked loop (PLL) introduces a negative-resistance-like behavior to inverter output admittance. High control bandwidth of the PLL makes the system sensitive to impedance-based stability issues when the inverter is connected to a weak grid that has high impedance. However, very conservative tunings lead to overly damped dynamic responses in strong grids, where the control performance and power quality can be improved by applying higher PLL control bandwidths. Continuous evaluation of grid conditions makes it possible to avoid the risk of instability and poor dynamic responses, as the inverter output admittance can be re-shaped online to continuously match the grid conditions. The present work proposes method for adaptive control of the PLL based on the real-time measurements of the grid impedance, applying pseudo-random binary sequence (PRBS) injections. The method limits the PLL bandwidth in weak grids to avoid stability issues and increases the control bandwidth in strong grids to improve voltage-tracking, and thus overall control performance. The method is verified through simulations and experimental laboratory tests in a kW-scale system. The results show that optimizing the PLL bandwidth with respect to the grid conditions is highly beneficial for system performance and stability.
8
Zhao, Bing, and Anand Asundi. "Microscopic grid methods—resolution and sensitivity." Optics and Lasers in Engineering 36, no. 5 (November 2001): 437–50. http://dx.doi.org/10.1016/s0143-8166(01)00071-9.
9
Ec¸a, L., and M. Hoekstra. "On the Grid Sensitivity of the Wall Boundary Condition of the k-ω Turbulence Model." Journal of Fluids Engineering 126, no. 6 (November 1, 2004): 900–910. http://dx.doi.org/10.1115/1.1845492.
Abstract:
This paper presents a study on the k-ω turbulence model with regard to the numerical implementation of the ω boundary condition at a solid wall, where ω tends to infinity. Three different implementations are tested in the calculation of a simple two-dimensional turbulent flow over a flat plate. Grid refinement studies in grids with different near-wall grid line spacings are performed to assess the numerical uncertainty of the predicted drag coefficient CD. The results are compared with the predictions of several alternative algebraic, one-equation, and two-equation eddy-viscosity turbulence models. For the same level of grid refinement, the estimated uncertainty of CD obtained with the k-ω model is one order of magnitude larger than for all the other models.
10
Pagaldipti, N., and A. Chattopadhyay. "A discrete semianalytical procedure for aerodynamic sensitivity analysis including grid sensitivity." Computers & Mathematics with Applications 32, no. 3 (August 1996): 61–71. http://dx.doi.org/10.1016/0898-1221(96)00113-7.
11
Vilmann, Benjamin, Peter Jan Randewijk, Hjörtur Jóhannsson, Jesper Hjerrild, and Ashraf Khalil. "Frequency and Voltage Compliance Capabilities of Grid-Forming Wind Turbines in Offshore Wind Farms in Weak AC Grids." Electronics 12, no. 5 (February 24, 2023): 1114. http://dx.doi.org/10.3390/electronics12051114.
Abstract:
Weak grid conditions challenge the grid integration of offshore wind farms. Especially grids with low inertia and large grid impedance questions frequency and voltage compliance capabilities. Grid-forming wind turbines are a promising technology for weak grids due to the nature of their control strategy. This paper explains the difference in how weak grid conditions are described in the literature and shows how the voltage stability margin changes with the short-circuit ratio and X/R ratio. With that knowledge, the frequency and voltage compliance capabilities of three grid-forming controls in an offshore wind farm are investigated and benchmarked. These three controls are a droop control, a virtual synchronous machine, and a synchronverter. This was done by quantifying their performance during a frequency disturbance with sensitivity to the short-circuit ratio, X/R ratio, and the inertia constant, H. It is concluded that the virtual synchronous machine is the most compliant grid-forming control and that DC-link modeling is of great importance when testing compliance during frequency disturbances.
12
Gentry, Megan S., and Gary M. Lackmann. "Sensitivity of Simulated Tropical Cyclone Structure and Intensity to Horizontal Resolution." Monthly Weather Review 138, no. 3 (March 1, 2010): 688–704. http://dx.doi.org/10.1175/2009mwr2976.1.
Abstract:
Abstract The Weather Research and Forecasting (WRF) model is used to test the sensitivity of simulations of Hurricane Ivan (2004) to changes in horizontal grid spacing for grid lengths from 8 to 1 km. As resolution is increased, minimum central pressure decreases significantly (by 30 hPa from 8- to 1-km grid spacing), although this increase in intensity is not uniform across similar reductions in grid spacing, even when pressure fields are interpolated to a common grid. This implies that the additional strengthening of the simulated tropical cyclone (TC) at higher resolution is not attributable to sampling, but is due to changes in the representation of physical processes important to TC intensity. The most apparent changes in simulated TC structure with resolution occur near a grid length of 4 km. At 4-km grid spacing and below, polygonal eyewall segments appear, suggestive of breaking vortex Rossby waves. With sub-4-km grid lengths, localized, intense updraft cores within the eyewall are numerous and both polygonal and circular eyewall shapes appear regularly. Higher-resolution simulations produce a greater variety of shapes, transitioning more frequently between polygonal and circular eyewalls relative to lower-resolution simulations. It is hypothesized that this is because of the ability to resolve a greater range of wavenumbers in high-resolution simulations. Also, as resolution is increased, a broader range of updraft and downdraft velocities is present in the eyewall. These results suggest that grid spacing of 2 km or less is needed for representation of important physical processes in the TC eyewall. Grid-length and domain size suggestions for operational prediction are provided; for operational prediction, a grid length of 3 km or less is recommended.
13
Chen, D., L. J. Zhang, Y. Z. Lv, B. H. Li, and H. P. Gu. "Sensitivity Study on Typical Parameters of Underwater Explosion Numerical Simulation." Journal of Physics: Conference Series 2478, no. 12 (June 1, 2023): 122031. http://dx.doi.org/10.1088/1742-6596/2478/12/122031.
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Abstract In the numerical simulation research for underwater explosion, the selection of simulation parameters has a great influence on the results of numerical calculation. Based on the one-dimensional spherical symmetry model, this paper systematically studies the influence of three factors: grid size, water state equation and artificial viscosity coefficient on the important physical parameters of water explosion when TNT explosive is exploded in water. The important physical parameters selected for the explosion in water are the shock wave intensity, the maximu m radius of the bubble and the pulsation period of the bubble. A series of studies are carried out on underwater explosions with different grid sizes, so as to obtain the corresponding recommended grids that meet the calculation accuracy. The influence of different water state equations on the simulation results is discussed. The effect of artificial viscosity coefficient on the simulation results is analyzed. Finally, the similarity law of the model is studied to verify the universality of the model parameters.
14
Akl, Robert, Priyanka Kadiyala, and Mohamad Haidar. "Nonuniform Grid-Based Coordinated Routing in Wireless Sensor Networks." Journal of Sensors 2009 (2009): 1–11. http://dx.doi.org/10.1155/2009/491349.
Abstract:
A nonuniform grid-based coordinated routing design in wireless sensor networks is presented. The conditions leading to network partition and analysis of energy consumption that prolongs the network lifetime are studied. We focus on implementing routing in densely populated sensor networks. By maintaining constant values for parameters such as path loss exponent, receiver sensitivity and transmit power, and varying between uniform and non-uniform grids, we observe energy consumption patterns for each of the grid structures and infer from the network lifetime the better suited grids for uniformly and randomly deployed sensor nodes.
15
Rizvi, Tanu, Satya Prakash Dubey, Nagendra Tripathi, Gautam Srivastava, Satya Prakash Makhija, and Md Khaja Mohiddin. "FSPV-Grid System for an Industrial Subsection with PV Price Sensitivity Analysis." Sustainability 15, no. 3 (January 30, 2023): 2495. http://dx.doi.org/10.3390/su15032495.
Abstract:
Renewable energy sources, particularly solar photovoltaic generation, now dominate generation options. Solar generation advancements have resulted in floating solar photovoltaics, also known as FSPV systems. FSPV systems are one of the fastest growing technologies today, providing a viable replacement for ground-mounted PV systems due to their flexibility and low land-space requirement. This paper presents a systematic approach for implementing a proposed FSPV–grid integrated system in Bhilai Steel Plant’s (BSP) subsections. BSP is a steel manufacturing plant located in Bhilai, Chhattisgarh, and the FSPV system has the potential to generate sufficient energy by accessing two of its reservoirs. The system was simulated in HOMER Pro software, which provided the FSPV system power estimations, area requirements, net present cost (NPC), levelized cost of energy (LCOE), production summary, grid purchasing/selling, IRR, ROI, paybacks and pollutant emissions. A sensitivity analysis for a hike in PV prices globally due to a shortage in poly silicone in international markets during the fiscal year 2021–2022 was undertaken for the proposed FSPV–grid system. Here, the authors considered hikes in the PV price of 1%, 9%and 18% respectively, since the maximum percentage increase in PV prices globally is 18%. The authors also compared the proposed FSPV–grid system to the existing grid-only system for two sections of the BSP and the results obtained showed that the NPC and LCOE would be much lower in the case of the FSPV–grid system than the grid-only system. However, with changes in the percentage hike in PV prices, the NPC and LCOE were found to increase due to changes in the proportion of FSPV–grid systems in production. The pollutant emissions were the minimum in the case of the FSPV–grid system, whereas they were the highest in the case of the existing grid-only system. Furthermore, the payback analysis indicated that the minimum ROI for the above-defined construction would be fully covered in 15.81 years with the nominal 1% pricing for FSPV–grid generation. Therefore, the overall results suggest that the FSPV–grid system has the potential to be a perfect alternative solar energy source that can meet the current electrical energy requirements of the steel manufacturing industry with nominal pricing better than the existing grid-only system, as well as addressing economic constraints and conferring environmental benefits.
16
Wang, Guangyu. "Phosphatidylinositol-4,5-biphosphate (PIP2)-Dependent Thermoring Basis for Cold-Sensing of the Transient Receptor Potential Melastatin-8 (TRPM8) Biothermometer." Physchem 4, no. 2 (March 26, 2024): 106–19. http://dx.doi.org/10.3390/physchem4020008.
Abstract:
The menthol sensor transient receptor potential melastatin-8 (TRPM8) can be activated by cold and, thus, serves as a biothermometer in a primary afferent sensory neuron for innocuous-to-noxious cold detection. However, the precise structural origins of specific temperature thresholds and sensitivity have remained elusive. Here, a grid thermodynamic model was employed, to examine if the temperature-dependent noncovalent interactions found in the 3-dimensional (3D) structures of thermo-gated TRPM8 could assemble into a well-organized fluidic grid-like mesh network, featuring the constrained grids as the thermorings for cold-sensing in response to PIP2, Ca2+ and chemical agents. The results showed that the different interactions of TRPM8 with PIP2 during the thermal incubation induced the formation of the biggest grids with distinct melting temperature threshold ranges. Further, the overlapped threshold ranges between open and pre-open closed states were required for initial cold activation with the matched thermo-sensitivity and the decrease in the systematic thermal instability. Finally, the intact anchor grid near the lower gate was important for channel opening with the active selectivity filter. Thus, PIP2-dependent thermorings in TRPM8 may play a pivotal role in cold sensing.
17
Sadrehaghighi, Ideen, Robert E. Smith, and Surendra N. Tiwari. "Grid sensitivity and aerodynamic optimization of generic airfoils." Journal of Aircraft 32, no. 6 (November 1995): 1234–39. http://dx.doi.org/10.2514/3.46869.
18
Overbye, Thomas J., Komal S. Shetye, Trevor R. Hutchins, Qun Qiu, and James D. Weber. "Power Grid Sensitivity Analysis of Geomagnetically Induced Currents." IEEE Transactions on Power Systems 28, no. 4 (November 2013): 4821–28. http://dx.doi.org/10.1109/tpwrs.2013.2274624.
19
Vieux, Baxter E., and Scott Needham. "Nonpoint‐Pollution Model Sensitivity to Grid‐Cell Size." Journal of Water Resources Planning and Management 119, no. 2 (March 1993): 141–57. http://dx.doi.org/10.1061/(asce)0733-9496(1993)119:2(141).
20
Cohan, Daniel S., Yongtao Hu, and Armistead G. Russell. "Dependence of ozone sensitivity analysis on grid resolution." Atmospheric Environment 40, no. 1 (January 2006): 126–35. http://dx.doi.org/10.1016/j.atmosenv.2005.09.031.
21
Liu, Fengcheng, Ruoqiang Feng, Konstantinos Daniel Tsavdaridis, and Guirong Yan. "Designing efficient grid structures considering structural imperfection sensitivity." Engineering Structures 204 (February 2020): 109910. http://dx.doi.org/10.1016/j.engstruct.2019.109910.
22
Lv, Changhao, Qingquan Jia, Lijuan Lin, and Jinwei Cui. "Local Frequency Modulation Strategy Based on Controllable Load Characteristic Identification of Multi-Port Power Router." Energies 16, no. 9 (April 24, 2023): 3651. http://dx.doi.org/10.3390/en16093651.
Abstract:
The scarcity of inertial resources in the new AC–DC hybrid grids makes the grid frequency prone to fluctuation. In this paper, the relationship between the grid-side and load-side characteristics of the power router is constructed. By adjusting the port load parameters, the load power can respond quickly to the fluctuation of the grid frequency, thereby realizing rapid support of the grid frequency. Firstly, two kinds of mathematical models for sensitivity identification of load characteristics, variable voltage and variable frequency, are established to calculate the characteristic parameters of a multi-port load. The allocation rules of port power and allocation coefficients are designed according to the parameters. A frequency modulation control method that matches the load response capability of the multi-port router is proposed. Then, taking into consideration the uncertainty of load group characteristics and power, a variable coefficient frequency modulation control strategy for a multi-port power router that can adapt to the adjustable margin of loads is proposed. The proposed model is built based on a Simulink platform for validation. The simulation results show that the proposed frequency modulation strategy can be added, and the frequency modulation performance of the power grid is further improved compared to the situation without this method. The frequency is suppressed to 49.93 HZ. It is verified that this method can make the controllable load respond sensitively and effectively to grid disturbance.
23
Lin, F. B., and F. Sotiropoulos. "Assessment of Artificial Dissipation Models for Three-Dimensional Incompressible Flow Solutions." Journal of Fluids Engineering 119, no. 2 (June 1, 1997): 331–40. http://dx.doi.org/10.1115/1.2819138.
Abstract:
Various approaches for constructing artificial dissipation terms for three-dimensional artificial compressibility algorithms are presented and evaluated. Two, second-order accurate, central-differencing schemes, with explicitly added scalar and matrix-valued fourth-difference artificial dissipation, respectively, and a third-order accurate flux-difference splitting upwind scheme are implemented in a multigrid time-stepping procedure and applied to calculate laminar flow through a strongly curved duct. Extensive grid-refinement studies are carried out to investigate the grid sensitivity of each discretization approach. The calculations indicate that even the finest mesh employed, consisting of over 700,000 grid nodes, is not sufficient to establish grid independent solutions. However, all three schemes appear to converge toward the same solution as the grid spacing approaches zero. The matrix-valued dissipation scheme introduces the least amount of artificial dissipation and should be expected to yield the most accurate solutions on a given mesh. The flux-difference splitting upwind scheme, on the other hand, is more dissipative and, thus, particularly sensitive to grid resolution, but exhibits the best overall convergence characteristics on grids with large aspect ratios.
24
Zhao, Pengfei, Ge Mu, Menglu Chen, and Xin Tang. "Simulation of Resonant Cavity-Coupled Colloidal Quantum-Dot Detectors with Polarization Sensitivity." Coatings 12, no. 4 (April 7, 2022): 499. http://dx.doi.org/10.3390/coatings12040499.
Abstract:
Infrared detectors with polarization sensitivity could extend the information dimension of the detected signals and improve target recognition ability. However, traditional infrared polarization detectors with epitaxial semiconductors usually suffer from low extinction ratio, complexity in structure and high cost. Here, we report a simulation study of colloidal quantum dot (CQD) infrared detectors with monolithically integrated metal wire-grid polarizer and optical cavity. The solution processibility of CQDs enables the direct integration of metallic wire-grid polarizers with CQD films. The polarization selectivity of HgTe CQDs with resonant cavity-enhanced wire-grid polarizers are studied in both short-wave and mid-wave infrared region. The extinction ratio in short-wave and mid-wave region can reach up to 40 and 60 dB, respectively. Besides high extinction ratio, the optical cavity enhanced wire-grid polarizer could also significantly improve light absorption at resonant wavelength by a factor of 1.5, which leads to higher quantum efficiency and better spectral selectivity. We believe that coupling CQD infrared detector with wire-grid polarizer and optical cavity can become a promising way to realize high-performance infrared optoelectronic devices.
25
Ibrar, Muhammad, Muhammad Awais Hassan, Kamran Shaukat, Talha Mahboob Alam, Khaldoon Syed Khurshid, Ibrahim A. Hameed, Hanan Aljuaid, and Suhuai Luo. "A Machine Learning-Based Model for Stability Prediction of Decentralized Power Grid Linked with Renewable Energy Resources." Wireless Communications and Mobile Computing 2022 (August 23, 2022): 1–15. http://dx.doi.org/10.1155/2022/2697303.
Abstract:
A decentralized power grid is a modern system that implements demand response without requiring major infrastructure changes. In decentralization, the consumers regulate their electricity demand autonomously based on the grid frequency. With cheap equipment (i.e., smart meters), the grid frequency can be easily measured anywhere. Electrical grids need to be stable to balance electricity supply and demand to ensure economically and dynamically viable grid operation. The volumes of electricity consumed/produced (p) by each grid participant, cost-sensitivity (g), and grid participants’ response times (tau) to changing grid conditions affect the stability of the grid. Renewable energy resources are volatile on varying time scales. Due to the volatile nature of these renewable energy resources, there are more frequent fluctuations in decentralized grids integrating renewable energy resources. The decentralized grid is designed by linking real-time electricity rates to the grid frequency over a few seconds to provide demand-side control. In this study, a model has been proposed to predict the stability of a decentralized power grid. The simulated data obtained from the online machine learning repository has been employed. Data normalization has been employed to reduce the biased behavior among attributes. Various data level resampling techniques have been used to address the issue of data imbalance. The results showed that a balanced dataset outperformed an imbalanced dataset regarding classifiers’ performance. It has also been observed that oversampling techniques proved better than undersampling techniques and imbalanced datasets. Overall, the XGBoost algorithm outperformed all other machine learning algorithms based on performance. XGBoost has been given an accuracy of 94.7%, but while combining XGBoost with random oversampling, its accuracy prediction has been improved to 96.8%. This model can better predict frequency fluctuations in decentralized power grids and the volatile nature of renewable energy resources resulting in better utilization. This prediction may contribute to the stability of a decentralized power grid for better distribution and management of electricity.
26
Alpak, Faruk O., and Tianhong Chen. "Dynamic effects of fault modeling on stair-step and corner-point grids." Journal of Petroleum Exploration and Production Technology 11, no. 3 (February 6, 2021): 1323–38. http://dx.doi.org/10.1007/s13202-020-01082-1.
Abstract:
AbstractFault modeling has become an integral element of reservoir simulation for structurally complex reservoirs. Modeling of faults in general has major implications for the simulation grid. In turn, the grid quality control is very important in order to attain accurate simulation results. We investigate the dynamic effects of using stair-step grid (SSG) and corner-point grid (CPG) approaches for fault modeling from the perspective of dynamic reservoir performance forecasting. We have performed a number of grid convergence and grid-type sensitivity studies for a variety of simple, yet intuitive faulted flow simulation problems with gradually increasing complexity. We have also explored the added value of the multipoint flux approximation (MPFA) method over the conventional two-point flux approximation (TPFA) to increase the accuracy of reservoir simulation results obtained on CPGs. Effects of fault seal modeling on grid-resolution convergence and grid-type sensitivity have also been briefly examined. For simple geometries, both SSG and CPG can be used for fault modeling with similar accuracy in conjunction with the pillar-grid approach. This is evidenced by the fact that simulation results from SSG and CPG converge to identical solutions. SSG and CPG yield different results for more complex geometries. Simulation results approach to a converged solution for relatively fine SSGs. However, a SSG only provides an approximation to the fault geometry and reservoir volumes when the grid is coarse. On the other hand, non-orthogonality errors are increasingly evident in relatively more complex faulted models on CPGs and such errors cannot be addressed by grid refinement. It has been observed that MPFA partially addresses the discretization errors on non-orthogonal grids but only from the total flux accuracy perspective. However, transport related errors are still evident. Grid convergence behaviors and grid effects are quite similar with or without fault seal modeling (i.e., dedicated fault-zone modeling by use of scaled-up seal factors) for simple geometries. However, in more complex test cases, we have observed that it is more difficult to achieve converged results in conjunction with fault seal modeling due to increased heterogeneity of the underlying problem.
27
Xie, Jiaping, Weisi Zhang, Lihong Wei, Yu Xia, and Shengyi Zhang. "Price optimization of hybrid power supply chain dominated by power grid." Industrial Management & Data Systems 119, no. 2 (March 11, 2019): 412–50. http://dx.doi.org/10.1108/imds-01-2018-0041.
Abstract:
Purpose The purpose of this paper is to examine the impact of renewable energy on the power supply chain and to study whether the renewable generator or the power grid that purchases power from the power spot market is better when the actual generation of renewable energy is insufficient. The authors want to compare and analyze the different power supply chain operation modes and discuss the optimal mode selection for renewable energy generator and power grid in different situations. Design/methodology/approach This paper studies the grid-led price competition game in the power supply chain, in which the power grid as a leader decides the price of transmission and distribution, and generators determine the power grid price. The renewable energy power generator and the traditional energy power generator conduct a price competition game; on the other hand, the power grid and power generators conduct Stackelberg games. The authors analyze the power supply of single power generator and two power generators, respectively, and research on the situation that the renewable energy cannot be fully recharged when the actual power generation is insufficient. Findings The study finds that both renewable and traditional power grid prices decline as price sensitivity coefficient of demand and installed capacity of renewable energy generators increase. Power grid premium decreases as the price sensitivity coefficient of demand increases, but rises as the installed capacity of renewable energy generator increases. When there is a shortage of power, if the installed capacity of renewable energy is relatively small and price sensitivity coefficient of demand is relatively large, the grid purchases the power from power spot market and shares cost with renewable energy generators, leading to higher expected profits of the renewable energy generators. On the contrary, the renewable energy generators prefer to make up power shortage themselves. For the power grid, purchasing the power by the renewable energy generators when there is a power shortage can bring more utility to the power grid when the installed capacity of renewable energy is lower and the demand price sensitivity coefficient is higher. When the installed capacity of renewable energy is high and the price sensitivity coefficient of demand is moderate, or the installed capacity of renewable energy is moderate and the demand price sensitivity coefficient is high, a generator that simultaneously possesses two kinds of energy source will bring more utility to the power grid. If the installed capacity of renewable energy and the demand price sensitivity coefficient both are small or the installed capacity of renewable energy and the price sensitivity coefficient of demand both are large, the power grid prefers to purchase the power by itself when there is a power shortage. Practical implications The goal of our paper analysis is to explore the implications of the theoretical model and address the series of research questions regarding the impact of the renewable energy on the power supply chain. The results of this study have key implications for reality. This paper sheds light on the power supply chain operation mode selection, which can potentially be used for the renewable energy generators to choose their operating mode and can also help traditional energy generators and power grid enterprises maximize their utility. This paper also has some references for the government to formulate the corresponding renewable energy development policy. Originality/value This paper studies the power operation mode under the uncertainty of supply and demand, and compares the advantages and disadvantages of renewable energy generator that makes up the shortage or the power grid purchases the power from power spot market then shares cost with the renewable energy generator. This paper analyzes the power grid-led coordination problem in a power supply chain, compares and analyzes the price competition game model of single power generator and dual power generators, and compares the different risk preferences of power grid.
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Sun, Jianlei, David Schechter, and Chung-Kan Huang. "Grid-Sensitivity Analysis and Comparison Between Unstructured Perpendicular Bisector and Structured Tartan/Local-Grid-Refinement Grids for Hydraulically Fractured Horizontal Wells in Eagle Ford Formation With Complicated Natural Fractures." SPE Journal 21, no. 06 (July 15, 2016): 2260–75. http://dx.doi.org/10.2118/177480-pa.
Abstract:
Summary In the context of modeling fractured horizontal wells, unstructured grids have been applied to generate simulation meshes for complex fracture networks. It is necessary to investigate how to choose an unstructured mesh to accurately simulate production performance. In this paper, a new unstructured gridding and discretization work flow is proposed to handle nonorthogonal and low-angle intersections of extensively clustered fractures with nonuniform apertures. The work flow is then validated with two models in terms of production behavior and central-processing-unit (CPU) performance: a synthetic model with one horizontal well and orthogonal intersected hydraulic fractures built by tartan grid, and a field-scale local-grid-refinement (LGR) model with three horizontal wells and irregular hydraulic fractures in a slightly dipping reservoir created by a commercial software plug-in. Good-quality matches are obtained between unstructured and structured grids in both pressure and production behavior. Sensitivity analysis of the meshing parameters suggests that refinement in the vicinity of fractures has improved both early and late production of a well, whereas background density has a dominant effect on the late production. Background-grid type and orientation have less influence as long as they have the same grid density. Fewer cells can be achieved by increasing reservoir-background size and size-progression ratio, replacing unstructured-background grids with structured grids, and reducing the complexity of the fracture networks without loss of the accuracy, resulting in improved CPU performance. This study applies unstructured grids to simulate multiple horizontal wells with complicated fracture networks, and provides detailed comparisons between unstructured and structured grids. Most importantly, it resolves the question regarding how to choose an appropriate mesh to yield both accurate results and high-quality CPU performance.
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Skinner, Christopher J., and Thomas J. Coulthard. "Testing the sensitivity of the CAESAR-Lisflood landscape evolution model to grid cell size." Earth Surface Dynamics 11, no. 4 (July 28, 2023): 695–711. http://dx.doi.org/10.5194/esurf-11-695-2023.
Abstract:
Abstract. Landscape evolution models (LEMs) are useful for understanding how large-scale processes and perturbations influence the development of the surface of the Earth and other planets. With their increasing sophistication and improvements in computational power, they are finding greater uptake in analyses at finer spatial and temporal scales. For many LEMs, the land surface is represented by a grid of regularly spaced and sized grid cells, or pixels, referred to as a digital elevation model (DEM), yet despite the importance of the DEM to LEM studies, there has been little work to understand the influence of grid cell size (i.e. resolution) on model behaviour. This is despite the choice of grid cell size being arbitrary for many studies, with users needing to balance detail with computational efficiency. Using the Morris method (MM) for global sensitivity analysis, the sensitivity of the CAESAR-Lisflood LEM to the grid cell size is evaluated relative to a set of influential user-defined parameters, showing that it had a similar level of influence as a key hydrological parameter and the choice of sediment transport law. Outputs relating to discharge and sediment yields remained stable across different grid cell sizes until the cells became so large that the representation of the hydrological network degraded. Although total sediment yields remained steady when changing the grid cell sizes, closer analysis revealed that using a coarser grid resulted in it being built up from fewer yet more geomorphically active events, risking outputs that are “the right answer but for the wrong reasons”. These results are important considerations for modellers using LEMs and the methodologies detailed provide solutions to understanding the impacts of modelling choices on outputs.
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Deilami, Sara. "Online Coordination of Plug-In Electric Vehicles Considering Grid Congestion and Smart Grid Power Quality." Energies 11, no. 9 (August 21, 2018): 2187. http://dx.doi.org/10.3390/en11092187.
Abstract:
This paper first introduces the impacts of battery charger and nonlinear load harmonics on smart grids considering random plug-in of electric vehicles (PEVs) without any coordination. Then, a new centralized nonlinear online maximum sensitivity selection-based charging algorithm (NOL-MSSCA) is proposed for coordinating PEVs that minimizes the costs associated with generation and losses considering network and bus total harmonic distortion (THD). The aim is to first attend the high priority customers and charge their vehicles as quickly as possible while postponing the service to medium and low priority consumers to the off-peak hours, considering network, battery and power quality constraints and harmonics. The vehicles were randomly plugged at different locations during a period of 24 h. The proposed PEV coordination is based on the maximum sensitivity selection (MSS), which is the sensitivity of losses (including fundamental and harmonic losses) with respect to the PEV location (PEV bus). The proposed algorithm uses the decoupled harmonic power flow (DHPF) to model the nonlinear loads (including the PEV chargers) as current harmonic sources and computes the harmonic power losses, harmonic voltages and THD of the smart grid. The MSS vectors are easily determined using the entries of the Jacobian matrix of the DHPF program, which includes the spectrums of all injected harmonics by nonlinear electric vehicle (EV) chargers and nonlinear industrial loads. The sensitivity of the objective function (fundamental and harmonic power losses) to the PEVs were then used to schedule PEVs accordingly. The algorithm successfully controls the network THDv level within the standard limit of 5% for low and moderate PEV penetrations by delaying PEV charging activities. For high PEV penetrations, the installation of passive power filters (PPFs) is suggested to reduce the THDv and manage to fully charge the PEVs. Detailed simulations considering random and coordinated charging were performed on the modified IEEE 23 kV distribution system with 22 low voltage residential networks populated with PEVs that have nonlinear battery chargers. Simulation results are provided without/with filters for different penetration levels of PEVs.
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Faizal, W. M., C. Y. Khor, N. N. N. Ghazali, and M. Z. Zainon. "Grid sensitivity studies for validation of human upper airways." IOP Conference Series: Materials Science and Engineering 932 (December 18, 2020): 012107. http://dx.doi.org/10.1088/1757-899x/932/1/012107.
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Panja, Palash, Tyler Conner, and Milind Deo. "Grid sensitivity studies in hydraulically fractured low permeability reservoirs." Journal of Petroleum Science and Engineering 112 (December 2013): 78–87. http://dx.doi.org/10.1016/j.petrol.2013.10.009.
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Luke, P. N., M. Amman, J. S. Lee, and H. Yaver. "Coplanar-grid CdZnTe detector with three-dimensional position sensitivity." Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 439, no. 2-3 (January 2000): 611–18. http://dx.doi.org/10.1016/s0168-9002(99)00873-6.
34
Stojkovic, Z., M. S. Savic, J. M. Nahman, D. Salamon, and B. Bukorovic. "Sensitivity analysis of experimentally determined grounding grid impulse characteristics." IEEE Transactions on Power Delivery 13, no. 4 (1998): 1136–42. http://dx.doi.org/10.1109/61.714473.
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Nwankwo, Chinonso, and Weizhong Dai. "Local Refinement and Adaptive Strategy for a System of Free Boundary Power Options with High Order Compact Differencing." Axioms 12, no. 6 (June 17, 2023): 602. http://dx.doi.org/10.3390/axioms12060602.
Abstract:
In this research, we propose fourth-order non-uniform Hermitian differencing with a fifth-order adaptive time integration method for pricing system of free boundary exotic power put options consisting of the option value, delta sensitivity, and gamma. The main objective for implementing the above scheme is to carefully account for the irregularity in the locality of the left corner point after fixing the free boundary. Specifically and mainly, we stretch the performance of our proposed method threefold. First, we exploit the non-uniform fourth-order Hermitian scheme to locally concentrate space grid points arbitrarily close to the left boundary. Secondly, we further leverage the adaptive nature of the embedded time integration method, which allows optimal selection of a time step based on the space grid point distribution and regional variation. Thirdly, we introduce a fourth-order combined Hermitian scheme, which requires fewer grid points for computing the near boundary point of the delta sensitivity and gamma. Another novelty is how we approximate the optimal exercise boundary and its derivative using a fifth-order Robin boundary scheme and fourth-order combined Hermitian scheme. Our proposed method consistently achieves reasonable accuracy with very coarse grids and little runtime across the numerical experiments. We further compare the results with existing methods and the ones we obtained from the uniform space grid.
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Zarzycki, Colin M., Kevin A. Reed, Julio T. Bacmeister, Anthony P. Craig, Susan C. Bates, and Nan A. Rosenbloom. "Impact of surface coupling grids on tropical cyclone extremes in high-resolution atmospheric simulations." Geoscientific Model Development 9, no. 2 (February 25, 2016): 779–88. http://dx.doi.org/10.5194/gmd-9-779-2016.
Abstract:
Abstract. This paper discusses the sensitivity of tropical cyclone climatology to surface coupling strategy in high-resolution configurations of the Community Earth System Model. Using two supported model setups, we demonstrate that the choice of grid on which the lowest model level wind stress and surface fluxes are computed may lead to differences in cyclone strength in multi-decadal climate simulations, particularly for the most intense cyclones. Using a deterministic framework, we show that when these surface quantities are calculated on an ocean grid that is coarser than the atmosphere, the computed frictional stress is misaligned with wind vectors in individual atmospheric grid cells. This reduces the effective surface drag, and results in more intense cyclones when compared to a model configuration where the ocean and atmosphere are of equivalent resolution. Our results demonstrate that the choice of computation grid for atmosphere–ocean interactions is non-negligible when considering climate extremes at high horizontal resolution, especially when model components are on highly disparate grids.
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Zarzycki, C. M., K. A. Reed, J. Bacmeister, A. P. Craig, S. C. Bates, and N. A. Rosenbloom. "Impact of ocean coupling strategy on extremes in high-resolution atmospheric simulations." Geoscientific Model Development Discussions 8, no. 9 (September 11, 2015): 7983–8007. http://dx.doi.org/10.5194/gmdd-8-7983-2015.
Abstract:
Abstract. This paper discusses the sensitivity of tropical cyclone climatology to ocean coupling strategy in high-resolution configurations of the Community Earth System Model. Using two supported model setups, we demonstrate that the choice of grid on which the lowest model level wind stress and surface fluxes are computed may lead to differences in cyclone strength in multi-decadal climate simulations, particularly for the most intense cyclones. Using a deterministic framework, we show that when these surface quantities are calculated on an ocean grid that is coarser than the atmosphere, the computed frictional stress is misaligned with wind vectors in individual atmospheric grid cells. This reduces the effective surface drag, and results in more intense cyclones when compared to a model configuration where the ocean and atmosphere are of equivalent resolution. Our results demonstrate that the choice of computation grid for atmosphere/ocean interactions is non-negligible when considering climate extremes at high horizontal resolution, especially when model components are on highly disparate grids.
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Beláň, Anton, Boris Cintula, Matej Cenký, Peter Janiga, Jozef Bendík, Žaneta Eleschová, and Adam Šimurka. "Measurement of Static Frequency Characteristics of Home Appliances in Smart Grid Systems." Energies 14, no. 6 (March 21, 2021): 1739. http://dx.doi.org/10.3390/en14061739.
Abstract:
The current transformation of power systems is aiming towards distributed source integration and general decentralization. Renewable energy sources and support of local energy supply create conditions for widespread use of new technologies and smart grids. As the electrical grids become more electrically independent, the importance of frequency control will rise. Stability of the system in such cases is no longer only relying on rotating inertia of generators as in the centralized grid. This known scenario has already been analyzed by many with computational models for optimal safety precautions of the grid. This paper aims to update the common home appliance frequency characteristics through measurements and compare them to those currently used. These devices were divided into two groups: general categorization and light sources. Subsequently, the frequency sensitivity coefficients were evaluated and analyzed home appliances were sorted into three categories according to the size of their frequency sensitivity coefficient values: positive, negative, and no effect. The results were compared with studies aimed at evaluating the static load characteristics. A simplified simulation of the frequency control, presented in the discussion section, was carried out to determine the consequences of the newly measured characteristics and concludes the paper.
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Potvin, Corey K., and Montgomery L. Flora. "Sensitivity of Idealized Supercell Simulations to Horizontal Grid Spacing: Implications for Warn-on-Forecast." Monthly Weather Review 143, no. 8 (August 1, 2015): 2998–3024. http://dx.doi.org/10.1175/mwr-d-14-00416.1.
Abstract:
Abstract The Warn-on-Forecast (WoF) program aims to deploy real-time, convection-allowing, ensemble data assimilation and prediction systems to improve short-term forecasts of tornadoes, flooding, lightning, damaging wind, and large hail. Until convection-resolving (horizontal grid spacing Δx < 100 m) systems become available, however, resolution errors will limit the accuracy of ensemble model output. Improved understanding of grid spacing dependence of simulated convection is therefore needed to properly calibrate and interpret ensemble output, and to optimize trade-offs between model resolution and other computationally constrained parameters like ensemble size and forecast lead time. Toward this end, the authors examine grid spacing sensitivities of simulated supercells over Δx of 333 m–4 km. Storm environment and physics parameterization are varied among the simulations. The results suggest that 4-km grid spacing is too coarse to reliably simulate supercells, occasionally leading to premature storm demise, whereas 3-km simulations more often capture operationally important features, including low-level rotation tracks. Further decreasing Δx to 1 km enables useful forecasts of rapid changes in low-level rotation intensity, though significant errors remain (e.g., in timing). Grid spacing dependencies vary substantially among the experiments, suggesting that accurate calibration of ensemble output requires better understanding of how storm characteristics, environment, and parameterization schemes modulate grid spacing sensitivity. Much of the sensitivity arises from poorly resolving small-scale processes that impact larger (well resolved) scales. Repeating some of the 333-m simulations with coarsened initial conditions reveals that supercell forecasts can substantially benefit from reduced grid spacing even when limited observational density precludes finescale initialization.
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Then, Daniel, Johannes Bauer, Tanja M. Kneiske, and Martin Braun. "Interdependencies of Infrastructure Investment Decisions in Multi-Energy Systems—A Sensitivity Analysis for Urban Residential Areas." Smart Cities 4, no. 1 (January 8, 2021): 112–45. http://dx.doi.org/10.3390/smartcities4010007.
Abstract:
Considering the European Union (EU) climate targets, the heating sector should be decarbonized by 80% to 95% up to 2050. Thus, the macro-trends forecast increasing energy efficiency and focus on the use of renewable gas or the electrification of heat generation. This has implications for the business models of urban electricity and in particular natural gas distribution network operators (DNOs): When the energy demand decreases, a disproportionately long grid is operated, which can cause a rise of grid charges and thus the gas price. This creates a situation in which a self-reinforcing feedback loop starts, which increases the risk of gas grid defection. We present a mixed integer linear optimization model to analyze the interdependencies between the electricity and gas DNOs’ and the building owners’ investment decisions during the transformation path. The results of the investigation in a real grid area are used to validate the simulation setup of a sensitivity analysis of 27 types of building collectives and five grid topologies, which provides a systematic insight into the interrelated system. Therefore, it is possible to identify building and grid configurations that increase the risk of a complete gas grid shutdown and those that should be operated as a flexibility option in a future renewable energy system.
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Then, Daniel, Johannes Bauer, Tanja Kneiske, and Martin Braun. "Interdependencies of Infrastructure Investment Decisions in Multi-Energy Systems—A Sensitivity Analysis for Urban Residential Areas." Smart Cities 4, no. 1 (January 8, 2021): 112–45. http://dx.doi.org/10.3390/smartcities4010007.
Abstract:
Considering the European Union (EU) climate targets, the heating sector should be decarbonized by 80 to 95% up to 2050. Thus, the macro-trends forecast increasing energy efficiency and focus on the use of renewable gas or the electrification of heat generation. This has implications for the business models of urban electricity and in particular natural gas distribution network operators (DNOs): When the energy demand decreases, a disproportionately long grid is operated, which can cause a rise of grid charges and thus the gas price. This creates a situation in which a self-reinforcing feedback loop starts, which increases the risk of gas grid defection. We present a mixed integer linear optimization model to analyze the interdependencies between the electricity and gas DNOs’ and the building owners’ investment decisions during the transformation path. The results of the investigation in a real grid area are used to validate the simulation setup of a sensitivity analysis of 27 types of building collectives and five grid topologies, which provides a systematic insight into the interrelated system. Therefore, it is possible to identify building and grid configurations that increase the risk of a complete gas grid shutdown and those that should be operated as a flexibility option in a future renewable energy system.
42
Mohd Sakri, Fadhilah, Mohamed Sukri Mat Ali, and Sheikh Ahmad Zaki. "Benchmark on the Dynamics of Liquid Draining Inside a Tank." E3S Web of Conferences 95 (2019): 02009. http://dx.doi.org/10.1051/e3sconf/20199502009.
Abstract:
Immense information and details observation of flow physics inside a draining tank can be achieved by adopting reliable numerical simulations. Yet the accuracy of numerical results has been always debatable and it is mainly affected by the grid convergence error and computational modeling approaches. Hence, this study is divided into two stages. In the first stage, this paper determines a systematic method of refining a computational grid for a liquid draining inside a tank using OpenFOAM software. The sensitivity of the computed flow field on different mesh resolutions is also examined. In order to study the effect of grid dependency, three different grid refinements are investigated: fine, medium and coarse grids. By using a form of Richardson extrapolation and Grid Convergence Index (GCI), the level of grid independence is attained. In this paper, a monotonic convergence criteria is reached when the fine grid has the GCI value below 10% for each parameter. In the second stage, different computational modeling approaches (DNS, RANS k-ε, RANS k-ω and LES turbulence models) are investigated using the finer grid from the first stage. The results for the draining time and flow visualization of the generation of an air-core are in a good agreement with the available published data. The Direct Numerical Simulation (DNS) seems most reasonably satisfactory for VOF studies relating air-core compared to other different turbulence modeling approaches.
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Liu, Wang, Wang, Zhu, and Lio. "Active Power Dispatch for Supporting Grid Frequency Regulation in Wind Farms Considering Fatigue Load." Energies 12, no. 8 (April 21, 2019): 1508. http://dx.doi.org/10.3390/en12081508.
Abstract:
This paper proposes an active power control method for supporting grid frequency regulation in wind farms (WF) considering improved fatigue load sensitivity of wind turbines (WT). The control method is concluded into two parts: frequency adjustment control (FAC) and power reference dispatch (PRD). On one hand, the proposed Fuzzy-PID control method can actively maintain the balance between power generation and grid load, by which the grid frequency is regulated when plenty of winds are available. The fast power response can be provided and frequency error can be reduced by the proposed method. On the other hand, the sensitivity of the WT fatigue loads to the power references is improved. The explicit analytical equations of the fatigue load sensitivity are re-derived to improve calculation accuracy. In the process of the optimization dispatch, the re-defined fatigue load sensitivity will be used to minimize fatigue load. Case studies were conducted with a WF under different grid loads and turbulent wind with different intensities. By comparing the frequency response of the WF, rainflow cycle, and Damage Equivalent Load (DEL) of the WT, the efficacy of the proposed method is verified.
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Mirhosseini, Mitra. "Sensitivity analysis, adaptability improvement and control of grid-connected photovoltaic power plants under grid frequency variations." Solar Energy 184 (May 2019): 260–72. http://dx.doi.org/10.1016/j.solener.2019.03.072.
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Rodrigues, Justino, Carlos Moreira, and João Peças Lopes. "Fault-Ride-Through Approach for Grid-Tied Smart Transformers without Local Energy Storage." Energies 14, no. 18 (September 7, 2021): 5622. http://dx.doi.org/10.3390/en14185622.
Abstract:
The Smart Transformer (ST) is being envisioned as the possible backbone of future distribution grids given the enhanced controllability it provides. Moreover, the ST offers DC-link connectivity, making it an attractive solution for the deployment of hybrid AC/DC distribution grids which offer important advantages for the deployment of Renewable Energy Sources, Energy Storage Systems (ESSs) and Electric Vehicles. However, compared to traditional low-frequency magnetic transformers, the ST is inherently more vulnerable to fault disturbances which may force the ST to disconnect in order to protect its power electronic converters, posing important challenges to the hybrid AC/DC grid connected to it. This paper proposes a Fault-Ride-Through (FRT) strategy suited for grid-tied ST with no locally available ESS, which exploits a dump-load and the sensitivity of the hybrid AC/DC distribution grid’s power to voltage and frequency to provide enhanced control to the ST in order to handle AC-side voltage sags. The proposed FRT strategy can exploit all the hybrid AC/DC distribution grid (including the MV DC sub-network) and existing controllable DER resources, providing FRT against balanced and unbalanced faults in the upstream AC grid. The proposed strategy is demonstrated in this paper through computational simulation.
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Bruning, Jhosefe, Adroaldo D. Robaina, Marcia X. Peiter, Miguel Chaiben Neto, Silvana A. Rodrigues, Laura D. Ferreira, Tonismar dos S. Pereira, and Luiz P. Kayser. "Economic performance of off-grid photovoltaic systems for irrigation." Revista Brasileira de Engenharia Agrícola e Ambiental 27, no. 1 (January 2023): 57–63. http://dx.doi.org/10.1590/1807-1929/agriambi.v27n1p57-63.
Abstract:
ABSTRACT Renewable energies are alternatives to replace fossil fuels and are crucial for the sustainability of the agricultural sector, besides being an important alternative for pumping water in irrigation. Thus, understanding revenues and expenses is fundamental in economic feasibility. Therefore, the aim of this study was to assess the behavior of economic indicators in off-grid solar energy system for irrigation based on different scenarios. Photovoltaic projects were developed for different irrigation powers ranging from 0.736 to 22.1 kW, and the costs for implementation and operation, as well as the occurrence of economy of scale were evaluated, and the levelized cost of energy for each power analyzed was determined. In addition, sensitivity analyses were performed, considering the variation in product price and investment cost, to demonstrate the responses in relation to economic indicators. Photovoltaic energy projects showed increasing costs with the increase in power, and the normalized cost per kW followed an economy of scale, while the levelized cost of energy showed feasibility, except for the power of 22.1 kW. The sensitivity analyses showed profitability for the analyzed configurations.
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Liu, Tuo, and Yi Zhang. "Research on Optimization Model of Overseas Investment for Power Grid Enterprise." Applied Mechanics and Materials 672-674 (October 2014): 1409–12. http://dx.doi.org/10.4028/www.scientific.net/amm.672-674.1409.
Abstract:
Basing on the Monte Carlo, this paper established a strategy planning model for international business strategic of power grid enterprise, by which estimating the possibility and sensitivity of a power grid enterprise.
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Roy, Rajib Baran, Sanath Alahakoon, and Shantha Jayasinghe Arachchillage. "Grid Impacts of Uncoordinated Fast Charging of Electric Ferry." Batteries 7, no. 1 (February 17, 2021): 13. http://dx.doi.org/10.3390/batteries7010013.
Abstract:
The battery energy storage system (BESS) is an indispensable part of an electric fleet (EF) which needs to be charged by electricity from local grid when the fleet is in the dockyard. The uncoordinated fast charging of BESS in Grid to Ferry (G2F) mode imposes sudden increments of load in the power grid, which is analyzed by a simulated model of grid connected marine load. The probable impact on system stability is examined by MATLAB Simulink and Power World Simulator based models. According to simulation results for IEEE 5 bus system, voltage unbalance factors are 0.01% and 200% for all buses at fundamental and third harmonics frequencies, respectively. The total harmonic distortion (THD) at fundamental frequency becomes 0.16%, 0.16%, and 0.18%, respectively, for three cases. The transient, voltage reactive power (V-Q), and voltage real power (V-P) sensitivity analysis are performed for 7 bus system with load increment contingencies. According to simulation results, the V-Q sensitivity for the assigned contingency is increased by the addition of a shunt generator to the load bus with lowest bus voltage. In case of V-P sensitivity for the selected contingency, the load buses share power among them, and the nose point is attained at maximum shift of power with high V-Q sensitivity.
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Ou, Rui, Wen Jiang, Yuqing Zhou, Wenzuo Tang, Yi Zhang, and Kai He. "Correlation Study Between Cooling Load and Temperature Sensitivity Considering the Cumulative Effect of Temperature." Journal of Physics: Conference Series 2503, no. 1 (May 1, 2023): 012007. http://dx.doi.org/10.1088/1742-6596/2503/1/012007.
Abstract:
Abstract To study the correlation between cooling load and air temperature, this paper uses the maximum load comparison method to calculate the cooling load based on the actual load data of the power grid, and uses the temperature correction model to correct the daily maximum temperature, and then establishes a high-order regression model of cooling load and corrected air temperature. The method is applied to the sensitivity analysis of cooling load and air temperature in the Chongqing power grid and sub-regions, and the corresponding change law is obtained, which provides an important reference basis for the production and dispatch, optimal operation, and marketing of the power grid.
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Cusandei, Rodrigo Mendes Batista. "SAGD process: a match up simulation and grid sensitivity analysis." Latin American Journal of Energy Research 1, no. 1 (June 26, 2014): 21–29. http://dx.doi.org/10.21712/lajer.2014.v1.n1.p21-29.
Abstract:
The use of fuel from bitumen has become highly demanded in the past years not only in Canada, but in many other countries, and it will still be one of the main sources of energy in the next decades. Also, new technologies for the exploration of these reserves are also being highly stimulated to achieve the huge amount of oil found in these reservoirs. For oil sands in Canada, the SAGD process is vastly used by all companies. It involves two horizontal parallels wells, usually located 5 meters apart from one another, one for the injection of steam, and the other for the producer of the heated oil. In this paper, two cases were analyzed, one is a match up reservoir simulation with a previous case paper, and the other is a grid sensitivity analysis for a new reservoir model. All the simulations were performed by CMG STARS simulator. For the match up case, it is noticed that every parameter is important in order to have similar plots in both simulations. Some parameters were used as default values; therefore, some results were slightly different. For the grid sensitivity case, the grid distribution plays a role in the results. Although the results were slightly shifted to one another, it can be seen that, the finer is the reservoir, the more detailed the results are. Plots such as cumulative oil, water and oil rates were shown in order to give a complete conclusion about the model in analysis.