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[IEEE 2019 IEEE International Conference on Automatic Control and Intelligent Systems (I2CACIS) - Selangor, Malaysia (2019.6.29-2019.6.29)] 2019 IEEE International Conference on Automatic Control and Intelligent Systems (I2CACIS) - Limiting THD of Grid Connected Photovoltaic System using PWM Switching Frequency Selection Based on Solar Irradiance Changing
摘要： Photovoltaic (PV) system becomes the best alternative energy to produce electricity that can replace fuel resource. Grid Connected Photovoltaic (GC-PV) system will supply the AC power generated to the utility grid then distributed to the consumer. Solar irradiance in Malaysia varies daily and throughout the year. The consequence of low irradiance level is the output of the PV array is low and thus the input of the inverter relatively becoming low. The inverter will exhibit large non-linearity when the inverter is operating at low power input during low level of solar irradiance and Total Harmonic Distortion (THD) will increased. Pulse Width Modulation (PWM) techniques that are Continuous Pulse Width Modulation (CPWM) and Discontinuous PWM (DPWM) are implemented in the inverter control of the GC-PV system using MATLAB/Simulink environment to investigate the effect of switching frequency on THD at different level of solar irradiance. THD is limit within standard requirement by selecting appropriate value of switching frequency. Results shows that CPWM has better performance in THD and switching losses at selected switching frequency.
关键词： total harmonic distortion,inverter,pulse width modulation,switching frequency,grid connected photovoltaic,solar irradiance
更新于2025-09-11 14:15:04
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Microstructure by design: An approach of grain refinement and isotropy improvement in multi-layer wire-based laser metal deposition
摘要： The additive production of metallic components with high-throughput is usually associated with high process temperatures and slow cooling rates. This typically results in strongly oriented columnar grain growth along the building direction of the structure having exceedingly large grain sizes. As a result, such structures show typically low strength and anisotropic mechanical behaviour in as-deposited condition. Consequently, post-processing is commonly performed to homogenize and eventually increase the mechanical properties of the deposited structures. In this regard, precise control of the applied process energy allows a modification of the local temperature distribution and cooling conditions during the additive manufacturing process, which strongly influence the resulting solidification microstructure. The aim of the present study is the development of an approach that allows to influence the solidification conditions in wire-based laser metal deposition of an Al-Mg alloy through specific adjustments of the laser irradiation. It was found that significantly different solidification microstructures in as-deposited condition can be achieved by adjusting the laser beam irradiance within a range resulting in conduction mode welding conditions while keeping the heat input constant. The application of high laser beam irradiances, close to the transition to keyhole mode welding, results in structures with a homogeneous large-grained solidification microstructure exhibiting a degree of anisotropy of around 12% between building direction and the direction of deposition. In contrast, the use of low laser beam irradiances close to the lower limit of stable melting, results in structures with a significantly refined microstructure. Consequently, an increase of yield strength of up to 16% and microhardness of up to 13%, as compared to structures processed with high laser beam irradiance, could be obtained. Moreover, the anisotropy of the as-deposited structure was reduced to a degree lower than 2%.
关键词： Direct Energy Deposition,Aluminium Alloy,Laser Metal Deposition,Additive Manufacturing,Laser Irradiance,Grain Refinement
更新于2025-09-11 14:15:04
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Analysis Performance of Grid Tie Photovoltaic Type Polycrystalline Using Solar Irradiance Simulation
摘要： Indonesia is a country consisting of several islands some of which are still not covered by electricity. It is this source of PV that can be used to meet the needs of people who are not yet affordable with PLN electricity. Basically, PV includes the generation of new renewable energy types. This new form of energy comes from sunlight. Using semiconductor materials can convert energy from sunlight to electrical energy. Because in Indonesia this includes tropical climates located on the equator line, making Indonesia has a very high intensity of light. Several factors affect electrical energy, namely the extent of PV to be used, the total irradiance received by PV, the decrease in performance due to weather and cleanliness of the PV used such as snow and oiliness. In this study explained the Analysis of Irradian-based Grid Tie photovoltaic performance with Polycrystalline PV types. Taking irradian data using a Solar Power Meter, irradiance and temperature data at a certain time will use the Incremental Maximum Power Point Tracking (MPPT) method, DC-DC boost converter, inverter, voltage source converter (VSC) using algorithm and equipment controls connected to network. This research is simulated using Matlab with the Simulink program.
关键词： Irradiance,PVArray,MPPT,Temperature,Grid,Solar Photovoltaic
更新于2025-09-11 14:15:04
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Field Demonstration Of A Nanophotonics Enabled Solar Membrane Distillation Reactor For Desalination
摘要： Nanophotonics Enhanced Solar Membrane Distillation (NESMD) is a highly innovative process that overcomes the intrinsic limitation of membrane distillation (MD) in energy consumption, thermal efficiency, and scalability. It applies nanophotonic materials based photothermal coating on a commercial PTFE membrane surface. The coating serves as a solar-thermal collector, absorbs sunlight, and generates highly localized heat, while the rest of the membrane performs the MD function. In the current work, an original pilot-scale NESMD reactor was designed, developed, built and tested at 29.7174° N, 95.4018° W to investigate the capability of NESMD reactor to desalinate 40 g/l NaCl solution under different intensities of solar irradiance. The preliminary experimental data showed a 99.8% salt removal with a water flux ranging between 0.12 LMH (Liter/m2 hr) at 88 W/m2 (cloudy condition) and 0.77 LMH (Liter/m2 hr) at 1012 W/m2 with an average water flux of 0.55 LMH without energy recovery. Further investigations and improvements are required to enhance the performance of the reactor since it is still a new technology.
关键词： thermal efficiency,water flux,Solar membrane distillation,photothermal coating,solar irradiance
更新于2025-09-11 14:15:04
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Solar irradiance estimations for modeling the variability of photovoltaic generation and assessing violations of grid constraints: A comparison between satellite and pyranometers measurements with load flow simulations
摘要： Global horizontal irradiance (GHI) is typically used to model the power output of distributed photovoltaic (PV) generation. On the one hand, satellite estimations are nonpervasive and already available from commercial providers, but they have a limited spatiotemporal resolution. On the other hand, local estimations, e.g., from pyranometers, sky-cameras, and monitored PV plants, capture local irradiance patterns and dynamics, but they require in situ monitoring infrastructure and upgrading the asset of electrical operators. Considering that in most power systems, PV generation is typically the aggregated contribution of many distributed plants, are local GHI estimations necessary to characterize the variability of the power ?ow at the grid connection point (GCP) and detect violations of the limits of voltages and line currents accurately? To reply, we consider GHI measurements from a dense network of pyranometers (used to model the ground truth GHI potential), satellite estimations for the same area, and information about a medium and low voltage distribution system. We perform load ?ows at different levels of installed PV capacity and compare the nodal voltages, line currents, and the power at the GCP when the irradiance is from pyranometers and when from satellite estimations, deriving conclusions on the necessity, or not, of highly spatiotemporally resolved irradiance estimations.
关键词： solar irradiance,grid constraints,satellite measurements,pyranometers,load flow simulations,photovoltaic generation
更新于2025-09-11 14:15:04
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[IEEE 2018 International Joint Conference on Neural Networks (IJCNN) - Rio de Janeiro (2018.7.8-2018.7.13)] 2018 International Joint Conference on Neural Networks (IJCNN) - Estimation of global solar irradiance with LDR sensor and artificial neural network embedded in an 8-bit microcontroller
摘要： This work deals with the estimation of global solar irradiance in an embedded platform through the use of a Light Dependent Resistor (LDR) sensor and its temperature. A prototype is built and has its values compared to the data obtained through a commercial pyranometer. An Multilayer Perceptron neural network is used to provide a non-linear regression between the voltage and temperature signals of the LDR on the commercial sensor irradiance data in a data analysis software. A regression with determination coef?cient of 96.466 % and with mean squared error of 0.04 was obtained. The neural network present in the embedded system has 100% accuracy in relation to the neural network present in the data analysis software used. The minimum response time of the prototype is 13.49 ms and its dissipated power is 27.2 mW, making the approach quite promising. This neural estimation, using simple sensors like the LDR, can help to reduce the cost of renewable energy applications and make it easier to implement.
关键词： solar irradiance,renewable energies,nonlinear regression,embedded systems,light dependent resistor,multilayer perceptron
更新于2025-09-10 09:29:36
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A Long-Term Dissipation of the EUV He?ii (30.4 nm) Segmentation in Full-Disk Solar Images
摘要： Some quiet-Sun days observed by the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO) during the time interval in 2010 – 2017 were used to continue our previous analyses reported by Didkovsky and Gurman (Solar Phys. 289, 153, 2014a) and Didkovsky, Wieman, and Korogodina (Solar Phys. 292, 32, 2017). The analysis consists of determining and comparing spatial spectral ratios (spectral densities over some time interval) from spatial (segmentation-cell length) power spectra. The ratios were compared using modeled compatible spatial frequencies for spectra from the Extreme ultraviolet Imaging Telescope (EIT) on-board the Solar and Heliospheric Observatory (SOHO) and from AIA images. With the new AIA data added to the EIT data we analyzed previously, the whole time interval from 1996 to 2017 reported here is approximately the length of two “standard” solar cycles (SC). The spectral ratios of segmentation-cell dimension structures show a signi?cant and steady increase with no detected indication of SC-related returns to the values that characterize the SC minima. This increase in spatial power at high spatial frequencies is interpreted as a dissipation of medium-size EUV network structures to smaller-size structures in the transition region. Each of the latest ratio changes for 2010 through 2017 spectra calculated for a number of consecutive short-term intervals has been converted into monthly mean ratio (MMR) changes. The MMR values demonstrate variable sign and magnitudes, thus con?rming the solar nature of the changes. These changes do not follow a “typical” trend of instrumental degradation or a long-term activity pro?le from the He II (30.4 nm) irradiance measured by the Extreme ultraviolet Spectrophotometer (ESP) either. The ESP is a channel of the Extreme ultraviolet Variability Experiment (EVE) on-board SDO.
关键词： Solar cycle, observations,Solar irradiance,Granulation
更新于2025-09-10 09:29:36
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An Ensemble Framework For Day-Ahead Forecast of PV Output in Smart Grids
摘要： The uncertainty associated with solar photo-voltaic (PV) power output is a big challenge to design, manage and implement effective demand response and management strategies. Therefore, an accurate PV power output forecast is an utmost importance to allow seamless integration and a higher level of penetration. In this research, a neural network ensemble (NNE) scheme is proposed, which is based on particle swarm optimization (PSO) trained feedforward neural network (FNN). Five different FFN structures with varying network complexities are used to achieve the diverse and accurate forecast results. These results are combined using trim aggregation after removing the upper and lower forecast error extremes. Correlated variables namely wavelet transformed historical power output of PV, solar irradiance, wind speed, temperature and humidity are applied as inputs to the multivariate NNE. Clearness index is used to classify days into clear, cloudy and partial cloudy days. Test case studies are designed to predict the solar output for these days selected from all seasons. The performance of the proposed framework is analyzed by applying training data set of different resolution, length and quality from seven solar PV sites of the University of Queensland, Australia. The forecast results demonstrate that the proposed framework improves the forecast accuracy significantly in comparison with individual and benchmark models.
关键词： clear day (CD),solar irradiance,cloudy day (CLD),clearness index,PV power output forecasting,ensemble network (EN),neural network ensemble (NNE),partially cloudy day (PCD),particle swarm optimization
更新于2025-09-10 09:29:36
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[IEEE 2018 International Conference on Platform Technology and Service (PlatCon) - Jeju (2018.1.29-2018.1.31)] 2018 International Conference on Platform Technology and Service (PlatCon) - Design of Band-type Device to Measure UV Index and UVB Irradiance in Everyday
摘要： UV (Ultraviolet) is known to negatively affect human body. Especially UVA promotes skin aging, and UVB enhances skin cancer prevalence. UVB, however, offers a useful function to support vitamin D production within human body. Therefore it is needed for people to be exposed to UV through proper outdoor activities and to acquire UV environmental information surrounding them. In this regard, this study devises a band-type device to measure UV irradiance in everyday life. The proposed device consists of a band to wear the device on user’s wrist, arduino-based micro controller, and a UV sensor measuring UV irradiance. The proposed band-type device is expected to induce appropriate outdoor activities in the UV environment that does not harm human body by offering precise information on UV index and UVB irradiance surrounding users.
关键词： UVB Device,Band-type Device,UVB Irradiance,UV Index
更新于2025-09-09 09:28:46
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A Physics-based Smart Persistence model for Intra-hour forecasting of solar radiation (PSPI) using GHI measurements and a cloud retrieval technique
摘要： Short-term solar forecasting models based solely on global horizontal irradiance (GHI) measurements are often unable to discriminate the forecasting of the factors affecting GHI from those that can be precisely computed by atmospheric models. This study introduces a Physics-based Smart Persistence model for Intra-hour forecasting of solar radiation (PSPI) that decomposes the forecasting of GHI into the computation of extraterrestrial solar radiation and solar zenith angle and the forecasting of cloud albedo and cloud fraction. The extraterrestrial solar radiation and solar zenith angle are accurately computed by the Solar Position Algorithm (SPA) developed at the National Renewable Energy Laboratory (NREL). A cloud retrieval technique is used to estimate cloud albedo and cloud fraction from surface-based observations of GHI. With the assumption of persistent cloud structures, the cloud albedo and cloud fraction are predicted for future time steps using a two-stream approximation and a 5-min exponential weighted moving average, respectively. Our model evaluation using the long-term observations of GHI at NREL’s Solar Radiation Research Laboratory (SRRL) shows that the PSPI has a better performance than the persistence and smart persistence models in all forecast time horizons between 5 and 60 min, which is more significant in cloudy-sky conditions. Compared to the persistence and smart persistence models, the PSPI does not require additional observations of various atmospheric parameters but is customizable in that additional observations, if available, can be ingested to further improve the GHI forecast. An advanced technology of cloud forecast is also expected to improve the future performance of the PSPI.
关键词： Cloud fraction,Global horizontal irradiance,Smart persistence,Solar forecasting,Cloud albedo
更新于2025-09-09 09:28:46