Today, the use of renewable energy is increasing day by day due to its advantages, to solve existing challenges such as the increase in power demand. Microgrids (MGs) which have AC, DC, and DC/AC ...types, have received much attention due to their many advantages. MGs can be a suitable solution for supplying power to remote and sensitive areas and they can also increase the reliability of the system. Like all systems, MGs need a reliable control system to provide proper operation. There are many control methods such as robust control and adaptive control and control structures can be divided into two types: centralized and decentralized. This paper provides an overview of different decentralized control methods for MGs, based on recently published research. The methods used in each study are fully described, along with their results. Also, several research questions have been suggested for future research that can be used.
Thermal condition monitoring of distribution transformers (DTs) as the most important and expensive equipment of the power grid is undeniable, and by accurate investigation of its thermal status, its ...failure can be prevented because the insulation condition of the transformer is directly related to the hotspot temperature (HST). In this paper, accurate and nonuniform magnetic-thermal analysis of DT is proposed for precise HST prediction. In the magnetic analysis, the DT is modeled as a 2D axial symmetry, and the losses calculation of the windings has been fulfilled as a nonuniform. In the thermal analysis, the DT is modeled as 3D and nonuniform, and the conservator and core stacking, which has a considerable effect on the HST, is precisely modeled. By taking advantage of optical fiber sensors (OFSs) in the understudied 500 kVA DT, the accuracy of the proposed nonuniform 3D CFD-based modeling during the temperature rise test (TRT) is validated. The empirical evaluation results depict that the presented nonuniform CFD-based thermal analysis for HST prediction is very precise, and there is an appropriate vicinity to the experimental values. The error percentage of the proposed 3D CFD-based thermal analysis is 0.11% (0.1 °C) compared to the OFSs measurements, which demonstrates the precision and effectiveness of the presented modeling. Also, the verification of the results of nonuniform 3D CFD-based thermal analysis in top-oil temperature (TOT) and bottom-oil temperature (BOT) during the experimental TRT is fulfilled via thermography. According to the attained evaluated results, temperatures of 3D CFD-based thermal analysis and thermography in the noted two points are in good accordance with each other. In short, the error percentage is less than 0.65%, which indicates the correctness and proper performance of the proposed nonuniform 3D CFD-based modeling. Finally, the proposed nonuniform 3D model was subjected to voltage imbalance of 0.95, 1.05, 1.1, 1.15, and 1.2 of rated voltage. The results demonstrate the HST increases by − 0.4, 0.4, 0.9, 1.3, and 1.8 °C, respectively, over the original model without voltage imbalance, which represents that this issue should be considered in the design and operation of the DT.
Distribution transformers (DTs) are deemed as one of the major and high-priced equipment of electrical grids and their destruction negatively affects the stability and security of the network. The ...insulation status of the transformer depends on the hotspot and oil temperatures. Accordingly, controlling and, if possible, reduction of transformer oil temperature will improve the insulation status. In this paper, the effect of using nano-oil on oil temperature and loading capacity increment (LCI) of DTs has been studied via the electro-thermal resistance model (E-TRM). The studied nanofluids are two volumetric concentrations of multi-walled carbon nanotubes (MWCNTs) and three volumetric concentrations of diamond nanoparticles dispersed in pure mineral oil (MO). First, the numerical results gained from the E-TRM method are compared and verified with the experiential results of a 500 kVA DT. As well as, the effect of using MWCNT, diamond and proposed ONF nanoparticles in the heat transfer capacity of the transformer are investigated and compared. The results demonstrate that the highest temperature reduction in comparison with MO among the studied nanofluids is about 1 °C and for nanofluid ODI2. While the use of hypothetical ONF nanofluid reduces the oil temperature by 2.7 °C. Finally, the LCI of DTs caused by the use of nanofluids is investigated by the proposed novel equation. The use of nanofluids, especially the proposed ONF nanofluid, leads to the LCI up to 5%.
•Proposing E-TRM model for thermal modeling of fin-folded distribution transformers.•Experimental test implementation for verification of the proposed E-TRM model.•Incorporating nanofluid properties into ETRM and investigating its heat transfer.•Thermal behavior estimation of transformer containing nanofluids.•Proposing a hypothetical ONF nanofluid with properties.
As autonomous electric vehicles and car-sharing services are becoming more popular, the contribution of shared autonomous electric vehicles (SAEVs) to the future of urban transportation is getting ...more achievable. Like conventional electric vehicles, SAEVs can provide power grids with ancillary services. This article proposes a new scheduling scheme for SAEV fleets within a cooperative plan to let power distribution networks benefit from the energy storage of vehicle batteries in recovering critical loads after a predictable extreme event. According to a long-term contract, the detailed request of the distribution system operator (DSO), together with desired constraints and perquisites, is sent to the SAEVs aggregator (SA) prior to the landfall of a predictable extreme event. Afterward, SA runs a targeted algorithm to schedule trip assignments and charging cycles of SAEVs so that the required constraints of DSO are satisfied. The SAEV participants will continue carrying passengers within the scheduled time horizon in addition to delivering energy to the distribution network at the scheduling deadline declared by DSO. This deadline is the time instant when the capacity of the SAEV fleet may be no more applicable to enhance the system preparedness against the approaching event. Numerical results illustrated that the proposed scheme helps improve the power grid resilience by delivering 2396.1 kWh of energy to the distribution network in addition to increasing the total income of each participant SAEV by about 130%. Thus, it is implied that the proposed method offers a win-win situation for both entities.
Botanical insecticides have long been considered as alternatives to synthetic chemical insecticides in IPM programs. Effects of aqueous and ethanolic extracts obtained from buttonwood, Conocarpus ...erectus L. (Combretaceae), leaves on a major kind of stored product pests, Tribolium castaneum Herbst (Coleoptera: Tenebrionidae), were evaluated under laboratory conditions. For this purpose, LC50, repellency, antifeedant properties, and some biological effects (including body weight, immature developmental time and survival) of the insect were determined. The aqueous and ethanolic extracts were highly toxic to the larvae and adults. Calculated LC50 values ranged between 2.6 and 193.4 (g/kg). Both extracts had repellent and antifeedant properties against the adults. The extracts adversely affected the larval and pupal weights, developmental time, and survival. Aqueous extracts were more effective only for the LC50 values and only in females. All other measured parameters do not differ between the two extracts. The bioactive properties might be related to high amounts of alkaloid, phenol and tannin. Aqueous extract of the plant leaves may be a useful alternative for chemical insecticides.
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•Conocarpus erectus extracts had insecticidal activity against Tribolium castaneum.•The extracts were repellent and antifeedant to the pest adults.•The extracts adversely affected biological parameters of the pest.•The properties may be related to high amounts of alkaloids phenols and tannins.
The proportional-integral-derivative controller is widely used in various industrial applications. But, in many noisy problems the strong methods are needed to optimize the ...proportional-integral-derivative parameters. In this paper, a novel method is introduced for adjusting the proportional-integral-derivative parameters through the model predictive control and generalized type-2 fuzzy-logic systems. The rules of suggested fuzzy system are online adjusted and the parameters of proportional-integral-derivative are tuned based on the fuzzy model such that a cost function to be minimized. The designed controller is applied on continuous stirred tank reactor and the performance is compared with other traditional approaches. The main advantages are that the accuracy is improved by online modeling and optimization and a predictive scheme is added to the conventional proportional-integral-derivative controller.
The importance of the distribution network is not overlooked by anyone. The transformer is one of the key equipment in this network. Therefore, great care and attention are needed in its design, ...maintenance and operation. Most of the oil-immersed distribution transformers are operated under solar radiation conditions. However, increasing the oil temperature due to solar radiation is not considered in their design. This increases the oil temperature above the design temperature value and thus reduces the life of the transformer. In this paper, due to the lack of specified equations for solar energy absorption by the fins and tank of the transformer, a novel method and equation are proposed for the calculation of the transformer solar radiation absorption amount. As well as, the effect of orientation on the corrugated tank distribution transformers oil temperature is investigated using the Electro-Thermal Resistance Model (E-TRM). For this purpose, two identical transformers with different orientations are tested experimentally and the results are compared and verified with the numerical results. The transformer tank color is one of the effective factors of solar radiation absorption. Depending on the absorption and emission rates, the effect of the different colors of the transformer tank on the oil temperature in different loading is investigated in this paper. The results show that the use of bright colors in comparison with dark colors can lower the oil temperature by about 3 °C on the rated loading of the transformer. In order to consider the effect of solar radiation on the transformer, the modified ambient temperature is introduced for the design of the transformer. Finally, the effect of transformer operation under solar radiation and with different colors is investigated and transformer loading de-rating is proposed by a novel equation.
The use of large-scale electric vehicles (EVs), along with technological advances in battery energy storage systems (BESS), offers numerous technical and economic benefits to the smart distribution ...system. Parking lots not only provide EV owners with the opportunity to charge their BESS but also contribute power to the grid
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vehicle-to-grid (V2G) technology, which significantly improves the reliability of distribution systems. In addition, parking lots equipped with V2G capability can participate in the electricity market as a producer. In this study, the reliability of a smart radial distribution system in the presence of EVs is investigated. It should always be borne in mind that parking lots can improve system reliability if the charging and discharging strategies are optimally and correctly scheduled. On the contrary, the parking lot participates in sending power to the grid in a situation where the profit is appropriate. Accordingly, in this study, first, five optimal strategies for scheduling the process of EV charging and discharging in a parking lot equipped with V2G capability are proposed to maximize parking profits. The proposed strategies include constraints on the amount of power exchange between the parking lot and the distribution system and the random and stochastic nature of quantities, such as when EVs enter and exit the parking lot and their BESS charge amounts when entering the parking lot. The results demonstrate that using the proposed optimal charging and discharging strategies scheduling increases the parking profit by 31% and also improves the reliability of the understudy distribution system by 9%.
Molecular Communication (MC) is a bio-inspired communication paradigm utilizing molecules for information transfer. Research on MC has largely transitioned from theoretical investigations to ...practical testbed implementations, harnessing microfluidics and sensor technologies. Accurate models for input-output relationships on these platforms are crucial for optimizing MC methods and understanding the impact of physical parameters on performance. Our study focuses on a practical microfluidic MC system with a graphene field effect transistor biosensor (bioFET)-based receiver, developing an end-to-end frequency-domain model. The model provides insights into the dispersion, distortion, and attenuation of received signals, thus potentially informing the design of new frequency-domain MC techniques, such as modulation and detection methods. The accuracy of the developed model is verified through particle-based spatial stochastic simulations of pulse transmission and ligand-receptor reactions on the receiver surface.
Direct current (dc) microgrids have gained significant interest in research due to dc generation/storage technologies—such as photovoltaics (PV) and batteries—increasing performance and reducing in ...cost. However, proper protection and control systems are critical in order to make dc microgrids feasible. This paper aims to propose a novel integrated control and protection scheme by using the state-dependent Riccati equation (SDRE) method for PV-battery based islanded dc microgrids. The dc microgrid under study consists of photovoltaic (PV) generation, a battery energy storage system (BESS), a capacitor bank and a dc load. The aims of this study are fast fault detection and voltage control of the dc load bus. To do so, the SDRE observer-controller—a nonlinear mathematical model—is employed to model the operation of the dc microgrid. Simulation results show that the proposed SDRE method is effective for fault detection and robust against external disturbances, resulting in it being capable of controlling the dc load bus voltage during disturbances. Finally, the dc microgrid and its proposed protection scheme are implemented in an experimental testbed prototype to verify the fault detection algorithm feasibility. The experimental results indicate that the SDRE scheme can effectively detect faults in a few milliseconds.
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