bluuebunny/crossref_metadata_2025_split huggingface dataset:
Magnetic, optical, structural and thermal properties of copper ferrite nanostructured synthesized by mechanical alloying
Authors: Younes Abderrahmane , Kherrouba Nabil , Bouamer Amirouche 
Published: January 2021

AbstractCuFe2O4 spinel nanostructured were elaborated by mechanical alloying technique from Cu, Cu2O and Fe2O3 under controlled atmosphere with different milling times at room temperature. The CuFe2O4 spinel crystalline has a body‐centred tetragonal structure at low temperatures with lattice parameters a ≅ 0.582 nm and c ≅ 0.869 nm and face‐centred cubic structure at high temperatures with lattice parameter a ≅ 0.842 nm. The average crystallite size and lattice strain determined from X‐ray diffraction for CuFe2O4 are 22.12 ± 5.47 nm and 0.781 ± 0.082 %, respectively. The FTIR‐ATR spectra of the samples shows that the vibration around of 400–1000 cm−1 corresponds to the CuFe2O4 absorbed at octahedral and tetrahedral sites. The mechanical alloying process results in CuFe2O4 agglomerated in clusters, which radically change their shape during milling time. Differential scanning calorimetry analysis shows two additional endothermic peaks around 715–781 °C and 863–957 °C, the first peak might be affected to the formation of Cu‐Fe‐O and the second peak may correspond to the transformation of CuFe2O4 from tetragonal to cubic structure. CuFe2O4 samples milled until 20 h are ferromagnetic at room temperature with saturation magnetization increasing from 29.8 to 59.6 emu/g with increasing the milling time. The coercivity decreases 254 Oe up to 230 Oe when the milling time increases from 0 to 20h.
Effect of carbon quantum dots on the photo‐absorption, photo‐response and photoelectrochemical performance of KNb3O8 film photoelectrode
Authors: Liu Xiaobin , Tan Tianjian , Que Wenxiu , Zhou Huanfu , Wang Kangguo 
Published: January 2021

AbstractThe KNb3O8 crystals and carbon quantum dots were synthesized via hydrothermal reaction method, their crystal structural and morphological properties were investigated by X‐ray diffraction, scanning electron microscope and transmission electron microscope, respectively. The X‐ray diffraction patterns of KNb3O8 film on FTO glass (SnO2 conductive glass doped with fluorine) show that the thin KNb3O8 crystals are apt to stack along the [020] direction of KNb3O8 crystal structure. Scanning electron microscope and transmission electron microscope results indicate that most of KNb3O8 crystals have a width of about 0.5 μm and a length of more than 5 μm and the carbon quantum dot has a graphite structure with a size of about 3 nm. The UV‐response KNb3O8 thin film electrode was loaded by carbon quantum dots and showed broader photo‐absorption characteristic (up to visible light region) and higher photocurrent (a bias of 0.4 V vs SCE), as compared of the pristine KNb3O8 film electrode. In addition, their photo‐electrochemical (PEC) performances were also investigated under different light irradiation conditions with an applied potential between −0.4 and 0.7 V versus SCE.
Experimental studies on viscosity, thermal and tribological properties of vegetable oil (kapok oil) with boric acid as an additive
Authors: Shankar Subramaniam , Manikandan M. , Raja G. , Priyadharashini G. Suganya , Pramanik Alokesh 
Published: January 2021

AbstractNon‐renewability and damage caused to the environment while using mineral based and synthetic based lubricants become the greatest concern of this century. Disposal issues initiated a global trend to utilize vegetable based lubricants in industries. Vegetable oils are environmental friendly, have low toxicity and highly biodegradable in nature. The main objective of this work is to improve the viscosity and reduce the friction and wear rate of Kapok oil using boric acid as an additive. The tribological properties of kapok oil with three different concentrations (1, 3 and 5 wt%) of boric acid is evaluated and compared with pure kapok oil using pin on disc tribometer. The worn out surface of the pin are analyzed using the optical microscope after the wear test. The viscosity and thermal properties of kapok oil with 5 wt% of boric acid possess the better performance compared to other samples. Boric acid particles suspension exhibits reduction in friction and wear when compared with pure kapok oil. Overall, the kapok oil combined with 5 wt% of boric acid acts as the better bio lubricant oil which would help to reduce the global demand of petroleum‐based lubricant sustainability.
Crystallization investigation of BaTiO3 coating layer on Ni nanoparticles
Authors: Qin Jing , Hao Yanan , Guo Limin , Bi Ke 
Published: January 2021

AbstractThe crystallization of oxide coating layer on base metal electrode (BME) has facing challenges for a long time. In this paper, a sol‐gel method was used to coat nickel (Ni) nanoparticles with polycrystalline BaTiO3 (BT). By adjusting the reaction condition, continuous and homogeneous BT coating layer was obtained based on the transmission electron microscopy (TEM) observation. Powder X‐ray diffraction (XRD) of the coated sample indicated that deionized water content, which can change the pH value of the reaction solvent, is the key factor to influence the crystallization of the BT layer. With the increase of the deionized water, the crystallinity of the BT layer increased, which greatly enhanced the anti‐oxidation properties of the Ni nanoparticles. When the amount of deionized water increased to 20 wt%, Ni3C impurity appeared and the properties of the Ni nanoparticles deteriorated. As a result, an optimized deionized water content of 16 wt% is adopted for the best performance of the BT coated Ni (Ni@BT) nanoparticles.
Estimation of the capacitor voltages in flying capacitor multi‐level converters
Authors: Escalante Miguel F. , Erdmann Alex P. 
Published: January 2021

AbstractFlying capacitor multi‐level converters use charged capacitors as a critical element. For proper operation, the capacitor voltages must be known and regulated. Direct measurement is straightforward, but when the number of required measurements is high, this is a complicated approach. This paper introduces an estimation method for n capacitor voltages. The scheme is based on a system of () equations, which is defined in a way that it incorporates information of the actual capacitor voltages and open‐loop estimates of the capacitor voltages. The solution of the system gives the best estimates of the capacitor voltages in the sense of least square errors. The method requires only output voltage and output current sensors and its computational burden is low, saving cost and design efforts, and simplifying the hardware system. The performance of the proposed scheme is evaluated experimentally in a 9‐level flying capacitor chopper, where the estimates are used by the voltage balancing strategy and by the output current controller.
Optimal energy scheduling of a solar‐based hybrid ship considering cold‐ironing facilities
Authors: Vahabzad Neda , Mohammadi‐Ivatloo Behnam , Anvari‐Moghaddam Amjad 
Published: January 2021

AbstractThere are many restrictions on shipping, which reduce or prohibit the use of diesel generators for feeding the energy demand of the electric ships, especially in ports. Therefore, the use of shore power system (SPS) together with renewable energies and energy storage systems (ESSs) can lead to many environmental benefits while ships are berthing in ports. In this study, the shipboard hybrid power system (HPS) is proposed, including diesel generators, solar photovoltaic panels (PV), ESS and cold‐ironing (CI) facilities for using SPS to efficiently supply the ship's electrical demand. With such HPS aboard, the solar generated power is estimated accurately based on the navigation route. By optimal energy scheduling in a real hybrid cruise ship, the use of diesel generators gets minimised, due to the utilisation of PV and ESS. In addition, using CI service instead of switching on auxiliary diesel generators in ports leads to a 3 h increase in charging and discharging times of the ESS. Furthermore, the efficient use of CI service results in less use of diesel generators even at sailing hours, reducing emissions and minimising the costs of supplying ship's energy demand. The total cost reduction of the HPS in different case studies, without the use of CI services is only 1% to 2%, while this reduction is about 6% to 7% by adding the CI facilities to the HPS. Moreover, the economic characteristics of the proposed diesel‐PV‐ESS‐CI by adding the CI facilities to the HPS are analysed and the profitability of this HPS in reducing the daily costs with considering the share of installation costs on the target day is proved.
Two stage unit commitment considering multiple correlations of wind power forecast errors
Authors: Wang Chengfu , Li Xijuan , Zhang Yumin , Dong Yunhui , Dong Xiaoming , Wang Mingqiang 
Published: January 2021

AbstractWhen the correlation of wind power output among wind farms is not considered, the integrated stochastic characteristics of wind power will not be captured accurately. Using this inaccurate feature may lead to an impractical even a failing result of unit commitment (UC). Therefore, this paper proposes a multiple correlations model for wind power forecast errors (WPFEs), and to capture this multiple correlation feature in UC problem, a two‐stage chance‐constrained interval UC (CIUC) model is proposed. First, an analytical expression of multiple correlations, including spatial, temporal and conditional correlations, is presented to improve the description accuracy of stochastic WPFEs. To strike a balance between risk and operational cost, a chance‐constrained decision method is developed to optimize the time‐varying interval of wind power output in the first stage. Subsequently, an interval UC model is established to determine the optimal operational schedule in the second stage. Finally, the proposed CIUC model is solved using a solution strategy that combines column‐and‐constraint generation and sample average approximation. The effectiveness and practicality of the proposed method are verified via the numerical results for IEEE 39‐bus and 118‐bus systems.
Impact of converter‐interfaced renewable generations on breaker failure protection of the emanant transmission lines
Authors: Radhakrishnan Asha , Das Sarasij 
Published: January 2021

AbstractThe presence of Converter Interfaced Generations (CIGs)
poses significant challenges to traditional protection schemes. This paper
studies the impact of CIGs on the Breaker Failure Protection (BFP) of
transmission lines emanating from CIGs. The instantaneous over‐current (50BF) setting and reset time of BFP have been
investigated. Fault current contribution of CIGs is usually comparable with
load currents. Low fault current contribution by CIGs may lead to significant
loss of security of BFP because of the existing practice of using lower setting
for 50BF. This paper proposes a voltage‐dependent adaptive setting of 50BF
element to enhance the security of BFP schemes while maintaining dependability.
Use of voltage helps in differentiating loads from fault situations. In traditional power systems, CT
subsidence current is known to delay the reset of BFP schemes. The impact of
low fault contribution by CIGs on the reset time of BFP has been studied.
Mathematical expression for CT subsidence current, which influences the reset
time, has been derived. It is observed that the BFP reset may not be delayed if
the fault current seen by the breaker is low due to the presence of CIG.
Discussions on the dependability and
security of proposed 50BF setting are also presented.
One‐sample optimal output smoothing method for wind farm with energy storage system
Authors: Koiwa Kenta , Ishii Tomoya , Liu Kang‐Zhi , Zanma Tadanao , Tamura Junji 
Published: January 2021

AbstractThis paper proposes a novel optimization method for energy storage systems (ESSs) to smooth wind farm output to satisfy the technical requirements and reduce the rated power (rated energy capacity) and charge/discharge loss of the ESS. The state of charge of the ESS operated by the proposed method can be regulated, guaranteeing some constraints. The proposed method has a very simple structure, does not require the wind farm output forecast and numerical optimization, such as particle swarm optimization. Therefore, a high‐grade functional computation device is not needed. The effectiveness of the proposed method is verified by comparative analysis with conventional approaches through simulations.
Efficient energy management system using Internet of things with FORDF technique for distribution system
Authors: Vinjamuri Usha Rani , Rao B. Loveswara 
Published: January 2021

AbstractEnergy management system for the distribution system using Internet of things with hybrid technique. The proposed hybrid technique is the joined execution of both the fruitfly optimisation algorithm and random decision forest and named as FORDF strategy. The main objective of the proposed system is to optimally manage the power and resources of distribution system by persistently screen the data from the Internet of things‐based communication system. In the proposed system, each home device is interfaced with data acquisition module with IP address bringing about a huge work wireless network of devices. So as to encourage the improvement of demand response for distribution system to deal with the energy, the Internet of things‐based communication system is utilised. So as to ideally deal with the energy, the optimal load demand prediction and the energy control PROCESSES are handled by the FORDF system. Besides, the optimum utilisation of the accessible resources and the flexibility of such networks are given and expanded by the Internet of things based distribution system. Furthermore the proposed technique is qualified to satisfy the general SUPPLY and energy demand. At long last, the proposed model is implemented in MATLAB/simulink platform and the exhibition is contrasted and different systems
Risk‐constrained optimal bidding strategy for a wind power producer with battery energy storage system using extended mathematical programming
Authors: Abhinav Rishabh , Pindoriya Naran M. 
Published: January 2021

AbstractWind power producers (WPP) in India, currently, are restricted from participating in the short‐term energy market due to the uncertainty in their power generation. Consequently, they might lose an excellent opportunity to maximise their revenue. WPPs, with installed BESS and proper risk management, could promisingly participate in the market and minimise the penalty for deviating from the schedule. This paper devises an optimal bidding strategy for a WPP to participate in the day‐ahead and real‐time energy markets considering the uncertainties present in wind power generation and market electricity price. At the same time, it also aims to minimise the power deviation during real‐time delivery. The paper incorporates CVaR as a risk measure and formulates a two‐layer stochastic optimisation problem while employing multiple scenarios of the uncertain data. The upper layer of the problem decides the day‐ahead offering, while the lower layer deals with the real‐time operation. The stochastic problem is further reformulated using extended mathematical programming, which benefits in reducing the mathematical complexity of the problem. Wind power data from an actual wind farm located in Gujarat, India is taken as a test‐study. Various potential case‐studies are presented to illustrate the effectiveness of the proposed bidding strategy.
Research on random fuzzy power flow calculation of AC/DC hybrid distribution network based on unified iterative method
Authors: Yang Guokang , Dong Ping , Liu Mingbo , Wu Huayi 
Published: January 2021

AbstractIn recent years, with the promotion of policies and technologies, a large number of distributed generations are connected to the urban distribution network in various forms. At the same time, the flexible DC transmission technology has become mature and gradually applied to the distribution network. In this condition, the AC/DC hybrid distribution networks with flexible regulation ability will be the trend of urban distribution network. This paper accurately considers the loss of voltage source converter, and proposes a unified iterative power flow method for AC/DC hybrid distribution network, which takes the voltage source converter control modes into account. Because of the uncertainties of the distributed generations and loads, a random fuzzy power flow model is proposed, in which cumulant method is applied in the random stage. In the fuzzy stage, the fuzzy simulation technology is applied. Finally, an improved PG&E 69‐Bus system is taken as an example to verify the effectiveness of the unified iterative method and the random fuzzy power flow calculation, and put forward some suggestions for the operation of distribution network with distributed generations.
A five bus AC–DC hybrid nanogrid system for PV based modern buildings
Authors: Dutta Subhendu , Chatterjee Kishore 
Published: January 2021

AbstractA five bus AC–DC hybrid transformerless nanogrid system for modern buildings, and its associated control strategy that can operate all the buses simultaneously, is proposed in this paper. The nanogrid has five buses that can exchange power among themselves. This feature improves the reliability of power availability in the system. Two DC buses and one AC bus can be operated in standalone mode as well as in grid connected mode which enables the scheme to operate with available DC microgrids and the AC utility grid. The PV array and the battery bank are interfaced with the remaining two buses which are PV bus, and the battery bus, respectively. In order to reduce the number of serially connected battery units, the voltage rating of the battery bus is kept low. Similarly, the voltage rating of the PV bus is maintained at a medium level to decrease the number of serially connected modules. Hence the effect of shading is minimized. The control strategy of the system is developed to judiciously operate all the buses. In order to validate the viability of the system, exhaustive experimental studies are carried out utilising a laboratory scale 1.2 kW nanogrid system developed for the purpose.
An Analytical method for detecting instability in grid‐connected doubly‐fed induction generator
Authors: Nasab Mohammad Rajabi , Yaghobi Hamid 
Published: January 2021

AbstractDoubly‐fed induction generator (DFIG) is among the most attractive technologies in wind farms. As the penetration of wind power into the grid has increased in recent years, protecting of wind farm's generators against grid disturbances has become a major issue for the power system industry. Transient instability (TI) is among the most frequent phenomena due to severe grid disturbances. This phenomenon might cause significant damages to network equipment. In DFIG based wind turbine (WT), when the crowbar circuit is activated, the rotor winding is short‐circuited and the power converter is blocked. At this moment, the DFIG operational mode is temporarily changed to squirrel‐cage induction generator (SCIG). This lead to reactive power absorption and voltage drop, that might cause electromechanical oscillations and unstable condition. This study presents an analytical method for detection TI of a grid‐connected DFIG based on analysis of angular velocity and acceleration data, which are readily obtained from locally measured quantities. This technique works on a setting‐free manner, i.e. revising would not be required even when the network configuration changes, which is a favourable feature in protective relaying. The performance of the proposed method is verified using MATLAB/Simulink. Simulation results prove the method's reliability and simplicity.
An MMTES algorithm for dynamic photovoltaic array reconfiguration to enhance power output under partial shading conditions
Authors: Varma G Harish Kumar , Barry Venugopal Reddy , Jain Rohit Kumar , Kumar Devanand 
Published: January 2021

AbstractPartial shading is a severe impediment to the effective use of photovoltaic systems. It will lead to performance degradation in the photovoltaic system. This work proposes a maximum–minimum tier equalisation swapping reconfiguration algorithm for total‐cross‐tied connection under shading conditions. The proposed reconfiguration algorithm uses a switch matrix to alter the interconnection of modules in a photovoltaic array. The switch matrix dynamically modifies the connections based on the equalisation of tier irradiance. This algorithm applies to the symmetrical and asymmetrical photovoltaic array. Further, simulation studies show the efficacy of the proposed algorithm by minimising the multiple peaks and enhancing the output power compared with the traditional total‐cross‐tied configuration. The performance of experimental tests ascertains the feasibility of the proposed method.
Performance evaluation and modelling of the Atir marine current turbine
Authors: Díaz‐Dorado Eloy , Carrillo Camilo , Cidras Jose , Román David , Grande Javier 
Published: January 2021

AbstractIn this study, the behaviour of a full‐size prototype of a platform for tidal energy was analysed. The turbine of this platform is formed by two counter‐rotating rotors aligned with the tidal current, such that one rotor is always under the wake of the upstream rotor. The platform was tested under real working conditions; the tidal current was emulated by towing. The results of these tests were used to develop and parameterize a turbine model, which is presented in this paper. The turbine was modelled in terms of power, torque, and thrust coefficients. This model was used to estimate the power curve of the platform and design control strategies that, in addition to maximizing energy production, contribute to the stability of the platform.
Global maximum power point tracking in partially shaded PV systems using plant reproduction algorithm
Authors: Krishnan G. Satheesh , V. Puthusserry Gireesh , T. Mithun , P. Simon Sishaj , P. Thazhakuni Bijilesh 
Published: January 2021

AbstractThe power–voltage curve of photovoltaic (PV) power generation system under partial shading conditions (PSC) is non‐monotonic with multiple power peaks and traditional methods do not guarantee global convergence which leads to energy loss. This paper proposes a new tracking scheme for global maximum power point (GMPP) on a shaded PV system based on plant reproduction algorithm (PRA). The concept of PRA is suitably tailored towards maximum power point tracking (MPPT) and lucidly explained in this work. The algorithm is applied towards MPPT in several shaded PV architectures through computer simulations and later verified through experimentation. Computed and measured results show that PRA quickly identifies GMPP and further provides significantly improved MPPT characteristic curves compared to established alternatives.