Minimum Generation Research Articles

Correlations between flexural stiffness, wingbeat frequency and aerodynamic force generation in hovering insect flight

We report a direct relationship between wing flexural stiffness, wingbeat frequency, and mean aerodynamic force generation based on the wing morphological database for various insect species in hovering flight condition. Proposed correlations have shown the potential to predict the minimum aerodynamic force generation in flapping wings for a given flapping frequency with reasonable accuracy. The robustness of these correlations is demonstrated by validating them against the available experimental data for the various artificial flapping-wing configurations. These regression models can be used as first-order design tools which will save computational and experimental time while developing flapping-wing drones.

Study on plant generator scheduling based on mixed integer model

Due to the outbreak of the new crown epidemic, the production plans of most factories have been affected to a certain extent, and there may be some changes in the production machinery and manpower arrangements of the factories. In this paper, we study how to arrange the dispatch strategy of generators under the condition of power demand in a specified time. Based on the minimum cost, a mixed integer model was established, which provided a solution for some factories to control the scheduling of machines on time during the outbreak of the epidemic. According to the established model, a factory is programmed to solve the problem, and the minimum power generation cost in a week is given 1589130 CNY. In special cases, the working generator set must set aside 20% of the power generation capacity margin to cope with the unexpected situation. At this time, the generator’s daily production cost is as small as 239870 CNY while giving the corresponding generator scheduling scheme. Finally, this paper does a sensitivity analysis of the total daily power generation cost when the power generation margin changes, and finds that the total daily cost of the generator is sensitive to the power generation margin.

A cooperative game theory-based approach to formulation of distributed slack buses

The conventional power flow formulation is based on a single slack bus model, which may not necessarily provide accurate values for minimum generation cost and minimum power losses. On the other hand, distributed slack buses, which are used to distribute the slack power (power mismatch) among different voltage-controlled buses, can overcome this problem. A cooperative game theory-based approach is proposed in this paper to calculate active power participation factors to distribute slack active power among different participating generators. In the first stage, the worth (or value) of individual participating generators and their coalitions are computed. In the second stage, the Shapley value, which is one of the solution concepts of cooperative game theory, is used to calculate the participation factors of individual participating generators. The participation factors are then used to distribute the mismatch power among different generators. The effectiveness of the proposed approach is demonstrated through case studies on the IEEE 14-bus, IEEE 30-bus, and IEEE 57-bus systems. The results show that the cost of generation and power losses are reduced in case of systems with distributed slack buses compared to that with a single slack bus.

Solution of Probabilistic Optimal Power Flow Incorporating Renewable Energy Uncertainty Using a Novel Circle Search Algorithm

Integrating renewable energy sources (RESs) into modern electric power systems offers various techno-economic benefits. However, the inconsistent power profile of RES influences the power flow of the entire distribution network, so it is crucial to optimize the power flow in order to achieve stable and reliable operation. Therefore, this paper proposes a newly developed circle search algorithm (CSA) for the optimal solution of the probabilistic optimal power flow (OPF). Our research began with the development and evaluation of the proposed CSA. Firstly, we solved the OPF problem to achieve minimum generation fuel costs; this used the classical OPF. Then, the newly developed CSA method was used to deal with the probabilistic power flow problem effectively. The impact of the intermittency of solar and wind energy sources on the total generation costs was investigated. Variations in the system’s demands are also considered in the probabilistic OPF problem scenarios. The proposed method was verified by applying it to the IEEE 57-bus and the 118-bus test systems. This study’s main contributions are to test the newly developed CSA on the OPF problem to consider stochastic models of the RESs, providing probabilistic modes to represent the RESs. The robustness and efficiency of the proposed CSA in solving the probabilistic OPF problem are evaluated by comparing it with other methods, such as Genetic Algorithm (GA), Particle Swarm Optimization (PSO), and the hybrid machine learning and transient search algorithm (ML-TSO) under the same parameters. The comparative results showed that the proposed CSA is robust and applicable; as evidence, an observable decrease was obtained in the costs of the conventional generators’ operation, due to the penetration of renewable energy sources into the studied networks.

Optimal Loss of Load Expectation for Generation Expansion Planning Considering Fuel Unavailability

In generation expansion planning, reliability level is the key criterion to ensure enough generation above peak demand in case there are any generation outages. This reliability criterion must be appropriately optimized to provide a reliable generation system with a minimum generation cost. Currently, a method to determine an optimal reliability criterion is mainly focused on reserve margin, an accustomed criterion used by several generation utilities. However, Loss of Load Expectation (LOLE) is a more suitable reliability criterion for a generation system with a high proportion of renewable energy since it considers both the probabilistic characteristics of the generation system and the entire load’s profile. Moreover, it is also correlated with the reserve margin. Considering the current fuel supply situation, a probabilistic model based on Bayes’ Theorem is also proposed to incorporate fuel supply unavailability into the probabilistic criterion. This paper proposes a method for determining the optimal LOLE along with a model that incorporates fuel supply unavailability into consideration. This method is tested with Thailand’s Power Development Plan 2018 revision 1 to demonstrate numerical examples. It is found that the optimal LOLE of the test system is 0.7 day/year, or shifted to 0.55 day/year in the case of considering the fuel supply unavailability.

ESTIMATION OF GROWTH IN SOME BLUE-GREEN ALGAE

Physiological characterization show that all the strains have more growth in nitrogen enriched medium compared to nitrogen deficient medium. The growth measurement in terms of dry weight indicated that genus Westiellopsis has produced the maximum biomass. Therefore it has more growth rate and minimum generation time.

Quantile regression analysis of time-space variation characteristics of tropical cyclones in the west North Pacific basin under global warming

ABSTRACT The enormous economic losses and casualties were caused by tropical cyclones in the southeast coastal areas of China every year. In order to understand the time-space variation characteristics of tropical cyclones (including intensity, minimum central atmosphere pressure, duration, and generation position) in the global and the western North Pacific basin, the monthly and interannual variation characteristics of tropical cyclones from 1949 to 2018 were analyzed by the quantile regression method and least square regression method. The results show that the global climate temperature and the annual maximum wind speed of tropical cyclones have a tendency to increase under different quantiles. While the maximum wind speed of tropical cyclones generated in the WNP basin basically decreases with the increase of years in El Niño, La Niña, and normal years under different quantiles. It is obvious that the interannual variation of the maximum wind speed of tropical cyclones is affected by the ENSO events. Similarly, minimum central atmospheric pressure, duration, and generation position of TCs from 1949 to 2018 are also analyzed in the present study. The results of this study can provide an effective reference for data analysis and trend prediction of tropical cyclones in the western North Pacific basin.

Electrocoagulation technique for removing Organic and Inorganic pollutants (COD) from the various industrial effluents: An overview

The treatment and reuse of industrial wastewater plays a foremost role in succeeding environmental protection and water security. The electrochemical treatment technology has attracted a great deal of attention because of its compact, high particulate removal, free from chemicals, automation, and minimum sludge generation. The objective of the study is to review the existing literature on COD (Chemical oxygen demand) removal from various industrial effluents using electrocoagulation technology, as well as the factors that influence the process. Electricity is passed through electro plates dipped in wastewater during the electrocoagulation process. Metal hydroxide formations occur, which removes pollutants from wastewater via the sedimentation and flotation mechanisms. After a thorough review of various literatures, a detailed discussion on the process influencing parameters such as pH, Current Density, Electrolysis Time, Conductivity, Stirring Speed, and Retention Time has been done which gives useful information on future scope of research in this area.

Valorization of microalgal biomass to value-added products using integrated supercritical CO2 extraction and sub-critical hydrothermal liquefaction

The study depicts the use of different extraction techniques to utilize each fraction of microalgal consortium biomass (Chlorella sp. and Phormidium sp.) for its conversion to value-added products (VAPs). The algal biomass was rich in proteins (30.8%), lipids (28.1%), carbohydrates and essential amino acids (36.29% of total protein). The lipid yield obtained after supercritical CO2 extraction (SFE) was found to be 3.0 ± 0.4% compared to the conventional soxhlet extraction (28.2 ± 2.3%) with chloroform: methanol (1:1 v/v). However, SFE extracted lipid showed higher Polyunsaturated fatty acids (PUFAs) content (20.68%) with the presence of eicosapentaenoic acid, docosahexaenoic acid, α-linolenic acid, linoleic acid and arachidonic acid. The PUFA content in lipid obtained after soxhlet extraction was only 3.48%. The residual biomass after SFE showed recovery of 17.1 ± 0.7% proteins and 27.1 ± 0.9 mg g−1 of total carotenoids. Subcritical-hydrothermal liquefaction (HTL) of the microalgae at 230 °C and 2.7 MPa produced 30.7% biocrude (dried biomass basis) containing aldehyde/ketone (37.14%), aromatics (27.63%) and alkanes/alkenes/alkynes (15.3%) along with other compounds. This fraction consisted of VAPs targeting multiple industries-food (11%), fuel (22%), pharmaceutical (56%) and cosmeceutical (12%). A novel approach including sequential SFE-HTL process showed a lower biocrude yield (8.6%) but showed upgradation in biocrude quality having 50% aromatic compound of which >48% were pyrazines derivatives (flavoring agents for the food industry) and 20.8% pharmaceutically valuable compounds, besides extracting PUFAs from SFE. Hence, a new microalgal valorization approach has been developed by integrating two extraction techniques to produce multiple VAPs to target a minimum waste generation approach.

Measurement of the effect of parasitic capacitance in minimum ignition energy spark generation circuits

To accurately measure electrostatic discharge energy, a resistive-capacitive voltage discharge approach was used to measure the parasitic capacitance in a circuit. As a result, an output-stage parasitic capacitance in the circuit during the discharge process and a non-negligible storage-stage parasitic capacitance during the charging process were identified. By comparing the data obtained from the resistive-capacitive discharge voltage model and spark current RCL circuit model, the maximum relative deviation from the total circuit capacitance was 5.4% for both approaches. A model based on graded-stage parasitic capacitance was established to analyze the effect of this capacitance on discharge energy. The energy stored in the charging process increased because of the storage-stage parasitic capacitance, and the discharge energy decreased because of the output-stage parasitic capacitance. The energy calculated by the graded parasitic capacitance model was larger than that calculated by the single-stage parasitic capacitance model, with a maximum relative deviation of 36.7% under the test conditions. The smaller the charging capacitor, the more evident the effect of the parasitic capacitance on the discharge energy.

Research on Erosion Wear of Slotted Screen Based on High Production Gas Field

Erosion wear is a common failure form of slotted screen in service. In this paper, based on CFD software and sand production data of a gas field in the Tarim Basin, the particle velocity and shear force at the slot of the flow field in the sieve tube were studied to determine the maximum area of erosion; at the same time, the velocity, viscosity, particle size and concentration of sand-carrying fluid were analyzed by orthogonal test, and the regression model of multi-factor maximum erosion rate was established. ① Through the analysis of the four factors on the degree of dependent variables, the order of the primary and secondary factors are: sand-carrying liquid flow rate, particle concentration, fluid viscosity, particle diameter, the effect of fluid viscosity and particle diameter on erosion rate is relatively small; ② According to the analysis of variance and range, the combination scheme of minimum erosion generation is obtained, and the calculation model of the erosion rate of the slotted screen is established. In order to reduce the erosion and abrasion in the actual oil and gas production process, the reasonable flow control and precise sand control method design and precision selection can be adopted; it provides a design basis for sand control and long-term effects of production in high-yield gas field.

A Global Diagnosis of Eddy Potential Energy Budget in an Eddy-Permitting Ocean Model

Abstract We use an interannually forced version of the Parallel Ocean Program, configured to resolve mesoscale eddies, to close the global eddy potential energy (EPE) budget associated with temperature variability. By closing the EPE budget, we are able to properly investigate the role of diabatic processes in modulating mesoscale energetics in the context of other processes driving eddy–mean flow interactions. A Helmholtz decomposition of the eddy heat flux field into divergent and rotational components is applied to estimate the baroclinic conversion from mean to eddy potential energy. In doing so, an approximate two-way balance between the “divergent” baroclinic conversion and upgradient vertical eddy heat fluxes in the ocean interior is revealed, in accordance with baroclinic instability and the relaxation of isopycnal slopes. However, in the mixed layer, the EPE budget is greatly modulated by diabatic mixing, with air–sea interactions and interior diffusion playing comparable roles. Globally, this accounts for ∼60% of EPE converted to EKE (eddy kinetic energy), with the remainder being dissipated by air–sea interactions and interior mixing. A seasonal composite of baroclinic energy conversions shows that the strongest EPE to EKE conversion occurs during the summer in both hemispheres. The seasonally varying diabatic processes in the upper ocean are further shown to be closely linked to this EPE–EKE conversion seasonality, but with a lead. The peak energy dissipation through vertical mixing occurs ahead of the minimum EKE generation by 1–2 months.

Hydroelectricity Modeling for Low‐Carbon and No‐Carbon Grids: Empirical Operational Parameters for Optimization and Dispatch Models

AbstractHydroelectric power has unusual technical characteristics that could become more valuable as the penetration of variable generation renewables grows, but its use for electricity generation is constrained by complex physical, safety, and socioenvironmental considerations. Hydroelectricity can therefore be difficult to represent in national‐scale energy models, and is frequently presumed to be either overly flexible or inflexible. While a few grid models address this complexity via detailed hydraulic process models, more simplified optimization and dispatch models could benefit from the use of empirical parameter values. In this study, we combine a new data set comprising 7.8 million flow‐hours of data from 2011 to 2016 at 158 dams across the United States with monthly and hourly generation data from the U.S. Energy Information Administration (EIA) to elucidate such empirical constraints for the continental United States. We introduce an approach for estimating power generation from hourly water discharge, then present regionally resolved interannual seasonal and diurnal generation patterns; frequency analyses of ramp rates; minimum and maximum generation rates; daily reversals; and load duration curves, all available interactively with a new data visualization tool. We suggest that due largely to hydropower's role as power generation that also serves non‐energy purposes, it acts as a predictable variable generator with constrained dispatchability, more like a supply side analog to demand response resources than like a battery. This observation is particularly relevant for high penetration renewable energy scenarios, given hydroelectric generators' expected value for grid stabilization and load balancing.

Violin Ceramic Joist Slabs: Evaluation and Proposal for Intervention with Duplex-Type Stainless Steel

Due to the present significant need to repair and maintain our buildings and the building repair sector’s minimal experience in special structural elements, we here describe a study on the repair of ceramic violin joist slabs in an actual intervention on a building erected in the 1950s that had been unsuccessfully repaired several times. Due to damp and being close to the sea, the main reinforcement elements had undergone considerable corrosion causing a significant risk to the building’s safety. The intervention necessarily involved replacing the affected steel rebars with appropriate elements with mechanical and corrosion resistance properties, as required by the latest building codes. An appropriate strengthening and repair system was developed with a stainless steel prosthesis fitted to the lower third of the joists that almost tripled their resistance, gave them 120 min of fire resistance, and increased their durability against corrosion at a cost of less than 50% of the current repair systems with minimum generation of construction waste. One of the most appealing characteristics of this new repair system is its avoidance of the full replacement of the joists, which can be considered as a relevant contribution to the sustainability of the construction industry.

Economic-emission load dispatch for power system operation using enhanced sunflower optimization

Conventional thermal power plant uses limited sources of gas, fuel or coal which contributes to the rise of air pollution. Thus, it is crucial to efficiently use the natural sources and minimize the emissions of greenhouse gases and other pollutants. This paper presents an optimal economic dispatch considering three factors which are cost of generation, loss of power transmission and amount of emission for an efficient operation of power generation. Enhanced sunflower optimization (ESFO) algorithm is applied to determine the solution for three different cases: economic load dispatch, emission load dispatch and economic-emission load dispatch. The optimal solution based on the minimum generation cost and emission is obtained for the IEEE 6-unit test system using MATLAB software

Probabilistic Scheduling of UFLS to Secure Credible Contingencies in Low Inertia Systems

The reduced inertia levels in low-carbon power grids necessitate explicit constraints to limit frequency's nadir and rate of change during scheduling. This can result in significant curtailment of renewable energy due to the minimum generation of thermal plants that are needed to provide frequency response (FR) and inertia. Additional consideration of fast FR, a dynamically reduced largest loss and under frequency load shedding (UFLS) allows frequency security to be achieved more cost effectively. This paper derives a novel nadir constraint from the swing equation that, for the first time, provides a framework for the optimal comparison of all these services. We demonstrate that this constraint can be accurately and conservatively approximated for moderate UFLS levels with a second order cone, resulting in highly tractable convex problems. Case studies performed on a Great Britain 2030 system demonstrate that UFLS as an option to contain single plant outages can reduce annual operational costs by up to {\pounds}559m, 52% of frequency security costs. The sensitivity of this value to wind penetration, abundance of alternative frequency services, UFLS amount and cost is explored.

Blue LED-Promoted Syntheses of Phosphorothioates and Phosphorodithioates.

An environmentally friendly and resourceful modular protocol for the synthesis of phosphorochalcogenoates, phosphorochalcogenothioates, and phosphinothioates under blue light-emitting diode irradiation is described. The blue LED-promoted P-S, P-Se, and P-Te bond constructions occurred under metal-free, ligand-free, oxidant-free, and photocatalyst-free conditions with minimum chemical waste generation and high atom economy providing the resulting phosphorochalcogenoates, phosphorochalcogenothioates, and phosphinothioates in good to excellent yields.

Electromembrane Extraction and Dual-Channel Nanoelectrospray Ionization Coupled with a Miniature Mass Spectrometer: Incorporation of a Dicationic Ionic Liquid-Induced Charge Inversion Strategy.

Green analytical chemistry aims at developing analytical methods with minimum use and generation of hazardous substances for the protection of human health and the environment. To address this need, a green analytical protocol has been developed for the analysis of anionic compounds integrating electromembrane extraction (EME), dual-channel nanoelectrospray ionization (nanoESI), and a miniature mass spectrometer. Haloacetic acids (HAAs) have attracted considerable public concern due to their adverse effects on human health and were selected as model analytes for method development. A flat membrane EME device was developed and assembled in-house. Optimization of fundamental operational parameters was performed using single-factor test and response surface methodology. Both the EME acceptor phase and an imidazolium-based dicationic ionic liquid (DIL), 1,1-bis(3-methylimidazolium-1-yl) butylene difluoride (C4(MIM)2F2), were subjected to dual-channel nanoESI and miniature mass spectrometry analysis based on a charge inversion strategy, where positively charged complexes were formed. Enhancement in signal intensity by as much as 2 magnitudes was achieved in the positive-ion mode compared to the negative-ion mode in the absence of the dicationic ion-pairing agent. The developed protocol was validated, obtaining good recoveries ranging from 82.7 to 109.9% and satisfactory sensitivity with limits of detection (LODs) and quantitation (LOQs) in the ranges of 1-5 and 2-10 μg/L, respectively. The greenness of the analytical procedure was assessed with a calculated score of 0.71, indicating a high degree of greenness. The developed method was applied to the analysis of real environmental or municipal water samples (n = 16), exhibiting appealing potential for outside-the-laboratory applications.

Analysis of optical and thermal properties of 940-nm vertical-cavity surface-emitting lasers

We achieve 13.5 mW optical output power, 48% power conversion efficiency, 1.17 W/A slope efficiency and 17 kW/cm2 laser power density with top-surface-emitting 940 nm oxide-confined vertical-cavity surface-emitting laser (VCSEL). The physical mechanism of minimum threshold current generation in oxide-confined VCSEL has been thoroughly studied theoretically and experimentally. Further, we also succeeded in 90.8 mW optical output power, 40% power conversion efficiency with 2 × 4 VCSEL arrays. We find an increase in output power and PCE of 2 × 2 VCSEL arrays as we increase the array spacing which we attribute primarily to increased heat dissipation and reduced thermal crosstalk between the emitters. Thermal properties in oxide-confined 2 × 2 VCSEL arrays were analyzed numerically and experimentally. The simulated results are in good agreement with the measurement. It is proved that theoretical simulation is very useful for the future device optimization.

Comparative analysis of dual second-order generalized integrator-phase locked loop based series hybrid filter and static synchronous compensator for load voltage compensation and power quality improvement with grid synchronization in islanded microgrid

PurposeThe purpose of this study is to eliminate voltage harmonics and instantly measure the positive sequence fundamental voltage during unbalanced grid conditions, the dual second-order generalized integrator-phase locked loop used in series hybrid filter structures is often used in grid synchronisation in three-phase networks. The preferred series active hybrid power filter simultaneously compensates for voltage balancing and current harmonics generated by non-linear loads.Design/methodology/approachThis paper examines the use of renewable energy–based microgrid (MG) to support linear and non-linear loads. It is capable of synchronising with both the utility and the diesel generator unit. Power is transferred from the grid throughout a stable grid situation with minimum renewable energy generation and maximum load demand. It synchronises with diesel generator set to supply the load and form an AC MG during outages and minimum renewable power generation. In islanded and grid-connected mode, the voltage and power quality issues of the MG are controlled by static synchronous compensator and series hybrid filter.FindingsBecause of the presence of non-linear loads, reactive loads in the distribution system and the injection of wind power into the grid integrated system result power quality issues like current harmonics, voltage fluctuations, reactive power demand, etc.Originality/valueThe voltage at the load (linear and non-linear) is regulated, and the power factor and total harmonic distortions were improved with the help of the series hybrid filter.