Peak Shaving Strategy of Concentrating Solar Power Generation Based on Multi-Time-Scale and Considering Demand Response

According to the multi-time-scale characteristics of power generation and demand-side response(DR)resources,as well as the improvement of prediction accuracy along with the approaching operating point,a rolling peak shaving optimization model consisting of three different time scales has been proposed.The proposed peak shaving optimization model considers not only the generation resources of two different response speeds but also the two different DR resources and determines each unit combination,generation power,and demand response strategy on different time scales so as to participate in the peaking of the power system by taking full advantage of the fast response characteristics of the concentrating solar power(CSP).At the same time,in order to improve the accuracy of the scheduling results,the combination of the day-ahead peak shaving phase with scenario-based stochastic programming can further reduce the influence of wind power prediction errors on scheduling results.The testing results have shown that by optimizing the allocation of scheduling resources in each phase,it can effectively reduce the number of starts and stops of thermal power units and improve the economic efficiency of system operation.The spinning reserve capacity is reduced,and the effectiveness of the peak shaving strategy is verified.

Elevated Temperature Properties of Bamboo Shaving Reinforced Geopolymer Composites

Geopolymer is a new alternative cement binder to produce concrete.In the present study,a novel geopolymer composites containing bamboo shaving(0–2 wt.%)were fabricated and exposed to the temperatures of 200℃,400℃,600℃and 800℃.Physical properties,micro-structure,and mechanical strengths of the geopolymer composites were evaluated before and after heating in order to understand their thermal properties,which are essential for the use as building materials.As the temperature rises,the drying shrinkage and apparent porosity of the composites increase,while the compressive and bending strengths decrease.At the temperature range of 200℃–800℃,the residual compressive strength rates of the geopolymer composite containning 2 wt.%bamboo shaving were respective 73.8%,61.47%,56.16%,and 29.56%,meanwhile,the residual flexural strength rates were respective 46.69%,8.68%,2.52%,and 2.33%.Correspondingly,the residual compressive strength rates of pure geopolymer were respective 72.81%,61.99%,54.55%,and 14.64%;the residual flexural strength rates were 48.87%,5.69%,3.22%,and 2.47%,respectively.Scanning electron microscope(SEM),optical microscope,and X-ray diffractometry(XRD)were applied to find the microscopic changes.The strength loss in the geopolymer composites was mainly because of the thermal degradation of bamboo shaving and shrinkage of geopolymer matrix.Bamboo shaving has great potential as reinforcer in developing low-cost geopolymer composites and may be used for applications up to 400℃.

Combined hybrid energy storage system and transmission grid model for peak shaving based on time series operation simulation

This study proposes a combined hybrid energy storage system(HESS) and transmission grid(TG) model, and a corresponding time series operation simulation(TSOS) model is established to relieve the peak-shaving pressure of power systems under the integration of renewable energy. First, a linear model for the optimal operation of the HESS is established, which considers the different power-efficiency characteristics of the pumped storage system, electrochemical storage system, and a new type of liquid compressed air energy storage. Second, a TSOS simulation model for peak shaving is built to maximize the power entering the grid from the wind farms and HESS. Based on the proposed model, this study considers the transmission capacity of a TG. By adding the power-flow constraints of the TG, a TSOS-based HESS and TG combination model for peak shaving is established. Finally, the improved IEEE-39 and IEEE-118 bus systems were considered as examples to verify the effectiveness and feasibility of the proposed model.

Synthesis and Characterization of a Novel Bamboo Shaving Geopolymer Composite

Geopolymers are inorganic aluminosilicate materials,which have been a great research interest as a material for sustainable development.However,they possess relatively low toughness properties similar to brittle solids.The limitation may be altered by fiber reinforcement to improve their strength and toughness.This research describes the synthesis of bamboo shaving(BS)reinforced geopolymer composites and the characterization of their mechanical properties.The effect of BS content(0–2 wt.%)on the physical and mechanical properties and microstructure of metakaolin based geopolymer paste were investigated.The workability,setting time,bulk density,apparent porosity,thermal conductivity,compressive strength,flexural strength,scanning electron microscopy(SEM),and X-ray diffraction(XRD)of geopolymer paste were determined.The results showed that the workability,setting time,density,and thermal conductivity decreased with the increasing of BS content.The BS content was proportional to the apparent porosity and a good linear relation was found between apparent porosity and BS content.The highest mechanical properties were achieved at an optimum BS content of 1.0 wt.%.The results of microstructural analysis revealed that BS act as inforcing phase in matrix,reducing cracks and making a dense geopolymer,which leads to favorable adhesion of the composites and produces a geopolymer composite with better mechanical properties than that of pure geopolymer.However,when the BS content exceeded 1.0 wt.%,interfacial bonding between BS and geopolymer matrix became less.XRD analysis showed that BS has little effect on the mineral composition of metakaolin-based geopolymer and no new phase is formed.

Collaborative optimization model of renewable energy development considering peak shaving costs of various flexibility resources

China has set carbon emission goals for 2030 and 2060.Renewable energy sources,primarily wind and photovoltaic power,are being considered as the future of power generation.The major limitation to the development of new energies is the limited flexibility of regulations on power system resources,resulting in insufficient consumption capacity.Thus,the flexible resource costs for peak shaving as well as the reasonable coordinated development and operation optimization of regional renewable energy need to be considered.In this study,a renewable energy development layout configuration analysis method was established by considering the composite cost of a power system,comprehensively analyzing the potential of various flexibility regulation resources for the power system and its composite peak shaving cost,and combining renewable energy output characteristics,load forecasting,grid development,and other factors.For the optimization of various flexible resource utilization methods,a peak shaving cost estimation method from the perspective of the entire power system was established by combining the on-grid electricity prices and operating costs of different power sources.A collaborative optimization model of power system operation that aims at the lowest peak shaving cost and satisfies the constraints of operation,safety,and environmental protection was proposed.Finally,a certain area of Gansu Province was used as an example to perform detailed analysis and calculation,which demonstrated that the model has an optimal effect.This model can provide an analysis method for regional renewable energy development layout configurations and system optimization operations.

Design and Manufacture of the Shaving Cutter with Unequal Depth Gashes

Gear shaving is a gear finishing operation of high efficiency and high precision. After shaved by shaving cutter of true involute profile, there are the "mid-concave" phenomena around the pitch points of the work gear tooth flanks inevitably. This problem severely affects the shaving accuracy and gear transmission quality, which hasn’t been resolved thoroughly for a long time. Aiming at the problem, based on shaving mechanism and the analysis on gear tooth profile mid-concave, a new-style shaving cutter with unequal depth gashes is designed and manufactured. As compared with common shaving cutter, its depth of gashes is zero on the pitch points of tooth profiles and gradually gets deeper to max. from pitch points to the tops of teeth or the roots. Because of no depth on the pitch points, there are no cutting edges, that is, no cutting action, so the work gear isn’t cutted around its pitch points and is only pressed during shaving operation. Therefore, the gear tooth errors are decreased greatly. And the experimentations have proved the shaved gear has better surface finish that achieves the expectant effect. In addition, this paper analyses the forming of gash on the basis of slotting principle, and proposes a design method of gash: gash bottom is formed by two involutes which intersect on the pitch point and are concentric with the base circle of involute profile of cutter. Furthermore, the equations of the two involutes are deduced and the solution is introduced. This paper analyses the forming of gash on the basis of slotting principle, and proposes a gash-designing method. And the experiment has proved that the shaved gear has better surface finish that achieves the anticipated effect.

Design of Plunge Shaving Cutters for Finishing internal Gears

ＤｅｓｉｇｎｏｆＰｌｕｎｇｅＳｈａｖｉｎｇＣｕｔｔｅｒｓｆｏｒＦｉｎｉｓｈｉｎｇ ｉｎｔｅｒｎａｌＧｅａｒｓＬＩＵＬｉｐｉｎｇ；ＬＩＨｕａｍｉｎ；ＳＵＮＪｉａｎｈｕａ（刘俐平，李华敏，孙建华）（Ｄｅｐｔ．ｏｆＭｅｃｈａｎｉｃａｌＥｎｇｉｎｅｅｒｉｎｇ...

Potential of Rooftop PV Systems on Weekly Peak Load Shaving in Saudi Arabia

In recent years, high annual increasing load demand in Saudi Arabia has led to large investments in the construction of conventional power plants, which use oil or gas as the main fuel. The government is considering a large deployment of renewable energy for its 2030 vision plan. The Kingdom of Saudi Arabia is one of the best potential candidates for harvesting solar energy because of the country’s geographical location, clear sky, and vast land area. A recent energy policy announced by the government involves harvesting solar photovoltaic (PV) energy to reduce the country’s reliance on fossil fuel and greenhouse gas emissions. Using rooftop PV systems can help to shave the peak load and lead to a significant savings in the power sector through the reduction of annual installation of conventional power plants and standby generators. Employing solar PV at the end user level helps to reduce the overloading of transmission and distribution lines as well as decreases power losses. This paper will provide ratings for different rooftop PV systems that are being considered for installation for customers with various needs. The distribution of PV installation among the customers is as follows: 5% residential, 10% commercial, and 20% government. The effect of PV output power on weekly peak demand has been evaluated. The paper has also investigated the impact of the temperature on PV output power, especially during the summer. The PV power contribution is analyzed based on the assumption that weekly peak power production of solar PV coincides with weekly peak load demand. The PV model is implemented in Matlab to simulate and analyze the PV power.

Determination of PCDD/F Levels in Wood Shavings Used as Bedding Material for Poultry Production

During 2006 and 2011, following the implementation of dioxin contamination monitoring in poultry meat, levels higher than legally allowed in meat from poultry slaughtered for human consumption, were found. The wood shavings used as bedding material in the poultry farm showed considerable high contaminations, indicating that these materials were the likely source of contamination of the animals. Wood shavings samples (n = 23), used as poultry litters in intensive farms of broilers, were analysed. In both episodes, contamination profiles of higher and lower concentrations, seem to be very similar, being OCDD, OCDF, 1,2,3,4,6,7,8-HpCDD and 1,2,3,4,6,7,8-HpCDF responsible for 97.4 % of the total contamination. The present work describes the analytical adapted, used methodology and the specific clean-up procedures, which revealed that recoveries of 13C12-Labelled compounds added to the wood shavings samples ranged from 71.3% to 86.3%.

A fast and efficient coordinated vehicle-to-grid discharging control scheme for peak shaving in power distribution system

This study focuses on the potential role of plugin electric vehicles(PEVs) as a distributed energy storage unit to provide peak demand minimization in power distribution systems. Vehicle-to-grid(V2 G) power and currently available information transfer technology enables utility companies to use this stored energy. The V2 G process is first formulated as an optimal control problem.Then, a two-stage V2 G discharging control scheme is proposed. In the first stage, a desired level for peak shaving and duration for V2 G service are determined off-line based on forecasted loading profile and PEV mobility model. In the second stage, the discharging rates of PEVs are dynamically adjusted in real time by considering the actual grid load and the characteristics of PEVs connected to the grid. The optimal and proposed V2 G algorithms are tested using a real residential distribution transformer and PEV mobility data collected from field with different battery and charger ratings for heuristic user case scenarios. The peak shaving performance is assessed in terms of peak shaving index and peak load reduction. Proposed solution is shown to be competitive with the optimal solution while avoiding high computational loads. The impact of the V2 G management strategy on the system loading at night is also analyzed by implementing an off-line charging scheduling algorithm.

Optimization of Urban Multi-energy Flow Systems Considering Seasonal Peak Shaving of Natural Gas

In order to alleviate the shortage of natural gas supply in winter,relevant policies have been issued to promote the construction of gas peak-shaving and storage facilities.Largescale gas storage can transfer the supply-demand relationship of natural gas in time sequence,which has great potential in improving the economy and reliabillity of urban multi-energy flow systems.Addressing this issue,this paper proposes a mid-and long-term energy optimization method for urban multi-energy flow system that considers seasonal peak shaving of natural gas.First,the energy supply and demand features of different energy subsystems are analyzed.Then,a network model of the electricity-gas-heat multi-energy flow system is established.Considering the time-of-use electricity price mechanism and the seasonal fluctuations of the natural gas price,a mid-and long-term energy optimization model maximizing the annual economic revenue is established.The alternative direction multiplier method with Gaussian back substitution(ADMM-GBS)algorithm is used to solve the optimal dispatch model.Finally,the proposed method is verified by employing the actual data of the demonstration zone in Yangzhong City,China.The simulation results show that the proposed method is effective.

Toxicity evaluation of collagen hydrolysates from chrome shavings and their potential use in the preparation of amino acid fertilizer for crop growth

Resource utilization of chrome shavings(CS)has attracted a lot of attention from scientists and technologists in leather industry.Especially,the collagen hydrolysates extracted from CS are expected to find potential application values in agricultural field.However,there is no biotoxicity analysis of collagen hydrolysates from CS.Herein,the collagen hydrolysates with different molecular weights were produced from CS by three hydrolysis dechroming methods including alkaline hydrolysis,enzymatic hydrolysis and alkaline-enzymatic synergistic hydrolysis,and the optimal hydrolysis process of CS was designed and conducted.To evaluate their toxicity,the three collagen hydrolysates were formulated into a nutrient solution for zebrafish development.The obtained results indicated that the hydrolysates with low concentrations(less than 0.6 mg/mL)were safe and could promote the development for zebrafish embryos.Furthermore,the three collagen hydrolysates were utilized as organic nitrogen sources and formulated into amino acid water-soluble fertilizers(AAWSF)including alkaline type fertilizer(OH),enzymatic type fertilizer(M)and alkaline-enzymatic type fertilizer(OH-M)for the early soilless seeding cultivation of wheat,soybean and rapeseed.It is worth mentioning that the chromium contents in the prepared AAWSF were less than 10 mg/kg,which is far less than the limit value in the standard(China,50 mg/kg).The growth and development of seedlings(germination rate,plant height,fresh weight of leaves,soluble sugar content and chlorophyll content)were investigated.The corresponding results showed that the growth of seedlings watered with AAWSF was better compared with the other treatments,and the OH-M fertilizer had the best promoting effect on the seedlings growth and development,followed by the M and OH fertilizers.The safe toxicity assessment of the collagen hydrolysates will expand their application scope,and the use of collagen hydrolysates extracted from CS for seedlings growth also provides an effective and reason-able way to deal with the chromium-containing leather solid waste,which is an effective way to realize its resource utilization.

Heat development at the knife roller during leather shaving

Leather,which is regularly tanned from whole hides of up to 5 m 2,needs a constant thickness over the entire surface in order to be processed into high-quality consumer goods such as shoes,furniture and car interiors.Precise adjustment of the thickness is achieved by shaving.On an industrial scale,rotating knife rollers are used to remove chips from the flesh side of semi-finished leathers whereby adjusting the specified thickness and generating a smooth surface.Care must be taken to prevent the temperature from rising above the denaturation temperature of the leather during shaving in order to avoid any loss of quality.Beside this,temperature rise is always a sign of friction showing avoidable energy expenditure.In order to localize the source of friction during shaving,actual temperature development at the roller knife is studied.Different measuring methods are used to evaluate the temperature increase at the blade roll of the shaving machine.The finite element method is used to thermally simulate the process.Measured temperatures,the geometry of the blade roll and process data are taken into account for modelling the temperature development close to the blade edge.The obtained results enhance the understanding of temperature generating processes during machine operation and allow conclusions about potential improvements in the design of the machine and blades.

Empirical investigation to explore potential gains from the amalgamation of phase changing materials(PCMs)and wood shavings

The reduction of gained heat,heat peak shifting,and the mitigation of air temperature fluctuations are some desirable properties that are sought after in any thermal insulation system.It cannot be overstated that these fac-tors,in addition to others,govern the performance of such systems thus their effect on indoor ambient conditions.The effect of such systems extends also to Heating,Ventilation and Air-conditioning(HVAC)systems that are set up to operate optimally in certain conditions.Where literature shows that PCMs and natural materials such as wood-shavings can provide efficient passive insulation for buildings,it is evident that such approaches utilise methods that are of a degree of intricacy which require specialist knowledge and complex techniques,such as micro-encapsulation for instance.With technical and economic aspects in mind,an amalgam of PCM and wood-shavings has been created to be utilised as a feasible thermal insulation.The amalgamation was performed in the simplest of methods,through submerging the wood shavings in PCM.An experimental procedure was devised to test the thermal performance of the amalgam and compare this to the performance of the same un-amalgamated materials.Comparative analysis revealed that no significant thermal gains would be expected from such amal-gamation.However,a significant reduction in the total weight of the insulation system would be achieved that,in this case,shown to be up to 20.94%.Thus,further reducing possible strains on structural elements due to the application of insulation on buildings.This can be especially beneficial in vernacular architectural approaches where considerably large amounts and thicknesses of insulations are used.In addition,cost reduction could be attained as wood shavings are significantly cheaper compared to the cost of PCMs.

A combined kinetic study on the pyrolysis of chrome shavings by thermogravimetry

Chrome shavings(CS),a kind of solid wastes discharged from tanneries,always pose serious environmental problems due to the presence of chromium.In this work,kinetic study of the pyrolysis of CS was investigated using a thermogravimetric analyzer in nitrogen atmosphere.The results obtained from the thermogravimetric analysis indicated that there are three stages in the temperature range 25 to 600℃.The second stage is the main weight loss stage and it could be mainly attributed to the pyrolysis of collagenous materials.Iso-conversional and generalized master-plots method were first employed to estimate the activation energy value and possible reaction mechanism of CS pyrolysis.The results showed that the pyrolysis process could not be described accurately by single-step reaction due to the heterogeneous nature of CS.Afterwards,the thermogravimetric kinetic of CS pyrolysis was studied using combined kinetic analysis.It was found that three-parallel-reaction model allowed better fitting relevance for CS pyrolysis.This information was important for simulating and predicting the pyrolysis behaviors of CS.

Investigation of different pre-treatments of chromium leather shavings to improve biogas production

Chromium shavings are wet by-products of the leather industry,of which thousands of tons accrue worldwide during leather manufacture.Due to their chromium content,chromium shavings are responsible for the most important ecological challenges caused by the leather industry.They are stable towards temperatures of up to 110°C and enzymatic degradation.This high stability is caused by the three-dimensional native structure,typical for collagen,and additional chemical cross-links between the collagen fibres achieved by Cr3+salts in the tanning process.Therefore,hitherto chromium shavings are not utilized industrially to produce biogas.In order to generate biogas,this stable structure has to be denatured.Chromium shavings were pre-treated by extrusion and hydrothermal methods.To prove the enzymatic degradability,the different pre-treatments were evaluated by differential scanning calorimetry(DSC),enzymatic assays,and by measuring the solubility in water.The biogas production potential was investigated using batch trials to examine feasibility.Results demonstrated that both pretreatments allowed enzymatic attack and increased degradability of the chromium shavings reducing the lag-phase of biogas production and the remaining waste.

“Extreme utilization” theory and practice in gas storages with complex geological conditions

Based on more than 20-year operation of gas storages with complex geological conditions and a series of research findings, the pressure-bearing dynamics mechanism of geological body is revealed. With the discovery of gas-water flowing law of multi-cycle relative permeability hysteresis and differential utilization in zones, the extreme utilization theory targeting at the maximum amount of stored gas, maximum injection-production capacity and maximum efficiency in space utilization is proposed to support the three-in-one evaluation method of the maximum pressure-bearing capacity of geological body, maximum well production capacity and maximum peak shaving capacity of storage space. This study realizes the full potential of gas storage(storage capacity) at maximum pressure, maximum formation-wellbore coordinate production, optimum well spacing density match with finite-time unsteady flow, and peaking shaving capacity at minimum pressure, achieving perfect balance between security and capacity. Operation in gas storages, such as Hutubi in Xinjiang, Xiangguosi in Xinan, and Shuang6 in Liaohe, proves that extreme utilization theory has promoted high quality development of gas storages in China.

Peak Electricity Demand Management and Energy Efficiency among Large Steel Manufacturing Firms in Nairobi Region, Kenya

To reduce peak electricity demand and hence reduce capacity costs due to added investment of generating additional power to meet short intervals of peak demand, can enhance energy efficiency. Where it is possible to adjust timing and the quantity of electricity consumption and at the same time achieve the same useful effect, the value of the energy service itself remains unchanged. Peak demand management is viewed as the balance between demand and generation of energy hence an important requirement for stabilized operation of power system. Therefore, the purpose of this study was to establish the correlation between peak electricity demand management strategies and energy efficiency among large steel manufacturing firms in Nairobi, Kenya. The strategies investigated were demand scheduling, Peak shrinking and Peak shaving. Demand scheduling involves shifting predetermined loads to low peak periods thereby flattening the demand curve. Peak shrinking on the other hand involves installation of energy efficient equipment thereby shifting the overall demand curve downwards. Peak shaving is the deployment of secondary generation on site to temporarily power some loads during peak hours thereby reducing demand during the peak periods of the plant. The specific objectives were to test the relationship between demand scheduling and energy efficiency among large steel manufacturing firms in Nairobi Region;to test the correlation between peak shrinking and energy efficiency among large steel manufacturing firms in Nairobi Region;and to test the association between peak shaving and energy efficiency among large steel manufacturing firms in Nairobi Region. The study adopted a descriptive research design to determine the relationship between each independent variable namely demand scheduling, peak shrinking, peak shaving and the dependent variable, the energy efficiency. The target population was large steel manufacturing firms in Nairobi Region, Kenya. The study used both primary and secondary data. The primary data was from structured questionnaires while secondary data was from historical electricity consumption data for the firms under study. The results revealed that both peak shrinking and peak shaving were statistically significant in influencing energy efficiency among the steel manufacturing firms in Nairobi Region, each with Pearson correlation coefficient of 0.903, thus a strong linear relationship between the investigated strategy and the dependent variable, energy efficiency. The obtained results are significant at probability value of 0.005 (p 0.05). The conclusion is that peak shrinking and peak shaving have an impact on energy efficiency in the population under study, and if properly implemented, may lead to efficient utilization of the available energy. The study further recommended that peak demand management practices need to be implemented efficiently as a way of improving the overall plant load factor and energy efficiency.

星点设计-效应面试验优化复方竹茹植物固体饮料的处方

为优化以竹茹(Bamboo shavings)、陈皮、茯苓(Poria cocos)、白茅根、干姜为原料制成的复方竹茹植物固体饮料的处方,以颗粒成型率、水分、休止角等为评价指标,通过单因素试验和星点设计-效应面试验考察稀释剂配比(甘露醇∶糊精)、稀释剂用量(干膏粉∶稀释剂),确定固体饮料的最佳工艺处方,并采用湿法制粒法制备复方竹茹植物固体饮料。结果表明,复方竹茹植物固体饮料的最佳成型工艺参数为稀释剂配比为2.3∶1,稀释剂用量为1.5∶1。该工艺条件下,颗粒成型率达94.30%,水分为1.44%,流动性好,研究可为复方竹茹植物固体饮料的工业化生产提供理论依据。

Battery Technologies for Grid-Level Large-Scale Electrical Energy Storage

Grid-level large-scale electrical energy storage(GLEES) is an essential approach for balancing the supply–demand of electricity generation, distribution, and usage. Compared with conventional energy storage methods, battery technologies are desirable energy storage devices for GLEES due to their easy modularization, rapid response, flexible installation, and short construction cycles. In general, battery energy storage technologies are expected to meet the requirements of GLEES such as peak shaving and load leveling, voltage and frequency regulation, and emergency response, which are highlighted in this perspective. Furthermore, several types of battery technologies, including lead–acid, nickel–cadmium, nickel–metal hydride, sodium–sulfur, lithium-ion, and flow batteries, are discussed in detail for the application of GLEES. Moreover, some possible developing directions to facilitate efforts in this area are presented to establish a perspective on battery technology, provide a road map for guiding future studies, and promote the commercial application of batteries for GLEES.