Coordinative Optimization Control of Microgrid Based on Model Predictive Control

This article describes how basing on the future behavior of microgrid system, forecasting renewable energy power generation, load and real-time electricity price, a model predictive control (MPC) strategy is proposed in this article to optimize microgrid operations, while meeting the time-varying requirements and operation constraints. Considering the problems of unit commitment, energy storage, economic dispatching, sale-purchase of electricity and load reduction schedule, the authors first model a microgrid system with a large number of constraints and variables to model the power generation technology and physical characteristics. Meanwhile the authors use a mixed logic dynamical framework to guarantee a reasonable behavior for grid interaction and storage and consider the influences of battery life and recession. Then for forecasting uncertainties in the microgrid, a feedback mechanism is introduced in MPC to solve the problem by using a receding horizon control. The objective of minimizing the operation costs is achieved by an MPC strategy for scheduling the behaviors of components in the microgrid. Finally, a comparative analysis has been carried out between the MPC and some traditional control methods. The MPC leads to a significant improvement in operating costs and on the computational burden. The economy and efficiency of the MPC are shown by the simulations.

Strategy in Dispatching Trucks and Shovels with Different Capacity to Increase the Operating Efficiency in Cao Son Surface Coal Mine, Vietnam

In surface mining operations, the operating costs of truck-shovel system constitutes 50-60% ofthe total. Only a little save in the operation costs in this system will bring large profit for the mines. Dueto many investment periods, the capacity of both trucks and shovels in Cao Son surface coal mine isdifferent. This leads to the low efficiency and the difficulty in dispatching strategy for the mine. Thispaper presents the current situation and selection of advanced dispatching strategy for increasing theefficiency trucks and shovels at this surface coal mine. The results show the detailed match factor reflectsthe state of each team of loader and trucks and should be use as the indicator for dispatching decision forthe heterogeneous truck and shovel fleet at Cao Son surface coal mine.

Analytical Optimization Model to Locate and Design Runway-Taxiway Junctions

Aims: Air traffic and airport operations are expected to experience significant growth worldwide in the upcoming years. One of the possible approaches to adapt to this demand-led growth in the sector, while guaranteeing optimal levels of airport services and operations safety, is to maximize the capacities of busy airport infrastructures (in particular runways) by evacuating them in the shortest time possible to be ready for hosting next operations. Background: The main research areas in this field range from statistical risk analyses based on the registered accidents databases to simulation analyses modelling the behaviour of the aircraft during landing operations. Objective: The main objective of this study is to determine precisely the optimal distances of runway-taxiway junctions from the runway’s threshold, according to numerous impact parameters such as airport climate pattern, operating aircraft categories, infrastructure type, and capacity, route connections, operating costs, and associated risks. Methods: The authors developed a mathematical model with the goal of simulating the dynamic behaviour of the aircraft during landing and possible consequences introduced by the presence of contaminants over the pavement surface, by calculating their braking distances, and finally to optimize the use of existing infrastructures, specially runway-taxiway junctions, of a commercial airport. In this regard, the interactions between landing gear, pavement, and fluid were carefully analysed. The dynamic pavement skid resistance values in wet pavement conditions were evaluated for optimizing the required landing distances, which are setting the base for optimizing the location of the taxiway junctions. An Italian international airport was selected as the case study to be simulated by the developed model in order to optimize its runway capacity and maximize its rate of operations. Results: In the process, two different scenarios are simulated with the developed model; a modified design of an existing runway and an alternative design solution for constructing a new runway. The developed model offers improvements for both scenarios with respect to the current runway configurations in terms of reduction in mean rolling distances. The simulation of the selected case study shows that the taxiway modification scenario achieves a reduction of 23% in the mean rolling distance for wet and 25% for dry pavement conditions. While, for designing a new runway, greater reductions of 27% for wet and 39% for dry pavement conditions are obtained due to the higher flexibilities and degrees of freedom in designing a runway from the beginning. Conclusion: The developed model can precisely propose new configurations of the runway-taxiway junctions with lower mean rolling distances, which lower the operation costs and fuel consumption, decrease the runway evacuation times and increase the capacity of the airfield. The main advantage of this model is its ability to cover a wider spectrum of boundary conditions with respect to the existing models and its applicability for designing new runways, plus to optimize the configuration of existing infrastructures in order to satisfy the evolution of the industry.

Integration of anammox into the MBR process for main stream sewage treatment

The integration of Anaerobic ammonia oxidation (anammox) into the membrane bioreactor (MBR) process (AX-MBR) is proposed in this study to reduce operating costs. The temperature was not controlled during the study. Anammox, denitrification, and nitrification were studied in the AX-MBR for 210 days. The reactor was fed with mainstream sewage from Guilin City, China. The results showed that AX-MBR could run with reduced dissolved oxygen (DO) concentration, and COD, NH4+-N, and total nitrogen removal were maintained or improved. The microbial analysis results demonstrated that the added anammox sludge could survive in the AX-MBR, but the sludge microbial diversity decreased. Nitrospira, Candidatus Kuenenia, and Nitrosomonas dominated the anammox sludge. In a word, the AX-MBR developed in this study could treat mainstream sewage with the appropriate management, and the operation costs are expected to reduce by decreasing the amount of aeration.

The trend of using solar energy of a green intelligent building and thermal energy storage to reduce the energy intensity of the building

The trend is to reduce the energy intensity of buildings. Thermal energy storage (TES) is the biggest challenge for buildings. It is a technology that supplies thermal energy by heating or cooling a tank, which then serves for the system in the building. Comparison of hitherto known systems ATES, BTES, PTES and research TTES. The most important factors for the accumulation of thermal energy are capacity (the energy stored in the system - depends on the storage process, the medium, and the size of the system), power (how fast the energy stored in the system can be discharged and charged), efficiency (the ratio of the energy provided to the user to the energy needed to charge the storage system. It accounts for the energy loss during the storage period and the charging/discharging cycle), storage (how long the energy is stored and lasts hours to months), charging and discharging (how much time is needed to charge or discharge the system), and cost (refers to capacity (€/kWh) or power (€/kW) of the TES system and depends on the capital and operation costs of the storage equipment and its lifetime).

Mobile Payments, Demographics and Firm Performance in Kenya

Technological advancements have presented firms with an opportunity to use mobile payments to enhance their performance. This study explores the relationship between mobile payments and firm performance in Kenya. The moderating effects of demographics are also studied. Using primary data collected from 289 supermarkets based in Nairobi City County, we determine whether the use of mobile payment has enhanced firm performance as defined by profitability, operation costs, revenues and the number of customers served. Empirical results from logit regression analysis reveal that the use of a mobile to make payments in supermarkets directly impacts the performance of supermarkets. Additionally, consumer characteristics have a significant moderating effect on the relationship between mobile payments and profitability of supermarkets. We conclude that the use of mobiles to make payments in supermarkets in Kenya has acquired the requisite critical mass level to be in a position to influence revenues of these firms.

Influence of Various Methods of Modelling the Welding Process in the CAE Environment nn the Obtained Deformation Results

By simulating the welding process, potential non-conformities can be detected before serial production is launched, which can significantly reduce operation costs. There are many different possibilities for modeling the process, therefore it is very important to choose a method that will ensure high accuracy of the solution in a relatively short time. The article will present the influence of various methods of modeling the welding process in the CAE environment on the obtained deformation results. For the given geometry and type of weld, the thermal deformations have been simulated based on the Finite Element Method. Several analyzes were carried out using different process modeling approaches (mesh type). Finally, a comparison of the results for the discussed cases is presented to determine the influence of the parameters used on the deformation results obtained.

Impact of Demand Response on Reliability Enhancement in Distribution Networks

This paper presents an innovative instantaneous pricing scheme for optimal operation and improved reliability for distribution systems (DS). The purpose of the proposed program is to maximize the operator’s expected profit under various risk-taking conditions, such that the customers pay the minimum cost to supply energy. Using the previous information of the energy consumption for each customer, a customer baseline load (CBL) is defined; the energy price for consumption costs higher and lower than this level would be different. The proposed scheme calculates the difference between the baseline load and the consumption curve with the electricity market price instead of calculating the total consumption of the customers with the unstable price of the electricity market, which is uncertain. In the proposed tariff, the developed cost and load models are included in the distribution system operation problem, and the objective function is modeled as a mixed integer linear programming (MILP) problem. Also, the effect of demand response (DR) and elasticity on the load curve, the final profit of the distribution system operator, and payment risk and operation costs are examined. Since there are various uncertainties in the smart distribution grid, the calculations being time-consuming and volumetric is important in the evaluation of reliability indices. Thus, when computation volume can be decreased and computation speed can be increased, analytical reliability analysis methods can be used, as they were in the present work. Finally, the changes in the reliability indices were calculated for the ratio of the customers’ sensitivity to the price and the customers’ participation in the proposed tariff using an analytical method based on Monte Carlo simulation (MCS). The results showed the efficiency of the proposed method in increasing the operator profit, reducing the operation costs, and enhancing the reliability indices.

Low density optimization of emulsion explosive to improve blasting quality (MNK Max70)

PT Multi Nitrotama Kimia is a mining service company engaged in providing blasting services and the largest sales of explosives in Indonesia. PT Pamapersada Nusantara jobsite Kideco Jaya Agung is one of the customers of PT Multi Nitrotama Kimia in the blasting service business unit. On a far more optimal side, the development of commodity price conditions and operational needs is a common concern. From these conditions, one of the best target cost controls for blasting and fragmentation is to make adjustments and improvement to the quality and quantity of the use of bulk products. The high use of bulk products at the Kideco Jaya Agung Jobsite is a particular concern, especially for rocks that require a high powder factor value, thereby increasing blasting operation costs. From this condition, PT Multi Nitrotama Kimia strives to optimize the bottom value of density product emulsion MNK Max70 using chemical improvement from the previous 1.15 gr/cc to 1.05 gr/cc. This improvement has brought good results, where optimization in terms of using bulks product and blasting quality such as fragmentation and Velocity of Detonation (VOD) values are still in accordance with product standards.

Optimization of Energy Efficiency, Operation Costs, Carbon Footprint and Ecological Footprint with Reverse Osmosis Membranes in Seawater Desalination Plants

This article shows the optimization of the reverse osmosis process in seawater desalination plants, taking the example of the Canary Islands, where there are more than 320 units of different sizes, both private and public. The objective is to improve the energy efficiency of the system in order to save on operation costs as well as reduce the carbon and ecological footprints. Reverse osmosis membranes with higher surface area have lower energy consumption, as well as energy recovery systems to recover the brine pressure and introduce it in the system. Accounting for the operation, maintenance and handling of the membranes is also important in energy savings, in order to improve the energy efficiency. The energy consumption depends on the permeate water quality required and the model of the reverse osmosis membrane installed in the seawater desalination plant, as it is shown in this study.