Utilization Of Available Capacity Research Articles

Effectiveness of demand response in achieving supply-demand matching in a renewables dominated electricity system: A modelling approach

Globally, electricity systems are undergoing transitions from robust, carbon-intensive, and firm power conventional systems to uncertain, intermittent, and variable renewable energy integrated low carbon systems. These transitioning electricity systems have moved from a situation of “matching available supply with dynamic demand” to “matching dynamic supply with dynamic demand.” These transformations have led to several new challenges - significant mismatch in periods of high supply and high demand, the shift in the method of accessing energy resources for electricity generation from “procure, store and generate when needed” to “generate when available,” continuous struggle to match variable supply with variable demand, and installed capacity redundancy, temporal as well as permanent leading to low plant load factors. Actions on the supply-side alone will not be enough to address these challenges and achieve optimal functioning of the electricity system. We need effective demand-side solutions, too, to manage variations in both supply and demand. In this paper, it is proposed to study the effectiveness of demand-side interventions as potential solutions for managing the variabilities introduced by renewable energy mainstreaming. Towards this, we develop a mixed-integer linear programming model to implement and validate emergency and economic demand response (DR) programs. DR options like load curtailment, short-, medium- and long-term load shifting are considered with both incentive-based and penalty-based pricing strategies to influence consumer participation. The Karnataka electricity system is used as a case study for model implementation and validation. The findings suggest that DR interventions are very effective in moderating variability in electricity demand by chopping the peak loads and topping the valleys. Further, benefits include postponement of installed capacity additions, enhanced utilization of available capacity, and minimization of demand variability.

An Automated Information System for Medium to Short-Term Manpower Capacity Planning in Make-To-Order Manufacturing

In today’s tough economy, it is important for (Make-To-Order) MTO companies to be responsive to customer demand and market fluctuations and to keep the costs as low as possible at the same time. Unlike in Make-To-Stock (MTS), MTO companies hold capacity in reserve. Thus, they are able to make efficient utilization of available capacity to satisfy customer needs. This then leads to a constant capacity planning problem. The companies are facing fluctuations between overload by lack of sufficient capacity, and idleness by excess of capacity comparing to the level of demand. Among all the planning resources, the available manpower is one of the most essential parts of the MTO operations. Therefore, the allocation and adjustment of manpower capacity that suits different planning horizons is a predominant measure to meet the changing capacity demands. Nonetheless, a signing each individual labor to various types of tasks and orders on a day to day basis continually for the planning horizon of several weeks or months is difficult. This paper presents an approach of automated manpower planning model which can be used by MTO operations to achieve a better transparency and synchronization of capacity load for short to medium planning horizons. The approach is implemented as a software tool to automate the data processing and analysis, which helps to dramatically reduce the corresponding data operation efforts and planning time. This paper also presents the validation of the approach and tool in a real production unit in a German small MTO manufacturing company.

Phase Balancing and Reactive Power Support Services for Microgrids

Alternating current (AC) microgrids are expected to operate as active components within smart distribution grids in the near future. The high penetration of intermittent renewable energy sources and the rapid electrification of the thermal and transportation sectors pose serious challenges that must be addressed by modern distribution system operators. Hence, new solutions should be developed to overcome these issues. Microgrids can be considered as a great candidate for the provision of ancillary services since they are more flexible to coordinate their distributed generation sources and their loads. This paper proposes a method for compensating microgrid power factor and loads asymmetries by utilizing advanced functionalities enabled by grid tied inverters of photovoltaics and energy storage systems. Further, a central controller has been developed for adaptively regulating the provision of both reactive power and phase balancing services according to the measured loading conditions at the microgrid’s point of common coupling. An experimental validation with a laboratory scale inverter and a real time hardware in the loop investigation demonstrates that the provision of such ancillary services by the microgrid can significantly improve the operation of distribution grids in terms of power quality, energy losses and utilization of available capacity.

Modelling of multi-period multi-product production planning considering production routes

The multi-period multi-product (MPMP) production planning problems, generally, deal with matching production levels of individual products with fluctuated demands over planning horizon. The conventional MPMP optimisation models suffer from insufficient utilisation of available capacity of machines. This fallacy is due to inappropriate formulation of machine capacity and material handling constraints. In this study, a novel mathematical model is proposed to simultaneously optimise production quantities and provide information about managerial decisions such as subcontracting, carrying inventory/backordering, and also hiring/layoff personnel. The problem is then formulated as a mixed integer linear programming (MILP) model by applying appropriate linearisation of non-linear components. The objective is to minimise production costs comprising of production, storage, shortage, subcontracting costs and costs associated with hiring/dismissing labourers. Superiority of the proposed model over existing ones, has been initially evaluated by solving the case presented by Byrne and Bakir [Byrne, M.D. and Bakir, M.A., 1999. Production planning using a hybrid simulation-analytical approach. International Journal of Production Economics, 59 (1), 305–311], and then evaluated by comparing the results obtained from solving both the proposed and the conventional MPMP production planning models using a 100-randomly-generated-test-problem.

Effect of surface fluorination and conductive additives on the electrochemical behavior of lithium titanate (Li 4/3Ti 5/3O 4) for lithium ion battery

Effect of surface fluorination and conductive additives on the charge/discharge behavior of lithium titanate (Li 4/3Ti 5/3O 4) has been investigated using F 2 gas and vapor grown carbon fiber (VGCF). Surface fluorination of Li 4/3Ti 5/3O 4 was made using F 2 gas (3 × 10 4 Pa) at 25–150 °C for 2 min. Charge capacities of Li 4/3Ti 5/3O 4 samples fluorinated at 70 °C and 100 °C were larger than those for original sample at high current densities of 300 and 600 mA/g. Optimum fluorination temperatures of Li 4/3Ti 5/3O 4 were 70 °C and 100 °C. Fibrous VGCF with a large surface area (17.7 m 2/g) increased the utilization of available capacity of Li 4/3Ti 5/3O 4 probably because it provided the better electrical contact than acetylene black (AB) between Li 4/3Ti 5/3O 4 particles and nickel current collector.

A novel distributed scheduling approach powered by central databases in optical burst networks

In terms of the growth rate, network capacity is slower than network traffic. To solve the mismatch between them, utilization of available capacity can be maximized to provide “best-fit” service for emerging applications (e.g., eBanking, Peer-to-Peer (P2P) file exchanges, etc.). To satisfy such a requirement, we propose a three-dimensional label scheduling algorithm (TD-LSA), which is a distributed scheduling approach powered by central databases. In the proposal, all connections are provisioned in three dimensions (i.e., space, time and wavelength) in a distributed way and uniquely identified by three-dimensional labels. And in this way a three-dimensional connection is more robust than a single-dimensional connection because the three-dimensional approach can avoid potential scheduling conflicts as much as possible by using central databases in a network. Thus, the central databases can reduce bandwidth consumption and offer “best-fit” service for three-dimensional connections. Furthermore, in order to further reduce bandwidth consumption and to match with a priority of traffic, K-least hop first path (K-LHPF) and a rescheduling mechanism are applied to our proposal. Simulation experiments demonstrate that our proposal achieves the expected performance gain against existing alternates.

Preparation and Discharge Characteristics of Solid Redox Polymerization Electrodes Employing Disulfide Polymers and Copolymers.

AbstractRecent work in our laboratory on polymeric organodisulfides has shown these materials to perform well as positive electrodes in solid-state batteries. The polymeric materials have been named solid redox polymerization electrodes (SRPE's) due to the reversible polymerization/depolymerization reaction that occurs on charge/discharge of the electrode. The cell reaction for SRPE-based cells can be described fora simple case as, 2n M + (SRS)n = n M2SRS, where M is an alkali metal (LiNaK) and R is an organic group. In the broader sense SRPE's can have more than two S groups per monomer R unit, and are reversible to other monovalent and divalent metals. In thefully charged state SRPE's consist of polydisulfide polymers and are depolymerized on discharge by scission of sulfur-sulfur bonds, leading to the formation of dithiolate salts in the fully discharged cell. SRPE's are easy to synthesize, are air stable, and should be very inexpensive in bulk quantities. Depending on the redox potential of the polydisulfide and reaction conditions, manydisulfides can be copolymerized by oxidizing a mixture of dithiols, x HSRSH + y HSR'SH + (x+y) l2 = (SRS)x(SR'S)y + 2(x+y) HI, allowing modification of the physical and/or redox properties of the SRPE's. A series of simple aliphatic dithiols including (HSCH2CH2SH), (HSCH2CH2OCH2CH2 SH), and (HSCH2CH2SCH2CH2SH) have been oxidized to polydisulfides and mixtures of the dithiols have been copolymerized. All of the resulting polymers and copolymers were evaluated in solid-state lithium cells, with some of the new materials demonstrating high levels of performance. The utilization of available capacity in the positive electrode was observed to be independent of electrode thickness for a number of SRPE's at loading levels up to 45% by weight. At 90°C, relatively thick positive electrodes based on (SCH2CH2S)n have been discharged to surface capacities of over 20 coulombs/cm2 at a current density of 0.5 mA/cm2. The discharge profiles for most of the aliphatic polydisulfides are exceedingly flat at slightly over 2 volts versus lithium. Although other polydisulfides such as those derived from the dithiazoles exhibit higher cell voltages, the low equivalent weight of materials such as (SCH2CH2S)n [46 g/equiv] and the low cost of such polymers indicates a potential for commercial application.

Planning available capacity in electrical power generation

In planning for the utilisation of available capacity, an electrical company needs to know the power requirements of the system. The load versus duration curve provides information on past demand patterns and thus forms a basis for planning future supply needs. Since electrical supply is discrete by nature, the load versus duration curve only approximates to the true supply requirements. This paper develops an algorithm for finding an optimal step function approximation to the load versus duration curve. It is based on the minimisation of a total penalty function.