45,279 research outputs found
Distributed control of reactive power flow in a radial distribution circuit with high photovoltaic penetration
We show how distributed control of reactive power can serve to regulate
voltage and minimize resistive losses in a distribution circuit that includes a
significant level of photovoltaic (PV) generation. To demonstrate the
technique, we consider a radial distribution circuit with a single branch
consisting of sequentially-arranged residential-scale loads that consume both
real and reactive power. In parallel, some loads also have PV generation
capability. We postulate that the inverters associated with each PV system are
also capable of limited reactive power generation or consumption, and we seek
to find the optimal dispatch of each inverter's reactive power to both maintain
the voltage within an acceptable range and minimize the resistive losses over
the entire circuit. We assume the complex impedance of the distribution circuit
links and the instantaneous load and PV generation at each load are known. We
compare the results of the optimal dispatch with a suboptimal local scheme that
does not require any communication. On our model distribution circuit, we
illustrate the feasibility of high levels of PV penetration and a significant
(20% or higher) reduction in losses.Comment: 6 pages, 5 figures
Local Control of Reactive Power by Distributed Photovoltaic Generators
High penetration levels of distributed photovoltaic (PV) generation on an
electrical distribution circuit may severely degrade power quality due to
voltage sags and swells caused by rapidly varying PV generation during cloud
transients coupled with the slow response of existing utility compensation and
regulation equipment. Although not permitted under current standards for
interconnection of distributed generation, fast-reacting, VAR-capable PV
inverters may provide the necessary reactive power injection or consumption to
maintain voltage regulation under difficult transient conditions. As side
benefit, the control of reactive power injection at each PV inverter provides
an opportunity and a new tool for distribution utilities to optimize the
performance of distribution circuits, e.g. by minimizing thermal losses. We
suggest a local control scheme that dispatches reactive power from each PV
inverter based on local instantaneous measurements of the real and reactive
components of the consumed power and the real power generated by the PVs. Using
one adjustable parameter per circuit, we balance the requirements on power
quality and desire to minimize thermal losses. Numerical analysis of two
exemplary systems, with comparable total PV generation albeit a different
spatial distribution, show how to adjust the optimization parameter depending
on the goal. Overall, this local scheme shows excellent performance; it's
capable of guaranteeing acceptable power quality and achieving significant
saving in thermal losses in various situations even when the renewable
generation in excess of the circuit own load, i.e. feeding power back to the
higher-level system.Comment: 6 pages, 5 figures, submitted to IEEE SmartGridComm 201
Practices for strategic capacity management in Malaysian manufacturing firms
While the notion of manufacturing capabilities is a long-standing notion in research on operations management, its actual implementation and management has been hardly researched. Five case studies in Malaysia offered the opportunity to examine the practice of manufacturing managers with regard to strategic capability management. The data collection and analysis was structured by using the notion of Strategic Capacity Management. Whereas traditionally literature has demonstrated the beneficial impact of an appropriate manufacturing strategy on the business strategy and performance, the study highlights the difficulty of managers to set the strategy, let alone implementing it. This is partly caused by the immense pressure of customers in these dominantly Make-To-Order environments for SMEs. Current concepts for manufacturing capabilities have insufficiently accounted this phenomenon and an outline of a research agenda is presented
Logistics outsourcing and 3PL selection: A Case study in an automotive supply chain
Outsourcing logistics functions to third-party logistics (3PL) providers has been a source of competitive advantage for most companies. Companies cite greater flexibility, operational efficiency, improved customer service levels, and a better focus on their core businesses as part of the advantages of engaging the services of 3PL providers. There are few complete and structured methodologies for selecting a 3PL provider. This paper discusses how one such methodology, namely the Analytic Hierarchy Process (AHP), is used in an automotive supply chain for export parts to redesign the logistics operations and to select a global logistics service provider
The role of learning on industrial simulation design and analysis
The capability of modeling real-world system operations has turned simulation into an indispensable problemsolving methodology for business system design and analysis. Today, simulation supports decisions ranging
from sourcing to operations to finance, starting at the strategic level and proceeding towards tactical and
operational levels of decision-making. In such a dynamic setting, the practice of simulation goes beyond
being a static problem-solving exercise and requires integration with learning. This article discusses the role
of learning in simulation design and analysis motivated by the needs of industrial problems and describes
how selected tools of statistical learning can be utilized for this purpose
Electronic information sharing in local government authorities: Factors influencing the decision-making process
This is the post-print version of the final paper published in International Journal of Information Management. The published article is available from the link below. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. Copyright @ 2013 Elsevier B.V.Local Government Authorities (LGAs) are mainly characterised as information-intensive organisations. To satisfy their information requirements, effective information sharing within and among LGAs is necessary. Nevertheless, the dilemma of Inter-Organisational Information Sharing (IOIS) has been regarded as an inevitable issue for the public sector. Despite a decade of active research and practice, the field lacks a comprehensive framework to examine the factors influencing Electronic Information Sharing (EIS) among LGAs. The research presented in this paper contributes towards resolving this problem by developing a conceptual framework of factors influencing EIS in Government-to-Government (G2G) collaboration. By presenting this model, we attempt to clarify that EIS in LGAs is affected by a combination of environmental, organisational, business process, and technological factors and that it should not be scrutinised merely from a technical perspective. To validate the conceptual rationale, multiple case study based research strategy was selected. From an analysis of the empirical data from two case organisations, this paper exemplifies the importance (i.e. prioritisation) of these factors in influencing EIS by utilising the Analytical Hierarchy Process (AHP) technique. The intent herein is to offer LGA decision-makers with a systematic decision-making process in realising the importance (i.e. from most important to least important) of EIS influential factors. This systematic process will also assist LGA decision-makers in better interpreting EIS and its underlying problems. The research reported herein should be of interest to both academics and practitioners who are involved in IOIS, in general, and collaborative e-Government, in particular
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