Grid Distribution System Research Articles

Locality-Preserving Clustering and Discovery of Resources in Wide-Area Distributed Computational Grids

In large-scale computational Grids, discovery of heterogeneous resources as a working group is crucial to achieving scalable performance. This paper presents a resource management scheme including a hierarchical cycloid overlay architecture, resource clustering and discovery algorithms for wide-area distributed Grid systems. We establish program/data locality by clustering resources based on their physical proximity and functional matching with user applications. We further develop dynamism-resilient resource management algorithm, cluster-token forwarding algorithm, and deadline-driven resource management algorithms. The advantage of the proposed scheme lies in low overhead, fast and dynamism-resilient multiresource discovery. The paper presents the scheme, new performance metrics, and experimental simulation results. This scheme compares favorably with other resource discovery methods in static and dynamic Grid applications. In particular, it supports efficient resource clustering, reduces communications cost, and enhances resource discovery success rate in promoting large-scale distributed supercomputing applications.

RealTime distributed congestion control for electrical vehicle charging

The significant load and unpredictable mobility of electric vehicles (EVs) makes them a challenge for grid distribution systems. Unlike most current approaches to control EV charging, which construct optimal charging schedules by predicting EV state of charge and future behaviour, we leverage the anticipated widespread deployment of measurement and control points to propose an alternative vision. In our approach, drawing from a comparative analysis of Internet and distribution grid congestion, control actions taken by a charger every few milliseconds in response to congestion signals allow it to rapidly reduce its charging rate to avoid grid congestion. We sketch three control schemes that embody this vision and compare their relative merits and demerits.

Study on the Performance of Distribution Grid System in Different Neutral Grounded Modes

In order to reduce grounded current and restrain arc-grounded over voltage during single-phase grounded faults in transmission line and realize fault-line selection, the neutral grounded mode with Peterson coil in parallel with big reactor is proposed in the paper. The simulation and comparative analysis of the performance of the 10 kV distribution grid systems in different neutral grounded modes have been done. The simulation results have shown that the neutral grounded mode via Peterson coil in parallel connection with big resistances can restrain the fault current effectively and it is the best mode.

G2G

Grid systems integrate distributed resources to form self-organization and self-management autonomies. With the widespread development of grid systems around the world, grid collaboration for large-scale computing has become a prevalent research topic. In this paper, the authors propose a meta-grid framework, named the Grid-to-Grid (G2G) framework, to harmonize autonomic grids in realizing a grid federation. The G2G framework is a decentralized management framework that is built on top of existing autonomic grid systems. This paper further adopts a super-peer network in a separate layer to coordinate distributed grid systems. A super-peer overlay network is constructed for communication among super-peers, thus enabling collaboration among grid systems. This study proposes the G2G framework for use in a Grid-to-Grid federation and implements a preliminary system as a demonstration. Experimental results show that the proposed meta-grid framework can improve system performance with little overhead.

BPM Architecture Design Based on Cloud Computing

Cloud Computing has become one of the popular buzzwords in the IT area after Web2.0. This is not a new technology, but the concept that binds different existed technologies altogether including Grid Computing, Utility Computing, distributed system, virtualization and other mature technique. Business Process Management (BPM) is designed for business management using IT infrastructure to focus on process modeling, monitor and management. BPM is composed of business process, business information and IT resources, which help to build a real-time intelligent system, based on business management and IT technologies. This paper describes theory on Cloud Computing and proposes a BPM implement on Cloud environments.

Probabilistic thermoeconomic risk assessment for evaluating climate change decisions

Climate change is often considered in terms of its macroscale implications. But macroscale policy decisions may also significantly impact the localised design of products and services in different business ecosystems. This paper addresses this disconnect by exploring a methodology that combines engineering economics, probabilistic risk assessment, and thermodynamic analysis to evaluate different policy choices. The approach is demonstrated in the context of a representative segment of a hypothetical electrical grid distribution system located between two Electric Power Generating Stations (EPGS) facing overload as additional customer demands are projected to be integrated with renewable sources in the near-term future.

Evaluation of cost and reliability of power systems with large numbers of distributed generators

AbstractThe authors have proposed the Flexible, Reliable and Intelligent ENergy Delivery System (called “FRIENDS”), which is a new concept for future power distribution systems. Also, a “micro grid” which is a similar concept to FRIENDS has been developed. In a micro grid, an independent distribution system can be constituted by a number of distributed generators. In this paper, FRIENDS, Micro grid, and conventional distribution systems are compared quantitatively in supply reliability and system cost through time sequential Monte Carlo simulations. In addition, for cost evaluation, interruption costs are included to show risk incurred by unsupplied energy. Finally, the authors search for preferable form with install and operation of distributed generators and network composition according to social cost including interruption cost and system cost. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 167(2): 28–37, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20659

Agents Network on a Grid: An Approach with the Set of Circulant Operators

In this work we present some matrix operators named circulant operators and their action on square matrices. This study on square matrices provides new insights into the structure of the space of square matrices. Moreover it can be useful in various fields as in agents networking on Grid or large-scale distributed self-organizing grid systems. Keywords— Pascal matrices, Binomial Recursion, Circulant Operators, Square Matrix Bipartition, Local Network, Parallel networks of agents.

A probabilistic and adaptive scheduling algorithm using system-generated predictions for inter-grid resource sharing

Rapid advancement and more readily availability of Grid technologies have encouraged many businesses and researchers to establish Virtual Organizations (VO) and make use of their available desktop resources to solve computing intensive problems. These VOs, however, work as disjointed and independent communities with no resource sharing between them. We, in previous work, have proposed a fully decentralized and reconfigurable Inter-Grid framework for resource sharing among such distributed and autonomous Grid systems (Rao et al. in ICCSA, [2006]). The specific problem that underlies in such a collaborating Grids system is scheduling of resources as there is very little knowledge about availability of the resources due to the distributed and autonomous nature of the underlying Grid entities. In this paper, we propose a probabilistic and adaptive scheduling algorithm using system-generated predictions for Inter-Grid resource sharing keeping collaborating Grid systems autonomous and independent. We first use system-generated job runtime estimates without actually submitting jobs to the target Grid system. Then this job execution estimate is used to predict the job scheduling feasibility on the target system. Furthermore, our proposed algorithm adapted itself to the actual resource behavior and performance. Simulation results are presented to discuss the correctness and accuracy of our proposed algorithm.

分散電源の導入・運用が経済性および供給信頼度に与える効果に関する研究

The authors have proposed Flexible, Reliable and Intelligent ENergy Delivery System (called “FRIENDS”), which is a new concept for future power distribution systems. Also, “Micro grid” which is the similar concept to FRIENDS has been developed. In Micro grid, on independent distribution system can be constituted by a number of distributed generators. In this paper, FRIENDS, Micro grid and conventional distribution systems are compared quantitatively in supply reliability and system cost through time sequential Monte Carlo simulations. In addition, for cost evaluation, interruption costs are included to show risk incurred by unsupplied energy. Finally, authors search for preferable form with install and operation of distributed generators and network composition according to social cost including interruption cost and system cost.

Asset management techniques

Deregulation and an increasing competition in electricity markets urge energy suppliers to optimize the utilization of their equipment, focusing on technical and cost-effective aspects. As a respond to these requirements utilities introduce methods formerly used by investment managers or insurance companies. The article describes the usage of these methods, particularly with regard to asset management and risk management within electrical grids. The essential information needed to set up an appropriate asset management system and differences between asset management systems in transmission and distribution systems are discussed. The bulk of costs in electrical grids can be found in costs for maintenance and capital depreciation. A comprehensive approach for an asset management in transmission systems thus focuses on the “life-cycle costs” of the individual equipment. The objective of the life management process is the optimal utilisation of the remaining life time regarding a given reliability of service and a constant distribution of costs for reinvestment and maintenance ensuring a suitable return. In distribution systems the high number of components would require an enormous effort for the consideration of single individuals. Therefore statistical approaches have been used successfully in practical applications. Newest insights gained by a German research project on asset management systems in distribution grids give an outlook to future developments.

Improvement of power supply to rural customers through grid-interactive distributed generation

The integration of Distributed Generation (DG) into distribution grid systems introduces problems in network operation, control and protection. Key issues associated with DG inclusion are voltage or current control, cost-effective operation, protection coordination and network transients. Better understanding of these issues and finding solutions to these problems are important to power industries. This paper has addressed the general issues and problems of DG implementation, and presented solutions for effective operation and control of the DG system. The impact of DG on distribution protection has been investigated and the level of fault contribution by DG during a fault has been determined. The contribution of DG to the improvement of power quality and reliability has been examined. Mitigation of voltage dip transients and reduction of harmonics in the network by DG have been analysed through modelling and simulations. Also, criteria to select DG technology and safety issues with DG integration have been discussed.

Multiple Distributed Generators for Distribution Feeder Voltage Support

Inclusion of voltage support distributed generation (VSDG) can reinforce the feeder voltage of distribution networks, especially in rural/remote areas where voltage dip and frequent blackouts are significant concerns for power utilities. However, installation of multiple distributed generators within a distribution grid system may introduce technical problems in network operation and control, including control interaction and/or voltage instability. This paper addresses the network issues that may occur during multiple VSDG inclusion in the network and presents analytical models and solutions to develop design criteria of VSDG installation in the networks. Voltage sensitivity of lines is investigated and the effect of DG real (P) and reactive (Q) power injections with Q priority is developed for optimal use of VSDG in correcting the network voltage. Interaction among VSDG controllers has been explored and a generalized model is presented to analyze this interaction between any number of VSDGs in the network. The model is tested on a sample VSDG system and test results are presented. The issue of which VSDG must be started recognizing the costs of starting is addressed using an inverse definite minimum time (IDMT) model. A prioritization and coordination scheme for start discrimination of multiple VSDGs is proposed which avoids hunting between multiple generators.

An Optimization of the Icosahedral Grid Modified by Spring Dynamics

We have investigated an optimum form of the modified icosahedral grid that is generated by applying the spring dynamics to the standard icosahedral grid system. The spring dynamics can generate a more homogeneous grid system than the standard icosahedral grid system by tuning the natural spring lenght: as the natural spring length becomes longer, the ratio of maximum grid interval to minimum one becomes closer to unit. When the natural spring length is larger than a critical value, however, the spring dynamic system does not have a stable equilibrium. By setting the natural spring length to be the marginally critical value, we can obtain the most homogeneous grid system, which is most efficient in terms of the CFL condition. We have analyzed eigenmodes involved in the initial error of the geostrophic balance problem [test case 2 of D. L. Williamson et al. (1992, J. Comput. Phys. 102, 211)]. Since the balance state in the discrete system differs slightly from the exact solution of the analytic system, the initial error field includes both the gravity wave mode and the Rossby wave mode. As the results of the analysis are based on Hough harmonics decompositions, we detected Rossby and gravity wave modes with zonal wavenumber 5, which are asymmetric against the equator. These errors are associated with icosahedral grid structure. The symmetric gravity wave mode with zonal wavenumber 0 also appears in the error field. To clarify the evolution of Rossby waves, we introduce divergence damping to reduce the gravity wave mode. From the simulated results of the geostrophic problem with various grid systems, we found that the spuriously generated Rossby wave mode is eliminated most effectively when the most homogeneously distributed grid system is used. It is therefore, concluded that the most homogeneous grid system is the best choice from the viewpoint of numerical accuracy as well as computational efficiency.

Risk Factors regarding the Application of Degraded Voltage Relaying at Nuclear Generating Stations

Nuclear generating stations utilize degraded voltage relaying schemes to protect electrical equipment against sustained low voltage conditions. Based on regulatory guidance, typical design involves the use of undervoltage relays which, when actuated, automatically disconnect the safety buses from the degraded offsite power supply and initiate reconnection to an alternate supply such as the diesel-generator. This automatic disconnection creates the risk of an unwanted separation from the offsite power supply. Although the industry recognizes the importance of ensuring that adequate voltage is supplied to critical plant equipment, the method of achieving this goal is a matter of ongoing discussion. The potential benefits of degraded voltage relaying schemes do not necessarily outweigh the additional risks that they create, and other measures not explicitly described in the regulations, including detailed analyzes of the transmission grid and onsite distribution system, and procedural controls, are essential elements of a reliable offsite power supply.