2,046 research outputs found

    Redundant IEC 61850 communication protocols in substation automation

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    The standard IEC 61850 has been adopted with open arms by the power system automation market. The first version of the standard published in 2005 did not however pay any attention to redundant communication aspects of the substation automation network. The recent extensions to the standard however corrected this defect and bring redundancy into view, adopting two high availability redundancy protocols from the existing standard IEC 62439-3: Parallel Redundancy Protocol (PRP) and High-availability Seamless Redundancy (HSR). These two protocols provide seamless (0 s.) network recovery times and fulfill even the most demanding requirements for substation automation network. In this thesis, these two redundancy protocols, their usage and possibilities in substation automation are investigated. At first, the IEC 61850 features, substation communication network topologies, and also the redundancy protocols and methods used today are presented. After this, the protocols PRP and HSR are discussed more deeply. The theoretical part is followed by a test of a system with PRP and ABB devices to give general notes and clarify possible problems when building such a system, and to investigate if the ABB PRP implementation is accordant with the standard IEC 62439-3. The objective of this thesis was to bring information and early experience about the two high-availability redundancy protocols, as they will be gradually introduced in the projects of the target company. The test confirmed that the current PRP version is ready to be used with the few ABB substation automation products that support it at the moment. However, a new version of PRP has been introduced and it will gradually replace the present version, bringing compatibility with HSR networks. HSR is not yet found on the market, but is expected to come to use in the very near future.fi=Opinnäytetyö kokotekstinä PDF-muodossa.|en=Thesis fulltext in PDF format.|sv=Lärdomsprov tillgängligt som fulltext i PDF-format

    Microspacecraft and Earth observation: Electrical field (ELF) measurement project

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    The Utah State University space system design project for 1989 to 1990 focuses on the design of a global electrical field sensing system to be deployed in a constellation of microspacecraft. The design includes the selection of the sensor and the design of the spacecraft, the sensor support subsystems, the launch vehicle interface structure, on board data storage and communications subsystems, and associated ground receiving stations. Optimization of satellite orbits and spacecraft attitude are critical to the overall mapping of the electrical field and, thus, are also included in the project. The spacecraft design incorporates a deployable sensor array (5 m booms) into a spinning oblate platform. Data is taken every 0.1 seconds by the electrical field sensors and stored on-board. An omni-directional antenna communicates with a ground station twice per day to down link the stored data. Wrap-around solar cells cover the exterior of the spacecraft to generate power. Nine Pegasus launches may be used to deploy fifty such satellites to orbits with inclinations greater than 45 deg. Piggyback deployment from other launch vehicles such as the DELTA 2 is also examined

    Platform Power Management

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    Design of Energy-Efficient A/D Converters with Partial Embedded Equalization for High-Speed Wireline Receiver Applications

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    As the data rates of wireline communication links increases, channel impairments such as skin effect, dielectric loss, fiber dispersion, reflections and cross-talk become more pronounced. This warrants more interest in analog-to-digital converter (ADC)-based serial link receivers, as they allow for more complex and flexible back-end digital signal processing (DSP) relative to binary or mixed-signal receivers. Utilizing this back-end DSP allows for complex digital equalization and more bandwidth-efficient modulation schemes, while also displaying reduced process/voltage/temperature (PVT) sensitivity. Furthermore, these architectures offer straightforward design translation and can directly leverage the area and power scaling offered by new CMOS technology nodes. However, the power consumption of the ADC front-end and subsequent digital signal processing is a major issue. Embedding partial equalization inside the front-end ADC can potentially result in lowering the complexity of back-end DSP and/or decreasing the ADC resolution requirement, which results in a more energy-effcient receiver. This dissertation presents efficient implementations for multi-GS/s time-interleaved ADCs with partial embedded equalization. First prototype details a 6b 1.6GS/s ADC with a novel embedded redundant-cycle 1-tap DFE structure in 90nm CMOS. The other two prototypes explain more complex 6b 10GS/s ADCs with efficiently embedded feed-forward equalization (FFE) and decision feedback equalization (DFE) in 65nm CMOS. Leveraging a time-interleaved successive approximation ADC architecture, new structures for embedded DFE and FFE are proposed with low power/area overhead. Measurement results over FR4 channels verify the effectiveness of proposed embedded equalization schemes. The comparison of fabricated prototypes against state-of-the-art general-purpose ADCs at similar speed/resolution range shows comparable performances, while the proposed architectures include embedded equalization as well

    Architecting Efficient Data Centers.

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    Data center power consumption has become a key constraint in continuing to scale Internet services. As our society’s reliance on “the Cloud” continues to grow, companies require an ever-increasing amount of computational capacity to support their customers. Massive warehouse-scale data centers have emerged, requiring 30MW or more of total power capacity. Over the lifetime of a typical high-scale data center, power-related costs make up 50% of the total cost of ownership (TCO). Furthermore, the aggregate effect of data center power consumption across the country cannot be ignored. In total, data center energy usage has reached approximately 2% of aggregate consumption in the United States and continues to grow. This thesis addresses the need to increase computational efficiency to address this grow- ing problem. It proposes a new classes of power management techniques: coordinated full-system idle low-power modes to increase the energy proportionality of modern servers. First, we introduce the PowerNap server architecture, a coordinated full-system idle low- power mode which transitions in and out of an ultra-low power nap state to save power during brief idle periods. While effective for uniprocessor systems, PowerNap relies on full-system idleness and we show that such idleness disappears as the number of cores per processor continues to increase. We expose this problem in a case study of Google Web search in which we demonstrate that coordinated full-system active power modes are necessary to reach energy proportionality and that PowerNap is ineffective because of a lack of idleness. To recover full-system idleness, we introduce DreamWeaver, architectural support for deep sleep. DreamWeaver allows a server to exchange latency for full-system idleness, allowing PowerNap-enabled servers to be effective and provides a better latency- power savings tradeoff than existing approaches. Finally, this thesis investigates workloads which achieve efficiency through methodical cluster provisioning techniques. Using the popular memcached workload, this thesis provides examples of provisioning clusters for cost-efficiency given latency, throughput, and data set size targets.Ph.D.Computer Science & EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/91499/1/meisner_1.pd

    Application of advanced technology to space automation

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    Automated operations in space provide the key to optimized mission design and data acquisition at minimum cost for the future. The results of this study strongly accentuate this statement and should provide further incentive for immediate development of specific automtion technology as defined herein. Essential automation technology requirements were identified for future programs. The study was undertaken to address the future role of automation in the space program, the potential benefits to be derived, and the technology efforts that should be directed toward obtaining these benefits

    A Companion Study Guide for the Cisco DCICN Data Center Certification Exam (200-150)

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    The official Cisco DCICN book and practice exams are great resources, but this is not an easy exam. This study guide is a companion to those resources and summarizes the subject areas into additional review questions with an answer description for each item. This book is not a braindump and it is not bootleg screenshots of the actual exam. Instead, this book provides additional context and examples, serves to complement other study guides, and provides additional examples. If you are getting ready to take the exam for the first time, I hope that this guide provides the extra help to pass! If you are up for re-certification, I hope that this guide serves as a refresher and reminder! Keep working hard, keep studying, and never stop learning…https://digitalcommons.odu.edu/distancelearning_books/1000/thumbnail.jp

    Viking '75 spacecraft design and test summary. Volume 1: Lander design

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    The Viking Mars program is summarized. The design of the Viking lander spacecraft is described

    A Dynamically Refocusable Sampling Infrastructure for 802.11 Networks

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    The edge of the Internet is increasingly wireless. Enterprises large and small, homeowners, and even whole cities have deployed Wi-Fi networks for their users, and many users never need to--- or never bother to--- use the wired network. With the advent of high-throughput wireless networks (such as 802.11n) some new construction, even of large enterprise build- ings, may no longer be wired for Ethernet. To understand Internet traffic, then, we need to understand the wireless edge. Measuring Wi-Fi traffic, however, is challenging. It is insufficient to capture traffic in the access points, or upstream of the access points, because the activity of neighboring networks, ad hoc networks, and physical interference cannot be seen at that level. To truly understand the MAC-layer behavior, we need to capture frames from the air using Air Monitors (AMs) placed in the vicinity of the network. Such a capture is always a sample of the network activity, since it is physically impossible to capture a full trace: all frames from all channels at all times in all places. We have built a monitoring infrastructure that captures frames from the 802.11 network. This infrastructure includes several channel sampling strategies that will capture repre- sentative traffic from the network. Further, the monitoring infrastructure needs to modify its behavior according to feedback received from the downstream consumers of the captured traffic in case the analysis needs traffic of a certain type. We call this technique refocusing . The coordinated sampling technique improves the efficiency of the monitoring by utilizing the AMs intelligently. Finally, we deployed this measurement infrastructure within our Computer Science building to study the performance of the system with real network traffic
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