456,138 research outputs found
Author, Geraldine Brooks at the National Library of Australia for the 2009 Ray Mathew Lecture, Canberra, 23 October 2009 [picture] /
No full textTitle from acquisitions documentation.; Part of the collection: Portraits of author, Geraldine Brooks during her visit to the National Library of Australia for the 2009 Ray Mathew Lecture, Canberra, 23 October 2009.; Acquired in digital format; access copy available online.; Mode of access: Internet via World Wide Web.; Photographed by a staff member of the National Library of Australia
Portrait of Robert Dessaix in the National Library of Australia bookshop, Canberra, 10 October 2008, 1 [picture] /
No full textTitle from acquisitions documentation.; Part of the collection: Portraits of author Robert Dessaix in the National Library of Australia bookshop, Canberra, 10 October 2008.; Acquired in digital format; access copy available online.; Mode of access: Internet via World Wide Web.; Photographed by a staff member of the National Library of Australia
Effects of power electronic compensation on distribution network thermal and voltage violations
No full textThis paper is concerned with the use of medium-voltage power electronics in providing active compensation to distribution networks. The primary purpose of using active compensation is to allow for network growth in the form of distributed generation or customer demand increases. With continuing growth, network thermal and voltage constraints would eventually be violated at some point, even with the use of power electronic compensation. Through the study of increasing generation on several hundred distribution network datasets, trends in the type and location of these constraint breaches are identified for both uncompensated and compensated networks. In comparing the initial types of constraint breaches in uncompensated and compensated networks, the use of power electronics is seen to eliminate overvoltage issues as the primary concern in many cases. In addition, while power electronic compensation is seen to make a significant change in the growth accommodated before constraint breach, the location of these initial breaches is not altered appreciably
Portrait of Robert Dessaix in the National Library of Australia bookshop, Canberra, 10 October 2008, 2 [picture] /
No full textTitle from acquisitions documentation.; Part of the collection: Portraits of author Robert Dessaix in the National Library of Australia bookshop, Canberra, 10 October 2008.; Acquired in digital format; access copy available online.; Mode of access: Internet via World Wide Web.; Photographed by a staff member of the National Library of Australia
Battery Storage System as Power Unbalance Redistributor in Distribution Grids Based on Three Legs Four Wire Voltage Source Converter
No full textThis article discusses the application of battery energy storage systems (BESSs) as power redistributors in three-phase distribution grids as an add-on functionality to typical BESS applications, such as congestion management and energy arbitrage. Combining those ancillary services into a single power unit is not yet performed in practice but may constitute an emerging business opportunity to increase the BESS revenues. The unbalanced operation of the BESS voltage source converter (VSC) leads to the circulation of low-frequency current harmonics in the dc-link through the capacitors and the battery cells. Therefore, it is particularly interesting whether relatively large 50- and 100-Hz currents can safely circulate within these components. Analytical modeling and design guidelines for the dc-link of a three-leg four-wire two-level VSC operating under unbalanced loads are detailed. Furthermore, a low-power VSC prototype is used to demonstrate the working principle of the BESS, providing power unbalance redistribution and symmetric power exchange. Additionally, the ICR18650-26F Lithium-ion cells are cycled to reach end-of-life with different current profiles and C-ratings. The analysis shows that charging with a 100 Hz ripple superimposed to the dc current leads to a 10% increment in degradation
Synchronising C/C++ and POWER
No full textShared memory concurrency relies on synchronisation primitives: compare-and-swap, load-reserve/store-conditional (aka LL/SC), language-level mutexes, and so on. In a sequentially consistent setting, or even in the TSO setting of x86 and Sparc, these have well-understood semantics. But in the very relaxed settings of IBM®, POWER®, ARM, or C/C++, it remains surprisingly unclear exactly what the programmer can depend on.
This paper studies relaxed-memory synchronisation. On the hardware side, we give a clear semantic characterisation of the load-reserve/store-conditional primitives as provided by POWER multiprocessors, for the first time since they were introduced 20 years ago; we cover their interaction with relaxed loads, stores, barriers, and dependencies. Our model, while not officially sanctioned by the vendor, is validated by extensive testing, comparing actual implementation behaviour against an oracle generated from the model, and by detailed discussion with IBM staff. We believe the ARM semantics to be similar.
On the software side, we prove sound a proposed compilation scheme of the C/C++ synchronisation constructs to POWER, including C/C++ spinlock mutexes, fences, and read-modify-write operations, together with the simpler atomic operations for which soundness is already known from our previous work; this is a first step in verifying concurrent algorithms that use load-reserve/store-conditional with respect to a realistic semantics. We also build confidence in the C/C++ model in its own terms, fixing some omissions and contributing to the C standards committee adoption of the C++11 concurrency model
Reducing passive filter sizes with tuned traps for distribution level power electronics
No full textThis paper proposes a filter topology intended for use with medium voltage grid-interfaced power electronics as an alternative to the widely-utilized LCL filter topology. The proposed topology utilizes multiple shunt RLC trap filters with parameters optimized to minimize the overall size of the filter while meeting performance requirements for connection to the distribution grid. Results indicate a potential for reduction of twenty-five to thirty percent in total filter volume for the scenario studied. In addition, total power losses taking place within the filter are slightly reduced
Benefits of distribution-level power electronics for supporting distributed generation growth
No full textIt is expected that distribution networks will be required to accommodate large amounts of distributed generation (DG). Keeping power flows and voltages within their limits will require either traditional infrastructure upgrades or active compensation. The form of active compensation (e.g., series, shunt, back to back, multiterminal), quantity, and rating of the compensator should be chosen to realize the best cost-benefit ratio. Distributed-generator and compensator placement algorithms are used with a power-flow and constraint satisfaction algorithm to analyze a large number of case studies (using real U.K. network data). From these cases, assessments of compensator performance are made and summarized statistically. When considering incremental deployment across all networks, with the site of greatest benefit chosen at each increment, it is found that static synchronous compensators provide the most favorable cost-benefit ratio. In contrast, multiterminal voltage-source converters tend to provide the greatest flexibility when considering uniform deployment across all networks. It is also observed that traditional reinforcement enhances the benefits provided by active compensation
New trends in active filters for improving power quality
No full textSince their basic compensation principles were proposed around 1970, active filters have been studied by many researchers and engineers aiming to put them into practical applications. Shunt active filters for harmonic compensation with or without reactive power compensation, flicker compensation or voltage regulation have been put on a commercial base in Japan, and their rating or capacity has ranged from 50 kVA to 60 MVA at present. In near future, the term of active filters will cover a much wider sense than that of active filters in the 1970s did. The function of active filters will be expanded from voltage flicker compensation or voltage regulation into power quality improvement for power distribution systems as the capacity of active filters becomes larger. This paper describes present states of the active filters based on state-of-the-art power electronics technology, and their future prospects toward the 21st century, including the personal view and expectation of the author</p
Peter Macinnis conducting a teachers' workshop at the National Library of Australia, Canberra, 22 October 2009 [picture] /
No full textTitle from acquisitions documentation.; Part of the collection: Teachers' workshop for the book Australian backyard explorer by author Peter Macinnis at the National Library of Australia, Canberra, 22 October 2009.; Acquired in digital format; access copy available online.; Mode of access: Internet via World Wide Web.; Photographed by a staff member of the National Library of Australia
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