121,983 research outputs found
On the linear profile of indices for the prediction of saddle-node and limit-induced bifurcation points in power systems
No full textThis brief analyzes the linear profiles presented by certain classes of bifurcation indices with respect to the variation of the loading parameter in power systems. The bifurcation indices discussed here are used in practice to predict proximity to saddle-node and some types of limit-induced bifurcations, given their special profiles. Thus, the linearity of these indices is studied with the help of a simple generic test system. Local analyses and observations are also presented and discussed for realistic power-system models
Loss reduction and loadability enhancement with DG: A dual-index analytical approach
No full textThe high penetration of distributed generation (DG) is a new challenge for traditional distribution systems. Power injections from DG units change network power flows, thereby influencing system losses and voltage stability. This paper presents a new multiobjective index (IMO)-based analytical approach to determine the optimal size and power factor of DG unit for reducing power losses and enhancing loadability. This index is defined as a combination of active and reactive power loss indices by optimally assigning a weight to each index such that the IMO can reach a minimum level. At this level, the optimal location and weights are identified. The proposed methodology has been tested on three typical distribution systems with different characteristics and validated using an exhaustive load flow (ELF) solution. The results show that DG operation with optimal power factor and appropriate weights for active and reactive power losses can significantly reduce power losses and enhance loadability
A simple approach for distributed generation integration considering benefits for DNO
No full textThis paper proposes a simple analytical strategy for distributed generation (DG) integration considering the benefit for distribution network operator (DNO) under the unbundled environment where DG units are owned by DG developers. This benefit arises from network reinforcement deferral and loss reduction due to optimal DG size and operating power factor. The optimal size and power factor are strategically calculated for each location to achieve the highest benefit using the analytical approach. A computational procedure is also developed to accommodate a predefined number of DG units using the proposed approach. The results obtained on a 69-bus test distribution system demonstrate the effectiveness of the proposed methodology and computational procedure. It is observed that the optimal power factor operation can achieve the maximum benefit for DNO, while achieving the optimum voltage profiles and maximizing DG penetration
A dual-index based analytical approach for DG planning considering power losses
No full textThis paper presents a new multiobjective index-based analytical methodology to calculate the optimal size and power factor of distributed generation (DG) unit at various locations. This multiobjective index (IMO) is related to real and reactive power losses. A computational procedure is also developed to specify the best location where the IMO value is the lowest. The results obtained on a 38-bus test system demonstrate the effectiveness of the proposed methodology and computational procedure as validated by an exhaustive load flow solution (ELF). The optimal power factor and indices weights can minimize the IMO value while maximizing DG penetration and achieving the best voltage profile
An optimal operating strategy of DG unit for power loss reduction in distribution systems
No full textThis paper presents a strategy for optimal operation of distributed generation (DG) unit for minimizing distribution system power losses. An analytical approach is used to determine the optimal size and power factor of DG unit when it is placed at various locations. A computational procedure is also developed to identify the best placement at which the total system loss is the lowest. The proposed approach has been tested on a 33-bus distribution system. Importance of operating DG unit at appropriate power factor (PF) for minimizing power losses is first highlighted using an exhaustive load flow solution. The developed method is then used to calculate the optimal power factor. The results demonstrate the validity of the proposed approach in terms of optimal power factor, loss reduction and computational time. It is also shown that the optimal power factor operation can minimize power losses while achieving the optimum voltage profile enhancement and maximizing DG penetration
Assessing the impact of loss reduction on distributed generation investment decisions
No full textThis paper proposes a methodology for evaluating the impact of loss reduction on DG investment decisions. In this methodology, new analytical expressions are first proposed to quickly capture the optimal power factor of each DG unit to maximize loss reduction. The decision for the optimal location, size and number of DG units is then obtained through a benefit-cost analysis over a given planning horizon. Here, the total benefit includes energy sales and additional benefits, namely loss reduction, network upgrade deferral and emission reduction. The total cost is a sum of capital, operation and maintenance costs. The methodology has been applied to a 69-bus test distribution system. The results show that the additional benefits including loss reduction are imperative. Inclusion of these in the analysis would result in faster DG investment recovery
A Multi-Language Comparison of Influences on Author Verification using Character N-Grams
No full textWe create a new multi-language corpus for author verification based on Wikipedia talkpages, and evaluate the influence that differences in topic and time have on character n-gram author profiles. Topic alignment between two texts is found to increase author verification precision, and an authors writing style is found to change over time, but not more significantly after 3 years than after 1 year.Information ArchitectureWISElectrical Engineering, Mathematics and Computer Scienc
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
The vanishing author in computer-generated works: a critical analysis of recent Australian case law
No full textAbstract
The use of software is ubiquitous in the creation of many copyright works, yet the requirement in copyright law that every work have a human author who engages in independent intellectual effort means that its use may prevent copyright subsistence. Several recent Australian cases have refocused attention on authorship as an essential criterion of copyright subsistence, and these cases suggest that much computer-produced output may be authorless and thus lack copyright protection. This article, the first in a two-part series, analyses how each case deals with the question of authorship of computer-produced works and why the use of software diminishes copyright protection for a significant number of computer-generated works. The article critiques the application of conventional notions of human authorship developed in the pre-computer age to modern productions and suggests alternative approaches to authorship that satisfy both the major objectives of copyright policy and the need to adapt to the computer age. The article argues that, without a broader judicial approach to authorship of computer-generated works, Parliament must remedy the lacuna in protection for these ‘authorless’ works. Possible solutions for reform are suggested. In a forthcoming article, the author comprehensively examines those reform proposals
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