The differential protection of power transformers appears to be more difficult than any type of protection for any other part or element in a power system. Such difficulties arise from the existence of the magnetizing inrush phenomenon. Therefore, it is necessary to recognize between inrush current and the current arise from internal faults. In this paper, two approaches based on wavelet packet transform (WPT) and S-transform (ST) are applied to recognize different types of currents following in the transformer. In WPT approach, the selection of optimal mother wavelet and the optimal number of resolution is carried out using minimum description length (MDL) criteria before taking the decision for the extraction features from the WPT tree. In ST approach,
the spectral energy index and the standard deviation (STD) are calculated from the S-matrix obtained by discrete S-transform. The two approaches are tested for generating a trip signal and disconnecting the transformer supply experimentally using 1KVA, 220/110V, 50Hz, ∆ / Y threephase transformer. The experimental results show that the trip signal is initiated faster in WPT approach while the transformer is disconnected from the supply after a delay of 10-15msec in the
two approaches due to computer interface and the relay circuit used.
Is the subject of the financial structure of the most important topics for which she received the interests of scientific research in the field of financial management , as it emerged several theories about choosing a financial structure appropriate for the facility and behavior change funding them , and in spite of that there is no agreement on a specific theory answer various questions in this regard , and a special issue of the financial structure optimization.
The objective of the research was to identify the most important theories of the structure of modern financial theory has been to focus on the capture of financial firms in two different stages of their life cycle , so-called growth and ma
... Show MoreThe Iraqi pharmaceutical sector faces significant challenges arising from the prevalence of substandard and falsified (S/F) medications, which pose a direct threat to public health safety. To strengthen regulatory oversight, health authorities have implemented national medicine track-and-trace system. However, the ultimate efficacy of these regulatory tools is heavily dependent on public awareness and the level of societal acceptance.
This study ai
Lead-acid batteries have been used increasingly in recent years in solar power systems, especially in homes and small businesses, due to their cheapness and advanced development in manufacturing them. However, these batteries have low voltages and low capacities, to increase voltage and capacities, they need to be connected in series and parallel. Whether they are connected in series or parallel, their voltages and capacities must be equal otherwise the quality of service will be degraded. The fact that these different voltages are inherent in their manufacturing, but these unbalanced voltages can be controlled. Using a switched capacitor is a method that was used in many methods for balancing voltages, but their respons
... Show MoreThe importance of this research has been to rationalize the cost of producing maize seeds through the followers of modern techniques and methods in agricultural activities such as genetic engineering for the purpose of increasing production efficiency of maize seeds as well as the importance of calculating seed cost rationalization through the ABC system and thus rationalizing government spending. The research is based on a single hypothesis that the use of genetic engineering on corn seeds works to:increase production efficiency of seeds and savings in agricultural inputs, calculation of rationalization through the cost system on the basis of activity ABC The research reached a number of conclus
... Show MoreThe aim of this research is to identify the extent to which the Conventional and Islamic banks are committed to implement the requirements of the corporate governance in its financial reports. In addition to its commitment to transparency and clarity in dealing with the shareholders and stockholders to protect their interests and to determine the impact of the commitment of the corporate governance on assessing the financial performance of the conventional and Islamic banks that participate in Bahrain Stock Exchange.
The study aimed to identify the reality of the application of cost accounting system in the contracting institutions in Saudi Arabia, and the extent of the reflection of the application of this system on the effectiveness and efficiency of the general performance of these institutions. Where the research community consists of the contracting institutions operating in the Saudi Arabia, and then a suitable random sample was selected from seventy one institutions. The researchers used the historical method to track the previous studies as well as the descriptive approach to conducting the field study. The study data were analyzed by SPSS statistical program.
The results of this study conclude that there is a
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