Transformer Monitoring by using Vibration Analysis

Abstract: Since power transformer is a complex and critical component of the power transmission and distribution system, their reliability is crucially important for the energy system operation. So, there is an increasing interest in applying monitoring systems and on line diagnosis methods to transformers, as these are one of the most expensive and critical apparatus of a power system. Detecting failures in an incipient stage can avoid major damages of power transformer, allowing important savings in investing, and giving time enough to plan transformer outages. In recent years, a great number of monitoring systems have been suggested. In this paper the use of a vibration model to be applied to transformer monitoring is proposed. The paper deals with the introduction of the comparative method of the state estimation of transformers using continuous monitoring of transformer vibration

Placement of Combined Heat, Power and Hydrogen Production Fuel Cell Power Plants in a Distribution Network

energie

THE EFFECT OF INCOME SMOOTHING IN PRICE BUBBLE FORMATION OF COMPANIES IN TEHRAN STOCK EXCHANGE

The main objective of this paper is to examine the effect of income smoothing in price bubble formation of companies in Tehran Stock Exchange (TSE). Along with this objective, all the companies accepted in Tehran Stock Exchange which had been presented required financial statements and financial information in 2000-2009 were examined. Totally 72 companies from various industries were selected. At first, income smoothing phenomenon was examined in a 10-year period, using Eckel model. Then by using Johansen & Joselius method, bubble test was done. In order to study the relation of income smoothing and price bubble, chi-square test was used. The results show that income smoothing and price bubble are two independent issues and there is not a significant relation between income smoothing and price bubble. So, income smoothing cannot be considered as an effective factor in price bubble formation