With the increasing age of the primary equipment of the electrical grids there exists also an increasing need to know its internal condition. For this purpose, offand online diagnostic methods and systems for power transformers have been developed in recent years. Online monitoring is used continuously during operation and offers possibilities to record the relevant stresses which can affect th...

This paper deals with three types of power transformer failure analysis tests which can help in monitoring the transformer condition. The three methods are Conventional oil test, Furan derivatives test and Markov models criteria. Conventional oil testing procedure includes determination of gas concentrations in the transformer oil sample and analyzing the fault by considering ratio of two suita...

In the future grid, power equipment will need to work with distributed generation, deregulation, and accelerated ageing. To this end, a model-based framework for the optimization of usage of power equipment is proposed. The framework uses a predictive health model of the equipment in order to optimize the usage of the equipment. In particular, the predictive health model predicts the hot-spot t...

Reliable energy flow is paramount and power transformers are critical, and costly, assets in the grid. As an asset class, power transformers constitute one of the largest investments in a utility’s system. For this reason transformer condition assessment and management is a high priority. In several parts of the world the transformer fleet is operating beyond its design life and with higher ave...

In the semantics of programming languages one can view programs as state transformers, or as predicate transformers. Recently the author has introduced ‘stateand-effect’ triangles which capture this situation categorically, involving an adjunction between stateand predicate-transformers. The current paper exploits a classical result in category theory, part of Jon Beck’s monadicity theorem, to ...

Transformers are important devices in power supply system. Since the testing data in fault diagnosis of transformers have features such as high dimension, uncertainty and incompleteness, existing fault diagnosis methods are incapable of dealing with the high-dimensional and abnormal data, and the diagnosis precision needs further improvement. This paper innovatively proposes a fault diagnosis m...

Smart grids have been constructed so as to guarantee the security and stability of the power grid in recent years. Power transformers are a most vital component in the complicated smart grid network. Any transformer failure can cause damage of the whole power system, within which the failures caused by overloading cannot be ignored. This research gives a new insight into overload capability ass...

Power transformers are essential components of substation equipment for the efficient and stable operation of electric power systems. There is demand for transformers with lower price and higher reliability. In addition, depending upon the onsite conditions, such as narrow roads, mountainous areas or highly congested urban areas, harmony with the surrounding environment is required throughout s...

The increasing utilization of piezoelectric transformers (PT) in power electronics requires fundamental analysis and design of PT power converters. In addition, the possibility of overcoming the essential limitations of PT power ability by a combined operation of PTs needs to be examined. These studies could provide wide opportunities for PT exploitation in power electronic circuits. The main o...

This paper presents an efficient wavelet and neural network (WNN) based approach for distinguishing magnetizing inrush currents from internal fault currents in three phase power transformers. The wavelet transform is applied first to decompose the current signals of the power transformer into a series of detailed wavelet components. The values of the detailed coefficients obtained can discrimin...