The traditional grid-connected PV inverter includes either a line frequency or a high frequency transformer between the inverter and grid. The transformer provides galvanic isolation between the grid and the PV panels. In order to increase the efficiency, to reduce the size and cost, the effective solution is to remove the isolation transformer. It leads to appearance of common mode (CM) ground...

Detecting and removing minor faults in power transformer winding is essential because minor faults may develop and lead to major faults and finally irretrievable damages occur. In this paper in order to detect the position of short-circuit in the winding, frequency response of the input impedance of a power transformer is analyzed. Common short-circuits are categorized and the results are compa...

Transformer fault detection and diagnosis is becoming more important due to the restructuring of the electric power industry. In this era of deregulation, loading transformers to their optimum capacity is becoming normal practice, which in turn applies high stresses on the insulation of the transformers and increases the probability of occurrence of internal incipient faults. Such faults can le...

The energizing of large power transformers has long been considered a critical event in the operation of an electric power system. When a transformer is energized by the utility, a typical inrush current could be as high as ten times its rated current. This could cause many problems from mechanical stress on transformer windings to harmonics injection, and system protection malfunction. There h...

The paper is concerned with transformer Weibull lifetime modelling which is recognised as essential for effective asset management within electric utilities. Two popular and widely adopted methods, maximum likelihood estimation and median rank regression, are discussed and compared for their properties in estimating transformer lifetime data. To greatly mimic the field collected transformer lif...

Power transformers use Kraft paper as insulation in the electrical windings present in the core, which is immersed in oil. In service, the temperature of the windings of core will go to 75C to 85C. If the transformer is over loaded, then the temperature can exceed upto 100°C causing the cellulose chains in the paper to cleave at an accelerated rate, which results in the degradation of mechanica...

This paper takes a typical 220 kV three-phase three-limb oil-immersed transformer as an example, this paper building transient field-circuit coupled model and 3D coupled magneto -fluid-thermal model. Considering a nonlinear B–H curve, the magneto model uses the field-circuit coupled finite element method (FEM) to calculate the magnetic flux distribution of the core and the current distribution ...