In this work, a new approach applied to digital differential protection relay for a large power transformer is presented. First, the Fourier sine and cosine coefficients required for fundamental, second, third and fifth harmonic extraction have been determined using rectangular transfer technique. Then, these harmonics have been used in harmonics restrain and blocking techniques applied to diff...

In the power system voltage sag become the important issue for industries. According to the survey 92% of the interruptions at industrial installations are voltage sag related. In various companies voltage sag may affect many manufactures and introduce sufficient losses in the power system. The voltage sag compensator, based on a transformer coupled series connected voltage source inverter, is ...

This paper presents a new approach for classifying transient phenomena in power transformers, which may be implemented in digital relaying for transformer differential protection. Discrimination of various operating conditions of the power transformer is achieved by combining wavelet transform with Adaptive Neuro Fuzzy Inference system (ANFIS). The wavelet transform is applied for the analysis ...

Among the most noticeable root causes of improper performance in power transformers, internal short circuit faults can be noted and if not quickly be identified and addressed in the accepted time interval, irrecoverable damages such as interruption or even collapse of the network connected to the power transformer would happen. In this contribution, three-phase transformer behaviors under magne...

rotection schemes employing the differential relaying principle exhibit certain limitations in applications with power transformers. This is because the detection of a differential current does not clearly distinquish between internal faults and other possible conditions. Among the phenomena most likely to upset the current balance and cause the relay to malfunction are inrush magnetizing curre...

this paper proposes a flexible power electronic transformer (fpet) for the application in the micro-grids. the low frequency transformer is usually used at the point of common coupling (pcc) to connect the low voltage grid and utility network to each other. the conventional 50hz transformer results in enhanced low voltage-grid power management system during grid-connected operation. in this pap...

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...

A new approach for protection of power transformer is presented using a time-frequency transform known as Wavelet transform. Different operating conditions such as inrush, Normal, load, External fault and internal fault current are sampled and processed to obtain wavelet coefficients. Different Operating conditions provide variation in wavelet coefficients. Features like energy and Standard dev...

A platform implemented with Digital Signal Controllers (DSCs) developed for real time studies of the dynamic behavior of the air-gapped current transformers (CTs) used in power grid protection and measurement systems is presented. The implemented algorithms simulate the fault current in an electric power system as well as the transient response of the current transformer. It is also presented a...