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This paper presents a combined method for discrimination between inrush current and internal fault current of power transformers. The mentioned method is based on wavelet analysis of power system frequency which is estimated by Prony method. The Prony method is utilized to estimate power system frequency with three consecutive samples rapidly and also Daubechies wavelet family uses the estimated frequency...
This paper presents a new multi-criteria stabilization algorithm of transformer differential protection. Proposed scheme bases on new criteria signals and appropriate operation thresholds. New algorithm employs fuzzy reasoning technique for better discrimination of inrush conditions. The developed stabilization algorithm has been tested with ATP-EMTP generated signals, proving to be reliable and much...
The new generation of current sensors, such as Rogowski coils, have performance characteristics that can improve design and operation of modern power systems. This paper presents novel solutions that integrate protection, control, and metering functions for power transformers and cables by sharing signals from the same Rogowski coils.
This paper presents an analysis of the main operating conditions that may lead to inappropriate differential protection operation. These conditions were simulated using the Alternative Transients Program (ATP) and the model of a real system. The saturable transformer was the main component of the ATP/EMTP simulations. The saturation and hysteresis effects are represented by a non-linear model of the...
This paper aims to present the modeling and simulation of numerical differential protection of power transformers using the software ATP/ATPDraw and its MODELS environment. In order to validate the relay model, simulations were carried out using a simplified electrical power system whose parameters were obtained from a real system. The results reveal the advantages of using this type of modeling,...
At present, gas protection and current differential protection are generally used as the main protection for traction transformer in China high-speed railway. Overcurrent protection with busbar low-voltage start-up is used as the backup protection installed at HV side and LV side of transformer. This paper introduces the principle of overcurrent protection with busbar low-voltage start-up, and then...
To feed electric train, the structure of traction power supply system is very different from utility grid. The single-phase traction loads result in some problems, such as negative sequence, harmonics, reactive power and crossing neutral sections. Based on the existing traction power supply system, the active power filter is used to construct cophase traction power supply system. It not only eliminates...
The paper will present implemented protection scheme on two, symmetrical, double core design Phase Shifting Transformers (PST) [6], each rated at 600MVA, 400kV, 866A, 50Hz, ±40° with in total 64 tap positions (32 advance and 32 retard). Thus, every individual tap introduce phase angle shift of 1,25°. The used PST protection scheme follows the protection recommendations published by IEEE [1]. It shall...
This paper reviews the characteristics of inrush current and analyses its causes. The development of digital substation and the concept of integrated protection are also outlined. The paper studies different models to simulate several kinds of inrush and internal short-circuit fault. Through these models, the new composite algorithm is analysed in order to verify the reliability and sensitivity of...
Every pump storage hydro power plant has at least three different operating modes of the synchronous machine which can cause possible challenges during the design of the plant protection scheme. These three operating modes are generating mode, pumping mode and machine starting into pumping mode. The main differences between the generating and pumping operating modes are changes in direction of the...
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