A novel method for decaying DC component removal with regard to frequency fluctuations

Abstract

2016),"Shape parameter selection for multi-quadrics function method in solving electromagnetic boundary value problems", COMPEL -The international journal for computation and mathematics in electrical and electronic engineering, Vol. 35 Iss 1 pp. 64-79 http://dx.(2016),"Semi-analytical determination of inductances in windings with axial and azimuthal wires", COMPEL -The international journal for computation and mathematics in electrical and electronic engineering, Vol. 35 Iss 1 pp. 2-15 http://dx.If you would like to write for this, or any other Emerald publication, then please use our Emerald for Authors service information about how to choose which publication to write for and submission guidelines are available for all. Please visit www.emeraldinsight.com/authors for more information. About Emerald www.emeraldinsight.comAbstract Purpose -Decaying DC component has important effect on extracting the fundamental component phasor. It directly affects the precision of protective relaying algorithms which act based on fundamental frequency component. It can be noted that decaying DC component, harmonic components and off-nominal frequency conditions are the major issues which strongly effect phasor estimation. The paper aims to discuss these issues. Design/methodology/approach -This paper proposes a novel hybrid approach for fundamental phasor estimation in order to remove the decaying DC component using Hilbert Transform and Discrete Fourier Transform. Findings -The proposed method (PM) converges to the original value in one cycle in presence of harmonic components and off-nominal frequency condition. In addition, proposed algorithm is able to detect the frequency fluctuation. Thus, it is applicable for static and dynamic conditions. An extensive set of simulation results across static and dynamic validations demonstrated that the proposed approach has faster convergence and better precision than the present methods. In addition, during harmonic distortion and also frequency fluctuation, the PM provides a correct and reliable response. Originality/value -The PM can calculate the DC component exactly from fault current signals and can be used in digital protection algorithms for phasor estimation.

Framework for current transformer saturation detection and waveform reconstruction

“…2. The characteristics of the power network and also utilised CTs are given in [22,23,26]. A total of 87 cases were simulated for generating inrush current signals considering the different level of voltage angle switching and different level of CT flux remanence including 46 scenarios with no saturation in CT and 41 scenarios with saturation in CT. Also, for simulating fault current signals, a total of 318 cases were conducted considering different fault types, fault resistance, fault locations and fault inception angle including 154 scenarios without CT saturation and 164 scenarios with CT saturation.…”

“…As discussed in [22], due to fault occurrence in power system, fault current signal may contain decaying DC component. Moreover, in [23,24], it has been discussed that the transient response of CT may cause another DC component.…”

Probabilistic analysis of current‐transformer dimensioning: A criterion for determining the level of exposure to saturation

“…According to Tajdinian, Seifi, and Allahbakhshi, Tajdinian, Jahormi, et al, and Tajdinian, Kouhsari, et al, the fault current may contain transient decaying DC component during fault occurrence in the power system. Also, as it has been mentioned in the studies of Tajdinian, Seifi, and Allahbakhshi, Tajdinian, Jahormi, et al, and Tajdinian, Kouhsari, et al, the fault current may be contaminated with high‐order unwanted harmonic components in which the level of even harmonic is negligible. According to the aforementioned assumption, the fault‐current signal can be described as follows: …”

“…It must be mentioned that in this paper, only the first cycle of fault‐current signal after fault inception is utilized to calculate τ dc , I dc , I 1 , and α 1 . As mentioned in the studies of Tajdinian, Seifi, and Allahbakhshi, Tajdinian et al, and Kundur, Balu, and Lauby, the frequency changes very slowly after fault because of power‐system inertia. Therefore, in the first cycle after the fault, the frequency remains almost unchanged.…”

“…Also, t ′ , t ″ , and t d are first time fault duration, second time fault duration, and dead time due to autoreclosing, respectively. 16,20,21 the fault current may be contaminated with high-order unwanted harmonic components in which the level of even harmonic is negligible. According to the aforementioned assumption, the fault-current signal can be described as follows:…”