A Fast Method for Sequence Component Filtering

2003 ◽  
Vol 40 (1) ◽  
pp. 66-71
Author(s):  
Y. G. Paithankar ◽  
S. R. Bhide
Keyword(s):  
Input Signal ◽  
Phase Shifts ◽  
Fast Method ◽  
Negative Sequence ◽  
Simple Addition ◽  
Sequence Components ◽  
Zero Sequence ◽  
Addition And Subtraction ◽  
The Difference ◽  
Minimal Hardware

In this paper a method to filter or segregate sequence components, using minimal hardware is presented. The method does not involve phase shifts other than that of 90 degrees. Thus it can be implemented using very simple hardware or if implemented in software will need considerably less amount of processing. The method consists in first separating the zero sequence component. Then the zero sequence component is subtracted from the input signal to get a signal which is sum of positive and negative sequence components. Further it is pointed out that difference between positive and negative sequence components is easily found from the difference of the phase quantities. Thus the sum and difference of positive and negative sequence components are available, from which individual positive and negative sequence components can be easily separated by simple addition and subtraction operations.

scholarly journals A Fast Method to Compute the Dynamic Response of Induction Motor Loads Considering the Negative-Sequence Components in Stability Studies

Energies ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1802
Author(s):  
Xiaoming Mao ◽  
Junxian Chen
Keyword(s):  
Induction Motor ◽  
Transient Stability ◽  
Practical Method ◽  
System Stability ◽  
Fast Method ◽  
Stability Studies ◽  
Simulation Accuracy ◽  
Negative Sequence ◽  
Transient Simulations ◽  
Sequence Components

This paper deals with the modeling and simulation of induction motor loads in power system stability studies considering the influence of the negative-sequence components. A practical method for computing the dynamic behavior of an induction motor under asymmetric faults is proposed and implemented in MATLAB. The accuracy of the proposed method is verified through classical electromagnetic transient simulations using the PSCAD/EMTDC software package. Compared with the existing traditional transient stability simulations, the method increases a little computational burden yet achieves much better simulation accuracy under asymmetric faults.

Bad Data

2018 ◽  
Author(s):  
Gary Smith
Keyword(s):  
Economic Model ◽  
Human Error ◽  
Blaise Pascal ◽  
French Mathematician ◽  
Simple Addition ◽  
Teaching Economics ◽  
Addition And Subtraction ◽  
The Difference ◽  
Bad Data

When I first started teaching economics in 1971, my wife’s grandfather (“Popsie”) knew that my Ph.D. thesis used Yale’s big computer to estimate an extremely complicated economic model. Popsie had bought and sold stocks successfully for decades. He even had his own desk at his broker’s office where he could trade gossip and stocks. Nonetheless, he wanted advice from a 21-year-old kid who had no money and had never bought a single share of stock in his life—me—because I worked with computers. “Ask the computer what it thinks of Schlumberger.” “Ask the computer what it thinks of GE.” This naive belief that computers are infallible has been around ever since the first computer was invented more than 100 years ago by Charles Babbage. While a teenager, the great French mathematician Blaise Pascal built a mechanical calculator called the Arithmetique to help his father, a French tax collector. The Arithmetique was a box with visible dials connected to gears hidden inside the box. Each dial had ten digits labeled 0 through 9.When the dial for the 1s column moved from 9 to 0, the dial for the 10s column moved up 1 notch; when the dial for the 10s column moved from9 to 0, the dial for the 100s column moved up 1 notch; and so on. The Aritmatique could do addition and subtraction, but the dials had to be turned by hand. Babbage realized that he could convert complex formulas into simple addition-and-subtraction calculations and automate the calculations, so that a mechanical computer would do the calculations perfectly every time, thereby eliminating human error. Babbage’s first design was called the Difference Engine, a steam powered behemoth made of brass and iron that was 8 feet tall, weighed 15 tons, had 25,000 parts. The Difference Engine could make calculations up to 20 decimals long and it could print formatted tables of results. After a decade tinkering with the design, Babbage began working on plans for a more powerful calculator he called the Analytical Engine. This design had more than 50,000 components, used perforated cards to input instructions and data, and could store up to one thousand 50-digit numbers.

scholarly journals Section Location Technology Based on Minkowski Distance of Three-phase Asymmetric Current Components

2021 ◽  
Vol 252 ◽  
pp. 01014
Author(s):  
Shi Kejian ◽  
Zhu Yidong ◽  
Zheng Zimo ◽  
Zhang Xinyu ◽  
Tian Ye ◽  
...  
Keyword(s):  
Power Distribution ◽  
Fundamental Wave ◽  
Minkowski Distance ◽  
Power Distribution Network ◽  
Before And After ◽  
Sequence Components ◽  
Calculation Results ◽  
Zero Sequence ◽  
The Difference ◽  
Threshold Setting

Fault components in the fault path and the non-fault path differ due to the unbalanced distribution of positive, negative and zero-sequence components in the line in the case of a single-phase earth fault in the power distribution network. Therefore, this paper proposes an improved fault section location algorithm based on phase current, which obtains the fault component current by the subtraction of currents before and after the fault and the fundamental wave amplitude of the corresponding current through Fast Fourier Transform (FFT). Meanwhile, considering that the fault section location cannot be completed accurately with the amplitude relationship alone, the Minkowski distance calculation formula is introduced to strengthen the difference between the fault path and the non-fault path, and the relationship between the calculation results of different sections and the threshold is compared by threshold setting to complete the section location. This paper proposes the specific fault section location process and criteria and verifies the feasibility of the algorithm through simulation experiment.

scholarly journals Earth Fault Location Using Negative Sequence Currents

Energies ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3759 ◽  
Author(s):  
Farughian ◽  
Kumpulainen ◽  
Kauhaniemi
Keyword(s):  
Fault Location ◽  
Single Phase ◽  
Distribution Networks ◽  
Practical Implementation ◽  
Negative Sequence ◽  
Medium Voltage ◽  
Different Types ◽  
Sequence Components ◽  
Zero Sequence ◽  
Negative Sequence Current

In this paper, a new method for locating single-phase earth faults on non-effectively earthed medium voltage distribution networks is proposed. The method requires only current measurements and is based on the analysis of the negative sequence components of the currents measured at secondary substations along medium voltage (MV) distribution feeders. The theory behind the proposed method is discussed in depth. The proposed method is examined by simulations, which are carried out for different types of networks. The results validate the effectiveness of the method in locating single-phase earth faults. In addition, some aspects of practical implementation are discussed. A brief comparative analysis is conducted between the behaviors of negative and zero sequence currents along a faulty feeder. The results reveal a considerably higher stability level of the negative sequence current over that of the zero sequence current.

The phase-functions method and scalar amplitude of nucleon–nucleon scattering

2016 ◽  
Vol 25 (11) ◽  
pp. 1650088
Author(s):  
V. I. Zhaba
Keyword(s):  
Single Channel ◽  
Scattering Amplitude ◽  
Nucleon Nucleon ◽  
Phase Shifts ◽  
Computational Method ◽  
Nucleon Scattering ◽  
The Difference ◽  
Scalar Scattering ◽  
Scalar Amplitude ◽  
Phase Functions

A known phase-functions method (PFM) has been considered for calculation of a single-channel nucleon–nucleon scattering. The following partial waves of a nucleon–nucleon scattering have been considered using the phase shifts by PFM: 1S0-, 3P0-, 3P1-, 1D2-, 3F3-states for nn-scattering, 1S0-, 3P0-, 3P1-, 1D2-states for pp-scattering and 1S0-, 1P1-, 3P0-, 3P1-, 1D2-, 3D2-states for np-scattering. The calculations have been carried out using phenomenological nucleon–nucleon Nijmegen group potentials (NijmI, NijmII, Nijm93 and Reid93) and Argonne v18 potential. The scalar scattering amplitude has been calculated using the obtained phase shifts. Our results are not much different from those obtained by using the known phase shifts published in other papers. The difference between calculations depending on a computational method of phase shifts makes: for real (imaginary) parts 0.14–4.36% (0.16–4.05%) for NijmI. 0.02–4.79% (0.08–3.88%) for NijmII. 0.01–5.49% (0.01–4.14%) for Reid93 and 0.01–5.11% (0.01–2.40%) for Argonne v18 potentials.

Examining Change Sensitivity to Vibrotactile Beats in a Hand-Held Touchscreen Device

2017 ◽  
Vol 61 (1) ◽  
pp. 1569-1569
Author(s):  
Youngbo Suh ◽  
Thomas K. Ferris
Keyword(s):  
Input Signal ◽  
Beat Frequency ◽  
Vibrotactile Feedback ◽  
Perceptual Ability ◽  
Sinusoidal Signals ◽  
The Difference ◽  
Touchscreen Device ◽  
Vibratory Signals

While recent research has employed vibrotactile feedback as a means of communication, one novel form of vibrotactile feedback involves the generation of “beats”. They are amplitude-modulated vibratory signals that can be created by sending multiple sinusoidal signals at dissonant frequencies (Lim, Kyung, & Kwon, 2012; Yang et al., 2014). The resulting perception of a rising-and-falling amplitude signal (a single “beat”), can be characterized per unit time as beat frequency, which is a function of the difference between the two input signal frequencies. Although vibrotactile beat cues have potentials in better supporting multitasking contexts that are visually demanding, the fundamental psychophysical characteristics of absolute and difference sensitivities have not been well-studied. To build on the promising but sparse findings involving the application of vibrotactile beats, it is important to define the limits of human perceptual ability to differentiate vibrotactile beats at distinct beat frequencies.

scholarly journals Learning Declarative Knowledge in Special Education Treatment Group

2018 ◽  
Vol 5 (1) ◽  
pp. 8
Author(s):  
Rickard Ostergren ◽  
Marie Ringborg Lindgren ◽  
Britt-Marie Lindgren ◽  
Joakim Samuelsson
Keyword(s):  
Special Education ◽  
Treatment Group ◽  
Small Group ◽  
Declarative Knowledge ◽  
Regular Instruction ◽  
Intervention Phase ◽  
Simple Addition ◽  
Intervention Level ◽  
Addition And Subtraction ◽  
The Impact

An organizing structure that in recent years has had a major impact on how to work with students who don’t respond to regular instruction is Response to Intervention (RTI). Efforts in RTI are divided into three different tiers of instruction: primary, secondary and tertiary. In our study, we investigate the impact of intensive secondary-tier instruction on students’ knowledge of basic combinations of digits in addition. We also focus on how the students develop their use of more advanced calculations in addition during the intervention.The results showed that students became faster at performing simple addition tasks, which indicates that their fluency – declarative knowledge – developed during the intervention phase. Our results thereby strengthen suggestions that a secondary-tier intervention level should take place in a small group of students 20-40 minutes four to five times a week. Meanwhile, the students developed their ability to solve two-digit arithmetic tasks in addition and subtraction, which could be explained by the fact that students had automated simple number combinations and thus could focus on the calculation procedure.

scholarly journals Modeling of three-phase electric motor operation by the MATLAB system with deteriorated power quality in the 0.38 kV distribution networks

2018 ◽  
Vol 58 ◽  
pp. 03016 ◽  
Author(s):  
I.V Naumov ◽  
N.V. Savina ◽  
M.V. Shevchenko
Keyword(s):  
Induction Motor ◽  
Power Quality ◽  
Electric Motor ◽  
Distribution Networks ◽  
Negative Sequence ◽  
Operation Modes ◽  
Three Phase ◽  
Sequence Components ◽  
Motor Operation ◽  
The Impact

One of the main operation modes that characterizes power quality in distribution networks is asymmetry of three-phase voltage system. Operation of an induction motor (IM) with disturbed voltage symmetry in the supply network can not be considered as a rated one. The system of voltages applied to the stator winding of IM under these conditions contains positive- and negative-sequence components. This worsens the performance characteristics of IM essentially. In order to balance the 0.38 kV network operation and enhance the efficiency of the three-phase electric motor operation it is suggested to use a special balancing unit (BU) that minimizes the negative-sequence components of current and voltage. The operation modes of the obtained system “supply source – induction motor – balancing unit” are simulated within the MATLAB software package of applied programs, which allows one to assess the impact of low quality of power on the operating characteristics of the electric motor and the efficiency of the balancing unit to increase the “durability” of the motor under the asymmetrical power consumption.

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