Differential Protection for High-Voltage Variable Frequency Motor Based on Sampled Values Algorithm

2013 ◽  
Vol 373-375 ◽  
pp. 1401-1405
Author(s):  
Shao Bo Yan ◽  
Yan Xu ◽  
Zong Jiang Mu
Keyword(s):  
High Voltage ◽  
New Method ◽  
Variable Frequency ◽  
Differential Protection ◽  
New Approach ◽  
Current Differential Protection ◽  
Calculation Results ◽  
Security Standard ◽  
The Impact ◽  
Motor Protection

With the application of inverter in high-voltage motor, the traditional current differential protection cant be used because of the variable frequency. So it adopts low sensitive current instantaneous protection as main protection, which doesnt meet the security standard of grid state. In order to improve the sensitivity and reliability of high-voltage motor protection, a new method based on current sampled values is proposed in this paper, which adapts to the variable frequency system. After a brief description about the impact of inverter on main protection of motors, it introduces the principle of sampled value current differential protection and variable RS sampled value algorithm. A matlab example is used to simulate. On the whole, the simulation and analysis of the calculation results verify the feasibility and reasonableness of the method. Therefore, it provides a new approach for the protection of high-voltage motor in variable frequency system.

scholarly journals The Communication System and its Impacts on Line Current Differential Protection in Distributed Feeder Automation

Energies ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1298
Author(s):  
Yilong Duan ◽  
Longfu Luo ◽  
Yong Li ◽  
Yijia Cao
Keyword(s):  
Communication System ◽  
Design Method ◽  
Parameter Determination ◽  
Differential Protection ◽  
Feeder Automation ◽  
Communication Mode ◽  
Line Current ◽  
Current Differential Protection ◽  
On Line ◽  
The Impact

As one of the core technologies of distributed feeder automation (DFA), line current differential protection (LCDP) can locate faults quickly and accurately and have the ability to cope with multi-directional flow. However, LCDP algorithm has high requirements for communication speed, and is sensitive to communication quality. In order to apply the LCDP algorithm to a real project, the communication system and its impacts on LCDP need to be studied in depth. In this paper, the design method of a communication system for LCDP, including communication mode, topology, communication protocol, and synchronization, is analyzed in detail. For better parameter determination, the communication models are investigated, and the impact of time delay, data loss, and jitter on LCDP are discussed. Further, the distribution network based on a real project is built in a cyber-physical co-simulation environment, and the impact of electrical fails and communication fails on LCDP are studied. The results show that the design method and parameters determination method proposed in this paper are effective.

scholarly journals Investigating the impact of network security on the line current differential protection system

2018 ◽  
Vol 2018 (15) ◽  
pp. 1199-1203
Author(s):  
Andreas Aichhorn ◽  
Andreas Unterweger ◽  
René Mayrhofer ◽  
Dominik Engel
Keyword(s):  
Network Security ◽  
Protection System ◽  
Differential Protection ◽  
Line Current ◽  
Current Differential Protection ◽  
The Impact

The Influence of Main Pump with High-Voltage Variable Frequency Drives on Electric Motors Periodic Repair

2014 ◽  
Vol 698 ◽  
pp. 3-6 ◽  
Author(s):  
V.A. Shabanov ◽  
M.I. Khakimyanov ◽  
E.F. Khakimov
Keyword(s):  
Service Life ◽  
High Voltage ◽  
Residual Life ◽  
Variable Frequency ◽  
Electric Motors ◽  
Start Time ◽  
Variable Frequency Drive ◽  
Oil Companies ◽  
Cyclic Transfer ◽  
The Impact

The main objective of the work - to investigate the effect on the wear of high voltage electric motors of main pump units periodic switching on and off in cyclical pumping. Frequent starts motors in a cyclic pumping lead to accelerated wear of the mechanical parts of the motor due to the impact of dynamic loads at start-up, as well as winding insulation due to high inrush currents flow. As a result of accelerated depreciation may decrease residual life, overhaul period and service life of electric motors. The main factor affecting the service life of insulation motors are winding temperature, and as a consequence, the thermal aging of the insulation. The use of variable frequency drive can significantly reduce the cyclic transfer modes, or even eliminate them. The authors obtained analytical expressions for the evaluation of insulation deterioration at the start of the motor, which allow us to study the impact of the following factors: insulation class, the start time, break time at work, initial and nominal temperature, the temperature rise of the windings over the ambient temperature. The effect on the deterioration of the insulation cold start and hot conditions, as well as the percentage of the hottest start-ups in the total number of starts. Obtained expressions for the depreciation of isolation to determine the change timing of overhauls of high voltage electric main pump units. The developed method was approved by the example of the use of a variable frequency drive on the oil pumping stations construction section Leninsk-Nurlino trunk pipeline Nizhnevartovsk - Kurgan - Kuibyshev. The analysis showed that the installation of a variable frequency drive motors on three main pump units technological area of the number of starts to decline by 14%. The results can be used for pipeline transport of oil companies when planning the timing and costs of the current and capital repairs of high voltage electric motors main pump units.

A new method showing the impact of pulp refining on fiber-fiber interactions in wet webs

2016 ◽  
Vol 31 (2) ◽  
pp. 205-212 ◽  
Author(s):  
Belle Jürgen ◽  
Kleemann Stephan ◽  
Odermatt Jürgen ◽  
Olbrich Andrea
Keyword(s):  
New Method ◽  
The Impact

A New Approach for the Analysis of Mixture Toxicity Data

1992 ◽  
Vol 26 (9-11) ◽  
pp. 2345-2348 ◽  
Author(s):  
C. N. Haas
Keyword(s):  
Quantitative Analysis ◽  
Mixture Toxicity ◽  
New Method ◽  
Metal Exposure ◽  
Positive Interactions ◽  
Toxicity Data ◽  
Data Set ◽  
New Approach ◽  
Negative Interactions

A new method for the quantitative analysis of multiple toxicity data is described and illustrated using a data set on metal exposure to copepods. Positive interactions are observed for Ni-Pb and Pb-Cr, with weak negative interactions observed for Ni-Cr.

scholarly journals New Method for Generating New Families of Distributions

Symmetry ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 726
Author(s):  
Lamya A. Baharith ◽  
Wedad H. Aljuhani
Keyword(s):  
Exponential Distribution ◽  
Real Data ◽  
Rate Function ◽  
New Method ◽  
Likelihood Method ◽  
Alpha Power ◽  
Unknown Parameters ◽  
Failure Rate Function ◽  
New Approach ◽  
Numerical Studies

This article presents a new method for generating distributions. This method combines two techniques—the transformed—transformer and alpha power transformation approaches—allowing for tremendous flexibility in the resulting distributions. The new approach is applied to introduce the alpha power Weibull—exponential distribution. The density of this distribution can take asymmetric and near-symmetric shapes. Various asymmetric shapes, such as decreasing, increasing, L-shaped, near-symmetrical, and right-skewed shapes, are observed for the related failure rate function, making it more tractable for many modeling applications. Some significant mathematical features of the suggested distribution are determined. Estimates of the unknown parameters of the proposed distribution are obtained using the maximum likelihood method. Furthermore, some numerical studies were carried out, in order to evaluate the estimation performance. Three practical datasets are considered to analyze the usefulness and flexibility of the introduced distribution. The proposed alpha power Weibull–exponential distribution can outperform other well-known distributions, showing its great adaptability in the context of real data analysis.

Survey Data Quality in Analyzing Harmonized Indicators of Protest Behavior: A Survey Data Recycling Approach

2021 ◽  
pp. 000276422110216
Author(s):  
Kazimierz M. Slomczynski ◽  
Irina Tomescu-Dubrow ◽  
Ilona Wysmulek
Keyword(s):  
Data Processing ◽  
Data Quality ◽  
Survey Data ◽  
A Priori ◽  
Data Sets ◽  
New Approach ◽  
Survey Quality ◽  
Survey Error ◽  
Ex Post ◽  
The Impact

This article proposes a new approach to analyze protest participation measured in surveys of uneven quality. Because single international survey projects cover only a fraction of the world’s nations in specific periods, researchers increasingly turn to ex-post harmonization of different survey data sets not a priori designed as comparable. However, very few scholars systematically examine the impact of the survey data quality on substantive results. We argue that the variation in source data, especially deviations from standards of survey documentation, data processing, and computer files—proposed by methodologists of Total Survey Error, Survey Quality Monitoring, and Fitness for Intended Use—is important for analyzing protest behavior. In particular, we apply the Survey Data Recycling framework to investigate the extent to which indicators of attending demonstrations and signing petitions in 1,184 national survey projects are associated with measures of data quality, controlling for variability in the questionnaire items. We demonstrate that the null hypothesis of no impact of measures of survey quality on indicators of protest participation must be rejected. Measures of survey documentation, data processing, and computer records, taken together, explain over 5% of the intersurvey variance in the proportions of the populations attending demonstrations or signing petitions.

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