New Method to Identify Sympathetic Inrush in Transformer Based on Hilbert Huang Transform

2012 ◽  
Vol 229-231 ◽  
pp. 863-867
Author(s):  
Mao Fa Gong ◽  
Wen Hua Xia ◽  
Guo Liang Li ◽  
Xing Zhen Bai ◽  
Lan Bing Li
Keyword(s):  
Second Harmonic ◽  
Fault Current ◽  
Differential Protection ◽  
Hilbert Huang Transform ◽  
Internal Fault ◽  
Good Ability ◽  
Simulation Results ◽  
Harmonic Restraint ◽  
Aperiodic Component ◽  
The Mathematical Model

Sympathetic inrush may cause the mal-operation of differential protection. Aiming at this problem, based on the characteristic that sympathetic inrush contains a lot of aperiodic component and high harmonics, this paper proposes to use Hilbert Huang transform to identify sympathetic inrush. Firstly, the mathematical model of sympathetic inrush is established to analyze its characteristic. Then Hilbert transform is used to obtain harmonic contents of sympathetic inrush and internal fault current. According to the proportion of fundamental to current, sympathetic current can be identified and differential protection can be blocked. The simulation results show that this method has better reliability and sensitivity than the second harmonic restraint scheme. Besides, it has a good ability against TA saturation.

Simulation Design of Transformer Differential Protection Based on Mat Lab

2013 ◽  
Vol 722 ◽  
pp. 282-286
Author(s):  
Hong Hua He
Keyword(s):  
Simulation Model ◽  
Relay Protection ◽  
Fault Current ◽  
Differential Protection ◽  
Protection Device ◽  
Simulation Design ◽  
Transformer Protection ◽  
Internal Fault ◽  
Simulation Results ◽  
Transformer Differential Protection

The microprocessor-relay protection device has gradually replaced regular simulation relay protection it is also difficult to visually determine protection device malfunction or tripping. Therefore, the use of the Mat lab toolbox to build transformer differential protection simulation model, the simulation results show that two-line ratio brake can correctly identify internal fault current, and rapidly remove fault, and the system also can provide convenient for microprocessor transformer protection.

Simulation of Transformer Protection Based on an Embedded MATLAB Function

2014 ◽  
Vol 960-961 ◽  
pp. 995-999
Author(s):  
Wei Cai ◽  
Lin Sun ◽  
Hua Ren Wu
Keyword(s):  
Simulation Model ◽  
Second Harmonic ◽  
Circuit Breaker ◽  
Inrush Current ◽  
Differential Protection ◽  
Transformer Protection ◽  
Function Block ◽  
Internal Fault ◽  
Harmonic Restraint ◽  
Transformer Differential Protection

This paper establishes a simulation model of a simplified power system with transformer differential protection based on an embedded Matlab function block. The differential protection consists of percentage restraint differential protection, second harmonic restraint, differential current instantaneous trip protection and over-excitation protection. The model is able to correctly simulate the transformer’s inrush current and internal and external faults. The results from the simulation show that the circuit breaker correctly operates for a transformer internal fault and provides a good braking effect for an external fault. In addition, the protection model is able to identify the inrush current of the transformer and avoid a protection mis-trip event.

scholarly journals THERMOELECTRICAL PROCESSES SIMULATION IN RESISTIVE SUPERCONDUCTING FAULT CURRENT LIMITER

2014 ◽  
pp. 100-106
Author(s):  
Dmytro Fedasyuk ◽  
Pavlo Serdyuk
Keyword(s):  
Mathematical Model ◽  
Computer Simulation ◽  
Fault Current ◽  
Fault Current Limiter ◽  
Electrical Behaviour ◽  
Superconducting Fault Current Limiter ◽  
Current Limiter ◽  
Simulation Results ◽  
The Mathematical Model

Simulations of superconducting fault current limiter (SFCL) include modelling of thermal and electrical behaviour of the limiter. In this paper the mathematical model for the analysis of thermoelectrical processes in resistive superconducting fault current limiter for microelectronics devices protection is presented. An effective and fast halfanalytical computer simulation of the model is presented. Simulation results are presented.

Recognition of the Transformer Sympathetic Inrush Current Based on Hilbert-Huang Transform

2013 ◽  
Vol 441 ◽  
pp. 227-230
Author(s):  
Bin Qiao Zhang ◽  
Wei Wei Yao
Keyword(s):  
Wave Form ◽  
Inrush Current ◽  
Fault Current ◽  
Hilbert Huang Transform ◽  
Characteristic Quantity ◽  
Current Wave ◽  
Internal Fault ◽  
New Type ◽  
Form Features ◽  
Set Up

Analyze the characteristic quantity difference between the transformer sympathetic inrush current and the internal fault current inside it depending on the Hilbert-huang transform and extract the new type Hilbert-huang criterion for the recognition of the sympathetic inrush current according to the transformed wave form features. Set up the transformer simulating models through PACAD for the sympathetic inrush current and internal fault current to extract their IMF component; identify the sympathetic inrush current and the internal fault current based on HHT criterion; verify whether HHT criterion can identify the sympathetic inrush current wave form and the transformer internal fault current correctly. The criterion has targeted feature with self-adaption ability.

Differential Protection Enhancement for Power Transformer

2021 ◽  
pp. 322-346
Author(s):  
Hamid Bentarzi ◽  
Rachid Bouderballa
Keyword(s):  
Power Transformer ◽  
Second Harmonic ◽  
Inrush Current ◽  
Differential Protection ◽  
Smart Power ◽  
The Third ◽  
Internal Fault ◽  
Harmonic Components ◽  
Magnetization Condition ◽  
Advanced Computer

A power transformer is protected against internal faults using a differential protection which is sensitive and a fast. However, during transformer magnetization (inrush current or over-excitation), the differential relay may operate unnecessarily. This phenomenon appears only when a transformer is first energized or after clearing external fault. During periodic magnetization condition due to over-excitation, the third and fifth harmonic components are largely noticed; however, during the normal apperiodic inrush conditions, the second harmonic is relatively high. In the conventional techniques, these harmonic components have been used to block differential protection to operate. However, in smart power transformer, these harmonic components are small even during the transformer magnetization; they cannot be used as block protection functions. The differential protection security has to be improved so that it can distinguish between differential current produced by magnetization and that produced by internal fault using the most advanced computer with most improved DSP algorithms.

Research on Dynamic Balance Method of Precision Centrifuge

2014 ◽  
Vol 945-949 ◽  
pp. 777-780
Author(s):  
Tao Liu ◽  
Yong Xu ◽  
Bo Yuan Mao
Keyword(s):  
Mathematical Model ◽  
Balance Control ◽  
Dynamic Balance ◽  
Dynamic Balancing ◽  
Structure Characteristics ◽  
Balance System ◽  
Simulation Results ◽  
Set Up ◽  
System Controller ◽  
The Mathematical Model

Firstly, according to the structure characteristics of precision centrifuge, the mathematical model of its dynamic balancing system was set up, and the dynamic balancing scheme of double test surfaces, double emendation surfaces were established. Then the dynamic balance system controller of precision centrifuge was designed. Simulation results show that the controller designed can completely meet the requirements of precision centrifuge dynamic balance control system.

The Feasible Analysis of Transformer Fast Reenergizing with Neutral Point Ungrounded

2013 ◽  
Vol 732-733 ◽  
pp. 958-964
Author(s):  
Yao Zhao ◽  
Yu De Yang ◽  
Yan Hong Pan ◽  
Le Qi
Keyword(s):  
High Voltage ◽  
Power Supply ◽  
Low Voltage ◽  
Second Harmonic ◽  
Neutral Point ◽  
Inrush Current ◽  
Differential Protection ◽  
Time Saving ◽  
Magnetizing Inrush Current ◽  
Transformer Differential Protection

The feasibility of transformer fast reenergizing with neutral point ungrounded after the external fault being removed is analyzed in this paper. By calculating overvoltage and discriminating magnetizing inrush current, it analyzes four ways to restore power of transformer and chooses the optimal strategy which is safe and time-saving. The result shows that in the case of transformer neutral point ungrounded, closing the low-voltage circuit side breaker before the high-voltage, which can effectively limit over-voltage in a safe range. The second harmonic characteristic of magnetizing waveform may disappear, while the intermittent angle characteristics are still significant. With the help of the intermittent angle principle, transformer differential protection may not misuse. The average time for each customer interruption is reduced from 40 minutes to 10 minutes and saves an hour for engineer on the way back and forth. It will greatly improve power supply reliability.

The Impact Analysis of Revolute Pair Clearance to the End Pose Accuracy of Welding Robot

2015 ◽  
Vol 778 ◽  
pp. 259-263
Author(s):  
Fa Jun Zhang ◽  
Lin Zi Li ◽  
Hui Lin ◽  
Yin Lin Pu ◽  
Zhu Xin
Keyword(s):  
Mathematical Model ◽  
Impact Analysis ◽  
Joint Clearance ◽  
Welding Robot ◽  
Movement Characteristic ◽  
Movement Stability ◽  
Simulation Results ◽  
The Impact ◽  
The Mathematical Model ◽  
Welding Position

Various uncertain factors affect the movement of the welding robot, thus welding gun tend to deviate from the theory of welding position which reduces the welding accuracy, of which the revolute pair clearance have an greater effect on the movement of the welding robot. In order to study the influence of revolute pair clearance to the end pose accuracy of welding robot, the mathematical model of revolute pair clearance was established, and the software SolidWorks was used for establishing the welding robot model, making simulations of the mechanical arm with joint clearance and no joint clearance. At last, the movement characteristic of the hinge shaft is attained. The simulation results showed that the shaft velocity and displacement of mechanical arm with joint clearance has a certain degree of fluctuation, which affecting the end pose accuracy of welding robot , and reducing the movement stability and the welding accuracy of welding robot.

Methods of Mathematical Modeling of the Leaching Process of Cobalt-Containing Solutions

2021 ◽  
Vol 316 ◽  
pp. 661-666
Author(s):  
Nataliya V. Mokrova
Keyword(s):  
Mathematical Modeling ◽  
Mathematical Model ◽  
Chemical Kinetics ◽  
Group Method ◽  
Data Handling ◽  
Multistage Processes ◽  
Leaching Process ◽  
Proposed Model ◽  
Simulation Results ◽  
The Mathematical Model

Current cobalt processing practices are described. This article discusses the advantages of the group argument accounting method for mathematical modeling of the leaching process of cobalt solutions. Identification of the mathematical model of the cascade of reactors of cobalt-producing is presented. Group method of data handling is allowing: to eliminate the need to calculate quantities of chemical kinetics; to get the opportunity to take into account the results of mixed experiments; to exclude the influence of random interference on the simulation results. The proposed model confirms the capabilities of the group method of data handling for describing multistage processes.

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