The Research of New Selective Leakage Protection Device Based on Additional DC and Zero-Sequence Power

2013 ◽  
Vol 457-458 ◽  
pp. 1185-1188
Author(s):  
Yan Wen Wang ◽  
Yin Sheng Wang
Keyword(s):  
Computer Simulation ◽  
Theoretical Analysis ◽  
Coal Mine ◽  
Protection System ◽  
Protection Device ◽  
Zero Sequence ◽  
Power Direction

By theoretical analysis and computer simulation,this paper has successfully solved the compatibility problembetween the Leakage protection with additional DCand zero-sequence power direction Leakage protection, and realized the goal of the two different ways of leakage protection sharingone set of electrical leakage protection system.This paper focuses on the basic components of "EDS-336/660 centralized-distributed selective leakage protection system"and its practical usage in Lvjiatuo Coal Mine.

The Protection System Design of Leakage, Undervoltage and Overvoltage for Electromagnetic Starter in Coal Mine

2014 ◽  
Vol 1049-1050 ◽  
pp. 720-725
Author(s):  
Hong Wei Ma ◽  
Wang Xing ◽  
Qing Hua Mao ◽  
Yu Liu
Keyword(s):  
Coal Mine ◽  
Supply Voltage ◽  
Phase Voltage ◽  
Voltage Transformer ◽  
Dc Power ◽  
Fault Protection ◽  
Three Phase ◽  
Protective System ◽  
Zero Sequence ◽  
Power Direction

For the problem of leakage, undervoltage and overvoltage fault protection of electromagnetic starter with supply voltage of 660 V and rated current of 200A, a leakage, undervoltage and overvoltage protective system based on PLC LM3108K was designed. This system uses voltage transformer to detect three-phase AC voltage. It protects undervoltage and overvoltage fault by judging effective value of three-phase voltage, protects leakage fault of main switch for electromagnetic starter by additional DC power and protects leakage fault of branch switch by using zero-sequence power direction. This system has good protection functions for leakage, overvoltage and undervoltage faults of electromagnetic starter in coal mine.

The Solution for Malfunction of the Leakage Protection System Caused by Mine-Used Converter

2014 ◽  
Vol 912-914 ◽  
pp. 1481-1484
Author(s):  
Yan Wen Wang ◽  
Hai Hong Li ◽  
Da Wei Wang ◽  
Zheng Fan
Keyword(s):  
Power System ◽  
Coal Mine ◽  
Protection System ◽  
Normal Operation ◽  
Coal Production ◽  
Actual Situation ◽  
Matlab Simulation ◽  
Zero Sequence ◽  
Working Principle ◽  
Isolation Transformer

The leakage protection system usually trends to make a misjudgment and tripping in normal operation after applying the converter in the coal mine power system. This seriously affects the safety in coal production. Based on the research of the structure and working principle of the converter, it has obtained the definite reason for the converter interfere the leakage protection system. It is the higher harmonics and pulses that generate the zero sequence current through the ground capacitance. Combined with the actual situation in coal mine, it has proposed two corresponding solutions: one is adding the isolation transformer in the output lines of the converter; another is modifying criterion of the leakage protection system. Both methods have their own characteristics, and have verified the feasibility of the methods through the MATLAB simulation.

Research of Comprehensive Protection Device in Underground Coal Mine Lighting Power Grid

2013 ◽  
Vol 329 ◽  
pp. 304-307
Author(s):  
Xu Dan
Keyword(s):  
Real Time ◽  
Coal Mine ◽  
Short Circuit ◽  
Power Grid ◽  
Protection System ◽  
Protection Device ◽  
Long Distance ◽  
Cable Insulation ◽  
Underground Coal Mine ◽  
Existing Problems

In view of the present our country underground lighting power grid comprehensive protection device existing problems, this paper introduces a DSP-based long distance lighting comprehensive protection device. Short-circuit protection using adaptive random setting mode. Leakage protection using additional DC measurement theory.The device has the function of cable insulation level, the network current is monitored real-time and grid parameters are displayed in turn, which make the protection system more perfect and reliable.

Study on Selective Leakage Protection System of Mine High Voltage Grid Based on Harmonic Phase Comparison

2015 ◽  
Vol 9 (1) ◽  
pp. 253-262
Author(s):  
Liu Zhongfu ◽  
Zhang Junxing ◽  
Shi Lixin ◽  
Yang Yaning
Keyword(s):  
High Voltage ◽  
Power Supply ◽  
Power Supply System ◽  
Supply System ◽  
Neutral Point ◽  
Arc Suppression Coil ◽  
Zero Sequence ◽  
Harmonic Extraction ◽  
Power Direction ◽  
The Stability

As for the wide application of arc suppression coil to the grounding in neutral point of mine high voltage grid, grid leakage fault rules and harmonic characteristics of the neutral point grounding system through arc suppression coil are analyzed, the selective leakage protection program “zero-sequence voltage starts, fifth harmonics of grid zerosequence voltage and zero-sequence current are extracted for phase comparison” is proposed, and corresponding fifth harmonic extraction circuit and power direction discrimination circuit are designed. The experimental results show that the protective principle applies not only to the neutral point insulated power supply system, but also to the power supply system in which neutral point passes arc suppression coil, which can solve selective leakage protection problems under different neutral grounding ways, improving the reliability of selective leakage and guaranteeing the stability of the action value.

Influences of Mining Depths of Coal Faces in Duanwang Coal Mine on the Gas Emission Law

2013 ◽  
Vol 295-298 ◽  
pp. 2874-2878
Author(s):  
Xin Xian Zhai ◽  
Yan Wei Zhai ◽  
Shi Wei Zhang
Keyword(s):  
Theoretical Analysis ◽  
Coal Mine ◽  
Production Capacity ◽  
Control Measures ◽  
Shanxi Province ◽  
Coal Face ◽  
Gas Emission ◽  
Average Value ◽  
Mining Depth ◽  
Selection Of

Duanwang Coal Mine in Shanxi province, China, is located at north of Qinshui coalfield which gently inclined and thick seams have been mined. Authorized production capacity of the coal mine is 1.8Mt/a. With the increase of mining depth, the mine gas emission quantity increased. The mine became high gassy one from low gassy mine. Using field measurement and theoretical analysis methods, the following conclusion can be drawn. Gas emission quantity of coal face is directly correlated with mining depth. With the increase of mining depth, both absolute and relative gas emission quantities at coal face increased. The gradient of gas emission quantity was 0.0438-0.1338m3/t/m, the average value was 0.1062m3/t/m. These results would provide a foundation for prediction of the gas emission quantity and selection of gas control measures.

scholarly journals A Security Wireless Monitoring and Automatic Protection System for CCEL

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Qiao-yan Sun ◽  
Xue-jiao Liu ◽  
Yu-mei Sun ◽  
Mei-chun Wang ◽  
Xiang Han ◽  
...  
Keyword(s):  
Chemical Engineering ◽  
Safety Information ◽  
Information Aggregation ◽  
Information Management System ◽  
Protection System ◽  
Gas Content ◽  
Protection Device ◽  
Wireless Monitoring ◽  
Security Information ◽  
And Control

A wireless monitoring and automatic protection system for laboratory safety is proposed to solve the security problems in chemistry and chemical engineering laboratories (CCEL). The system is based on a wireless sensor network (WSN), including indoor wireless security monitoring node, information aggregation and management node, portable handheld terminal, and laboratory security information management system. Each indoor safety wireless monitoring node can monitor the laboratory security information (for example, fire information, toxic gas content, abnormal sound in chemistry, and chemical engineering laboratory) and control the corresponding protection device. The portable handheld terminal can remind the safety responsible person to check the safety status of the laboratory remotely and can issue corresponding operation and control instructions. According to the instructions it sends, the indoor security wireless monitoring and control node can start the corresponding automatic protection device. The experimental results demonstrate that the system can realize all-weather online monitoring of indoor safety information, ensuring that some important scientific research experiments can be conducted continuously and safely, significantly reduced the workload of laboratory managers, and precisely reported the location and conditions of accidents; the loss caused by the accident can be minimized based on the automatic protection device. The system can also be used in dangerous goods warehouse and inflammable and explosive places.

The Control Technology of the Z-Source Three-Phase Four-Leg Inverter Based on Computer Simulation

2014 ◽  
Vol 981 ◽  
pp. 688-694
Author(s):  
Ming Su ◽  
Xue Yan Ma ◽  
Yan Sun
Keyword(s):  
Computer Simulation ◽  
Output Voltage ◽  
Control Method ◽  
Control Technology ◽  
Modulation Technique ◽  
Three Phase ◽  
Unbalanced Load ◽  
Zero Sequence ◽  
Current Flows

Z-source inverter can boost the voltage of the DC-side, allow the two switches of the same leg conducting at the same time and it has some other advantages. The zero-sequence current flows through the fourth leg of the three-phase four-leg inverter so the three-phase four-leg inverter can work with unbalanced load. This paper presents a Z-source three-phase four-leg inverter which combines a Z-source network with three-phase four-leg inverter. The circuit uses simple SPWM modulation technique and the fourth leg uses fully compensated control method. The inverter can maintain a symmetrical output voltage when the proposed scheme under the unbalanced load.

Smoke Control in Subway Tunnel Fires

2014 ◽  
Vol 638-640 ◽  
pp. 2027-2030
Author(s):  
Xiao Xiong Zha ◽  
Sheng Zeng ◽  
Yi Yan Chen ◽  
Rui Juan Jiang
Keyword(s):  
Computer Simulation ◽  
Theoretical Analysis ◽  
Critical Velocity ◽  
Simple Formula ◽  
Control Mode ◽  
Subway Tunnel ◽  
Smoke Control ◽  
Release Rates ◽  
Tunnel Fires ◽  
Ventilation Velocity

This paper concerns the smoke control modes and the critical ventilation velocity when the subway tunnel on fires. The standard for the smoke control mode is making sure the smoke exhausting in the shortest way. The critical ventilation velocity means it is just sufficient to prevent the smoke spreading upstream. The critical velocity in different heat release rates obtained though theoretical analysis and computer simulation. In the end, a simple formula to calculate the critical velocity can be fitting out.

Target Range and Velocity Measurement to Reduce False Targets in FMCW Automotive Anti-Collision Radar

2012 ◽  
Vol 253-255 ◽  
pp. 1410-1417 ◽  
Author(s):  
Zhi Gang Li ◽  
Qiong Chan Gu
Keyword(s):  
Computer Simulation ◽  
Theoretical Analysis ◽  
Continuous Wave ◽  
Target Range ◽  
Multiple Targets ◽  
Fmcw Radar ◽  
Wave Radar ◽  
Frequency Modulate ◽  
Inherent Problem ◽  
Simulation Results

For frequency modulate continuous wave radar, it is necessary and difficult to search the pairs of beat frequencies in an up-chirp mode and a down-chirp mode t o measure range and velocity of multiple targets. However, the inherent problem of FMCW radar is multiple targets detection. False targets can appearance because of mistaking the combination of these beat frequencies. A novel waveform named double-slope symmetrical saw-tooth wave is proposed and its corresponding algorithm is also introduced to resolve the problem of multiple targets detection for automotive anti-collision radar. Computer simulation results and theoretical analysis prove that the method is effective and practical for multiple targets detection in intelligence transportation system.

Sign in / Sign up

Export Citation Format

Share Document