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Загальна кількість знайдених документів : 4 Представлено документи з 1 до 4 |
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Le Xuan Thanh Analyzing and identifying the limits of 660V grid pa-rameters to ensure electrical safety in underground coal mines [Електронний ресурс] / Le Xuan Thanh, Ho Viet Bun // Naukovyi visnyk Natsionalnoho Hirnychoho Universytetu. - 2021. - № 6. - С. 101-106. - Режим доступу: http://nbuv.gov.ua/UJRN/Nvngu_2021_6_18 Purpose. To study the relation between leakage current and time, then to identify some limits of grid parameters to ensure electrical safety as well as explosion safety corresponding to all operating modes of leakage relay in Vietnam underground mines. Methodology. In underground coal mines of Vietnam, 660 V grids are characterized by ungrounded neutral point electric system. They require very serious and strict operation conditions including electrical safety and explosion safety. In daily operation, the earth leakage currents (earth fault currents) must be lower than the allowance limit. However, when utilizing many new power electronic devices such as variable speed drive (VSD), the quantity of connected equipment changes due to the change in capacitance current. After measuring the grid parameters, leakage currents are computed in terms of 3 compensating levels of earth fault relays. The resulting values of currents are used to build up limit curves. Findings. Curves of the graphs present the relation between the leakage current and the length of transmission cables associated with various connecting equipment. The curves may be used to operate the electric system safely and effectively. Originality. The proposed equations and simulation in Matlab may be applied to all underground mining grids with different input parameters. Practical value. Operating curves of the graphs are used to identify the most suitable grids parameters which could ensure electrical safety (keeping the leakage current within the allowance limits). It could help operators or technicians optimize the structure of grid and ensure its safety. | ||
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Ho Viet Bun A new approach to improving the sensitivity of earthing relay and reducing the over-voltage in 6 kV grid of open-pit mines [Електронний ресурс] / Ho Viet Bun, Le Xuan Thanh // Naukovyi visnyk Natsionalnoho Hirnychoho Universytetu. - 2022. - № 2. - С. 54-60. - Режим доступу: http://nbuv.gov.ua/UJRN/Nvngu_2022_2_11 Purpose. Earthing relays are utilized very commonly in open-pit mines for disconnecting the failure part of 6 kV electric system from earthing incident. Much previous research is mentioned on searching either an optimal method for improving the effect of relays or improvements of reducing the overvoltage caused by grounding separately. The paper presents a new approach to not only improving the relays' sensitivity but also to limiting the over-voltage. A new algorithm is also proposed to control automatic connection of an additional resistor in order to achieve both above mentioned purposes of 6 kV earthing relay. Methodology. The propose controlling diagram is implemented on PROTEUS to get 3U | ||
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Pham Thanh Loan Data collection system with signal optimal-routine for the mining and environmental monitoring in Vietnam [Електронний ресурс] / Pham Thanh Loan, Le Xuan Thanh // Naukovyi visnyk Natsionalnoho Hirnychoho Universytetu. - 2023. - № 1. - С. 149-153. - Режим доступу: http://nbuv.gov.ua/UJRN/Nvngu_2023_1_24 Purpose. To develop a data acquisition which is optimized for suitable purposes in monitoring/warning or decision-making assistance in the field of geography accident in mining activities or agroforestry. Methodology. In activities related to mining, agroforestry and environmental monitoring, many climate factors must be taken into account including humidity, soil moisture or level of rainfall. Those data play a key role in pre-warning or assisting in decision-making for operators who are responsible for risk warning. In this paper, we present an optimized data acquisition system which is reasonable in cost, simple and easy in installation. The system includes a sensor station (SS) and a central station to collect data from specified monitoring points. The latter one is used to gather data from SS through a new and optimized Lora WAN communication system. When sending gathered data to a cloud sever, an assistant system based on 3G module is established to warn of abnormal scenarios of the mining procedure or environmental parameters. The system is experimented, tested and implemented in the North Mountain area (Northwest) of Vietnam. Findings. A development of an acquisition system with optimized-data for alarming/warning and monitoring in the field of geography accident, mining activities and environment. The system could get sensing signal in both direct way and indirect way despite of bad weather. Originality. An improved Dijkstra algorithm is implemented to optimize and simulate the routing paths of a network. The optimization could show the best way for getting signal from sensor station indirectly to other ones, then to the central station. Practical value. A simple, reasonable-cost and easy-installation system is formed for monitoring, risk warning in the field of geography, mining, and climate. | ||
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Le Xuan Thanh A new approach on ai application for grounding resistor prediction in underground mines of Vietnam [Електронний ресурс] / Le Xuan Thanh, Ho Viet Bun // Naukovyi visnyk Natsionalnoho Hirnychoho Universytetu. - 2022. - № 5. - С. 158-163. - Режим доступу: http://nbuv.gov.ua/UJRN/Nvngu_2022_5_25 Purpose. To apply artificial intelligence (AI) technology for predicting the earthing resistor of underground mines with consideration of climate change parameters. Methodology. In underground coal mines of Vietnam, the earthing system are everywhere equipped with individual rods combined with centralized grounding bed; this system significantly influences electrical safety and explosion safety. In daily operation, the resistor of the earthing system must be measured and tested regularly to ensure their value lower than the allowance limit (<$E 2 SIGMA>). However, because of being affected by climate parameters (humidity and temperature in mines) this value varies frequently. By applying a new Neural Network with 3 hidden layers including variable parameters, the paper presents a new approach on predicting the earthing resistor. An algorithm is formed with visible and easily usable software for assisting the operator to predict the resistor. The prediction could be used for onsite management of a mine operator in the field of observing and testifying the earthing system in underground mines. Findings. Software is developed based on AI technology for assisting the operator to predict the value of the earthing resistor corresponding to climate change. Originality. Neural network with AI technology application is utilized relying on onsite measurements. Practical value. Prediction results could be used in case of difficulty in measurement. It will also help to correct or eliminate the measurement error from a mining technician. | ||
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