Study On Condition Monitoring And Fault Diagnosing Early-warning System Of Coal Mine High Voltage Cable

The project in this thesis is one important part of the project " Safety Status Monitoring and Fault Diagnosis Forecast of Mine Ventilation Power Supply System" (No:2007BAK29B05), sponsored by the National Key Technology R&D Program of China during the Eleventh Five-year Plan Period. The work is proposed in accordance with the lack of the condition monitoring and fault diagnosing early-warning system for coal mine high voltage cable. Power transmission cables in coal mines, one of the key equipment production safety, charged with the task of production safety. According to incomplete statistics, accidents of coal mine power equipment, cable fault occupies 2/3, it is one of main reason about coal mine gas explosion.Therefore, developing the system of coal mine high voltage cable condition monitoring and fault diagnosing early-warning system, detecting cable insulation defects during operation timely, extracting early-warning information, can prevent cable fault happen. It has important practical significance to improve coal mine supply system safety and reliability, reduce the frequency and duration of power outages, underground long-term security and stable guarantee.Paper analyzes coal mine high voltage cable common faults, fault mechanism, online monitoring tools, develop fault diagnosing early-warning of coal mine high voltage cable system based on dual-CPU, the technology of multi-sensor information fusion. Through signal detection, feature extraction and information fusion, achieve fault diagnosing early-warning, provid the technical support of the cable reliable operation. The main contents of this thesis are as follows:After domestic and abroad literature reviewing, site investigation, participate in high-voltage electrical on-line monitoring technical training, the developmental trend of the monitoring system and fault diagnosing early-warning technology in the coal mine is conscientiously analyzed, describe the type of coal mine high voltage cable common fault and cause leading. Study the mechanism of coal mine high voltage cable insulation falling, establish a mathematical model of cable insulation, integrate application in fault diagnosing early-warning of artificial neural network, expert system, virtual instruments and intelligent database. Investigate on-line monitoring ways and means of characteristic, summarizes the internal relations of characteristic and faults. Combined with the actual network of underground cable, determine the structure of the distributed-line monitoring system. The system consists of each monitoring station and the IPC of underground central substation, which forms a condition monitoring local network system. Each monitoring station collection and simple processing the date of characteristic, IPC do the work of complex digital signal treatment, comprehensive and judgment and transmit the end result to the ground.According to the needs of cable condition monitoring, designed and produced a weak current sensor and partial discharge high-frequency signal sensor, sampling of the sensor resistance and the number of turns, etc. Through experimental study, achieve good results. Starting from system requirement, propose dual-CPU detection mode. Use 51 series STC89C51 and Altera Cyclone II series FPGA EP2C20F484C8 as system CPU. Use high-speed AD about AD9283, expand large capacity memory of SDRAM, SRAM and FLASH. Meet the system requirements of high speed signal acquisition and storage. Design a data acquisition unit and signal conditioning circuit of features, serial communication circuit between MCU and FPGA, CAN bus communication circuit between FPGA and IPC. Completed circuit board production and debugging, build system experiment platform, carried out various fault experiments. Achieve real-time data collection, synthesis and processing, The results show that hardware to meet the system real-time requirements, sent the data to the IPC timely.The application programs of the IPC and monitoring station are compiled by modular programming method, which include several subroutines such as analog acquisition and processing subroutine, MCU communication subroutine, FPGA test routines, HMI subroutine, IPC filter subroutine, proposed technology of filter out white noise and narrowband interference using wavelet.Downloading the program to the MCU and the FPGA, debugging the system, sample variety of characteristic digital signal. Experimental results show that the characteristic can be sampled and converted by the controller accurately and quickly. This made a groundwork for the experiments of the next step.