Study on the Insulation On-line Monitoring System of HV Motor
|School||Taiyuan University of Technology|
|Course||High Voltage and Insulation Technology|
|Keywords||High-voltage Motor Insulation On-line Monitoring C8051F020 LabVIEW|
The content of this paper is an important part of "Mine ventilation and power system security condition monitoring and fault diagnosis of early warning systems" (No:2007BAK29B05), which is sponsored by the National Key Technology R&D Program of China during the Eleventh Five-year Plan Period.With the rapid development of modern industry, the number of high voltage motors used in the production system is continuously increasing, and the failure rate of motor and the corresponding economic losses are also rising. Then, higher requirements of the motor itself as well as its matching online monitoring system will be put forward. The current monitoring system can just detect and process the conventional parameters such as current, voltage and temperature, etc. It can’t monitor the running state from many aspects, and can’t provide reliable basis for fault diagnosis and early warning. Therefore, it has important practical significance to study the online insulation monitoring system of high-voltage motor.The motor insulation aging mechanism and its relevant parameters characteristics are analyzed in this paper. The high-voltage motor online insulation monitoring system is developed combined with the actual operation situation. The details are as follows:Firstly, the stator winding insulation materials, insulation structure and insulation processing technology are investigated, and the main reasons of insulation fault are analyzed. The objects of on-line monitoring system are determined based on the traditional motor insulation off-line testing method.Secondly, the characteristic of each monitored object is analyzed. The on-line monitoring circuit of the insulation resistance, temperature and partial discharge are designed as well as co-processing control module. The on-line monitoring circuit of insulation resistance is consisted of a series of separate circuit including an additional DC power supply circuit, a sampling resistor circuit, a programmable controlled amplifier circuit, a DC-DC linear isolation circuit, an analog-digital conversion circuit, a switch signal isolation circuit and a digital signal isolation circuit. The temperature on-line monitoring circuit can reduce the nonlinearity error of the temperature sensor PT100, and then it has high measuring accuracy. The partial discharge on-line monitoring circuit includes a programmable gain control circuit, a programmable band pass filter circuit and a synchronous signal generation circuit, and it has wide measurement frequency band, small measurement error and high reliability.Thirdly, a set of program is designed by modular programming method, which includes system initialization program, RS485 communication program, SPI communication program, I2C communication program, insulation resistance signal acquisition program, temperature signal acquisition program, partial discharge signal acquisition co-processing program. The host computer software is complied by graphical programming approach, which consists RS485 communication, signal de-noising, parameter calculation, feature extraction, data displaying and database reading and writing processes. The software has high signal-to-noise ratio, short scan cycle and high running efficiency.Finally, the designed on-line monitoring system of high voltage motor is simulated and debugged. The results show that the hardware circuit has high monitoring accuracy and high reliability. The software has reasonable structure, strong readability and portability. Each level of the system can coordinate well. The system can monitor each relevant parameter of the motor, which satisfied the design requirements.