Douhe Power Plant, Tangshan 063028, China; North China Electric Power Research Institute Co., Ltd., Beijing 100045, China; Harbin Institute of Large Electric Machinery, Harbin 150040, China) The practical significance of the application of on-line vibration monitoring devices for motor stator winding ends.
The 7th generator of Douhe Power Plant is the XFQS-200-2 steam turbine generator produced by Harbin Electric Machinery Factory. Since it was put into production on November 22, 1986, there have been 4 cases of stator coil insulation damage accidents. There are some problems in manufacturing, and there is a direct relationship with the vibration of the unit bar. For example, on July 7th, 1989, minor repairs found that the steam-insulated 3 insulated box hollow wire fatigue fracture, the main insulation wear of the steam-side 3, 4 upper-layer bar groove is 3~5mm, and the lower-layer bar main insulation wears 1mm, both Caused by vibration. When the generator was burned on December 6, 1990, the end leads V6 and W2 were fixed in the insulation of the splint, and there was a putty-like powder around it, which was also caused by vibration. In the subsequent large and small repairs, the end plate and the screw loosening of the bracket were found many times.
In 1998, during the overhaul of the natural frequency measurement and modal test of the stator winding end of the generator, the North China Electric Power Research Institute found that most of the bars have a natural frequency of about j07, 108H>, and the mode shape is elliptical. It is considered that the winding is easy to resonate with the electromagnetic force, and in the line, 1 may be worn due to vibration, causing winding failure. GB/T7064-1996 Turbine Synchronous Motor Technical Requirements and DL/T 596-1996 Power Equipment Preventive Test Procedures and DL/T735-2000 Large Turbine Generator Stator Winding End Vibration Characteristics Measurement and Evaluation It is stipulated that the natural frequency of the end bar of the generator stator winding should avoid twice the power frequency of 100 Hz. A large number of generator operation practices also show that some stator end short-circuit accidents are related to the resonance of the end structure and electromagnetic force.
There is an elliptical vibration mode in the dangerous frequency range at the end of the stator winding of the generator. In order to ensure safe and stable operation in the future, the structural processing of the end of the stator winding should be performed according to the relevant regulations. Leaders of various departments attach great importance to this. The Biotechnology Department of North China Power Group Corporation and the Production Department of Datang Power Co., Ltd. specialize in organizing Harbin Electric Machinery Research Institute, North China Electric Power Research Institute, Shandong Electric Power Research Institute, Harbin Electric Machinery Factory, Relevant experts from Beijing Heavy Machinery Plant and leaders and professionals of Douhe Power Plant held a professional meeting at the Douhe Power Plant to discuss research solutions. The Harbin Electric Machinery Factory and the Beijing Heavy-Duty Motor Factory respectively proposed a treatment and transformation plan, which required about RMB 3 million and a construction period of 80 days.
The WU is not within the specified range of 1* operation because the stationary state of the generator is cold. The piezoelectric crystal accelerometer starts measurement and shows the vibration value of the most f value of 105! After hl half a year, the maximum test is 102! ,) Fiber-optic transmission, mg fiber-optic vibration monitoring system sets the actual condition of the ampere-clearing property of the unit itself. In order to further verify the actual operating state of the unit, the relevant experts suggest to install online vibration at the end of the generator winding. The monitoring device determines whether to renovate based on the results of the monitoring during operation.
Therefore, it was decided to carry out the installation of the monitoring device during the minor repair of the 7 units.
2Technical scheme 2.1 Adding fiber optic vibration sensor In the maximum amplitude of the nose end of the generator stator coil confirmed by the modal test on both sides of the generator steam and excitation, 6 fiber optic sensors, 3 steam side and 3 excitation side are installed. The E-side 13-bar mounted sensor measures the tangential vibration of the bar, the 23 and 43 bar-mounted fiber optic sensors measure the bar radial vibration, and the T-side 53 bar-mounted sensor measures the bar tangential vibration, 25 and 41 The bar mounted sensor measures the radial vibration of the bar. The vibration light signal collected by the sensor is sent to the sealed conversion box on the generator casing through the cable lead, converted into an electrical signal and then transmitted by the wire to the monitoring device installed on the platform. The vibration monitoring device is arranged on the same dial as the partial discharge and hydrogen measuring device. The monitoring device for vibration data processing and analysis is the PCU*100 programmable vibration monitor produced by Canada Maintenance Monitoring System Company-i-), which can display the vibration amplitude of the wire rod monitoring part at any time during operation and set the alarm. Values ​​and hazard values, based on which the operating personnel can understand the operating conditions of the generator and determine the operation and maintenance plan based on changes in the vibration state.
2.2 Adding a piezoelectric crystal vibration sensor While installing a fiber-optic vibration sensor, a piezoelectric crystal type acceleration sensor is also installed at a low potential of the stator coil on both sides of the generator steam side and the excitation side. 3 and each side of the excitation side. The specific installation position is the corresponding position on both sides of the 10, 28, and 46 wire rods, and all the measuring rods are radially vibrated. The piezoelectric crystal sensor housing is electromagnetically shielded, and its leads are led out at a low potential to avoid insulation failures that may be caused thereby. The vibration signal is led to the temperature measurement terminal board, and a fixed signal data processing and display device is not installed. The vibration amplitude needs to be measured regularly by the Harbin Institute of Electrical Engineering with instruments.
3 Vibration test results and analysis Vibration analysis instruments measured by two different test principles, including vibration test under various load conditions at start-up and re-test after half a year of operation, online vibration monitoring in long-term operation, the results show that the generator Although the modal test failed the 107=108H elliptical mode, the vibration of the end structure was so large that the vibration of the bar under running load was far less serious than originally thought. It is still in the vibration limiter. The maximum vibration measurement is 149pm (the maximum vibration during operation is 178!n), which is less than the current allowable vibration standard of 250 in China! n. Test data see the appendix. At the same time, it is within the monitoring range of ABB's 100=200jum and the monitoring range of Westinghouse's 192pm. Therefore, according to the measurement results, the vibration condition of the 7 generators of the Douhe Power Plant is still meeting the requirements of normal operation, and it is not necessary to carry out the end structure modification. Whether it will be modified or processed in the future will be determined according to the development of vibration monitoring values ​​during operation.
After installing the vibration detecting device, the operating personnel can monitor the vibration condition of the wire rod of the unit at any time, record the vibration amplitude of each point, observe the development trend of the vibration of the wire rod, and do a good job in the operation status of the unit to avoid power generation. The occurrence of machine accidents and future state maintenance are very helpful. In November 2000, the 43-bar vibration value of the unit increased by 75 å©, and returned to the original value after 10 days. For this situation, the key inspection during the inspection revealed that the bracket screws between the 44 and 45 wire rods were loose and timely processed. . At the same time, it provides first-hand information on the retrofit design of the other 200MW generators of the power plant and even the modification of the domestic units.
4 Conclusions 1) For the modal test to confirm that there is a generator close to the 100H elliptical mode at the end of the stator winding, in order to prevent the resonance phenomenon from causing damage to the winding end structure, it should be related to the modification of the stator end structure by relevant experts. The program conducts research. Although the 7-generator of Douhe Power Plant has experienced stator winding end failures or accidents many times in history, in view of the fact that no serious end fastener loosening and insulation wear have been found in the recent long operating period, the installation of generators is adopted. The device for monitoring vibration on the end of the stator winding can intuitively and accurately understand the actual vibration state of the end of the stator winding in the generator operation, and then decide whether it is necessary to carry out the overall transformation of the end. This treatment is very correct. of. The experience of the Douhe Power Plant shows that the monitoring device has little investment, but it plays a key role in ensuring the safe operation of the generator. The experience of the Douhe Power Plant provides a good example of the treatment of generators that have problems with the stator winding ends through modal tests.
2) The vibration sensor for long-term on-line monitoring of the stator winding end of the generator, the installation quantity should be determined according to the actual situation. The installation position fiber sensor can select the maximum amplitude confirmed by the modal test, and the piezoelectric acceleration sensor should only be installed at low. Potential. The measured data shows that the vibration data of the two vibration sensors can be mutually verified, and they are all at reasonable values. The test results are reliable. Both test methods can achieve the purpose of monitoring the vibration state of the stator winding ends of the generator, but because With advantages, fiber optic vibration sensors should be preferred. ! The fiber-optic vibration monitoring system installed in 7 generators of Douhe Power Plant has the functions of automatically recording data and vibration amplitude limit alarms, which effectively provides real-time monitoring of the vibration state of the end windings of the stator windings during generator operation. The reliability of the safe operation of the generator provides strong support for the further maintenance of the generator.
4) Since the vibration monitoring of the end of the stator winding indicates that the vibration state is always within the prescribed allowable limit, the generator will continue to monitor for a long period of time, and no modification of the end structure is required. Therefore, more than 300 million yuan of reconstruction funds are saved, not including other The overhaul cost, while eliminating the modification time of 80 days, avoided the economic loss of hundreds of millions of kWh of electricity caused by the shutdown of the generator, improved the equivalent availability factor of the unit, and achieved good economic benefits.
Appendix: 7 generator stator end vibration test record Schedule 1 fiber optic sensor measurement point record July 3, 002) Note: the measurement point is E side 13 line bar, 2 measurement point is E side 23 line bar, 3 measurement points For the E side 43 line bar, 4 measuring points for the T side 25 line bar, 5 measuring points for the T side 41 line bar, 6 measuring points for the T side 53 line bar attached table 3 piezoelectric acceleration sensor measuring point record 2000 3 Test on the 22nd of the month) Steam 1 steam 2 steam 3 excitation 1 excitation 2 excitation 3 Schedule 4 piezoelectric acceleration sensor measurement point record January 11, 2001 test) Steam 1 steam 2 steam 3 excitation 1 excitation 2 excitation 3 1 power Measurement and evaluation of the vibration characteristics of the stator winding end of the large-scale turbo generator in the industry standard DL/T 735-2000. 6. Schedule 2 Piezoelectric accelerometer measuring point record November 22, 1999 test) Steam 1 steam 2 steam 3 Reinforced 1 Reinforced 2 Reinforced 3 胙 Intro Profile Chang Yaping 1963-) Female, Hebei Xianghe, graduated from North China Electric Power College in 1983 with a major in electrical and power system automation.
Zheng Baozhen 1964-), male, Tangshan, Hebei, graduated from Beijing Radio and Television University power plant and power system in 1989
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