Applied Study Of On-line Monitoring Of Partial Discharge For Hydro-Generators

The large generator is one of the most important devices in power system. Partial discharge (PD) in large generators can lead to deterioration of the insulation, resulting in insulation breakdown and short circuit. Traditional off-line test cannot present the real status of generators in operating station, so it cannot ensure safe-operation of generators. Insulation faults were still reported now and then. It's necessary to develop a complete and practicable on-line monitoring system of partial discharge in large generator insulation.Research on the On-line Monitoring of Partial Discharges on Large Generator Stator WindingsAbstractThe on-line monitoring of partial discharge on large generator statorwindings is an effective way to diagnose the insulation condition of statorwindings. In this paper the time features and the frequency features of three different types of partial discharge (PD) occurred on generators, such as delamiantion PD, end winding PD and slot PD, were analyzedbased on the laboratory test of generator stator winding model bars. This article unified the need of water power station large-scale generator partialdischarge on-line monitoring, has researched and developed a set based on the virtualinstrument technology large-scale generator partial discharge on-line monitoring system, and successful apply to the scene has monitored middle, has raised the scene part discharging signal's to monitor mass and the malfunction diagnose level. This partial discharge monitoring system uses the advanced virtual instrument technology, will have the computer mainstream technology and function formidable virtual instrument software and the high performance modulation hardware will unify in together, will realize the traditional instrument hardware electric circuit function with software.The article has described owing systematic measurement principle, soft hardware design process and functionare composed of, reality has measured, verified the validity being system's turn by the scene. The on-line monitoring system has tested the partial discharge of the large-scale generator, and the result of the experiment is, this system has a higher sensitivity. After had deal with the test data and analyzed, we had a planar chromatogram of the discharge, has made up with the cumulative discharge q, the phase of dischargeΦ, the times of discharge N. Form the chromatogram we had picked-up the discharge impulse's characteristic well and truly, and has established a foundation for the on-line monitoring and diagnostic technology for insulations of the large-scale generator. Analyzed form the chromatogram of the discharge impulse, the on-line monitoring system catch a generator failure exactly, by Analyzed the phase of discharge has found the inter phase's failure characteristic obviously, after the field survey, we finally found the failure on the stator. Thus it can be seen, this system can monitor the partial discharge signal of the large-scale generator effectively, and the veracious monitoring data can found the disfigurement of the generator early and effectively. This system has provided the technology foundation for putting in practice the condition based on maintenance.