engleski

System for detection of excitation winding shorted turns in hydro generators

Important issue in the operation of all machines is the proper and reliable work. In economic terms it means to achieve the maximum financial benefit and to stay within technical constraints. Because of that, reducing unplanned downtimes and unnecessary maintenance is very important. To enable a better asset management detection of machine fault conditions is of great significance. The most important goal of every detection method is early fault detection. In that case problem can be fixed before it causes major damage. One of the problems that can occur in hydro generators is excitation winding short turn. Shorted-turns are the result of failed insulation between individual windings. As generators age, shorted turn problems become likely. The impact of operating with shorted turns ranges from no-problem at all, to abnormal vibration, load limits, higher operating temperatures and forced outages. The magnitude of the effects of running with shorted-turns depends on location and number of shorted turns. The measuring of air-gap magnetic flux waveform, as most important part of the generator for information collection, has proven effective in the detection of generator rotor winding shorted turns. As a result of many years of work and research of the rotating machines magnetic field, we have developed “System for Detection of Excitation Winding Shorted Turns in Hydro Generators” (HG-WFD). Based on numerous numerical calculations by which a magnetic field in the air gap of the machine was calculated (in both good working condition and with the presence of excitation winding shorted turn), experiments on simulation models in the laboratory and field tests, our own method for generator excitation winding shorted turns is developed. It is based on a differential measurement of a magnetic field in the machine, and it is a patent-pending method. This new innovative method can detect excitation winding shorted turns with high resolution using two measuring coils. In addition to this new innovative method, the system also uses a classical method for winding shorted turns detection using one measuring coil. HG-WFD can be used with all types of the hydro generators. It is easy to use and enables automatic generation of measuring report and data analyses with all the important results. It can be concluded that HG-WFD system, by providing insight into machine fault conditions, which can cause major damage and thus major repair costs, allows improved asset management.

Synchronous generator; rotor winding inter-coil short circuit; fault diagnostics; fault detection

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