Virtual Instrument Application To The Power Unit Fault Diagnosis For The Generator Excited System

The generator excited system, which has a direct effect on stable operation and feasibility of the generator, is an important control unit for synchronous generator, whereas, the power unit consists of the most part for excited system. There are transistor faults of conduction through and open easily to be happened in the power unit of generator excited system. The phase voltage instantly comes to short circuit as soon as the existing transistor fault of conduction through happens meantime, the short circuit current has the protection circuit act; as against, there is existing transistor open fault(such as the destroyed gate of transistor device or trigger pulse missed etc.), the power unit yet to be running , but the pulsing of output exciting voltage will be increased and unstable working state of the generator and increased disturbance of electric net; therefore, carrying on generator fault analysis is in favor of swiftly fixing the position and properties of fault, shortening the mean value will be decreased, which leads to distorting waveform of exciting voltage , the stop and troubleshooting time for the generator together with improving the feasibility.Firstly, the fault analysis of brief account , purpose and significance are introduced in the paper. study the power unit's fault analysis of brief account , method and feature for the generator excited system. Secondly , give an outline of virtual device and applied software LabVIEW. Finally, make the research program of the topic, which mainly includes two sides of theoretical analysis and concrete practice. On the theoretical analysis side, the exciting voltage waveform is particularly studied under power unit's normal working and fault state in the paper, summary and induction of fault state is dealt with according to exciting voltage waveform. An improved fault analysis method of pattern recognition is presented through the logical preprocessing of fault waveform; on the basis of PCI —6221 data acquisition card of national instruments, the fault analysis system of power unit for the generator excited system is developed grounded on virtual device on the purpose of implementation of fault system. There are two main parts including hard ware and soft ware in the fault system. Hard ware: signal conditioning circuit and data acquisition card; soft ware: program for data acquisition ,program for calculating parameters and program for fault analysis together with human-machine interface etc..At last, carried out the fault analysis test on a small generator in the laboratory, during the test process.simulate all kinds of the fault state. The results showed that the better conclusion can be obtained and the concrete fault category also be indicated from the analysis system making the Power unit of generator excited system running with fault so that the purpose of fault analysis and monitoring is arrived at.