Research On On-line Moitoring And Diagnosis Of Winding Deformation Of Power Transformer

Transformer is the key equipment for the stable operation of power system. There are several parameters need to be monitored, including oil temperature, gas chromatography, dielectric loss and so on. Among them, it is need to be prevented for the winding deformation of transformer, which is a major transformer failure risks, because the cumulative effect will cause breakdown of the transformer windings. In this paper, on-line monitoring system of transformer winding deformation is based on short-circuit reactance as the parameter, more timely and effective to find error than off-line testing.In this paper,relationship between short-circuit and transformer winding deformation are derived, and the method of voltage and current measurement is introduced. Secondly, the hardware design ideas of on-line monitoring system are proposed. In addition, this paper analyzes the data process of on-line monitoring, including false data removed, voltage and current measurement and short-circuit reactance finalizcd.It is shown from the digital simulation that the complete-wave Fourier algorithm, which is calculated on voltage and current have a lot of erros.So this paper proposes improved algorithm, which have been proved. Based on the theory above, on-line diagnosis system of winding deformation of transformer and diagnostic strategy are developed, and this paper establish a database of various parameters about transformer status.In this paper, five state of rating scale are proposed, so the winding deformation of transformer is repaied in time ultimately.Last but not least, it builds the model of three-phase transformers, the accuracy of short-circuit reactance calculated by voltage and current measurement have been certificated by simulation calculations. The simulation calculations show that it is reliable to be calculated by voltage and current measurement in short-circuit reactance with the conditions that the three-phase transformer windings of different connection groups. Furthermore, the errors of measurement, hardware and software are analyzed in on-line monitoring system and improvements are developed in this paper.