Research On Inrush Current Of Converter Transformer

With the more and more high voltage direct current (HVDC) transmission system built and put into operation, China gradually formed AC/DC hybrid system of grid pattern. Converter transformer as the main element of the station, to ensure the reliable operation is particularly critical. As a result of the converter transformer’s characteristics and the operation mode of the different, and converter transformer protection configuration and general power transformer exist some differences. So it is necessary to research the rheological inrush current and sympathetic inrush.In this paper, based on the analysis of the characteristics of the converter transformer and its protection configuration, a comprehensive study on the current problem of the converter transformer is given in this paper, based on the analysis of the characteristics and the protection configuration of the converter transformer. First of all, based on YUN-GUANG ± 800 kV UHVDC transmission system operation mode, the inrush current condition analysis, from the angle of transformer flux. The theoretical analysis of the effects due to change the rheological and common variable differences caused by the converter transformer magnetizing inrush current, focus on the change characteristics and occurring mechanism of the rheological special magnetizing inrush current. Secondly, in-depth analysis for current transformer and current characteristics, the analysis results show that influenced by the system connection mode, mode of operation, system impedance, no power compensation device, switch angle and remanence and other factors, AC/DC hybrid system exist in various forms of and inrush current. Then, the author analyzes the different phase compensation methods for rheological inrush current of converter transformer differential protection, commutation transformer differential protection and backup protection and other protection of transformer inrush current exchange flow were obtained and pointed out that in some cases, for rheological desert differential protection, converter transformer overcurrent protection and the superior line current protection will be due to the converter transformer inrush current caused by misoperation, and is the cause of the malfunction condition were detailed analysis. Finally, based on the influence of the change of the flow on the relay protection, the simulation analysis of the three ways to suppress the flow of the flow of the method, and compared the three suppression methods.