Development of a high accuracy digital voltage transformer and a test bed supporting IEC 61850 and IEEE C37.118

Abstract

Digital substations are essential components of the smart grids of the future. Advanced operation and control strategies should be implemented there by acting on data in a digital form. However, the data quality hugely depends on the input analog signals sourced from instrument transformers. Although considerable efforts have been made to improve their operation, many problems still remain unsolved. The main focus of this study is designing a new voltage transformer based on a resistive voltage divider. The test results have revealed that a few characteristics of the new transformer are significantly better compared to many existing solutions. The new measuring device is now being equipped with a digital interface supporting both IEC 61850 and IEEE C37.118, which is seen as a prerequisite for utilizing the developed transformer in a digital substation environment. In order to make sure that the signal conversion into the digital domain is correct, a test bed has been developed and is also discussed in this paper.