On the Use of Quality Flags for Digital Transformers in the Sampled Values Protocol IEC 61850

This work is devoted to a detailed description of the quality flags of the Sampled Values protocol of the IEC 61850 standard for digital current and voltage transformers. The relevance of this article is due to the fact that the quality flags are not strictly and in detail described in the standard itself, therefore, manufacturers of equipment for digital current and voltage transformers fill in the quality flags if there are problems with data or device at their own discretion. The first part provides information on the structure of interaction between elements of a digital measuring system, describes the advantages of using quality flags in digital data transmission protocols relative to traditional transformers. In the second part, special attention is paid to the interpretation of quality flags in the IEC 61850 standard and the lack of a clear formulation of their applicability in real devices. The third part offers new interpretation of these quality flags with an example of use based on the developed measuring system. At the end of the article, evidence of the correct operation of the described quality flags is provided using a test bench and equipment for analyzing the Sampled Values protocol.