Design Approach for a Stand Alone Merging Unit

In order to enhance levels of security and reliability of power systems, allowing for advanced remote diagnostics, Merging Units (MUs) play a key role. Some of the benefits are a more efficient transmission of electricity and a better integration with renewable energy systems. In this paper an implementation of a Stand Alone Merging Unit (SAMU), compliant with the IEC 61850-9-2 standard and based on a low cost ARM microcontroller, is described. It acquires two signals, one voltage and one current, and it sends the samples over the Ethernet connection. A high-resolution analog to digital converter (ADC), synchronized to the Universal Time coordinated (UTC) through a Global Positioning System (GPS) disciplined oscillator, is used. The results of the characterization of the ADC are presented.