Stand Alone Merging Unit

Abstract

The ever increasing demand for power in the world has put immense pressure not only on power generation but also on distribution grids. So, the world has started moving from conventional grid to smart grid in order to reduce distribution losses. This also brings a level of automation, for real time control of digital substation. Digital substation extends the intelligent protection, measurement and monitoring to the process level in substation; as compared to conventional subsystem where it was restricted to the station level. Digital substation automation(DSA) has brought in a pool of intelligent electronics devices for measurement, monitoring and controlling the process. This thesis looks into the design of one such smart digital product for monitoring instrument transformer parameters, named Stand Alone Merging Unit (SAMU). The device continuously samples the data from instrument transformer and provides it over the ethernet. The device is based on electrical ratings taken from the standard International Electrotechnical Commission (IEC) 60044-8 and communication profile from IEC 61850. Interfacing of SAMU with instrument transformer is governed by IEC 61869-9, defining the sampling rates, conformance class, accuracy and rated error. An effort has been made to provide a network based solution for Stand Alone Merging Unit using a microcontroller based design. Design uses a simple dsPIC based starter kit for sampling and then transfer these values over ethernet with the help of ENC28J60, an ethernet control IC. It also publishes the data provided by the device over the webpage using dynamic variables in a webpage. Interfacing these two controllers and using a state of the art control algorithm the prototype was able to provide the sampled data over the ethernet. Sampled data was visible over the network bus and can be accessed on any computer placed in the network.