IED Design for a Small-Scale Microgrid Using IEC 61850

This paper presents a communications test-rig based on a customized Intelligent Electronic Device (IED) for its use in a laboratory-scale microgrid. The laboratory setup for this work uses the following three types of subsystems: distributed energy resources DERs (solar, wind), energy storage (batteries) and loads (active, reactive, linear and nonlinear). A Raspberry Pi computer, using the Linux operating system, allows programming the algorithms needed by the communications platform. The protocol employed for data exchange, between the different subsystems and the central supervisor module, is the IEC 61850 standard. Three experimental test cases serve to show the proposed IEDs performance. The first test transfers data between a solar source and a client station. The second test transfers data, in distributed mode, between four nodes associated to different generation sources. The last test shows a secondary control using two experimental inverters operating in parallel connection. The IEDs communicate the compensating values for regulating frequency and voltage in the system composed of a master and one or more slave inverters.