Interoperability and interchangeability for microgrid protection systems using IEC 61850 standard

Microgrids have been proposed in an effort to handle the impact of distributed generators (DGs) and make conventional grids suitable for large scale deployments of DGs. However, the introduction of microgrids brings some challenges such as the protection of a microgrid and its entities. Due to the existence of generators at all levels of the distribution system, the fault currents vary substantially. Furthermore, grid connected and islanded modes introduce two different sets of fault currents. Consequently, the traditional fixed current relay protection schemes need to be improved. Several adaptive protection schemes have been developed in the literature. These protection approaches, despite addressing protection challenges, require extensive communication and control. In order to achieve a standard way of modeling this communication infrastructure power engineers have been using IEC 61850 and its extensions, such as IEC 61850-7-420. As a result, it has been found out that several concepts such as interoperability and interchangeability have to be considered in networks designed with IEC communication standards. This paper studies the modeling structure in IEC 61850 standard and some challenges associated with it. Then, IEC 61850 based modeling of a novel adaptive microgrid protection scheme is given in detail. The challenges and potential pitfalls related to virtualization of power system in IEC modeling world are analyzed. Finally, some insights are shared on the required steps that shall be taken to unleash capabilities of microgrids in current smart network era.