Droop-Controlled Inverters as Educational Control Design Project

Electric grids are seeing increasing adoption of renewables interfaced with power electronics. As the share of renewable generation increases, the inverters are expected to operate in grid-forming mode to replace large conventional synchronous generation. Further, in geographical islands and isolated/rural areas, inverters interfacing renewable generators and storage are used to form the grids and share the loads. Given the expected presence of grid-forming inverters in future power systems, there is an urgent need to revise education curricula about the stability issues arising from these interconnected inverters. Existing training is overly reliant on numerical simulation or on expensive tools such as real-time simulators. In this paper, we present a laboratory hands-on project dealing with small-signal stability in droop-controlled inverters. It entails simulation and hands-on experimentation for which an inexpensive microgrid set up was developed in-house at the National University of Singapore. The design project can be integrated into power engineering courses offered to senior and postgraduate students.