Control of inverter-based micro-grids

The predicted growth of small-scale non-50/60 Hz power sources and the desire to be able to support loads independently of the public electricity grid requires the development inverter-based micro-grids. Power electronic interfaces have very different characteristics to conventional electrical machines and, therefore, different operation, control and protection schemes are required. Attention also needs to be given to the dominance of single-phase harmonically distorting loads in some networks and control schemes put in place that maintain voltage quality. A control scheme that exploits the controllability of inverters to operate a micro-grid and provide good power quality is examined and compared with both traditional power systems and with control of dc/dc power converters. The limitations of communication and control bandwidth are discussed. Experimental results are used to illustrate the performance that can be achieved with various combinations of linear and non-linear, three-phase and single-phase loads.