A Dynamic Control Approach for AC Micro-Grids Including Non-Inverter and Inverter Based Energy Resources

Microgrids harness the benefits of non-inverter and inverter-based Distributed Energy Resources (DER) in grid-connected and island environments. Adoption of them with the various types of electric loads in modern MGs has led to stability and power quality issues. In this paper, a two-level control approach is proposed to overcome these problems. A state-space dynamic model is performed for Micro-Grids, for this goal, the state-space equations for generation, network, and load components are separately developed in a local DQ reference frame, and after linearization around the set point, then combining them into a common DQ reference frame. In the first level, the control of inverter-based DERs and some types of loads with fast response are activated, and in the second level, the control of synchronous diesel generator resources with slower response is used. In order to validate and evaluate the effectiveness of the proposed control approach, numerical studies have been established on a standard test MG under normal and symmetrical three-phase fault conditions. Finally, the simulation results are summarized.