Distributed Generation Micro-Grid Operation: Control and Protection

Performing intentional islanding or micro-grid operation of Distributed Generators (DGs) can improve the power system service quality and increase the power system reliability. Despite the benefits micro-grid operation can bring to the power system, many challenges and technical issues constraint its operation. This paper addresses two main challenges associated with the operation of micro-grids: voltage/frequency control and protection. The main aim of this paper is three-fold. First, a control strategy for inverter based DGs is proposed to control both voltage and frequency during islanded operation. Secondly, a protection scheme is proposed to protect both the lines and DGs during islanded operation. Lastly, both the control scheme and the protection scheme are coordinated to avoid nuisance tripping of the DGs and non-critical loads. The study is performed using a digital computer simulation approach PSCAD/EMTDC.