ABSTRACT
Emerging new technologies like distributed generation (DG), renewable energy, energy storage, demand-side load management, adaptive and intelligent control, and power electronics are changing the way that we generate and utilize energy. These technologies enable pollutant reduction, improving the electric grid reliability, stability, and efficiency by optimizing the energy streams and allowing local energy generation and control. Today, researchers, engineers, and policy makers are seeking ways to meet the world’s growing demand for energy while addressing critical issues such as energy security, reliability, and sustainability. By smartly applying future energy production, consumption, and storage techniques, a more efficient electricity supply chain can be achieved. Evolutionary changes in the regulatory and operational climate of traditional electric utilities and the emergence of smaller generating systems have opened new opportunities for on-site power generation by electricity users. Distributed energy resources (DERs) have been receiving increasing attention over the past decades as alternatives to centralized electricity generation. However, the use of renewable energy and DG, controllable loads, and energy storage come also with significant changes in control, protection, operation, and management of medium-voltage (MV) and low-voltage (LV) networks. Many believe that microgrids (MGs) have the potential to address most of these issues while increasing DG and renewable energy sources into distribution networks. In the next few decades, MG penetration is expected to grow dramatically. The bulk of DERs will be integrated into existing electricity distribution networks through the LV and MV MGs. Despite the benefits that MG operation can bring, there are several technical challenges to be addressed. MG protection and control are considered two of the new challenges and technical issues facing future power system operation. To maximize the economic and reliability benefits of these installations, distributed systems will evolve into networked MGs. However, the realization of future LV MGs requires that all technical issues, such as power and energy balance, MG control, and power quality and protection, are solved. Some of the most crucial issues are the protection and control of LV MG during normal and island operation.
