A Thorough Overview of Hierarchical Structure of Microgrid Systems

Today, the microgrid system is attracting the attention of many researchers because it brings plenty of benefits to the conventional power system such as enhancing the reliability of the system, reducing the transmission cost, and diversifying energy sources. In fact, a microgrid system is a small-scale of a distribution system including three main elements: (i) distributed resources, (ii) storage system, and (iii) measurement system. The main purpose of a microgrid system is ensuring the continuous supply energy in a small or isolated area, thus it has two main operation modes: (i) independent and (ii) connected to the main power grid. One of the main challenges of the operation of a microgrid system is the smooth and optimal shift between these two operation modes in cases of any contingencies from both sides. Thus, the operation of a microgrid system requires designing various advanced control methods for this activity, in which the hierarchical control technique is widely using in the real application. Therefore, an overview of this method is very necessary for the research community since there are many works have done in recent years. In this paper, the authors present the hierarchical control technique and focus on investigating various methods of the primary control of this technique because this level is responsible for the independent operation mode of a microgrid system known as the main advantage of a microgrid system.