etc.There are two manners of operation of a micro-grid namely, connected to grid manner, and the other one is island manner. In GC mode a microgrid is in link with the conventional power grid. It is capable of participating in the energy market as a seller or buyer that can exchange energy with the utility. However, in the islanded manner, micro-grid functions as an autonomous body, as disconnected from the utility network. The island condition occurs due to several reasons such as geographical position on earth, brownout and economic issues.
Generally, the microgrids face a problem of supplying demand properly due to insufficient energy generation. This problem is because of the irregularity of loads and the RE sources [4]. So, a management system is required to deal with the problem. This management system is called a management system of energy (MSE).
The management system of energy (MSE) is the collection of different control approaches and different active, ongoing exercises along with hardware and software to mitigate the energy management objectives problems. It is a multiple functionary system. It is a system which distributes the generated power optimally and economically to the load with proper voltage regulation and frequency regulation of the micro-grid. So, we can get a smooth changeover between connected to grid manner and isolated manner of micro-grid systems, according to micro-grid components and real-time load conditions of operation. This system can be used to get high-quality power, sustainability, reliability and environmentally friendly power source.
Due to this, researchers started focusing extensively on MSE strategies for various micro-grids ranging from small home (small scale) to cities or towns (large scale) as shown in the different scales of MG of Figure 1.4.
Exploration has started on a study of the practicability of the parts of micro-grid, and it is modeled by scheduling the DGs, and forecasting the data of environmental conditions such as irradiance of sunray, speed of wind flow and water speed, forecast of energy demand and on availability optimization algorithms in the intention of cost-effective benefits with minimum impact on the atmosphere. Figure 1.5 shows the central micro-grid arrangement and components related to the energy management system. It shows that the research is mainly focused on the resolution of different problems regarding the micro-grid by means of an energy management system.
Figure 1.4 Various ranges of MG.
Figure 1.5 Components of micro-grid.
This is a review of the different features of micro-grid and management of energy that are presented in various current topics, starting from various units of MG, synchronization of components to the recent optimization methodology with system limitations and objective functions for MSE.
Afterwards, the different configuration and components of micro-grid are deployed in Section 1.2. Here the different structures used in an energy management system with various distributed energy sources, various storage systems and different type of load or the consumer behavior are illustrated. Followed by Section 1.3, it depicts the MG–MSE and different modes of operation. Further, Section 1.4 discusses about the recent techniques and algorithms used for optimization in energy management systems. Finally, Section 1.5 concludes the different sections and further deliberates the strategy for further research in this area.
1.2 Generation and Storage System in MicroGrid
1.2.1 Distributed Generation of Electrical Power
In recent years, a great number of researchers are discussing the issues in micro-grids. Nowadays, the verities of micro-grid structures have been presented in the literature. In micro-grid the different distributed generations are utilized because of its geographical characteristic, economic benefits, environmental condition and impact on the surrounding. In Ref. [5], there is a discussion on predictive MSE with its control strategies and communication of micro-grid to the independent utility grid. A 1.5 MW wind energy associated with the battery as a storage system is analyzed. In Ref. [6] a hybrid hydrokinetic system HKT battery is used in GC mode. The surplus power of HKT is utilized for charging a battery or trade to the grid. Whether the power will be sold to the main grid or not is determined by the charge condition of the battery and the principle of the utility grid network. The power requirement of the load is provided by the HKT. The excess power is utilized to charge the storage body. Then also, if there is an excess quantity of power, that can return back to the utility grid network. However, the utility grid supplies the load directly when the distributed generation system and the battery can’t entirely meet the load demand.
The universally used energy storage system is the battery. The battery system also has some limitations, as some charging and discharging current issues and unreliability according to the lifespan of the battery. So, techno-electronic indexes of micro-grid-based hybrid renewable energy resources are significantly increased by applying the distributed system of the generation with the storage system of energy [7]. Ref. [8] is a study of hybrid solar power as PV and diesel power in a distributed system supplying a load of a rural school in Ethiopia. The paper has compared the hybrid PV/Diesel distributed system with the storage system to the distributed generation system without storage as the net instantaneous rate of energy. Here a software named Homer is applied for analysis. The result was concluded that the hybrid distributed generation system with storage is having technical and economic advantages than that without storage. In Ref. [9] the authors proposed that the energy management system for hybrid micro-grid consist of photovoltaic and wind power as renewable energy sources (RES) and fuel cell (Hydrogen cell), ultracapacitor or battery as storage system of energy (SSE).
1.2.2 Incorporation of Electric Car in Micro-Grid as a Device for Backup
Nowadays the incorporation of an electric vehicle with micro-grid is viral because of its effect of low emission, inexpensive charging and decreased usage of conventional fuels. The electric car with MG can function in car-to-grid (C2G) mode or grid-to-car (G2C) mode. In Ref. [10] planned power management is proposed in the MG, including storage systems categorized into two types: regenerative fuel cell (RFC) and electric car (EV). That paper approaches with multi-goal optimization to minimize operational cost, line losses and maximise the value of energy stored in terms of RFC and EC. There are two functioning schemes planned for EC working in C2G mode to decrease the net running cost of the system. The combination of particle swarm skim of optimization as well as front and back sweep algorithm is used to solve complication, non-linear action and multidimensional property of the objective function. In Ref. [11] a large-scale electric vehicle charging station is proposed by the author, in which the required power is supplied by solar and wind power. Here both the PV and wind work with a unified MPPT technique. In Ref. [12] the author incorporated the plug-in charger of the electric vehicle in the distribution grid in both directions by using various converters. The bidirectional converters are coupled to the capacitor at the link with DC. The grid voltage may be regulated in the C2G configuration using the capacitor at the link with DC, which provides compensation for reactive power, which avoids the risk of voltage sag in the main. The mixed charging electrical car battery is used for peak load shaving and load levelling. Ref. [13] illustrates a real application of electric vehicle charging
