## 5 Various Concepts Aligned with the Smart Grid  
The topic of smart grid has many dimensions and can be considered as an umbrella for many concepts. Some of the widely popular concepts include as follows:  
Grid resiliency is the first and foremost concern of a smart grid, which have a greater scope for adaptability than conventional grids due to their adaptability, self-monitoring and self-healing capability. Resiliency is defined as the retraction to the previous stable condition after the grid has been exposed to a disturbance. It can either indicate its adaptation to the change, or its recovery from the instability. Resilient technologies are mostly implemented in the critical infrastructures. Smart grid are comparatively more resilient than concurrent grid groundwork, possessing more potentiality in dealing with various contingencies due to bad weather or poor engineering. In order to augment the smart grid robustness against catastrophes, proper resilience planning, along with in-depth analysis of response and recovery schemes with respect to the cyber-physical system and existing infrastructures are to be studied. Various forecasting technologies such as Machine Learning and Deep Learning tools are being built to analyze the system behavior and predict anomaly to sustainably improve the grid resilience. Figure 8: ICT infrastructure of SG. It consists of intelligent layer and electricity delivery layer. This layer-based ICT infrastructure is capable of avoiding illegal access and protecting against cyber-attack. Microgrids are seen as the key to integrating renewable energy sources into the smart grid. A microgrid can be defined as a small-scale grid, which has its own generating supplies, loads, and storage units, which are connected together. Usually, it can operate independently from the main grid. It should have its own control and energy management system. If the main grid is available, the microgrid may also be connected to the grid, but in case of disconnection, it should be able to supply its own loads. A microgrid usually uses renewable energy sources; however, other conventional generating units may also be used. Normally, it is connected to the main power grid through a single point of common coupling [68]. The microgrid can function in an islanded mode when the common coupling is disconnected. The islanding operation is expected to provide a high reliability [69; 70]. The Global Smart Grid Federation (GSGF) was formed in 2010 to accelerate the development of smart grid technologies. The GSGF has also reported a number of projects related to microgrids [71]. The microgrid system is being transformed by exploiting new digital technology. Some examples are smart metering, smart sensors, automation, digital network technologies, Internet of things (IoT) and power-consuming connected devices [72]. The Virtual Power Plant (VPP) is a power plant, which is formed by combining a group of distributed energy sources such as wind, PV, fuel, energy storage, grid, etc. It also consists of different types of load such as civil load, industrial load, interruptible load, etc. Battery swap station, where EV's can charge and also supply to the grid is also available here. The VPP should be made in a way to have similar characteristics of conventional generating units with a total capacity comparable to typical conventional power plants. Its energy management system should be developed to make the VPP dispatchable [2]. The basic elements of virtual power plant are shown in Figure 9 [73]. Demand response is defined as reduction in the load initiated by the consumer, in response to the price signals. The system should be designed in a way to shift the load to the time when the renewable energy generation is at its high level. Non-emergency demand response to reduce the peak load can provide substantial benefits in reducing the need for additional generators [74]. To implement demand response strategies, some control schemes and metering techniques should be developed.