## 3 Smart Grid  
The smart grid is proposed to solve the issues of electricity grid (e.g., low reliability, high outages, high greenhouse gas and carbon emission, economics, safety, and energy security) [34]. One of the definitions for the smart grid is that the smart grid is a communication network on top of the electricity grid to gather and analyze data from different components of a power grid to predict power supply and demand which can be used for power management [8]. For comprehensive details and information about characteristics and benefits of the SG, comparison between a power grid and SG, and general requirements of a communication network in a SG, the readers can see chapter 3 of [35]. In a proposed model for the smart grid by the national institute of standards and technology, the smart grid has 7 domains and roles of these domains are defined so that required information can be exchanged and necessary decisions can be made [7]. Some of the required functionalities to deploy the smart grid are as follows [10]:  
1. Communication networks: Public, private, wired, and wireless communication networks that can be used as the communication infrastructure for smart grid [36]. 2. Cybersecurity: Determining measures to guarantee availability, integrity, and confidentiality of the communication and control systems which are required to manage, operate, and protect smart grid infrastructures [37]. 3. Distributed energy resources: Using different kinds of generation (e.g., renewable energies) and/or storage systems (batteries, plug-in electric cars with bi-directional chargers) that are connected to distributed systems [38]. 4. Distribution grid management: Trying to maximize the performance of components in distribution systems such as feeders and transformers and integrate them with transmission systems,increase reliability, increase the distribution system efficiency, and improve management of distributed renewable energy sources [39]. 5. Electric transportation: Integrating plug-in electric vehicles in a large-scale [40]. 6. Energy efficiency: Providing mechanisms for different kinds of customers to modify their energy usage during peak hours and optimizing the balance between power supply and demand [41]. 7. Energy storage: Using direct or indirect energy storage technologies such as pumped hydroelectric storage technology [42]. 8. Wide-area monitoring: Monitoring of power system components over a large geographic area to optimize their performance and preventing problems before they happen [43]. 9. Advanced metering infrastructure (AMI): AMI as one of the key components of SG creates a bidirectional communication network between smart meters (SMs) and utility system to collect, send, and analyze consumer energy consumption data [44; 45; 46]. AMI is an improved and modified version of automatic meter reading. In an automatic meter reading, data from different types of meters were collected automatically and were sent to a central system through a one-way communication network for future analysis and billing purpose. Since the automatic meter reading couldn't provide bidirectional communications, AMI was introduced. AMI has many tasks such as the ability to self-heal, adaptive power pricing, demand-side management, energy efficiency enhancement, improving the reliability of SG, interoperability with other systems, monitoring and control of power quality, outage management, providing communications between central system and SMs, saving energy, and updating the software of SMs [44]. AMI components are a central system, two-way communication networks, data concentrators, and smart meters. SMs are installed at customers' locations or other positions in smart grid to measure consumption data and send them to the central system via communication networks for billing, informing consumers for their consumptions, etc. In direct load control, SMs can give power consumption overviews and schedule times for turning on and off devices to shift the load in SG.