# Communication Technologies for Smart Grid: A Comprehensive Survey
## 2 Overview of Smart Grid
### Smart Grid Infrastructure
#### 2.1.1 Smart Grid Domains  
SGs are complex systems, interfacing the power grid with communication technologies by deploying a large number of interconnected components for measuring, controlling, and monitoring. SGs consists of different domains responsible for different parts of the SG infrastructure [20; 21]. To structure the different areas of a SG environment, The National Institute of Standards and Technology (NIST) [12] proposed seven domains of SG with electrical interfaces and communication interfaces in its conceptual model for SG information networks in 2009. The conceptual model has later been updated with more communications and electrical interfaces to better reflect the increase in distributed energy sources and automation of distribution systems [14; 22]. Table 2 shows the definition of these domains. The domains are; Customer, Distribution, Transmission, and Generation including DER, Markets, Operations, and Service Providers. The first four are related to transmission of electricity on the power grid. \begin{table}
\begin{tabular}{l l l} \hline  & **Traditional Grid** & **Smart Grid** \\ \hline Information flow & One-way communication & Two-way communication \\ Power generation & Centralized power generation & Distributed power generation \\ Grid topology & Radial & Network \\ Integration of distributed & Low degree & High degree \\ energy sources & Low degree & High degree \\ Sensors & Manual monitoring & Self-monitoring \\ Outage recovery & Manual restoration & Self-reconfiguration \\ Testing & Manual & Remote \\ Ability to control & Limited & Pervasive \\ Efficiency & Low & High \\ \hline \end{tabular}
\end{table} 
Table 1: Comparison of traditional power grid and smart power grid [3]. * **Market Domain:** Grid assets and services are bought and sold within the domain. The market domain handles actors such as market management, wholesale, trading, and retailing. The market domain communicates with all other domains in the SG. Communication between market domain and the energy supplying domains are critical, due to the need for efficient matching of production and consumption [14]. * **Operations Domain:** The domain is responsible for operations of the grid. Including monitoring, control, fault detection and management, grid maintenance, and customer support. These are typically the responsibilities of the utilities today. With SGs more of these responsibilities will move over to service providers [12; 13]. * **Service Provider Domain:** Actors in the domain support business processes of power producers, distributors, and customers. Ranging from utility services such as billing to management of energy use and generation. The communication interface is shared with the Generation, Distribution, Markets, Operations, and Customer. Communication with the operations domain is critical to ensure system control and situational awareness [12; 13]. * **Generation Domain:** The power generation domain is responsible for power generation in bulk or non-bulk quantities. This can be from, for example, fossil fuels, water, wind, or solar. For the case of Norway, this is typically hydropower, these are grid-connected power generation stations. Power generation include distributed energy resources. SGs allow for end-users to also operate as producer of electrical energy, for premise use, storage, or for resale. [13; 24]. With SGs, power generation is no longer limited to large fossil or hydroelectric power facilities feeding the transmission grid. SGs allow for smaller scale distribution-grid-connected power generation. This can be wind power parks, solar parks, photovoltaic panels mounted on end-users roof-tops, or electric vehicles feeding the grid [13; 25]. Communication with the transmission and distribution domains are important to maintain energy delivery to customers [12; 13]. * **Transmission Domain:** The power transmission domain is responsible for the transfer of power from the power generation source to the distribution system.