## 2 Operation and Control
### Communications and Automation
#### 2.2.4 Standards and Communications Protocols  
One of the fundamental pillars that support the intelligence of a SG resides in the capacity of effective management of the information coming from the different equipment and systems that constitute it. For there to be an efficient exchange of information, it is necessary to define communication standards that allow the use of a common language.  
The issue of standardization is fundamental, both for groups in Europe and those in the US. The SG has one of its main focuses in the standardization. A key element is the standardization in the electrical network. Already in 1997, [PERSON] [37] considered essential communications standardized architecture. Collaboration between institutions is necessary to address efficient standardization, as proposed by [PERSON] et al. [38]. Standardization is complicated, and we must consider that there are many existing standards, [PERSON] et al. [39] presented and analyzed 17 standards (wire and wireless). The incompatibility between protocols and architectures has been the consequence of the emergence of efforts by uncoordinated groups, as presented by [PERSON] et al. [40].  
It is essential to define standards and communications protocols in SGs. Some works focus on power line communications (PLCd), SG can have a communications solution based on narrow band power line communications (NB-PLC), with an architecture based on IEEE 21451, as presented by [PERSON] et al. [41] and [PERSON] et al. [42]. This solution enables interoperability, both for intelligent measurement and for protection, control, automation and operation and management.  
The protocols must also be updated or improved. In this sense, a new protocol called integrated authentication and confidentiality (IAC) is presented by [PERSON] et al. [43]. It is a protocol that guarantees the confidentiality and integrity of the data.  
The standards and protocols based on PLC should be reviewed, as [PERSON] et al. [44]. Perhaps, the most demanding issue for PLC is to integrate it with internet protocol (IP) or its problems with real time.  
[PERSON] et al. [45] present an overview of some of the candidate solutions and proposes a mesh-radio-based solution, an enhanced version of the routing protocol for LLN (RPL) protocol.  
Small scale data exchange can be addressed through Distributed Network Protocol 3.0 over TCP/IP (DNP3 over TCP/IP), as shown in [PERSON] et al. [46]. Another aspect of interest, as shown by [PERSON] and [PERSON] [47], is the use of multicast communications and their authentication within the SG.  
New performance metrics are needed, in this sense, [PERSON] et al. [48] present a new metric called accumulated bandwidth distance product (ABDP), which reports on the total of communication resources used in the SG.  
Many of the standards presented in the SG (for example, IEC 61850-5) focus on the electrical substation, and the rest of the areas of the SG are forgotten. This is included in the work of [PERSON] et al. [49], and these authors propose a new communication and control architecture focused on low voltage.  
Wireless technology presents some practical limitations in an SG scenario. Therefore, and to solve these limitations, [PERSON] et al. [50] propose a spectrum-aware and cognitive sensor networks (SCSNs), which has a high performance.  
In addition, and no less important, semantic interoperability must be addressed. It is very important the ability of computer systems to exchange data, this technique is called semantic interoperability. Semantic interoperability refers to the transfer of data and its meaning, so it is a very interesting concept. The data and its meaning are transported at the same time, so the package is independent of the information system that supports it.