rel="nofollow" href="#ulink_13364acb-be4c-5bcf-b774-30e8d686ef15">Table 1.1).
Underground MV lines are considered safer and statistically more reliable than overhead ones. However, installation costs are significantly higher, although their maintenance cost is lower. Underground MV cables are basically a metallic conductor surrounded by an insulation system and a protective system. Its structure consists of the following elements: the inner conductor, the conductor shield, the insulation, the insulation shield, the neutral or shield, and the jacket. Underground cables can be single‐core or three‐core (thus three phases can be grouped together) and can have additional armored layers over the insulation to provide the cable with additional mechanical protection.
Table 1.1 Typical components of overhead medium voltage conductors.
| Acronym | Name |
|---|---|
| AAC | All‐aluminum conductor |
| AAAC | All‐aluminum alloy conductor |
| ACSR | Aluminum conductor steel reinforced |
| ACAR | Aluminum conductor alloy reinforced |
| ACSS | Aluminum conductor steel supported |
| AACSR | Aluminum alloy conductor steel reinforced |
| PE | Polyethylene |
| XLPE | Cross‐linked polyethylene |
| PVC | Polyvinyl chloride |
| EPR | Ethylene propylene rubber |
LV lines carry electricity from SSs to individual LV customers. In European countries, the LV grid is usually a larger infrastructure than the MV grid ([16] reports that LV is more than 63% of the distribution grid), while in North and Central American practice utilities' LV grids are practically nonexistent.
In Europe, the output from a transformer in an SS is connected to LV panels via a switch or simply through isolating links. LV panels usually have from 4 to 12 LV‐way, three‐phase, four‐wire distribution fuse boards or circuit‐breaker boards and connect electricity to LV feeders reaching out to customers (link boxes may be found along the way, as far as an LV distribution cabinet located at the entrance of buildings and houses, with fuses that often delimit the edge of the utility grid), where electricity meters are located. In the USA, e.g., the common structure is that the distribution is effectively carried out at MV, such that the MV grid is, in fact, a three‐phase four‐wire system from which single‐phase distribution networks (phase and neutral conductors) supply numerous single‐phase transformers. These transformers are center‐tapped in their secondary windings to produce LV single‐phase three‐wire supplies that usually reach customer meters through overhead lines.
LV overhead lines may use either bare conductors (usually aluminum or copper) supported on glass/ceramic insulators or an aerial bundled cable system to be laid outdoor on poles or wall‐mounted.
LV underground lines are often found in medium‐ to large‐sized towns and cities, inside utility tunnels, laid in ducts or tubes, or directly buried in trenches. These cables show a typical structure of conductor insulated with similar materials to those discussed for MV (the metallic screen is not mandatory) and are protected by an outer PVC jacket.
1.3 A Practical Definition of the Smart Grid
Electric power systems have evolved and adapted to the growing needs of electrification both in terms of reach and of power consumption increase. From the first isolated and single‐purpose grids to the nowadays interconnected power systems, the grid has enlarged its capability and has achieved the high marks that allow the rest of the society assume the supply of energy as a commodity.
However, the adoption of changes in power systems is not as dynamic as in other domains, industries, or services. Indeed, a fast transformational pace is not a key characteristic of utilities both because technology cycles in utility industry take longer than in other industries, due to the substantial investments required by many of their infrastructures, the regulation and the endurance expected in electricity service.
All in all, the evolution of the grid over the last decades, probably since the 1980s, has been accelerated, but more strongly since the term Smart Grid was coined. However, there is no standardized or globally accepted definition of it; instead, Smart Grids are defined differently around the world, in different world regions, in different utilities, by different regulators, etc., to reflect local requirements and goals [17]. Moreover, from the initial references to the Smart Grid concept in the 1990s (when Smart Grid was not the commonly agreed expression yet – see [18–20]), the successive examples, implementations, and instances of Smart Grids have shown such a divergence as the one included in the wide scope of the ideas behind the concept.
Grid modernization [21] has been an overarching concept in the Smart Grid evolution. Although the idea collates a great variety of grid evolutionary material aspects, grid assets refresh, adoption of new grid‐edge technologies [22], new technologies in energy storage and microgrids domains, and large shares of renewable energy (i.e., DER) have emerged as principal components. All these elements aim at a change toward a more resilient, responsive, and interactive grid [21], to improve the reliability of the system (network and services).
For this purpose, these technologies must be properly integrated in the systemic, operational, and regulatory framework of utility business. Therefore, referring to utility business, legislative and regulatory actions have been taking place to allow these business changes to be introduced. Indeed, utility business, regulatory framework, and associated utility rates are in constant revision to adapt to the new reality. In this new context of energy as an enabler of our Society progress, and with the environmental concern as a major one, the role of consumers comes also into perspective. Consumers overcome their role as passive objects of the electric system and appear as active pieces of the overall service experience taking an active role in system‐wide performance (helping to shape the system requirements and operations through their active participation producing and storing energy or adapting consumption patterns). The active participation of the different stakeholders (customer being a central element) in the system will achieve higher levels of energy efficiency across the value chain.
Future power grids may not be equal to those of today. However, taking into consideration the history behind power systems, we can state that power grids will not be radically different in neither the short nor the medium term, and the changes will happen in an evolutionary way. Thus, existing grid infrastructure will play a key role, and its integration with the new grid technology is both a must and a key in the process of leveraging existing assets.
And it is here that ICTs, also commonly referred to as digital technologies [23], come into play. The advances in electronics, computation, and telecommunications gathered around the ICTs are continuously impacting different aspects of our Society.
Utility industry is a very special (neither minor, nor simple) example of adoption of ICTs. Although some in utility industry write the equation “Smart Grid = Grid + ICT,” this is an excessive simplification. While it is true that ICTs integration is one of the most prevalent ideas behind the quest for “Smart” in the Grid, there are many other components that are instrumental. What it is also true is that
