3. Electricity
• Electricity is the universal and standard way to transform energy and get it
transported everywhere and to everyone.
• To carry the energy from the places where it is most conveniently produced
to the places where it is needed requires
• a network of interconnected elements (e.g., generation systems, power lines,
substations) spread over necessarily large geographical areas and integrated to work
as a whole.
• This network is referred to as
• the grid (aka, the power grid, the electric power system, or the electricity supply
system)
• Hence, the grid is required for transmission and distribution of electric
power.
• The use of electric batteries and other storage apparatus for this purpose is not
feasible currently.
4. Electricity
• Electricity must be generated and transmitted to be consumed,
• Hence, a real-time dynamic balance between generation and demand is
necessary.
• Electric power pathways cannot be chosen freely across the network
• Physics (Kirchhoff’s laws) determines where electricity flows,
• depending on the impedances in the power lines and the rest of the grid elements.
• Thus, the current distribution cannot easily be forced to take any given route,
and alternative routes in the grid are highly interdependent.
5. Electricity
• From an operational perspective,
• deviations from normal operation may cause the instantaneous
reconfiguration of power flows
• that may have substantial effects on facilities (e.g., substations, power lines, etc.) in the
grid and propagate almost instantaneously across the entire system.
• Electric power consumption is sensitive to the technical properties of
the electricity supply
• devices may malfunction or simply cease to operate unless the voltage wave
is stable over time within certain parameters including shape (sinusoidal),
frequency (cycles per second), and value (voltage).
• Hence, the system must have mechanisms to react (detect and respond)
instantly to unexpected situations and avoid degradations in service quality.
6. The Grid - Definition and General Overview
• Defined by International Electrotechnical Commission (IEC) as,
• All installations and plant provided for the purpose of generating, transmitting
and distributing electricity.
• The power grid is a hierarchical infrastructure:
• Consists of a set of interconnected elements for providing electricity service
to its end-customers.
8. The Grid - Definition and General Overview
• Traditional Conception:
• Generation involves big power plants (thermal, nuclear, and hydro) which
transform energy into electricity
• Transmission steps generated voltage levels up, to transport it over long
distances with the minimum energy losses
• Distribution drives electric energy to all the disperse locations where it is
consumed
• Consumption Points are the locations where energy is ultimately delivered
• May be commercial and industrial or residential customers
9. The Grid – A Technical Perspective
• Generation
• Power plants convert the potential energy of existing resources such as
renewable energies (water, wind, solar, etc.) and fuel (coal, oil, natural gas,
enriched uranium, etc.) into electric energy.
• Traditional centralized power plants generate AC power from generators.
• Voltage is usually no more than 6–40 kV
• The voltage in the power generation stage is stepped up by a transformer,
normally to a much higher voltage.
• At that high voltage, the generator connects to the grid in a substation and
electricity starts its journey toward the Consumption Points.
10. The Grid – A Technical Perspective
• Distributed Generation (DG) and/or Distributed Energy Resources
(DER)
• small (0 to 5 MW), modular power generation technologies dispersed
throughout a utility’s distribution system
• power generation closer to end-customers
• In contrast, centralized big power plants in the traditional grid were placed
farther away from consumers.
• DERs may contain storage systems
• solar photovoltaic panels, small wind turbines, natural-gas-fired fuel cells,
combined heat and power systems, biomass combustion or cofiring,
municipal solid waste incineration, and even Electric Vehicles (EV) may be
included
11. The Grid – A Technical Perspective
• Transmission
• Power from Generation is connected to the Transmission part of the grid, with
transmission lines that carry electric power at various HV levels.
• The Transmission grid is the backbone of the electric power system covering
long distances to connect large and geographically scattered generation
plants to demand hubs where Distribution system starts.
• It is a networked, meshed topology connecting generation plants and
substations together into a grid that usually is defined at 100 kV or more.
• The electricity flows over HV transmission lines to a series of substations
where the voltage is stepped down by transformers to levels appropriate for
Distribution systems.
12. The Grid – A Technical Perspective
• Distribution
• Distribution segment is widely recognized as the most challenging part of the
grid due to its ubiquity.
• Distribution networks are more subject to failures than Transmission
networks.
• The Distribution network consists of power lines connecting primary
substations (PSs) and secondary substations (SSs)
• the former in charge of transforming voltage from HV to MV and
• the latter from MV to LV.
• The parts of the Distribution network with the higher complexity are the MV
and LV grids.
13. The Grid – A Technical Perspective
• MV grid topologies can be classified in three groups, although their
operation is radial:
• Radial topology
• Radial lines are used to connect PSs with SSs, and the SSs among them.
• These MV lines (often named “feeders”) can be used exclusively for one SS or can reach
several of them.
• Radial topologies show a tree-shaped configuration when they grow in complexity.
• Ring topology
• A ring topology is an improved evolution of the radial topology, connecting SSs to other MV
lines to create redundancy, and from there to a PS to close the ring.
• This topology is fault-tolerant and overcomes the weakness of radial topology when one
element of the MV line gets disconnected.
• Networked topology
• Networked topology consists of PSs and SSs connected through multiple MV lines to provide a
variety of distribution alternatives.
• In the event of failure, many alternative solutions may be found to reroute electricity.
14. Medium voltage common topologies
Distribution networks are run by
Distribution Network Operators (DNOs).
They are also referred to as DSOs (Distribution System
Operators) in their evolution
15. The Grid – A Technical Perspective
• Consumption Points
• Customers’ concurrent energy consumption patterns drive the needs of the
electric power system.
• Thus, the Consumption Points are extremely relevant from a technical perspective.
• Traditionally, electric grids have been oversized due to the difficulties to
measure, understand, and modify these consumption patterns.
• However, behind a Consumption Point, customers can be found, and as stakeholders of
the system, their contribution to it needs to be considered.
• Customers need to receive a reliable and agreed-quality electricity service, as
they connect their loads to the grid and must be guaranteed that the supply
will be available
17. The Grid – A Regulatory Perspective
• Regulation
• series of principles or rules to control individual and collective human
behavior
• Governments regulate industries to improve their performance, be it
to guarantee that no agent
• goes against the common interests, to steer an industry’s performance
toward improving “general welfare,” to protect consumers, and to protect
investors from the State.
• Regulation is implemented through the design of rules, the
structuring of the industry, and the supervision of agents’ behavior
and industry performance
18. The Grid – A Regulatory Perspective
• The core underlying criterion supporting the regulation of electric power
systems is
• the maximization of social and environmental welfare in the production and
consumption of electric power.
• This involves several fundamental concerns.
• First, efforts should be devoted to minimizing the costs incurred in providing the
service (both investment and recurring costs).
• Second, the quality of supply must also be satisfactory (including reliability – security
in short-term operation, and adequacy for long-term evolution, and “product”
quality factors).
• Third, sustainable development, defined as the one meeting the needs of today
without compromising those of the future, is needed.
• All these concerns may be contradictory and trade-offs should be established.
19. Regulatory Models
• Regulatory models for electric power systems are different in every
country, although they often deal with two dimensions that classically
determine how the model is implemented
• Which activities, of all the activities needed in the electric power system, need to be
separated from the others? These activities are to be unbundled.
• Which activities can be performed on a competitive basis? These activities can be
deregulated or regulated in a different way.
• In one extreme, if none of the activities are unbundled or deregulated, we
have
• the vertically integrated monopoly.
• In the other extreme, the activities (including Generation, supply
(Transmission and Distribution) – and energy trading) are said to be
• vertically disaggregated and are performed competitively.
20. Regulatory Models
• In a vertically integrated monopoly
• electric utilities are awarded a territory to supply electricity to.
• Thus, the utilities own and operate all the generation and network assets in
those territories, and
• they plan and implement the expansion of production and network capacity
• under the guidelines and authorization of the regulatory authority,
• within a remuneration for the utility based on
• the incurred cost of service (including a rate of return for invested capital),
• an agreed price for end-users within a satisfactory reliability level,
• and with the allowed environmental impact.
21. Regulatory Models
• In an organization of the electric power systems where activities are
vertically disaggregated
• The competition is introduced through wholesale electricity markets, which are open
to
• all generators (incumbents and new entrants) and
• to all consumer entities.
• In a wholesale electricity market,
• the electricity market price is fixed by competing forces and serves as a reference for
medium-and long-term contracts of different types.
• The agents trading on such markets are
• generators,
• different categories of supplier companies representing consumer interests, or acting as
intermediaries.
• In this context, consumers are clients free to choose the supplier based on the available
commercial propositions.
22. Regulatory Models
• The beginning of the power sector (nineteenth and the early
twentieth century) was driven by private initiative and competition
• Soon, in most countries, the situation was superseded by strong
governmental intervention in the form of public ownership or utilities
as regulated monopolies.
• States in most countries assumed a heavy planning and intervention,
being the sole regulator.
• The situation has remained like this until the 1990s, when unbundling
and regulation of network activities has happened, to separate them
from the business part that can be performed in a competitive way.
23. Regulatory Models
• Nevertheless, even in highly deregulated environments, Transmission and
Distribution grids are subject to the existence of business-relevant regulation.
• These networks, part of the whole system, are considered natural monopolies, as
they do not have characteristics that allow the provision of their services under a
market-based regulatory regime.
• Consequently, these networks have enormous market power, and this is the reason why
these grid-associated activities must at least be wholly independent of other competitive
businesses within the electric power system (i.e., generation and retailing – offering
electricity to end-users).
• Thus, their remuneration must be regulated, and they must be obliged to provide
open and nondiscriminatory access to their facilities, allowing the rest of the
competitive framework to happen.
• This highly regulated nature of Transmission and Distribution activity is extremely
important, as networks are one of the most important elements in Smart Grids.
24. Smart Grid Definitions
• The Smart Grid European Technology Platform
• A smart grid is an electricity network that can intelligently integrate the actions of all
users connected to it (generators, consumers, and those that do both) to efficiently
deliver sustainable, economic, and secure electricity supply.
• The U.S. Department of Energy
• A smart grid uses digital technology to modernize the electric system – from large
generation, through the delivery systems to electricity consumption – and is defined
by seven enabling performance-based functionalities
• Customer participation.
• Integration of all generation and storage options.
• New markets and operations.
• Power quality for the twenty-first century.
• Asset optimization and operational efficiency.
• Self-healing from disturbances.
• Resiliency against attacks and disasters.
25. Smart Grid Definitions
• The International Energy Agency (IEA)
• A smart grid is an electricity network that uses digital and other advanced
technologies to monitor and manage the transport of electricity from all
generation sources to meet the varying electricity demands of end-users.
Smart grids coordinate the needs and capabilities of all generators, grid
operators, end-users, and electricity market stakeholders to operate all parts
of the system as efficiently as possible, minimizing costs and environmental
impacts while maximizing system reliability, resilience, and stability
26. Smart Grid Definitions
• The World Economic Forum
• Key characteristics of the Smart Grid
• Self-healing and resilient.
• Integrating advanced and low-carbon technologies.
• Asset optimization and operational efficiency.
• Inclusion.
• Heightened power quality.
• Market empowerment.
27. Smart Grid Characteristics
• Resilient electric power system.
• Grid infrastructure modernization.
• Power quality assurance.
• Efficiency in the power delivery system and in the customers’ consumption.
• Reduced environmental impact of electricity production and delivery.
• Combination of bulk power generation with DG resources.
• Storage as technology increasingly available in the grid edge.
• Automation of operational processes.
• Increased number of sensors and controls in the electricity system.
• Monitoring and control of critical and non-critical components of the power
system.
28. Challenges of the Smart Grid in Connection
with Telecommunications
• There are some Smart Grid challenges tightly connected to the use of
telecommunications technologies and services.
• They can be grouped in two broad categories
• Customer Engagement
• Grid Control.
29. Customer Engagement Challenges
• The Consumption Point is now transformed into a customer, with
changing needs and capabilities, in contrast to its view as a plain
electricity service subscriber.
• It is important not only that, as a customer, it demands a quality
service but also that the customer has a potential to contribute to the
electric power system in various forms.
30. Customers as Smart Electricity Consumers
• The customer is the entity driving the consumption patterns and
electricity demands that, when aggregated across all the different
types of customers (residential, industrial, etc.), define the power
system load curve
31. Customers as Smart Electricity Consumers
• The major concern of electric power system operators, (apart from the
hourly consumption prediction to manage generation sources in real time),
• is the general reduction of the curve peaks,
• and the possibility to control the load (consumption) at the moments where the
system may not be prepared to cope with it.
• If the consumption pattern can be influenced, the total electricity demand
can be flattened, while keeping total energy consumed the same.
• This effect implies that the system does not need to be dimensioned to cope with
the worst-case condition of electricity demand.
• On the other hand, the system operator needs to have tools available to control the
loads present in the network (i.e., to be capable of reducing the number of them
connected or, to curtail their consumption) in a near-real-time manner.
• Demand Side Management (DSM)
32. Customers as Energy Generators
• Customers have now a set of technologies, i.e. Distributed Energy
Resources (DER) that allow them to participate as agents having the
possibility of producing part of the energy they need, and even help
the grid, making any excess of generation available for the system.
• There are multiple DER elements,
• including Distributed Generation (DG) but also Energy Storage (ES),
• Electric Vehicles (EVs), that play different roles for the system
• positive, as “batteries on wheels”
• challenging, as “moving loads”)
• further than their direct environmental impact (reduction in fossil energy sources
consumption).
• Renewable Energy Sources (Wind, Solar, etc.)
33. Grid Control Challenges - Transmission
• Within the Transmission segment,
• challenges are those inherent to its role in the system.
• The need to keep energy loss at a minimum justifies the need to
understand and control the different power line parameters involved in
ampacity (i.e., maximum value of electric current – Amperes) calculations.
• Grid stability is another concept of great importance, as the connection of
bulk-generation at different parts of the network can cause instability if
the voltage phase difference between the power signals is too different at
the two ends of the line.
• Last but not least, harmonics of the fundamental frequency (50 or 60 Hz)
have to be controlled, as they would be propagated along the grid,
impacting overall quality of the electricity wave.
34. Grid Control Challenges - Transmission
• There are other needs related to the physical aspects of the cables,
• Useful life of infrastructure must be extended to ensure its availability over a
long period.
• There is the need to easily detect the origin of faults in the power lines and be
able to identify and communicate its exact location.
35. Grid Control Challenges - Distribution
• Distribution grid challenges are the ones that have been driving the
evolution of the Smart Grid concept in the network control side.
• The paradigm of a static unidirectional network delivering electricity
from the core to the edge has changed into an entangled mix of new
technologies and assets, with varied properties, that need to be
organized.
• The new idea of a “platform”, rather than a “grid” that can serve the
different Distribution grid stakeholders, has become popular due to
its use in some major initiatives.
36. Grid Control Challenges - Distribution
• Automation tries to drive the grid toward becoming a self-healing
entity.
• Automation in utilities consists of
• Substation Automation (SA) and
• Distribution Automation (DA).
• Automation process started at substation level, mainly PSs (hence
SA), and moved out toward the edge (hence DA), increasing its
ambition to reach every corner of the grid with that kind of automatic
signals driving electricity through the most appropriate routes
37. Grid Control Challenges - Distribution
• Distributed Energy Resources alter the traditional equilibrium of
things in the Distribution grid.
• E.g. Distributed Generation and Electric Vehicles come with some caveats that
change the landscape of traditional grid operation.
• On the more general side, operational procedures need to be modified as they can no
longer assume that energy flow is not unidirectional.
• On the other, a greater visibility and control of the elements of the grid, including those
of the new technologies close or in the Consumption Points, to enable the operational
procedures.
