Future Electric Power System Transformations: Prospects and Challenges

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Book Chapter
Future Electric Power System
Transformations: Prospects and
Challenges
Nikolai Voropai*
Energy Systems Institute, Russia
*Corresponding Author: Nikolai Voropai, Energy Systems
Institute, Lermontov Str. 130, 664033 Irkutsk, Russia
Published March 03, 2021
This Book Chapter is a republication of an article published by
Nikolai Voropai at Energies in October 2020. (Voropai, N.
Electric Power System Transformations: A Review of Main
Prospects and Challenges. Energies 2020, 13, 5639.
https://doi.org/10.3390/en13215639)
How to cite this book chapter: Nikolai Voropai. Future Electric
Power System Transformations: Prospects and Challenges. In:
Fan Xiao, editor. Advances in Energy Research: 2nd Edition.
Hyderabad, India: Vide Leaf. 2021.
© The Author(s) 2021. This article is distributed under the terms
of the Creative Commons Attribution 4.0 International
License(http://creativecommons.org/licenses/by/4.0/), which
permits unrestricted use, distribution, and reproduction in any
medium, provided the original work is properly cited.
Funding: The Research was carried out under State Assignment
Project (no. FWEU-2021-0001) of the Fundamental Research
Program of the Russian Federation 2021-2030.
Conflicts of Interest: The author declare no conflict of interest.

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Abstract
The paper deals with the main prospects and challenges of
radical transformations of electric power systems (EPSs) with
changes in their structure and properties conditioned by wide
use of innovative energy-related technologies and
digitalization and intellectualization of system operation and
control. Structural trends of EPS development are the focus of
the analysis. Consideration is given to changes in EPS
properties driven by the use of new technologies, to the
problems of system flexibility and to its enhancement. EPS
―resiliency‖ and ―survivability‖ notions are subjected to
comparison. The main factors favoring the formation of
future EPSs to cyber- physical systems are discussed.
Objective trends of EPS control and protection system
development are under consideration.
Keywords
Electric Power Systems; Innovative Technologies;
Transformation; Trends; Structure; Properties; Flexibility;
Survivability (Resiliency); Control And Protection Systems
Introduction
In the course of their development, electric power systems
(EPSs) have continuously changed their structure and properties
under the influence of objective factors. These include, for
example, the broader use of innovative technologies for power
generation, transmission, storage, distribution and consumption.
This is followed by the rapid development of renewable
energy sources and distributed generation, the new role of
consumers in the power supply process that is driven by a new
paradigm of client-oriented power supply, the role of EPSs as a
critical infrastructure and some others [1–3].
The structure of future EPSs may be represented in an
aggregate form as a three-level super- mini-micro-system
(Figure 1 in [4]). Super systems include large power plants
(thermal, hydraulic and nuclear), large parks of wind and

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solar power plants, energy storages of large capacity and
transmission networks of high and super-high voltages,
including delivery points transmitting power to the next
level, to the level of mini-systems. Mini-systems include
power mini-sources connected to a distribution network
(thermal power mini-plants, mini-plants on the basis of gas
turbine, gas piston, steam turbine and other technologies,
mini-parks of wind and solar power plants), system power
mini-storages, as well as distribution grids themselves,
including distribution substations. In a mini-system, the unit
capacity of mini-sources and power storage is unambiguously
determined not to exceed 25 MW [5,6]. Micro-systems include
micro-turbine power plants, isolated wind mills and photo
panels, power micro-storages and internal electric networks of
households or of their clusters and public and production
facilities with a voltage of 6/0,4 or 20/0,4 kV. The unit
capacity of micro-sources and micro-storages even when taking
into account multiple estimates can be assumed not to exceed
25 kW [7,8].
Figure 1: Three-level structure of future electric power systems [4].
The motivation of this paper is based on the rapid transformation
of EPSs in the last 2–3 decades due to using innovative
technologies. Taking into account this dynamic process, we can
very quickly find ineffective and unreliable EPS operation.
From the other side, because of the infrastructural role of EPSs,
digitalization of industrial technologies for consumers and mode
in life, and moving to the electrical internet, the requirements

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of consumers for the reliability of power supply and quality of
electricity are very high.
This paper deals with qualitative estimations for the
appearance for future EPSs. These estimations do not connect
with any concrete period of concrete EPSs in any concrete
country. Some new innovative technologies can be ready
before the others or after. Taking into account these aspects,
the author does not touch upon the economical side of the
discussed problem.
In view of the above, the paper gives detailed consideration to
the trends in the EPS structure transformation and changes in
the main features of the architecture of future systems (Section
2). EPS properties depend on not only the structure of these
systems, but also technologies of production, transportation,
distribution, storage and consumption of electricity. Therefore,
the transformation of the future EPS properties under the
influence of innovative technologies and new problems of EPS
flexibility are discussed (Section 3). Possible measures for
flexibility enhancement of the future EPSs are presented
(Section 4). A tendency in growing the number and
consequences of EPS blackouts worldwide leads to the
necessity to consider the EPS resiliency problem, which
corresponds to the term ―survivability‖ (Section 5). Possible
measures for enhancing the resiliency/survivability are
suggested (Section 6). Considering the EPS
resiliency/survivability problem, it is important to analyze
cascading emergencies and EPS restoration (Section 7).
Taking into account rapid development of information–
communication sub-systems of EPSs due to information
technologies and digitalization of these systems, it is necessary
to discuss cyber-physical EPSs (Section 8). Last, but not least,
the development trends of EPS management and control
systems are discussed in this paper (Section 9).
Structural Trends in the EPS Development
Let us first consider the main trends in the EPS architecture
transformations at the level of a super system. A number of

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objective factors, both conventional and new ones, define those
tendencies. A key conventional factor is the implementation
of technical system effects occurring during joint operation of
different EPSs [9,10]. Technical effects are assumed to
include capacity, structure, frequency and operational and
environmental effects. According to the estimates given in [9],
the use of those effects in the unified power system (UPS) of
the former USSR at the end of the 1980s allowed for the
reduction of the required installed capacity of power plants by
10–12 GW. A similar effect for the West European Energy
Interconnection (UCPTE) in 1989, according to the estimates
of the European Economic Commission, was as high as 34 GW
[11].
It should be noted that proposed estimates of using the system
technical effects owing to joint operation of EPSs are, in a
sense, the maximum possible ones. The degree of their
implementation depends on the structure and mechanisms
governing the electric power markets [10,12]. System effects
are hereby considered as system services. The Association of
System Operators of the largest EPS in the world, G015 [13],
draws attention to a new understanding of the considered
system services with reference to Electric Power Research
Institute (EPRI, USA) studies that single out five categories of
services provided by electric power systems at the level of super
systems, namely:
 Warranted access to electric power of EPSs as an
infrastructure system at any time, in any amount, at
required reliability and quality;
 Availability of starting currents to start up large electric
engines and power plants that lost power for ancillary
services in the course of an emergency;
 Provision of high-quality voltage and frequency;
 Higher efficiency of EPS operation;
 Ability to select counteragents and to minimize local
monopolism of separate segments of the electric power
market.

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The creation of mega centers of power generation on the basis
of renewable energy sources, for example, large-scale
hydropower plants - HPP (―Three Gorges‖ HPP on the Cháng
Jiāng River in China, a large HPP on the Congo River in
Central Africa and others) and mega parks of windmills in the
North Sea and on the Arctic coast of Russia, solar power plants
in the Sahara and Gobi Deserts, and others, is a relatively new
factor [14,15]. Figure 2 gives an example of a mega project of
West European Electric Power Interconnection development on
the basis of wind turbines in the North Sea and solar power
plants in the Sahara Desert [16].
Figure 2: Mega-project of West European Electric Power Interconnection [16].
Electric power generated by these mega centers shall be
transmitted long distances, which is a driving force for creating
the super-high voltage Global Energy Interconnection [17]
(Figure 3). We should like to note that [18] demonstrates, in a
sense, fantastic potential of renewable power generation by
2050 for 143 countries. Furthermore, according to estimates
given by the authors of [18], refusal of conventional energy
sources would allow for the reduction of energy consumption by
more than 55%.

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The above factors and tendencies are expected to have high
probability of implementation, particularly owing to the active
development and reduction of production costs of technologies
for long-distance transfer of ultra-high voltages, direct and
alternating currents [19].
Figure 3: Possible scenario of Global Energy Interconnection development
[17].
The scenario of the intensive development of distributed
generation in the marginal case up to the gradual abandonment
of large power plants and main super-high-voltage electric
networks is sometimes considered to be, in a sense, the
opposite one. The implementation of such a marginal scenario
in the foreseeable future is deemed to be improbable despite
obvious and well-known objective benefits of developing
distributed generation (more stringent environmental
requirements stipulate more rapid development of renewable
energy; rapid adaptation to power demand uncertainty owing to
the commissioning of generating units; unloading of the main
electric network of a super system; general reduction of
capacity and power losses and some others). A scenario of
collaborative development of relatively large power plants at
the level of super systems (centralized power supply) and

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distributed generation units at the level of mini-systems
(decentralized power supply) is thought to be realistic and have
a high probability of implementation.
According to the estimates given in [20], the ratio between
centralized and decentralized power supplies shall follow the
―golden section‖ rule: 0.62/0.38 for the systems with high-
density loads and, vice versa, 0.38/0.62 for areas with
distributed consumers. As far as the stage of rapid industrial
development is substituted by the development of systems
with poorly concentrated loads, the decentralized power
supply acquires stimuli for dynamic development. Despite the
fact that power production by large power plants is far more
efficient, the principle of convenience for consumers dominates
over the economic principles. Furthermore, power supply for
large consumers (whose power supply cannot be ensured by
renewable sources) needs to be of high quality (in terms of
voltage and frequency), and this will be the main reason for
keeping large centralizer power sources in the EPS.
An ever-growing density and complex closing of the main and
distributed electric networks due to the growth of loads that
require commissioning of additional lines on the background
of total reduction of their length becomes a general structural
tendency of super and mini-systems. As a result, energy
continues to develop in densely populated areas (e.g., in
Western Europe), whereas in the regions with territorially
extended EPSs, the energy hubs are connected by the
available long- distance lines and cutsets (e.g., in Russia,
Brazil, etc.), which is typical of power supply systems of
megacities and results in the occurrence of new properties in the
energy interconnection as a whole.
Power supply systems of megacities with short lines and
developed structure are characterized by a lack of ―angular‖
stability problems, whereas the probability of the occurrence of
―voltage‖ instability is rather high. This is confirmed by an
analysis of the 2005 Moscow blackout [21], by large-scale
emergencies in the West European Interconnection [22] and by
some other examples.

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The territorial expansion of interconnections raises the
following question: are there technical limits for such
expansion? [23,24]. Studies have shown that there are neither
physical nor technical constraints for EPS expansion. The
maximum distance of power transmission within the
interconnection is determined by a comparison of technical and
economic factors. These include the relative location of
generating sources and power consumption centers, cost of
power transmission, transmission capacity limits, amount of
active power losses during transmission and some others. As a
result, local zones of free power flows may be formed in an
extended interconnection; unlimited power exchange within
such zones is technically feasible and economically beneficial,
but between those local zones are limitations on load flows.
Thus, the structure of large interconnections in the general
case becomes more and more heterogeneous, cases of voltage
instability in the concentrated parts of the interconnection
become more and more probable, and problems of angle
stability are maintained in long-distance sections with
extended electric ties. As a result, the nature of EPS behavior
in emergencies become more sophisticated, which requires the
adjustment and development of mathematical models of
transient processes in the system, and updating of the methods
for studying the behavior of such EPSs under disturbances.
A more complicated structure of developing EPSs on the
background of general growth of installed capacity and scales
of energy interconnections aggravate consequences of system
cascading emergencies, which is confirmed by the USA
statistics for 1991–2005 (Figure 4) [25]. Unfortunately, the
author did not find more recent data, such as in EPSs [25], but
he believes in this objective trend for complicated EPSs with a
large value of generating installed capacity and heterogeneous
electrical network structure under the influence of innovative
technologies.

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Figure 4: Tendency for electric power system (EPS) blackout problems [25]. (1)
The number of outages
affecting more than 50,000 consumers; (2) The number
of outages greater than 100 MW.
Micro systems are traditionally designed to run with an
alternating current. Many electrical power devices of
consumers currently operate on a direct current, and for
connection to EPSs, reversible converters are used. For this
reason, micro-systems are mainly developed on the direct
current or as hybrid AC/DC micro-systems [6–8].
Micro-systems may operate together with EPSs on the level of a
mini-system or independently. Isolated micro-systems are
characteristic of the power supply systems of islands (e.g.,
Greece [7], South Korea [10]). The project in Mongolia
called ―1,000,000 solar photo-panels‖ [26] is a unique project
of DC micro-systems for the power supply of isolated
consumers. A standard mix of electric devices of a present-day
yurt of an isolated power consumer under that project includes
the following appliances (maximum): lighting, an electric
stove, a refrigerator, an electric heater and a digital TV.
For balancing the irregularities of power supply from photo
panels, the micro-systems use electric storage devices.
The author of [7] gives data (for the moment of publication) on
some implemented pilot projects of power supply micro-systems
in some countries of the world:

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 In Europe:
- Kitnos (Greece) with decentralized intelligent load control;
- Mannheim (Germany)—transition from joint operation
with EPS to islanded operation;
- Bronsberger (Netherlands)—islanded operation of a
micro-system and of an intelligent electric storage
facility.
 In Japan:
- demonstration projects of micro-systems, including a
demonstration project in New Mexico.
 In China:
- micro-systems on islands, in industrial, commercial and
residential areas and in remote areas.
 In the USA:
- a roadmap of studies and demonstration projects of power
supply micro-systems.
Certain activity on developing the power supply micro-systems
is also observed in Russia [27]. Thus, structural changes of
future EPSs at all three levels—in super, mini- and micro-
systems— cause changes in their properties and originate new
challenges that require solutions.
Transformation of the Future EPS Properties
under the Influence of Innovative
Technologies. EPS Flexibility
Alongside basic structural changes in the future EPSs, radical
transformations can be expected in their properties. Some
new objective factors emerged lately that stimulated studies
on EPS flexibility and on justifying the means for its
enhancement.
EPS flexibility is a relatively new notion characterizing EPSs’
ability to maintain normal or close to normal operating
conditions under the effect of internal (sudden changes and
fluctuations of the load, power flows in the lines and in
generation) and external (sudden disturbances of different

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origin) random (uncertain) factors [28]. It should be noted that
EPS flexibility in its essence is close to security of the systems.
EPS flexibility, along with other aspects of its definition,
reflects ―internal activity‖ of the system which is evidenced by
its ability to self-adapt to influencing factors and by
undertaking a number of ―active‖ measures to raise the EPS
flexibility. In this respect, the security is a kind of ―external‖,
―passive‖ assessment of the system’s ability in the considered
sense [29].
The self-healing of a present-day EPS and its ability to dampen
internal and external disturbing factors are dependent on the
actions of regulating effects of load in terms of voltage and
frequency and frequency characteristics of speed controllers of
synchronous generators, as well as by inertia of rotating masses
of rotors of synchronous and asynchronous machines, and by
the actions of control by emergency control systems, and by
automatic protection devices. Owing to the EPS self-healing
property, it adapts to sudden changes in conditions and to
disturbances within the admissible (standardized) ranges of
their values, and when parameters of conditions and
disturbances go beyond the permissible limits, the emergency
control system is activated that prevents the cascade
propagation of the emergency by its localization and liquidation
[1].
Present-day EPSs, subject to the use of conventional energy
and electric power technologies, means and control systems,
are characterized by rather high flexibility owing to the
mentioned self- healing and self-stabilization relative to internal
and external destructive factors.
Electric power systems of the 21st century undergo radical
changes in their properties not only due to the transformation of
their internal structure, but also due to use of innovative
technologies in electric power generation, transmission, storage,
distribution and consumption. Those changes considerably
lower the ability of future EPSs of self-adaptation and self-
stabilization and lower their flexibility level. Internal EPS
factors that cause those consequences are related to large-scale

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use of power electronics and rectifying invertors for
connection with EPSs of high-speed gas turbine and gas piston
generating units, wind generators, photovoltaic units, power
storage devices, DC lines and links and frequency-controlled
electric motors.
Growth in the scope of EPS use at the levels of super systems
and mini-systems of the above named technologies and units
considerably lowers the above listed frequency and voltage
control effects of consumers, frequency-controlled
characteristics of generators and inertia abilities of the system
that, as a consequence, lower its flexibility [1,28].
On the other hand, growth in the share of randomly fluctuating
generation of renewable energy sources (windmills, solar photo
panels, small-scale hydropower plants) raises the negative
impact of those fluctuations in the generating capacity on self-
adaptation and self-stabilization of the system, i.e., on the EPS
flexibility. Therefore, a new problem of damping the power
imbalances occurring as a result of such random fluctuations
arises. The solution for this kind of problem is the use of power
storage on the basis of rapidly developing innovation
technologies. Control systems using power electronics Flexible
Alternating Current Transmission System (FACTS), which were
in detail studied in [30], power storages, DC lines and links
have a high efficiency of control and stabilization. Large- scale
use of such devices in the future EPSs would radically
enhance the controllability of those systems and, hence, their
flexibility, stability and survivability [1,28].
Possible Measures for Flexibility Enhancement
of the Future EPSs
In order to ensure the EPS flexibility, it is necessary to consider
capabilities of generation of an electric network and loads; it
can also be ensured by protection and control systems; it is
also necessary to estimate the effects of the integrated use of
different means at different levels. Those capabilities include
the following [28]:

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 As was noted above, frequency characteristics of speed
and frequency control systems of conventional
synchronous generators play a major role in ensuring the
EPS flexibility as they enhance the self-adaptation and
self-stabilization ability of systems for damping the
negative impact of internal and external factors. The
flexibility of generating units can additionally be enhanced
by a higher speed of loading and unloading, by their
deeper unloading, by maintenance of the required levels
of rotating and operating reserves of active generating
capacity, by reliable fuel supply for power plants and by
power plant restoration from the ―black-start‖ level in the
case of auxiliary power loss due to faults.
 The flexibility of transmission and distribution networks
can be enhanced by the liquidation of weak points in the
network, by the reduction of transfer capability constraints
of weak cutsets and by a higher efficiency of using the
transfer capability of weak links. The application of
FACTS devices, which are manufactured now by various
companies [30], whose control systems allow for the
stabilization of EPS mode variables and maintain the
required transfer capability margins of links in normal,
maintenance, emergency and post-emergency conditions,
is a reliable means to ensure that. Higher flexibility of
active transmission and distribution electric networks can
be ensured by automatic reconfiguration of the network
[31].
 Load flexibility is ensured by the abovementioned
frequency and voltage control effects, by automatic load
control owing to shifting the controllable electric
facilities to the zone of a minimum daily load curve [32]
and by using the distributed generation units available with
the consumers (prosumers) [33].
 Power storages of different capacities and energy intensities
will play a major role in enhancing the EPS flexibility,
particularly in the case of random fluctuations in power
supply by units based on renewable energy sources (RESs)
at all levels, i.e., in super, mini- and micro-systems [34].
 Integrated multi-energy systems allow for additional
means for enhancing the EPS flexibility when using units

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generating the required type of energy by the use of
another type of energy (for example, heat pumps, electric
boilers, etc.) [35]. Innovative gas supply systems within
integrated energy systems allow for further enhancement of
power generation flexibility owing to more efficient gas-
based technologies, especially with the combined
production of heat and power [33,35].
 Efficient protection and control systems play a key role in
ensuring the EPS flexibility [36]. The efficiency of those
systems when using the intelligent technologies can be
notably enhanced by raising the accuracy of EPS state
variable forecasts, by the reduction of time for preparation
of control actions, and by raising the frequency of their
implementation [28].
 In this connection, a detailed review given in [37] is worth
mentioning that gives 393 names of quoted papers. The
authors analyze practically all the above listed measures for
enhancing the EPS flexibility.
 The use of market mechanisms is an efficient means for
stimulating the EPS flexibility enhancement [38].
Consequently, there are numerous capabilities to enhance the
flexibility of future EPSs and selection of the most expedient
means is not a simple task to be solved for standard conditions
of transformed EPS operation and development. However,
extreme conditions occurring under the effect of internal and
external factors remain topical and need detailed consideration.
Resiliency and Survivability of EPSs
The tendency of the consequences of cascade systems
emergency in EPSs (Figure 4) to be aggravated was
determined by conventional factors related to larger scales,
structural complexity and territorial extension of the
considered systems. The abovementioned basic changes in the
structural characteristics and internal properties of future
EPSs would exacerbate this negative tendency. The described
circumstances have lately initiated discussions and studies on
the problems related to a new EPS ―resiliency‖ (elasticity)
notion. The most succinct interpretation of ―resilience‖ is given

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in [39], where it is defined as a property of any system to
withstand any changes or interrupted events by reducing their
initial negative impact and by mitigation of consequences for
the system (damping ability), self-adaptation of a system to
those changes and events to mitigate consequences (self-
healing ability) and system restoration by appropriate
controlling actions during the minimum time possible
(restoration ability). The main details of this definition are
shown in Figure 5.
In [25,40–42], the resiliency problem is studied as applied to
EPSs; to be more particular, in [25,42], it is studied
considering the cascade system emergencies, and in [40,41] for
the cases of natural disasters.
A Russian term corresponding to ―resiliency‖ as applied to EPSs
is ―survivability‖ that is defined as the ability of the system to
withstand emergencies preventing their cascade propagation
which are followed by a large-scale interruption of power supply
to consumers, and the ability of the system to restore its initial
state or the state close to it [43]. Let us make some comments
on what is illustrated in Figure 6 to explain the term
―survivability of EPS‖: line 1 shows the level of a normal
operation state before the emergency; line 2 presents the so-
called marginal (limiting) state, which is lower then the
triggering event and the EPS meets a catastrophic
uncontrollable cascading process, which notes by number 4; line
3 shows the cascading process before the marginal state and
triggering event, when the emergency control system and
operating personnel try to prevent (interrupt) the cascading
disturbance and to restore the normal state of the EPS (lines 6);
line 5 presents an extreme disturbance like a storm, earthquake
and so on; line 7 shows the recovery (restoration) stage.
The abovementioned definition shows that survivability
includes damping and adaptation abilities of the system that
were considered in [39] as applied to resiliency, and its ability
to recover. A comparison of key components of the two terms
additionally proves their identity (Figures 5 and 6): the
elasticity margin and marginal state; the move to collapse and

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catastrophic cascade process; adaptive behavior and recovery;
robust behavior and opposition to cascade propagation of
the emergency (the first component of the comparison belongs
to resiliency, the second one to survivability).
Figure 5: Main regularities of the system’s stable and unstable behavior in
terms of resiliency [39].
Figure 6: Illustration of EPS behavior in terms of survivability [43,44].
The relations between EPS resiliency and flexibility are of
interest. An analysis of definitions of those properties shows
that a higher flexibility of the system causes growth in damping
and adaptation ability of the EPS that are characteristic of
resiliency.

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Possible Measures for Enhancing the
Resiliency/Survivability of EPSs
These measures include [28]:
 Elaboration of reliability standards for submission of the
reliability requirements when planning the EPS
development and condition control; it is necessary to
note the necessity of elaborating special reliability
standards for the cases of natural disasters with the
identification of specific requirements for the power
supply reliability of major consumers in those
conditions;
 Creation of a large-scale efficient protection system
and emergency control system that is primarily
important for preventing the cascade propagation of an
emergency;
 Development of efficient procedures for EPS recovery
after large disturbances. It is obvious that those
procedures shall be different for the cases of system
recovery after a cascade emergency and after natural
disasters;
 Organization of regular training for dispatchers. The
contents of that training shall be different for the cases of
a cascade emergency and for natural disasters;
 Generalization of the nature and mechanisms of
occurrence and development of large emergencies.
Each system cascade emergency is unique but their
analysis and generalization allow for the identification of
the key factors whose elimination would reduce the
probability of such emergencies and mitigate their
probable consequences. Considering the basic
importance of such generalizations, let us consider this
aspect of the problem in greater detail.

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Analysis of Cascading Emergency Mechanisms
and EPS Restoration
Many different disturbances occur in complex extended EPSs
every year for different reasons: short circuits of electric
equipment, failure of system elements, errors of operating
and servicing personnel, etc. The major share of those
disturbances is eliminated by relay protection and emergency
control devices (ECDs). If efficiency and reliability of relay
protection and ECDs are not sufficient, a cascade propagation
of the emergency occurs that is interrupted by the next stage of
the ECD or/and by the control actions of personnel. Such
circumstances in an integrated interconnection (e.g., Unified
Energy System (UES) of Russia or Electric Power
Interconnection of the Northeast USA and east of Canada) may
take place up to several times during a year. Such cascade
emergencies, as a rule, do not cause sensible consequences for
consumers and the system, and remain unnoticed by the public.
If an emergency control system and operating personnel cannot
interrupt the cascade emergency, it becomes irreversible and
blackouts occur that often have catastrophic consequences for a
system and consumers; examples of such system emergencies
are the 2003 blackouts in North America and Europe, the
Moscow emergency in 2005 and some others [21,22].
It should be noted that there are two basically different
ideologies for opposing the cascade propagation of system
emergencies, namely, whether a dispatcher plays a leading role in
this process, or an automatic control system. Russian experience
shows that automatic interruption of cascade emergencies is
more preferable due to their fast occurrence. The probability of
erroneous actions of an operator in high-stress circumstances is
rather high, which exacerbates the situation [44,45].
Although the role of emergency control systems in preventing the
occurrence and propagation of heavy system cascade
emergencies is the major one, and analysis and generalization
of mechanisms effecting the basic peculiarities of the states,
events and processes during such emergencies become of major
importance. The most typical approaches to such generalizations

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are considered in [42,45–50]. Key provisions of those
generalizations can be stated as follows.
1. Several of the most characteristic events and stages of
occurrence, and cascade propagation of the system
emergency, are to be singled out: initial disturbance
(initiating event); cascade process of the emergency
propagation with implementation of control actions to
prevent the steady-state progression; marginal state (―point
of no return‖); a triggering event; catastrophic
uncontrollable avalanche-like high-speed cascade; EPS
restoration (Figure 7) [44].
2. The authors of [47], on the basis of statistics of large
emergencies in North America in 1984–2006, analyze a
number of hypotheses and discard the hypotheses on
frequency reduction of such emergencies with time; on
independence of the frequency of emergencies from the
season of the year; on independence of the frequency of
emergencies from the time of the day; on the
correlation between the scale of the emergency
consequences and time for the system restoration.
3. The authors of [42,44,48–50] stress the decisive role of
emergency control systems in preventing the occurrence of
emergencies, in opposing the propagation of heavy
emergencies and in rapid restoration of the system. An
emergency control system is to perform three groups of
functions: prevention of a cascade emergency in the pre-
emergency conditions; adaptive opposition to emergency
propagation; adjusting the control in the post-emergency
conditions;
4. The authors of [42,46] note certain correlations between
factors of EPS liberalization in terms of actualization of
congestion problems due to the growth of power exchange
volumes at the spot market and growth in the large system
emergency probability.
5. The role of the EPS restoration process step by step from
the final state with the active participation of a dispatcher
and by an automatic emergency control means [42–44,48–
52]. The restoration process shall not be interrupted by
irrational control actions that aggravate the emergency
situation.

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Figure 7: Typical stages of a cascading system emergency [44].
The described elements of the analysis and generalization of the
mechanisms of occurrence and propagation of cascade
emergencies and EPS restoration comply with the
survivability/resiliency notions.
Cyber-Physical EPSs
A present-day electric power system is a complex facility
consisting of two closely related subsystems: physical
(technological) and information-communication (ICS). The
sophistication and role of present-day and future technological
and information-communication subsystems in ensuring the
normal EPS operation are comparable [53].
In the conditions of energy industry digitalization that
implies both faster interpretation of digital information and
higher efficiency of technological processes in EPSs that use
the innovative power equipment of new generation operated
as per the standards of the International Energy Commission
(IEC), and considering the development of new software for
controlling newly created digital substations, local electric
grids, etc., an EPS shall be perceived as a complex cyber-
physical system whose ICS may not operate properly due to
internal defects (errors in the algorithms, etc.), and may be
subjected to external effects, namely, cyberattacks [54,55]. The
possibility of internal and especially of external factors

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(cyberattacks) causing an improper operation of ICS raises
EPS cyber security concerns [56].
The analysis of events occurring during the propagation of
cascade emergencies in different countries [25,42,44,47]
shows the possibility of a mutual impact of failures and
disturbances in the physical and information-communication
subsystems of EPSs. The uncertainty of information on the
current EPS conditions or on its loss due to internal defects
of digital devices or on external cyberattacks against ICS may
be the cause of erroneous control actions and the development of
a fault process in a physical subsystem. The failure or fault of
an element in the physical subsystem may lead to emergency
conditions in this subsystem and to a failure of ICS components.
Considering these relations, physical and information-
communication factors shall be integrated at the level of
justifying the development of cyber-physical EPSs [56,57] and
for the solution of different problems of operating condition
control [55,58].
Thus, the scope of factors necessitating the transformation of
EPS structure and properties and generating a list of urgent
problems to be studied for ensuring the flexibility and
resilience of those systems becomes much larger for the
present-day systems or even worse in future.
Development Trends of EPS Management and
Control Systems
The abovementioned evidence shows the key role of control in
ensuring the normal operation of complex cyber-physical EPSs
of the future. Along with the transformation of EPSs, the
control systems, principles of their design, methods and means
of their implementation will be transformed as well. The
complication of EPS structure and processes due to new
properties of the systems is one of the main trends of EPS
development. Those complicating factors shall be considered in
developing the principles and methods of control. According
to W.R. Ashby [59], sophisticated principles embedded in a
control system shall be adequate to develop the sophistication of
a controlled facility and processes occurring in it.

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When considering the structure of future control systems for
EPS conditions, the majority of investigators agree that those
systems shall have a hierarchical structure [42,48,60–62]. For the
general case, they consider three stages of control [42,61]:
preventive control in pre-emergency conditions; adaptive
control during emergency, and corrective control in post-
emergency conditions. As applied to the problem of opposing
the cascade propagation of emergencies in EPSs, they discuss
coordinated hierarchical control [42,60]. They also stress the
role of artificial intelligence in enhancing the efficiency of
control [62].
When identifying the perspective trends in the development of
principles of control and in EPS control systems, they use:
 wide area monitoring, protection and control systems
(WAMS, WAPS and WACS);
 ideology implemented on the basis of phasor measurements
of EPS state variables;
 present-day data transfer;
 processing and visualization means for monitoring current
operating conditions;
 adaptive methods for generating the control actions.
Adaptation in this case is based on prediction, which
requires the use of applicable methods for forecasting the
EPS state variables.
An example of perspective approaches may be an intelligent
system proposed in [63]. The system is based on multi-agent
technologies and algorithms of computer-aided learning for early
prevention of critical voltage instabilities. Large-scale use of
grid-related control means (energy storage systems, FACTS
devices, etc.) and potentials of active consumers is also typical of
such approaches.
In the roadmap that was discussed, special consideration shall
be given to the operating and designed emergency control
system for EPSs of Russia that, along with other components,
includes a key subsystem of adaptive automatic emergency
control [36,44,64]. This subsystem has a hierarchical structure.

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Its lower level is represented by numerous automatic devices
based on micro- computers and on implementing specific
control actions to localize and liquidate an emergency, and to
prevent its propagation. Control actions of the upper level that
are performed by devices of the lower level are adjusted in a
cyclic way with regard to the current EPS conditions, thus
ensuring adaptive control. Furthermore, an echeloned principle
of automatic device operation is implemented: if a subsystem of
automatic prevention of stability loss failed to ensure EPS
stability at the first stage, the next group of automatic devices
starts operating to oppose the dramatic emergency cascade.
Therefore, a system of automatic emergency control operating
in EPSs of Russia even now has many functions and
peculiarities of a future control system.
The basic concepts of control system transformation described
above belong predominantly to the level of super systems and can
be considered as basic ones for designing the control systems for
mini- systems. The ideology of control systems for micro-systems
has been rapidly developed in recent years. The designed control
systems are implemented on the basis of multi-agents using
algorithms of consensus control that imply the use of appropriate
agents’ consensus protocols during control [65,66].
Concluding Remarks
EPS development on the basis of innovative technologies and
means in a physical and information-communication subsystem
in the conditions of digitalization and intellectualization of EPS
operation and control of their modes will necessitate radical
transformation of their structure and properties. Future electric
power systems in the long run will become sophisticated
intelligent cyber-physical EPSs that could radically differ from
present-day systems. This transformation will require a
comprehensive review of available principles and methods for
modeling such systems, for studying their new properties and
for justifying their development and control of their operation.
Technologies like artificial intelligence shall become the basis
of new models and methods, along with traditional ones. New
future control systems shall become a key factor in ensuring

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normal operation of transformed EPSs. The ideology of their
construction and operation shall go before the needs of
transformed cyber-physical EPSs.
References
1. Voropai NI, Osak AB. Electric power systems of the future.
Energeticheskaya Polit. 2014; 5: 22–29.
2. Marvasti AK, Fu Y, DorMohammadi S, Rais-Rohani M.
Optimal Operation of Active Distributio Grids: A System of
Systems Framework. IEEE Trans. Smart Grid. 2014; 5: 1228–
1237.
3. Quint R, Dangelmaier L, Green I, Edelson D, Ganugula V, et
al. Transformation of the Grid: The Impact of Distributed
Energy Resources on Bulk Power Systems. IEEE Power
Energy Mag. 2019; 17: 35–45.
4. Voropai NI, Stennikov VA. Integrated smart energy system.
Izv. RAN Energ. 2014; 1: 64–72.
5. Ackermann T, Andersson G, Söder L. Distributed generation:
A definition. Electr. Power Syst. Res. 2001; 57: 195–204.
6. Marnay C, Nordman B, Lai J. Future roles of mili-, micro-,
and nano-grids. In Proceedings of the CIGRE Symposium
―Electric Power System for the Future—Integrating
Supergrids and Microgrids‖, Bologna, Italy. 2011.
7. Hatziargiriou N, editor. Microgrids: Architectures and
Control. New York: IEEE Press-Wiley. 2014.
8. Marnay C, Abbey C, Joos G. Microgrids 1: Engineering,
economics, and experience—Capabilities, benefits, business
opportunities and examples—Microgrids evolution roadmap.
Electra. 2015; 283: 71–75.
9. Ershevich VV, Antimenko YL. Operation efficiency of
Unified electric power system on the territory of former
USSR. Izv. RAN. Energ. 1993; 1: 22–31.
10. Voropai NI, Podkovalnikov SV, Osintsev KA. From
interconnections of local electric power systems to Global
Energy Interconnection. Global Energy Interconnect. 2018; 1:
4–10.
11. Commission of the European Communities. The Benefits of
Integration in the European Electricity System, Work
Document. Brussels: Commission of the European

Advances in Energy Research: 2nd Edition
26 www.videleaf.com
Communities. 1990.
12. Voropai NI, Trufanov VV, Selifanov VV, Sheveleva GI. About
the efficiency analysis of Unified electric power system of
Russia. Elektrichestvo. 2000; 5: 2–9.
13. Opadchy F. The Necessity in the Large Power Systems Does
not Decrease, but Increase, Interview of Vice- President of
International Association for System Operators G015 F.
Elektroenergiya. Peredacha i Raspred. 2020; 1: 146–150.
14. Mano S, Ovgor B, Samadov Z. Gobitec and Asian Super Grid
for Renewable Energies in Northeast Asia. Available online at:
https://www.renewable-
ei.org/images/pdf/20140124/gobitec_and_ASG_report_ENG
_BOOK_final.pdf (accessed on 15 October 2015).
15. Deng C, Song F, Chen Z. Preliminary study on the
exploitation plan of the mega hydropower base in the lower
reaches of Congo River. Glob. Energy Interconnect. 2020; 3:
12–22.
16. Strbac G, Pudjianto D, Aunedi M, Papadaskalopoulos D,
Djapic P, et al. Cost-Effective Decarbonization in a
Decentralized Market: The Benefits of Using Flexible
Technologies and Resources. IEEE Power Energy Mag. 2019;
17: 25–36.
17. Liu Z. Global Energy Interconnection. Amsterdam: Elsevier.
2015.
18. Jacobson MZ, Delucchi MA, Cameron MA, Coughlin SJ,
Hay CA, et al. Impacts of Green New Deal Energy Plans on
Grid Stability, Costs, Jobs, Health, and Climate in 143
Countries. One Earth. 2019; 1: 449–463.
19. Liu Z. Ultra-High Voltage AC/DC Grids. Amsterdam:
Elsevier. 2015.
20. Bushuev VV. Energy-information systems as the basis of neo-
industrial and socio-humanitarial civilization.
Energeticheskaya Polit. 2016; 3: 7–24.
21. Gerasimov AC, Esipovich AK, Koshcheev LA, Sulginov NG.
Operating conditions study of Moscow power system during
emergency development at May 2005. Elektrichestvo. 2008;
1: 2–12.
22. Paris L, Valtorta M, Manzoni EA. Rapport de la mission
d’enquete sur la panne d’electricite du 19 decembre 1978.
Electr. France. 1979; 1: 31–49.

Advances in Energy Research: 2nd Edition
27 www.videleaf.com
23. Paris L, Zini G, Valtorta M, Manzoni G, Invernizzi A, et al.
Present limits of very long distance transmission systems. In
Proceedings of the CIGRE 1984 Session. Paris, France. 1984;
37–112.
24. Mueller HC, Haubrich HJ, Schwarz J. Technical limits of
interconnected systems. In Proceedings of the CIGRE 1992
Session, Paris, France. 1992; 37–301.
25. Amin M. Challenges in reliability, security, efficiency, and
resilience of energy infrastructure: Toward smart self-healing
electric power grid. In Proceedings of the 2008 IEEE Power
and Energy Society General Meeting— Conversion and
Delivery of Electrical Energy in the 21st Century. Pittsburgh,
PA, USA. 2008.
26. Voropai NI, Bat-Undraal B, Enkhsaikhan E. Ways and
problems of micro-systems of power supply of isolated
consumers in Mongolia. Izv. RAN Energ. 2019; 6: 43–50.
27. Vassiliev S. Green roofs of Russia or micro-generation in
Russia. Energy Econ. Tech. Ecol. 2018; 5: 69–72.
28. Voropai N, Rehtanz C. Flexibility and Resiliency of Electric
Power Systems: Analysis of Definitions and Content. In
Proceedings of the EPJ Web of Conferences, International
Workshop on Flexibility and Resiliency of Electric Power
Systems. Irkutsk, Russia. 2019.
29. Marceau RJ, Endrenyi J, Allan R, Alvarado FL. Power system
security assessment: A position paper. Electra. 1997; 175: 49–
77.
30. Zhang XP, Rehtanz C, Pal BC. Flexible AC Transmission
Systems: Modelling and Control. Berlin: Springer. 2012.
31. Sun H, Wang Y, Nikovski D, Zhang J. Flex-Grid: A dynamic
and adaptive configurable power distribution system. In
Proceedings of the 2015 IEEE Eindhoven PowerTech. The
Netherlands: Eindhoven. 2015.
32. Chulyukova M, Voropai N. Flexibility Enhancement in an
Islanded Distribution Power System by Online Demand-Side
Management. In Proceedings of the EPJ Web of Conferences,
International Workshop on Flexibility and Resiliency of
Electric Power Systems. Irkutsk, Russia. 2019.
33. Chen X, Kang C, O’Malley M, Xia Q, Bai J, et al. Increasing
the Flexibility of Combined Heat and Power for Wind Power
Integration in China: Modeling and Implications. IEEE Trans.

Advances in Energy Research: 2nd Edition
28 www.videleaf.com
Power Syst. 2015; 30: 1848–1857.
34. Styczynski Z, Adamek F, Irovani F, Voropai N. Electric
Energy Storage System. CIGRE Brochure, WG C6.15. 2011.
Available online at:
file:///C:/Users/MDPI/AppData/Local/Temp/2017_Bookmatte
r_ElectricEnergyStorageSystems.pdf
35. Koeppel G, Andersson G. The influence of combined power,
gas, and thermal networks on the reliability of supply. In
Proceedings of the 6th World Energy System Conference.
Torino, Italy. 2006.
36. Shulginov NG, Pavlushko SA, Dyachkov VA. Effective
control of electric power operating modes of UES of Russia in
current conditions. Energetik. 2013; 6: 20–24.
37. Lund PD, Lindgren J, Mikkola J, Salpakari J. Review of
energy system flexibility measures to enable high levels of
variable renewable electricity. Renew. Sustain. Energy Rev.
2015; 45: 785–807.
38. Bistline J. Turn Down for What? The Economic Value of
Operational Flexibility in Electricity Markets. IEEE Trans.
Power Syst. 2018; 34: 527–534.
39. Nan C, Sansavini G, Kröger W, Sansavini G. Building an
Integrated Metric for Quantifying the Resilience of
Interdependent Infrastructure Systems. In Proceedings of the
9th International Conference on Critical Information
Infrastructure Security. Limassol, Cyprus. 2011.
40. Wang Y, Chen C, Wang J, Baldick R. Research on resilience
of power systems under natural disasters— A review. IEEE
Trans. Power Syst. 2016; 31: 1604–1612.
41. Panteli M, Mancarella P, Trakas DN, Kyriakides E,
Hatziargyriou ND. Metrics and Quantification of Operational
and Infrastructure Resilience in Power Systems. IEEE Trans.
Power Syst. 2017; 32: 4732–4742.
42. Kezunovic M, Overbye TJ. Off the Beaten Path: Resiliency
and Associated Risk. IEEE Power Energy Mag. 2018; 16: 26–
35.
43. Voropai NI. The problem of large electric power system
survivability. In Proceedings of the IEEE Power Tech.
Stockholm, Sweden. 1995.
44. Besanger Y, Eremia M, Voropai N. Major grid blackouts:
Analysis, classification, and prevention. Handbook of

Advances in Energy Research: 2nd Edition
29 www.videleaf.com
Electrical Power System Dynamics: Modeling, Stability, and
Control. Hoboken: IEEE Press-Wiley. 2013; 789–863.
45. Sovalov SA, Semenov VA. Emergency Control in Power
Systems. Moscow: Energoatomizdat. 1988.
46. Bialek JW. Blackouts in the US / Canada and continental
Europe in 2003: Is liberalisation to blame? In Proceedings of
the 2005 IEEE St. Petersburg Power Tech. St. Petersburg,
Russia. 2005.
47. Hines P, Apt J, Talukdar S. Large blackouts in North America:
Historical trends and policy implications. Energy Policy.
2009; 37: 5249–5259.
48. Pourbeik P, Kundur P, Taylor C. The anatomy of a power grid
blackout—Root causes and dynamics of recent major
blackouts. IEEE Power Energy Mag. 2006; 4: 22–29.
49. Martins ACB, Gomes P, Alves F. Lessons learned in
restoration from recent blackout incidents in Brazilian power
system. In Proceedings of the CIGRE 2012 Session. Paris,
France. 2011.
50. Li B, Gomes P, Baumann R. Lessons learnt from recent
emergencies and blackout incidents. Electra. 2015; 279: 66–
73.
51. Feltes J, Grande-Moran C. Down, but Not Out: A Brief
Overview of Restoration Issues. IEEE Power Energy Mag.
2014; 12: 34–43.
52. Che L, Khodayar M, Shahidehpour M. Only Connect:
Microgrids for Distribution System Restoration. IEEE Power
Energy Mag. 2014; 12: 70–81.
53. Voropai NI, Kolosok IN, Korkina ES, Osak AB. Cyber-
physical electric power systems: Transformation of properties
and new problems. Avtom. I IT Energetike. 2018; 110: 31–35.
54. Voropai NI, Gubko MV, Kovalev SP, Massel LV.
Development problems of digital energetics in Russia. Probl.
Upr. 2019; 1: 2–14.
55. Mehrdad S, Mousavian S, Madraki G, Dvorkin Y. Cyber-
Physical Resilience of Electrical Power Systems Against
Malicious Attacks: A Review. Curr. Sustain. Energy Rep.
2018; 5: 14–22.
56. Hull J, Khurana H, Markham T, Staggs K. Staying in control:
Cybersecurity and the modern electric grid. IEEE Power
Energy Mag. 2011; 10: 41–48.

Advances in Energy Research: 2nd Edition
30 www.videleaf.com
57. Khaitan SK, McCalley JD. Cyber physical system approach
for design of power grids: A survey. In Proceedings of the
2013 IEEE Power & Energy Society General Meeting.
Vancouver, Canada. 2013.
58. Cai Y, Cao Y, Li Y, Huang T, Zhou B. Cascading Failure
Analysis Considering Interaction Between Power Grids and
Communication Networks. IEEE Trans. Smart Grid. 2016; 7:
530–538.
59. Ashby WR. An Introduction to Cybernetics. London:
Chapman and Hall. 1957.
60. Fardanesh B. Future trends in power system control. IEEE
Comput. Appl. Power. 2002; 15: 24–31.
61. Ilic M, Allen H, Chapman W, King C, Lang J, et al.
Preventing Future Blackouts by Means of Enhanced Electric
Power Systems Control: From Complexity to Order. Proc.
IEEE. 2005; 93: 1920–1941.
62. Ruano A, Ge SS, Guerra TM, Lewis FL, Principe J, et al.
Computational intelligence in control. In Proceedings of the
19th IFAC World Congress. Cape Town, South Africa. 2014.
63. Voropai NI, Kurbatsky VG, Tomin NV, Panasetsky DA.
Intelligent Software for Preventing Large Emergencies in
Power Systems. Novosibirsk: Nauka. 2016.
64. Gerasimov AS, Koshcheev LA, Kritskiy VA, Lisitsyn AA.
Automatic emergency control in power systems. Elektr.
Stantsyji. 2020; 1: 41–49.
65. Olfati-Saber R, Fax JA, Murray RM. Consensus and
Cooperation in Networked Multi-Agent Systems. Proc. IEEE.
2007; 95: 215–233.
66. Qin J, Wan Y, Yu X, Li F, Li C. Consensus-Based Distributed
Coordination Between Economic Dispatch and Demand
Response. IEEE Trans. Smart Grid. 2018; 10: 3709–3719.