Identification and Analysis of Technical Impacts in the Electric Power System Due to the Integration of Microgrids

Abstract

In a modern and technological world that has a great demand for energy, a versatile energy market, and a renewed electric infrastructure capable of expanding the electric power system under the premise of universal access to electricity, that seeks to minimize the effects of climate change, and that requires an improvement in its reliability, security, and resilience, microgrids are born as one of the systems that have the potential to supply each of these requirements in order to guarantee an adequate decarbonization, decentralization, digitalization, diversification, and democratization of the future grid. However, the integration of microgrids into the electric power system will generate impacts that are currently under study. This paper identifies and analyzes the technical impacts in the electric power system due to the implementation of microgrids, based on what has been recognized in the literature, so that those who have purposes of installation, creation, innovation, and research of microgrids, such as grid operators, technology providers, companies, and researchers, can establish criteria and indicators through which the feasibility of projects involving microgrids can be determined. The concept, importance, and characteristics of microgrids are given, along with a technical justification of the impacts. In addition, technical impacts on some study cases of real microgrids around the globe are identified. Finally, an analysis of the identified technical impacts is offered, and conclusions are drawn.

1. Introduction

Globally, several efforts to mitigate climate change have been recognized. However, adapting to the actions imposed to face this phenomenon has proven to be an actual challenge; one of them lies in the traditional way of generating and consuming electric energy since it is one of the largest sectors, which is mainly related to the use of fossil fuels. According to the International Energy Agency (IEA), the CO₂ emissions related to energy use and production had a direct impact on greenhouse gas (GHG) emissions, which had their highest peak in 2021, as shown in Figure 1 [1].

To achieve the 13th Sustainable Development Goal [2], whose objective is to reduce the phenomenon of global warming, which advocates for climate action, a solution is proposed by the United Nations (UN) that introduces a new term known as decarbonization and diversification, in which occurs a green transition directed into the use of renewable sources that are capable of generating electric energy efficiently [2], thus reducing CO₂ emissions. As a result, alternative solutions involving microgrids (MGs), distributed energy resources (DERs), and distributed generation (DG) [3] have emerged, as long as they use non-conventional renewable energy sources.

Likewise, the modernization and implementation of new technologies in all productive sectors have determined a growth in energy demand; hence, it must be ensured that the infrastructure and new developments in the energy sector can supply the amounts of energy required by the users while maintaining the characteristics of reliability, security, and resilience. This whole process is due to the digitalization that demands a change in terms of energy and that is transforming not only the components of the electric power system (EPS) but also most of the sectors around the world.

In the same way, the expected transition of the energy market and the search for its democratization will allow widespread access to the energy produced by introducing the new concept of the prosumer, used to refer to the new users of the system that are capable of producing, managing, and using electrical energy, thus opening up the boundaries of energy production that uses diverse renewable and non-renewable sources and new technologies, bringing benefits in terms of energy costs, and encouraging the disarticulation of some monopolies in the actual market.

Finally, the expansion of the EPS into the non-interconnected zones (NIZs) and the ones that belong to the interconnected national system (INS) is also one of the actual challenges globally; the UN’s 2030 vision sets out the goal of universal access to electricity [4], which is expected to reach all populations on the planet by expanding the range of coverage in the NIZs and by improving the energy service delivery in the systems connected to the EPS. This brings with it the decentralization and independence that belong to the new sources that can provide energy without having to be attached to the interconnected systems and the traditional ways of generation.

Therefore, in a modern and technological world that has a great demand for energy, a versatile energy market, and a renewed electric infrastructure capable of expanding the EPS under the premise of universal access to electricity, that seeks to minimize the effects of climate change, and that requires an improvement in its reliability, safety, and resilience, microgrids (MGs) are born as one of the systems that have the potential to supply each of these requirements in order to guarantee an adequate decarbonization, decentralization, democratization, digitalization, and diversification of the future grid [5]. However, the integration of MGs in the EPS will generate technical impacts that are currently under study [6,7]. The objective of this paper is to give an overview of the technical impacts due to the implementation of MGs in the EPS found in the current scientific literature. This review article offers an analysis of the different impacts, methods, and results that were obtained during the investigation.

The document’s sections are organized as follows: A general overview of microgrids is given in Section 2. Technical impacts on the electric power system are described in Section 3. The discussion is presented in Section 4, and the conclusions are offered in Section 5.

2. Microgrids: General Overview

Since the concept of MGs is referred to by many authors, and there is no standard definition for MGs, it is important to first explore more general concepts such as the smart grid (SG) before an MG concept is built. It is then possible to consider the SG as an updated system of transmission lines, substations, transformers, smart meters, and other elements that, by means of digital and information technology, allow bidirectional communication between the user and the EPS so that energy can be delivered and received efficiently with reliability and security [8,9].

Once the SG is defined, the MG can be understood as a “group of interconnected loads and distributed energy resources with clearly defined electrical boundaries that acts as a single controllable entity with respect to the grid and can connect and disconnect from the grid to enable it to operate in both grid-connected and islanded modes” [10]. That is why the importance of MGs lies in the fact that they are a mechanism that is not limited to providing energy only as a backup when the grid is out of operation, but in the same way, they are a system with the ability to reduce costs, expand the market, and use energy as an opportunity for communities to enjoy the benefits of electricity with better conditions that include independence and environmental care [11].

It is then possible to identify an MG by three important characteristics [12]:

1.

Intelligent

It belongs to the SG and contains advanced control, metering, and communication systems by means of a central controller.

2.

Independent

It can operate in stand-alone mode by disconnecting from the main grid, which offers reliability, flexibility, and resilience. This is possible because it integrates renewable sources, or DERs, with the EPS through a point of common coupling (PCC) and various control systems and contains elements such as grid-forming inverters [13] that increase the benefits that autonomy can offer.

3.

Local

Due to their voltage level, MGs are generally located in the distribution section of the SP in levels I, II, III, and IV, according to Colombian Resolution CREG 097-2008 [14]. This gives the MG the ability to generate energy locally, as it is close to the user with DG and, in some cases, an ESS.

2.1. Classification of Microgrids

Table 1. Types of microgrids.

Parameter	Type	Description	Ref.
Size	Small Scale	<10 kW	[7,15]
	Medium Scale	10 kW–1 MW
	Large Scale	>1 MW
System	DC	Contains a common DC node and uses inverters and rectifiers to deliver power	[16]
	AC	All DERs are connected to a common node, and it uses inverters and rectifiers when any DC resource is being used
	Hybrid	It is a combination of AC and DC MG and contains both types of nodes
Operation	Connected	Contains a PCC that allows the connection with the EPS, where it exchanges energy unidirectionally or bidirectionally	[7]
	Stand-alone	It is never connected to the grid and feeds remotely different loads, forcing it to maintain a reactive and active power balance
Architecture	Radial	Has a single generation point with load branches; it is noncomplex, cheaper, and susceptible	[17]
	Ring	Allows different interconnected generation points that allow flexibility and security
Configuration	Single-phase	It feeds single-phase loads and cannot be connected to high-power systems due to load unbalance	[18]
	Three-phase	It feeds three-phase loads and can be connected to the INS and the interconnected regional system (IRS)
Scenario	Residential	Supplies residential loads for type I voltage level	[14]
	Industrial	Feeds industrial-type loads for voltage levels type I
	Commercial	Serves commercial loads at the type I voltage level
	Institutional	Delivers energy for institutions and is considered a critical infrastructure when located in hospitals or research and development centers	[19]
	Military	Critical infrastructure that supplies energy to military institutions in different locations and areas with little or no electricity coverage
Source	Flexible Generation	Uses diverse energy sources that depend on human beings
	Non-Flexible Generation	Uses diverse energy sources that depend on uncontrollable conditions such as climate or the environment
	Hybrid Generation	Uses flexible and non-flexible sources
Mode	Cluster	High-level structures consisting of several microgrids connected by low- and medium-voltage feeders that can be connected in parallel or in cascade	[20]
	Single	Infrastructure created by a single MG

Source: authors.

summarizes each type of MG found in the scientific literature according to a parameter of classification, type, and a brief description.

Figure 2 displays the different parameters of classification of microgrids described in Table 1.

2.2. Technical Advantages and Disadvantages

Table 2. Technical advantages and disadvantages of microgrids.

Advantages	Disadvantages	Ref.
Better control systems	Problems in control and protection systems due to the high intermittency of DERs and non-linear loads in island mode and problems of integration with the system in grid-connected mode	[6]
More flexibility, power quality, and adaptability	Require higher maintenance	[19]
Viable alternative to supply the growing demand for energy in a more reliable way in NIZs and INS	System designs are more difficult	[6,17]
Allows the optimization of the available energetic resources, which makes it a more efficient system	There is a change in demand forecasting models because they now consider injections from renewable sources and have uncertainties due to variations in generation	[6,21]
The smart characteristic of the MG allows it to have power exchanges, advanced sensors, and bilateral information	It can present problems related to compatibility due to the diversity of technologies integrated	[21]
Reduces the energy demand from the EPS side, which allows for a decongestion of the zones and peak hours	As they have more communication infrastructure, they are at higher risk of cyber threats because they are a new attack surface	[22,23]
Allows the introduction of renewable distributed energy sources	Due to its ability to work in island or grid-connected mode, it generates disadvantages in the EPS	[22]
Shorter response times to disruption events		[6]
They have a greater capacity for expansion, in addition to being an easier process		[24]
It is more efficient because it has lower transmission and distribution losses		[21]
The different types of microgrids make it possible to adapt this type of system to a wide variety of applications

Source: authors.

presents some technical advantages and disadvantages, based on the literature, that MGs can offer to the EPS.

2.3. Integration of Microgrids in Non-Interconnected Zones and Interconnected National System

The vast adaptability of MGs allows them to be integrated into the INS and NIZs, as shown in Figure 3; this opens the possibility of obtaining different benefits that depend on the type of system or zone into which the MGs will be integrated, as shown in Figure 4.

2.3.1. Interconnected National System

The aim of the integration of MGs in an INS is to increase the reliability, security, and resilience of the system in order to seek a more stable operation, which in turn ensures an ideal energy supply that helps prevent different events that can affect the fulfillment of demand programs [25].

2.3.2. Non-Interconnected Zones

MGs in NIZs turn out to be one of the ways to obtain universal access to electricity. This brings technical benefits that are related to expanding the system’s coverage and encourages different technological advances in zones that do not have access to electrical energy.

Finally, Figure 5 presents the actual overview of Colombia’s INS and NIZs; this is one of the many countries that have future plans for MG implementation, such as the PIEC 2019–2023 that promotes the integration of MGs in NIZs in accordance with a set of parameters [26], and also different laws, such as Law 142-143 1994 for the INS.

3. Technical Impacts in the Electric Power System

Due to the different advantages offered by MGs and since they are part of the solution to different problems that currently arise, the integration of MGs in the EPS is on the upswing; however, it is due to the implementation of this type of system that conditions and/or effects are being generated in the EPS due to a series of impacts of an economic, technical, social, and environmental nature in the electrical networks since a transformation that involves interdisciplinary fields is being carried out.

However, for this paper, it is important to understand and classify according to the scientific literature the different technical impacts that are generated due to the implementation of AC MGs in the grid from transmission to distribution, as well as identifying the causes, effects, advantages, and/or disadvantages that MGs can offer, so that those who have purposes of installation, creation, innovation, and research of MGs, such as grid operators, technology providers, companies, and researchers, can establish criteria and indicators through which the feasibility of projects involving MGs can be determined.

Nowadays, the proliferation of MGs is occurring globally; however, in the case of Colombia, this is not as developed given the fact that the country is beginning the EPS transformation process that involves MGs as one of the main actors. It is because of this grid evolution that the energetic profile of the country is changing and now has the active participation of renewable sources, as shown in Figure 6, whose integration in the EPS may require the presence of MGs.

Nevertheless, it is also interesting to recognize that internationally there are already several systems that integrate both small- and large-scale MGs and that recently there has been an interest in understanding the different technical impacts, making it difficult to find studies and information to identify in the literature the impacts shown below.

3.1. Technical Impact Justification: Causes, Effects, Advantages, and Disadvantages

As stated in the previous section, the implementation of MGs in the EPS brings with it different technical impacts, and it is interesting to understand the causes and effects and how this can be interpreted by the EPS to be able to recognize if they represent an advantage or a disadvantage to the system. That is the main reason why, in this section, the characteristics of the technical impacts found in the scientific literature are presented.

3.1.1. Protections

Electricity is a fundamental element in the development of human life, hence the importance of the correct operation of the EPS since it oversees supplying electric power to final users. However, the different stages of the system and the grids that compose it are threatened by a series of failures that endanger the supply of this fundamental energy, which is why a protection system (PRS) has been set up to guarantee reliability and ensure the safety of the different electrical equipment, people, living beings, and installations. Nonetheless, the PRS is not only about designing and selecting a series of relays and identifying each of their protective functions, but also about the way in which they will act in conjunction with the elements of the system to guarantee the services on which millions of people depend [27]. That is why the reliability of the systems resides in the correct selection process of the PRS, which works under the principle of coordination and adjustment, and seeks greater reliability and protection in the EPS operation.

Finally, it is important to also consider that the implementation of MGs in the EPS represents for the PRS a transformation in the configuration of the grid, which is why it is necessary to readjust the PRSs; otherwise, the grid update will not allow protections to act correctly. This can be explained as follows: MGs change the structures of the traditional grid, making them variable over time, which generates changes in the parameters under which the design, construction, selection, and operation of protections are based, and this change in the configuration of the grid generates in most cases a disability in the traditional protection systems [28,29].

Some of the technical impacts identified in protections due to the implementation of MGs in the EPS are presented as follows:

Fault Current Parameters

The DG component of the MGs can generate a change in the magnitude and direction of the fault current; this has two direct impacts on protections:

• Erroneous Operation
  This phenomenon occurs when a fault appears and the MG together with the system contribute to the short circuit, causing the fault current level to change, so the protection equipment is not able to identify and recognize that it is a faulty situation, and this impacts the sensitivity of the protection equipment [9,29,30].
• False Tripping
  Due to the presence of MGs, the short-circuit levels rise, and this affects the nearby grids [31]. This is presented when a fault occurs in a system and an MG is operating in a neighboring grid; the DG component of the MG contributes to the fault and generates a change in the parameters that were established in the PRS. The most common case of false tripping occurs when the relay’s pickup current value changes. This produces tripping of the relay in a protection zone that is not presenting any faults, while the relay that should clear the fault does not act or acts with delay, affecting the selectivity and speed of the PRS [27,29,30,32,33].

Resynchronization

If initially the presence of the MG in the system is not considered, normally when the fault occurs, the reclosers located in the distribution systems act and clear the fault.

However, in a system in which the MG is connected to the system, in the presence of a fault, the DG component of the MG will be in charge, along with the distribution grid itself, of contributing to the fault. If the traditional reclosers operate when the fault occurs, they would only be able to clear the situation on the network side, leaving the MG as the only contributor to the fault [27,29,33]; therefore, the fault goes from a transient state to a permanent one [30,31], and when the connection of both systems is restored, problems will be generated due to the union of the two unsynchronized systems [9].

Blindness

When an operating MG is connected to the system, a change in the equivalent impedance occurs, which results in a reduction in the value of the fault current [27,31]. However, the fault current is an important configuration parameter of the protection equipment because it allows the selection of the operating ranges of the relays. Then, if the fault current decreases or changes significantly, the operation of the protection equipment can be severely limited and affected, and this represents partial or total blindness of the relay [9,29,30,33].

Fault Current Level

When an active system is connected to the grid, the fault current level changes [27,30]; however, this is highly dependent on conditions such as the type of system, connection, operation, nature of the generation source, and impedance of the grid [31,33]. Nonetheless, this variation in the fault current directly affects the interaction between the elements of the PRS, resulting in a loss of coordination, and affects the operation ranges of the relays, which increases the possibility of the occurrence of faults with higher magnitudes that are harder to control or eliminate [34].

Distance Relay

The functioning principle of the distance relay is based on the existent fault current and its direct relation to the impedance between the fault point and the relay. Nevertheless, when the MG operates together with the system, a variation in the impedance and the fault current magnitude occurs [30,31], disturbing the operation of the relay that, in the worst-case scenario, is unable to operate because its configuration parameters contain information that has been obtained from the traditional system that does not consider the effects that the operating MG creates in the grid when connected.

Interoperability

With the integration of MGs in the EPS, new protection elements will be added to the electrical grid, such as intelligent electronic devices (IEDs). This carries different interoperability, compatibility, and security issues [27,30,31] because of the coalescence of advanced technologies with traditional systems. However, these new elements modernize the grids and open the possibility of making the PRS a much more efficient system.

Bidirectionality

MGs are versatile systems capable of supplying the demanded energy in a determined time; nevertheless, there are situations in which bidirectional energy flows in the grids since the MGs can send or receive energy. This causes problems in the PRS and in other systems that belong to the grid because most of the relays are designed unidirectionally [21,29], which implies that they are incapable of detecting faults that occur if the current changes direction [30].

Selectivity

The implementation of MGs affects the selection process of protection equipment due to the changes in the parameters on which its operation is based. That is why the selection of these elements and the identification of their operation ranges have to be based on the variations that the system has when an MG connects or disconnects from the EPS [31,35].

3.1.2. Power Supply

Due to the implementation of MGs, EPS networks are no longer passive systems [36] but active systems [31,37,38] since the generation elements are now located in different stages of the system, such as distribution and transmission. It is due to these changes that different impacts are generated that bring with them certain advantages and disadvantages, such as the opening of greater options for both end-users and operators or, on the other hand, the security problems that may arise.

3.1.3. Cybersecurity

MGs in the EPS bring with them changes in the grid infrastructure that are accompanied by major technological transformations, which give the MGs greater intelligence capacity and increase the benefits that can be offered to the different users and operators of the grid; however, this progress in terms of intelligence and automation of MGs opens a large surface that is exposed to cyberattacks. That is why EPSs that involve MG implementation are exposed to cyberattacks that may have severe consequences [39,40]. Nevertheless, new technology also brings more benefits in terms of autonomy, efficiency, and control, among others. Likewise, systems such as supervisory control and data acquisition (SCADA) systems [41], substation automation systems (SASs), phasor measurement units (PMUs), MGs, and DERs that are implemented in actual SGs involve different communication protocols such as MODBUS and Distributed Network Protocol (DNP3), but the above does not guarantee or imply protection against cyberattacks [39,42,43], which makes the EPSs more vulnerable group.

To identify the impacts on the cybersecurity of the EPS after the MGs are implemented, it is important to clarify that the existence of vulnerabilities and threats is considered an impact; however, vulnerabilities are non-materialized impacts, while threats are materialized impacts by means of different techniques and agents. Now, some impacts on the cybersecurity of an EPS with the integration of MGs are presented.

Internet

The MG’s control center allows the MG to connect to the internet, making it a much more intelligent system since it can exchange data and obtain information on factors such as energy prices, status, and weather forecasts. However, through the internet, the MG is exposed to cyberattacks, and this causes the EPS to be compromised, which can lead to interruptions in the power flows between the EPS and the MG [39,43,44].

Wireless Communications

MGs can communicate wirelessly, allowing them to block any physical access to data and information so that it can travel faster; however, this exposes the system by creating possible backdoors that can be intercepted by cybercriminals so that they have much easier access to the information than to that in wired systems [39,43].

Components

The number of components that belong to the MG makes it much more difficult to control, monitor, and secure each of them [39], which makes the visibility and management of these systems harder, so the networks can be exposed [45].

Infrastructure

The use of the old infrastructure and the merging of new technologies, as well as the way in which networks are shared between different network operators and user MGs can make the system much more vulnerable as control and visibility over both systems are largely lost [39,42,44].

External Communications

The need for MGs to communicate externally allows them to increase their operating capacity while increasing their security by exchanging data with different operators [39]. However, this increases the amount of exposure that the system can suffer since communications go outward and travel to other different sectors of the grid [42].

Automation and Control

Automation and control systems in MGs increase effectiveness and flexibility by reducing the possibility of errors occurring and allowing greater speed, monitoring, and flow of data. However, the automation systems can generate new vulnerabilities as new access points are opened, which increases the possibility of a cyberattack occurring [39,43].

3.1.4. Decentralization

Currently, the EPS is centralized since it depends mostly on large generation plants that have different parameters with which the different dispatches are programmed to meet the demand and requirements of the different end-users. However, with the implementation of MGs in these systems, electrical energy generation becomes more independent and local, which can be best described by the term decentralized [36], since the generation points are not located in the large power plants but can be found throughout the different stages of the EPS, bringing different advantages in terms of the services that the system can offer with implemented MGs.

3.1.5. Resilience

One of the main goals of the EPS is to be able to continuously meet the demand. Because electrical energy is a fundamental service on which the regulatory and daily operations of human beings are based, it is currently a matter of great interest to have a much more resilient EPS, in which it is possible to have the ability to supply the demand when the system is compromised due to low-probability events that have a high impact, which may be of natural or human origin, such as natural disasters, equipment failures, or cyberattacks [23,46,47].

However, the implementation of MGs in the system has proven to increase the resilience of the system [47,48], under various factors that highly depend on the type and severity of the events [46], due to the fact that MGs constructively have functions such as load regulation and increased reliability of the EPS; in addition, they have the ability to have different operation modes in which they connect and disconnect from the grid, which is a great advantage to be able to supply the required demand when this function is compromised in the EPS; in addition, given the event where the MG is damaged by a high-impact natural event, in most cases it is able to self-operate to ensure the flow of power to as much load as possible, which allows the system to be reestablished much faster, prioritizing the end-user, compared to conventional service restoration processes, which must start by restoring the major stages of the EPS, which include generation, transmission, distribution, and end-users, while with MGs, the service is first restored to the users [23,47].

3.1.6. Power Quality

As the years go by and technology penetrates more and more into the systems, current electrical grids are becoming more complicated, and implementing microgrids in them can bring problems due to their variable generation component [6,49,50]. Therefore, it is of the utmost importance to constantly monitor the power quality (PQ) in the grids [42,51], since a poor quality can endanger the equipment connected to the system and even living beings. However, it is also essential for the EPS to maintain a good PQ because the MG also needs it as a basic operating condition since renewable sources are very sensitive to PQ problems. Considering the above, depending on the level of MG implementation in the system, the geographical location, and the availability of the generation resource [37], different disturbances in the PQ can be generated [52], which cause major problems in stability and security [49]. Now some impacts on PQ due to the implementation of MGs in the EPS are presented.

Harmonic Distortion

One of the major problems of PQ is the presence of harmonics in the grids, as they represent a threat to the reliable operation of the system [6]. The implementation of MGs in the EPS can cause the system to suffer variations in its PQ due to harmonic injection that can be caused by the non-linear loads of the MGs, the DG’s variable and intermittent nature, and the power electronics elements such as inverters and rectifiers [53]. This can generate power losses in the transmissions lines, increased thermal stresses, increased total harmonic distortion (THD), resonance effects between the inverters and the grid, overheating in the system transformers, and even unwanted tripping in the protections [6,41,49,52,54,55,56,57,58].

However, the existence of standards such as IEEE 519-2022 and IEEE Std 1547-2018 must be considered, as they indicate the levels of maximum harmonic distortion allowed in voltage and current, respectively, in the PCC [59,60]. Even so, harmonic distortion turns out to be such an important problem that in some cases, the MG, due to its high harmonic pollution, exceeds the levels set by the standards [55,56].

Unbalance and Variation in Voltage

In flexible generation MGs, the DG component is variable, so there are several problems with controlling the voltage magnitude [37,49]. Similarly, the various changes in the MG operating modes generate unbalances and voltage variations since the system undergoes a change in topology each time the transfer between the connection with the system and the island mode is made. Finally, due to the low dynamic responses and the low inertia of the MG, the voltage variation is sudden in the event of any change [6,53]. All the above can generate serious effects due to the occurrence of sag and swell phenomena during voltage changes, which are short-duration phenomena where the RMS values of the voltage waves vary and partially or totally affect the system equipment in general. Similarly, associated with voltage variations, there are also phenomena called short and long duration, which are caused by the opening and closing of the cut-off element located at the MG’s PCC and by the different variations in the system loads or the switchover of capacitor banks present in the MGs.

Nevertheless, it should be clarified that the existence of power electronics elements and hierarchical control strategies in MGs allows the minimization of some unbalances in the system [61]. Finally, it has also been identified that, in some cases, the integration of MGs in the system improves voltage regulation due to the introduction of reactive energy in the grid [9].

Frequency Variation

The frequency can present deviations from the values at which it should operate due to the different changes in the system when the MG operates with the grid or when it leaves the system [62,63]. In addition, depending on the scale of the MG to be implemented, there are greater possibilities that the frequency change is compromised; in addition, the MG’s DER component and its high dependence on variable phenomena such as weather, in the case of non-flexible generation MGs, makes the frequency change and causes different changes in the loads [51], which make the generators decrease or increase their speed, not being able to adjust suddenly to the changes in demand. These variations cause problems that must be solved by the different grid operators in order not to incur penalties, since changes in frequency can reduce the useful life of the equipment or, in the worst case, cause damage to the equipment, increase losses, and, in the most extreme case, can cause a total or partial blackout of the system. Such is the impact on frequency that the large-scale implementation of MGs with photovoltaic modules can generate changes in the speed of the system generators, and this can seriously affect their constructive issues [37].

Overvoltage

Voltage levels increase due to the bidirectionality of the MG’s power flows, since the magnitude of the voltage increases as it passes through the capacitor banks and regulators in the opposite direction. This mainly affects the distribution transformers since the overvoltage alters the voltage regulation (AVR) systems, the on-load tap changer (OLTC), their operating power factor, and efficiency since there is a significant difference between the amount of active and reactive power supplied by the distribution grid because the MG provides most of the active power requirements of the load, leaving the reactive power to the distribution network, so the efficiency and power factor decrease [37].

Nevertheless, it is important to clarify that there are several standards, such as IEEE 1547 [36,60], that indicate different general conditions; within are the requirements and some actions that must be carried out to maintain the frequency and voltage within the established parameters in accordance with the system; also, the level of this impact depends largely on the scale of implementation of the MG in the system, the climatic conditions, and the location of the MGs [21,37,49]. However, these standards are constantly being changed and updated in order to adjust and parameterize some of the limits already established [53].

3.1.7. Grid Modernization

When the grid is updated, systems recognized as cyber, which contain advanced sensors, communication technologies, information, and data management, are introduced; this makes the grid an intelligent system called a cyber–physical distribution network (CPDN), which consists of the integration of cyber tools with the physical tools of the EPS at the distribution level [38]. This integration and union of different systems generates a cybernetic impact that can affect the technical and economic operation of the system.

Similarly, it should be clarified that MGs are systems that contain many diverse components that are designed for different generation capacities. This set of elements suffers from problems of compatibility with the grid as they bring with them limitations and requirements in the communications and control systems of both the MG and the system in which they are implemented [21]. However, this can be seen as an opportunity to have more and more multifaceted and interoperable equipment, so it is an impetus for technology to change [34].

3.1.8. Planning, Dispatch, and Operation

In the non-flexible MGs, the DG component is intermittent since it depends highly on uncontrollable conditions, and this variable nature severely affects the operation of the EPS [37]. To achieve an adequate system operation, correct planning, different weather forecasting, and DG service schedules must be carried out so that the requirements of the demand are fulfilled; otherwise, there could appear uncertainties in the dispatch, operation, and reliability of the MG, which can affect the dispatch models of the overall system.

3.1.9. Ancillary Services

A large-scale MG implementation requires more flexible grids that can compensate the different changes in the MG’s output power flows. Because of this, backup systems will be needed in the system, and they require the presence of storage and ancillary services that are capable of counteracting the variable effects of the MG and making the grids more flexible as they can adapt to the different changes in generation; however, the economic effects or losses of these systems must be considered before their implementation [37].

3.1.10. Synchronization

Different parameters, such as frequency, amplitude, and phase sequence, must be considered to make the interconnection between the MG and the grid. This is why there are several control methods in the MGs that allow a satisfactory synchronization with the grid; however, despite having strategies to perform a correct synchronization, an incorrect MG–system connection can generate instability, load imbalances, equipment damage, unwanted tripping in protections, and other effects that can lead to a total interruption of the service, making the system vulnerable [37]. In addition, the effects of MG synchronization on systems that are presenting an unfavorable condition, such as the presence of a fault, should be considered.

3.1.11. Electromagnetic Interference (EMI)

Photovoltaic (PV) modules and wind turbines used in the production of solar and wind energy generate EMI that can affect control signals, communications, measurement, and system equipment because they generate electromagnetic noise and, in some cases, can behave as antennas [37,64].

3.1.12. Reliability

Reliability allows a good relationship between the final user and the grid operator; this is the basis for the establishment of the electric power supply as a fundamental service. One of the great advantages that MGs provide to the system is that they can increase its reliability [38,65,66,67,68,69,70] as they decentralize the generation points through the EPS stages, increasing the proximity between generation stations and loads [71], which translates into a decrease in the different rates of power supply interruptions [72]. Increased reliability can manage the energy demand more efficiently, and this has a direct impact on the decisions regarding priority and the reliability requirements of different loads based on the generated and stored capacity of the MG [66].

However, the reliability of the system is both strengthened and based on the PRSs, which must be more flexible and already be able to operate under the different modes of the MG; the hierarchical controls, which must be decentralized and robust in all the MG [73]; the communication infrastructure, which must be very flexible, distributed, and secure; the planning and operation that must have a relevant forecasting and optimization process [68,74]; and finally, the power electronics, which must increase and be more secure, reliable, and resilient [75].

3.1.13. Interconnected National System (INS)

An MG can reduce the distance between the generation points and the load, which reduces losses and overloads in transmission and distribution systems [61].

3.1.14. Cluster

Clustered MG implementation brings some advantages and disadvantages to the EPS where they will be integrated, which are described as follows:

Efficiency and Reliability

The unification of several MGs can increase the efficiency of the system [76,77] in terms of resource utilization because when an MG cannot supply one of the system loads, the other MGs can provide the amount of power required by the user, which in turn increases the reliability of the provided service [78,79,80].

Stability

High integration of DERs in clustered MGs can create problems related to stability, which generates unbalances in frequency, angles, and voltages. This is much more difficult to control in interconnected MGs compared to a single MG, requiring much more advanced and robust control structures [78].

Resilience

Clustered MGs can supply power to the system in the case where a fortuitous event occurs since they are able to work together in a synchronized way. In addition, it has been found that the probability of failure of all clustered MGs is very low, which is why they can significantly improve the resilience of the system compared to a single MG [76,77,78,81].

3.1.15. Control Systems

With the implementation of MGs, much more flexible control systems must be in place to ensure safe transfers between the different modes of operation of the MG and also to take care of various variables such as voltage, frequency, power, and commercial operations [82,83,84]. If these control systems fail, the ability to manage the MG is lost, and this can endanger the main grid to which it is connected. Therefore, control systems must have three hierarchical levels of primary, secondary, and tertiary control that can guarantee the correct operation of the MGs in the systems [44,47,83,85,86]. In addition, it must be considered that, given the existence of bidirectional energy flows and the high variability of the energy sources of the MG, new control stages are required that can decrease or mitigate the variation in voltage and the instability that this can cause [87,88,89,90]. The most demanding, detailed, robust, and flexible control systems can mitigate most of the impacts shown in this document since the control is transversal to all of MG’s areas; in addition, new technologies that can manage the hierarchical control needed in the MG by means of Internet of Things (IoT) are arising [91].

This impact can represent an advantage to the system since it is an opportunity to implement improvements in these systems; if they fail, this represents a great risk for the system; therefore, this impact also represents a disadvantage.

Finally, in

Table 3. Summary of impacts due to the implementation of MGs with identification of causes, effects, advantages, and/or disadvantages for the EPS.

Identified Technical Impact	Identified Case	Cause	Effect	Advantage	Disadvantage	Ref.
Protections	a. Fault Current Parameters	Changes in magnitude and direction of fault current due to MG implementation	Erroneous operation		X	[9,29,30]
			False tripping		X	[9,27,29,30,31,33]
	b. Resynchronization	Traditional protection conditions MG contribution to faults	Problems in synchronization of both the system and MG’s protections		X	[9,27,29,30,31,33]
	c. Blindness	Changes in the equivalent impedance of the system due to the MG connection	Protection blindness		X	[9,27,29,30,31,33]
	d. Fault Current Level	Changes in the fault current level due to the implementation of an active system such as an MG	Direct impact on the coordination between elements of the PRS and their operating ranges		X	[27,30,31,33,34]
	e. Distance Relay	Changes in the impedance and in the magnitude of the fault current detected by the distance relay due to the operation of MG in the system	Erroneous operation of the distance relay		X	[30,31]
	f. Interoperability	New protection elements in the electrical grids	Interoperability, compatibility, and security issues Modernization and the possibility of making PRS more efficient	X	X	[27,30,31]
	g. Bidirectionality	The presence of bidirectional energy flows in the grids since the MG can send or receive energy	In most cases, inability to detect faults when there is a change in direction in the fault currents		X	[21,29,30]
	h. Selectivity	Variations in different system parameters when an MG is connected and disconnected	Difficult selection process of protection equipment due to changes in the parameters on which its operation is based		X	[31,35]
Power Supply		Implementation of MGs, which include the active generation component at different stages of the system	EPS grids cease to be passive systems and become active systems, which opens greater options as an improvement Some problems related to security can be created, and good planning is required	X	X	[31,36,37,38]
Cybersecurity	a. Internet	MG’s ability to connect to the internet	The MG becomes a more intelligent, dynamic, and autonomous system capable of providing great benefits to users and operators Possibility of cyberattacks that can expose the EPS	X	X	[39,43,44]
	b. Wireless Communications	Transition from wired to wireless communications	Elimination of the possibility of physical access to data; greater speed in obtaining and sending the necessary information to other areas of the system EPS’s exposure to cyberattacks makes it easier to intercept information	X	X	[39,43]
	c. Components	Great number of components used by MGs	Difficulties in the control, monitoring, communication, and security of each of the elements that comprise the MG make visibility and protection of each of the elements difficult and can expose the system to attacks		X	[39,45]
	d. Infrastructure	Shared old and new infrastructure for the union between the passive and active systems	Loss of control and visibility over both MG and EPS assets, opening new attack surfaces		X	[39,42,44]
	e. External Communications	MG’s external communication requirements	Increased operating capacity and increased security due to data exchange with the different network operators The system becomes more vulnerable because communications are directed outwards	X	X	[39,42]
	f. Automation and Control	Increased installation of automation and control systems and equipment	Increased effectiveness and flexibility by decreasing the possibility of errors and increasing the speed, monitoring, and flow of data Generation of new vulnerabilities represented in access points	X	X	[39,43]
Decentralization		When implementing MGs, power generation becomes more independent and local	Decentralization of the system by reducing the dependence on large generation plants	X		[36]
Resilience		Presence of MGs in the EPS, MG operating modes (stand-alone and grid-connected), ESSs, DERs, load regulation, self-operation, and service restoration capability with user-focused priority	General increase in the system’s resilience	X		[23,46,47,48]
Power Quality	a. Harmonic Distortion	MG’s non-linear loads, DG’s variable and intermittent nature and power electronics elements	Power losses in the transmission lines, increased thermal stress, increased total harmonic distortion (THD), resonance effects between the inverters and the grid, overheating in the system’s transformers, and unwanted protection tripping can be generated in the grid		X	[6,41,49,52,53,54,55,56,57,58]
	b. Unbalance and variation in voltage	Variable nature of the DG component in flexible generation MGs; changes in operating modes; low dynamic responses; low inertia of the MG; opening and closing of the PCC-located cut-off element; different variations in the system loads or the switchover of MG’s capacitor banks Implementation of control techniques and power electronics equipment	Sag and swell phenomena, of long and short duration, that partially or totally affect the elements that are connected to the system Improvements to unbalances and voltage profiles		X	[6,9,37,49,53,61]
	c. Frequency Variation	Changes in the operation modes of the MG, the MG’s scale of implementation, the DER component, and high dependence on variable phenomena in non-flexible generation and changes in loads	Reduction in the equipment’s lifespan or total damage, increase in losses, and, in the most extreme case, can cause a total or partial blackout of the system		X	[37,51,62,63]
	d. Overvoltage	Power flows through capacitor banks and voltage regulators in the opposite direction as a result of the bidirectionality that the MG can maintain	Direct impact on AVR systems, OLTC, power factor, and efficiency of system distribution transformers		X	[21,36,37,49,53]
Grid Modernization		Introduction of cybernetic infrastructure in the EPS Large number of diverse components in the MG that are designed for different generation capacities	Cybernetic impact that can affect the technical and economic operation of the system Network compatibility issues as they bring with them limitations and requirements in communications and control systems Opportunity to have more multifaceted and interoperable equipment seen as an improvement in technology	X	X	[21,38]
Planning, Dispatch, and Operation		Variable nature of the DG component of the MG, in non-flexible generation	Uncertainties in dispatch, operation, and reliability of the MG and the system		X	[37]
Ancillary Services		Large-scale MG implementation	There is a need for a more flexible EPS in which ESSs and/or ancillary services should be implemented to meet the changes generated by MGs	X	X	[37]
Synchronization		Incorrect synchronization between MG and grid	Instability, load imbalances, equipment damage, unwanted tripping of protections, and other effects that can lead to a total interruption of the service, which makes the system vulnerable		X	[37]
Electromagnetic Interference (EMI)		EMI produced by PV modules and wind turbines in MGs	Affects the control signals, communications, measurement, and system equipment		X	[37,64]
Reliability		Decentralization of the generation points through the EPS stages increasing the proximity between the generation stations and the loads	Increased reliability by reducing the different rates of power supply interruptions More efficient management of energy demand as it is more prioritized and based on the MG’s generated and stored capacity	X		[38,65,66,67,68,69,70,71,72,73,74,75]
Interconnected National System (INS)		Reduction in the distance between the generation points and the load	Diminishment in losses and overloads in transmission and distribution	X		[61]
Cluster	a. Efficiency and Reliability	Implementation of clustered MGs in the system	Increased efficiency and reliability in the system since it can supply the load’s required power when one of the interconnected MGs cannot supply it	X		[76,77,78,79,80]
	b. Resilience	Implementation of clustered MGs in the system	Significant improvement in the system’s resilience compared to a single MG	X		[78]
	c. Stability	High DER penetration in clustered MGs	Unbalances in frequency, angles, and voltages; difficulties in control; and advanced and robust control system requirements		X	[76,77,78,81]
Control Systems		Bidirectional flows and high variability of non-flexible energy sources in the MG	There is a need for control systems with primary, secondary, and tertiary hierarchical levels to ensure the correct operation of the MGs in the systems, in addition to more demanding, detailed, robust, and flexible control systems	X	X	[44,47,82,83,84,85,86,87,88,89,90]

Source: authors.

, the causes, effects, advantages, and/or disadvantages of the identified technical impacts shown above, as seen from the EPS, are summarized and recognized.

3.2. Identified Technical Impact Classification

A classification of the identified technical impacts is presented in this subsection since it is important to organize and synthesize the obtained information. The following is a classification of the identified technical impacts, with the objective of organizing and synthesizing the information previously shown to be able to construct what has been called the classification diagram of technical impacts. To make this possible, four classification parameters have been established that are mainly affected by the implementation of the MGs in the EPS.

The classification parameters and their definitions are as follows:

1.

Electrical Variables

These are those technical impacts that affect at least one of the electrical variables that are mainly influenced by the implementation of MGs, such as frequency (f), voltage (V), active power (P), reactive power (Q), and Current (I).

2.

Grid Configuration

Technical impacts that take place in the system due to the implementation of MGs and that are related to changes that occur in the system configuration.

3.

Technology

Technical impacts related to the renovation of the system in terms of the introduction of new technologies.

4.

Service

Technical impacts that affect the services offered by the system to the network operator and/or user.

Table 4. Classification of the identified cases in technical impacts.

Identified Technical Impact	Identified Case	Electrical Variables	Grid Configuration	Technology	Service
Protections	a. Fault Current Parameters	X		X	X
	b. Resynchronization	X		X	X
	c. Blindness	X		X	X
	d. Fault Current Level	X			X
	e. Distance Relay	X		X	X
	f. Interoperability			X	X
	g. Bidirectionality	X	X	X	X
	h. Selectivity			X	X
Power Supply			X	X	X
Cybersecurity	a. Internet	X		X	X
	b. Wireless Communications	X		X	X
	c. Components			X	X
	d. Infrastructure		X	X	X
	e. External Communications			X	X
	f. Automation and Control		X	X	X
Decentralization		X	X	X	X
Resilience					X
Power Quality	a. Harmonic Distortion	X			X
	b. Unbalance and Variation in Voltage	X			X
	c. Frequency variation	X			X
	d. Overvoltage	X			X
Grid Modernization				X	X
Planning, Dispatch, and Operation					X
Ancillary Services		X	X	X	X
Synchronization		X		X	X
Electromagnetic Interference		X		X	X
Reliability					X
Interconnected National System		X			X
Cluster	a. Efficiency and Reliability	X			X
	b. Resilience				X
	c. Stability	X		X	X
Control Systems		X		X	X

Source: authors.

shows the classification of the identified cases in technical impacts according to the parameters defined above.

3.3. INS and NIZs

Table 4, which considers the causes and effects as well as the advantages and disadvantages of the cases identified with their respective technical impact, has allowed the recognition of the way in which the impacts studied are related to the INS and the NIZs. Based on this information,

Table 5. Technical Impacts in the INS and NIZs.

No.	Identified Impact	INS	NIZ
1	Protections	X
2	Power Supply	X	X
3	Cybersecurity	X
4	Decentralization	X	X
5	Resilience	X	X
6	Power Quality	X	X
7	Grid Modernization	X
8	Planning, Dispatch, and Operation	X
9	Ancillary Services	X	X
10	Synchronization	X
11	Electromagnetic Interference	X	X
12	Reliability	X	X
13	Interconnected National System	X
14	Control Systems	X
15	Cluster	X	X

Source: authors.

is presented.

3.4. Qualitative Assessment

Table 6. Qualitative assessment of identified technical impacts due to implementation of MGs in EPS.

No.	Identified Impact	Qualitative Indicator
		Positive	Negative
1	Protections		X
2	Power Supply	X	X
3	Cybersecurity	X	X
4	Decentralization	X
5	Resilience	X
6	Power Quality		X
7	Grid Modernization	X	X
8	Planning, Dispatch, and Operation		X
9	Ancillary Services	X	X
10	Synchronization		X
11	Electromagnetic Interference		X
12	Reliability	X
13	Interconnected National System	X
14	Control Systems	X	X
15	Cluster	X

Source: authors.

shows the qualitative assessment, by means of an indicator, of the technical impacts identified from the literature for each case; however, it should be noted that this is a topic that should be subjected to a detailed analysis in future research to seek a quantitative assessment.

3.5. Technical Impact Identification in Real-Life Projects Involving Microgrids

Table 7. Identification of Technical Impacts in Real-Life Microgrid projects.

Study Microgrid	Description	Location	Year	Identified Technical Impact	Proposed Solution to Negative Impacts	Ref.
Inland Empire Utilities Agency	MG with wind, solar, and fuel cell power of 13.5 MW for utility operation optimization	USA	2008–2017	Power Supply	-	[92,93]
				Decentralization	-
				Resilience	-
				Power Quality: Unbalance and Variation in Voltage	Battery energy storage systems (BESSs): Li-ion batteries
				Ancillary Services	-
				Reliability	-
				INS	-
San Diego Zoo Solar-to-EV Project	Solar-to-EV Project with EV charging stations with solar power of 190 kW total capacity	USA	2012	Power Supply	-	[92]
				Decentralization	-
				Resilience	-
				Grid Modernization	-
				Ancillary Services	-
				Reliability	-
				INS	-
2500 R Midtown Development	Net zero energy (ZNE) community development with integrated solar power for 34 single-family homes with a total capacity of 280 kW	USA	2014	Power Supply	-	[92,94]
				Decentralization	-
				Resilience	-
				Power Quality: Harmonic Distortion, Unbalance and Variation in Voltage and Frequency	Solar integration system (SIS) in an integrated energy management solution (IEMS)
				Ancillary Services	-
				Reliability	-
				INS	-
				Cluster	-
Alpha Omega Winery	MG of 500 kW total capacity with solar power for a sustainable winery	USA	2015–2016	Power Supply	-	[92]
				Decentralization	-
				Resilience	-
				Ancillary Services	-
				Reliability	-
				INS	-
				Control Systems	-
L & T Chennai Campus	Solar-, wind-, and diesel-powered MG of 1.82 MW	India	2017	Power Supply	-	[92]
				Decentralization	-
				Resilience	-
				Reliability	-
				Control Systems	-
Utah-based Energy Company	Solar- and wind-powered farms	USA	2019	Cybersecurity	Response to the incident Upgrade vulnerable components—CISCO Firewall	[95,96]
Microgrid with 100% Inverter-Based Resources	MG with solar power with a total capacity of 11.3 MW	USA	2020	Protections	Adaptative protections according to the MG’s operation mode	[97]
				Power Supply	-
				Decentralization	-
				Grid Modernization	-
				INS	-
				Control Systems	-
Laguna Grande	Solar and wind-powered MG for Laguna Grande’s community (which belongs to the NIZs of Peru)	Peru	2021	Power Supply	-	[98]
				Decentralization	-
				Resilience	-
				Reliability	-
Engineering School of the Federal University of Mina Gerais	Solar-powered MG	Brazil	2022	Power Quality: Unbalance, Variation in Voltage and Frequency	Grid operational support (GOS) for improving the power quality of the upstream grid	[99]
				Grid Modernization: Combination of Different Battery Technologies	Centralized coordinated control strategy for proportional sharing and equalization of usable energy of batteries
				Control Systems	-
				Decentralization	-
				Resilience	-
				Reliability	-
				Control Systems	-

Source: authors.

shows some cases of real-life MG projects found in the reviewed literature, in which some of the technical impacts shown in this section were identified. In addition, different solutions applied to each project are presented that seek to mitigate or solve some negative technical impacts identified according to the limitations of the information found in the literature.

4. Discussion

Based on the information presented in Section 3, an analysis of the obtained results is carried out. Based on the results presented in Table 3, Table 4, Table 5 and Table 6, a series of graphs were constructed that organize in a quantitative manner the information shown previously and with which a detailed analysis of the results is carried out.

The above allows a visualization of the general panorama of the information that has been investigated, as well as the importance of the section in terms of the subsequent drawing of conclusions and the proposal of new ideas for future research that consider what has been shown in this document as a foundation. Likewise, it allows summarizing the research carried out and pointing out the ideas that have been presented in the different previous sections, allowing the reader to better understand and see what is behind the research, in addition to further substantiating the importance of this work.

4.1. Identification of Study Cases Pertaining to Technical Impacts Due to the Implementation of MGs in the EPS

Based on the information shown in Table 3, which considers 32 cases identified in the literature, the results represented by Figure 7 are presented.

The large percentage of cases identified as disadvantageous for the EPS is evident; however, this value, which corresponds to 56%, should not be translated into an impediment or barrier for the implementation of MGs; on the contrary, it is a result that supports the existing necessity to work more on the creation of regulations and standards [31] that allow addressing each of the challenges encountered. However, although there are still no clear and precise regulations in some countries for the implementation of microgrids, as in the Colombian case,

Table 8. Some standards and regulations for MGs.

Regulation/Standard	Description
IEEE 1547-2018	IEEE Standard for Interconnection and Interoperability of Distributed Energy Resources with Associated Electric Power Systems Interfaces
IEEE 1547a-2020	IEEE Standard for Interconnection and Interoperability of Distributed Energy Resources with Associated Electric Power Systems Interfaces—Amendment 1: To Provide More Flexibility for Adoption of Abnormal Operating Performance Category III
IEEE 519-2022	IEEE Standard for Harmonic Control in Electric Power Systems
IEEE 2030.2-2015	IEEE Guide for the Interoperability of Energy Storage Systems Integrated with the Electric Power Infrastructure
IEEE 2030.7-2017	IEEE Standard for the Specification of Microgrid Controllers
IEEE 2030.8-2018	Standard for the Testing of Microgrid Controllers
IEEE 2030.10-2021	IEEE Standard for DC Microgrids for Rural and Remote Electricity Access Applications
IEEE 2030.9-2019	IEEE Recommended Practice for the Planning and Design of the Microgrid
IEEE P2030.12	IEEE Draft Guide for the Design of Microgrid Protection Systems
IEEE 2050-2018	IEEE Standard for a Real-Time Operating System (RTOS) for Small-Scale Embedded Systems
IEC 61850	Communication networks and systems for power utility automation
IEC 62443	Industrial communication networks—Network and system security
Colombian Regulations
RETIE	Reglamento Técnico de Instalaciones Eléctricas
NTC 2050	Código Eléctrico Colombiano
PIEC 2019-2023	Plan Indicativo de Expansión de Cobertura de Energía Eléctrica
Law 1715	Integración de las energías renovables no convencionales al sistema energético nacional

Source: [31] adapted and complemented by authors.

presents some advances in national and international regulations [100] to address the integration of microgrids both at the INS and NIZ levels.

On the other hand, the 56% obtained stimulates the study, improvement, and/or creation of test systems for MGs that could be based on emerging technology; in addition, it is an incentive for the proposal of new solutions that can Dmitigate, change, or eliminate the impact so that it represents an advantage for the system.

It is important to clarify that, despite being a small percentage, the 16% of impacts that represent an advantage for the system are very important because they show the potential capacity of MGs to bring technical advantages to the EPS, which supports the research and the efforts to continue addressing the current challenges of integrating MGs in the EPS. Finally, the results shown are a quantitative indicator of the panorama in which the identified cases are involved, allowing grid operators to consider and analyze the feasibility of projects that implement MGs.

4.2. Classification of Identified Technical Impact Cases

Table 4 made possible the classification of the 32 cases identified according to four parameters, and with the results of the classification, the diagram shown in Figure 8 was constructed.

It is evident that most of the identified cases will not affect the grid’s structure when the MG is integrated, since only 18.75% have an impact on the configuration of the system; on the contrary, the most affected parameters are technology with 66% and electrical variables with 62.5%, and all these effects will always be reflected in changes in the service and in the close relationship that the system has with the users, which is represented by 100%. The presented results show how important it is to study the technical impacts due to the implementation of MGs in the EPS, since behind the classification it can be seen how different multidisciplinary actors that belong to the EPS are involved, including companies, technology developers, researchers, and the different grid operators.

The classification of the identified cases of technical impacts is substantial for the grid operator and for companies in the sector, since it allows them to quantitatively visualize the number of identified cases that are classified according to the defined parameters, and this makes it easier to establish priority attention strategies for projects that involve MGs since these actors will have to have control over the service, the technology, the electrical variables, and the configuration of the grid. Similarly, it is important for technology developers whose market changes transversally with the system by introducing more and better technology when integrating MGs. On the other hand, the classification can provide researchers with the possibility of understanding and studying the changes that the system will have to undergo with the arrival of MGs in order to propose solutions that minimize, improve, or eliminate the cases identified in this document.

4.3. Technical Impacts in INS and NIZs

By means of Table 5, the technical impacts that take place in the INS and NIZs have been identified, from which the diagrams shown in Figure 9 and Figure 10 have been developed.

These results are very important because they reveal that there is a major challenge due to the integration of MGs in the INS, since 100% of the technical impacts identified in this document may be present in the system at the time the MGs are integrated, which represents a difficulty for the planning, operation, and management of the EPS as it will seek to mitigate, improve, or eliminate the impacts shown.

On the other hand, the 53% obtained for the case of the NIZs in Figure 9 shows that, even though most of the identified technical impacts also occur in the NIZs, it could be easier to deal with them. Likewise, the panorama shown in Figure 10 is very promising since it is evident that the integration of MGs will bring greater benefits since 50% of the eight impacts identified that may occur in these zones are positive. Given the results, MGs are currently a widely used system in the NIZs.

4.4. Qualitative Assessment of the Identified Impacts in INS

Table 6 provides a qualitative assessment of the 15 technical impacts identified based on the information presented in Table 3 and the diagram shown in Figure 11.

The current impacts identified in the literature that can be seen as positive, negative, or positive/negative are distributed in equal proportion with 33%; i.e., there is no predominant characteristic among them. This shows that the integration of MGs in the network is still incipient and cannot offer much information about the technical impacts, which is why there is a long way to go in terms of research, information, and real case studies; however, it is motivating to recognize the existence of positive and positive/negative impacts since they show that there are reasons based on the technical aspects that show that MGs have the potential to become large systems that can work together with the system. The 33% that represents the negative impacts also shows the great efforts that still need to be made by the grid operators, companies, technology developers, and researchers to propose new solutions to these impacts so that they can promptly change the percentages shown in this figure as it illustrates the challenges posed by the integration of MGs in the INS.

4.5. Technical Impact Identification in Real-Life Projects Involving Microgrids

Table 7 shows, in a general way, some real MG projects at a global level. From this information, it is difficult to find reports of real microgrids that show in a technical way the difficulties and benefits obtained due to the implementation of MGs in the EPS. This is believed to be mainly because they are very expensive projects that require a lot of time for implementation, study, analysis, and various resources. However, it is important to know at a real level the panorama and the situations that occur, in addition to the proposed solutions that seek to mitigate or eliminate possible negative impacts that may occur, so more resources should be allocated to research involving real MG projects.

5. Conclusions

• Based on what has been identified in this document, it can be concluded that the implementation of MGs in the EPS must be accompanied by transversal changes in the current system, regulations, and standards; otherwise, if the system does not undergo a transformation simultaneously with the process of implementing MGs, the potential advantages that these systems can offer to the network will be significantly lower compared to the disadvantages.
• Currently, the evidence presented in this article indicates the imminent need to initiate an energy transformation; however, this work allows showing and recognizing that it is not an easy process, that it is necessary to have control over many parameters and to consider many factors that most of the time are not controllable, neither by human beings nor by technology. Therefore, the process of integrating MGs into the system must be carried out gradually, considering the impacts it may have on the system and the research carried out in this regard.
• The results presented in Figure 7 show that despite the fact that the implementation of MGs in the system is mostly disadvantageous (56%), it is important to consider the different regulations, standards, laws, and lines of research that seek solutions to meet the current challenges of integrating these systems.
• Figure 8 shows very important results as it demonstrates how, behind the identified cases belonging to the different technical impacts, there is a whole branch of multidisciplinary actors, such as companies in the sector, grid operators, technology developers, and researchers, who must actively participate as they will be affected in the same way as the system is affected by the implementation of MGs.
• The results shown in Figure 9 and Figure 10 allow us to recognize that the challenges related to MG integration are completely present in the INS (100%), since, despite the fact that the NIZs had impacts at the time of integrating MGs (53%), these were mostly positive (50%), which represents a great advantage and urges towards a much simpler integration.
• The assessment presented in Figure 11 shows some of the current technical impacts based on the literature and how the process of integrating MGs into the EPS is incipient, as it is represented by an equal 33%, as it does not count with much information and requires a long way to go that must be accompanied by more research, testing, and other efforts. However, although the figure shown in this paper is not as positive and does not provide solutions and/or answers to all the questions surrounding this topic, in approximately 5 to 10 years, this picture may change for the better.
• Finally, it is concluded that the subject presented in this work belongs to a topic that corresponds to further review and analysis and that is expected to continue developing in the coming years, since it is extremely important to achieve a viable EPS integration capable of providing great benefits to all parties involved.