Renewable microgrids provide a remarkable alternative to the
general use of centralized generation sources, mostly supported by
conventional fossil fuel resources. An advanced microgrid concept is
networked microgrids, or multi-microgrids, formed by a group of microgrids.
They provide reliability, resilience and robustness to the grid, reducing
operational costs. Nevertheless, problems related to variability and
uncertainty of these renewables impose remarkable difficulties to control and
operate multiple microgrids at distribution and transmission level. Different
solutions have been proposed to overcome these drawbacks. Moreover, some
contributions suggest coordinated control, architectures and energy
management strategies to be applied at networked microgrids. This paper
identifies and analyzes aggregated and/or coordinated renewable-based
microgrids being able to provide ancillary services, market participation and
communication. These characteristics increase grid flexibility and
reliability, promoting the variable renewable energy integration. Recent
issues, such as cyber-security and cyber-attacks in microgrid networked
operation, are also reviewed as for possible research directions in the
future.
ABSTRACT Analysing jointly communities and projects requires
address energy projects from a socio-technical view. Including communities in
the development of projects requires a better understanding of their social,
economic, environmental, and cultural affairs. Consequently, this work
focuses on a methodological formulation to prioritise energy projects
considering community participation. The community evaluation considered the
Human Development Index and Sustainable Development Goals and adjusted them
according to the information available, and the project evaluation uses the
Net Present Value. The Analytic Hierarchy Process evaluates communities and
projects jointly and establishes prioritisation objectives. Moreover, the
co-construction methodology is the basis to formulate guidelines for
community work. This research found a close relationship between the projects
for improving life quality and education in Nariño.
Summary The Energy Management System (EMS) is a strong need for
achieving cost-effective, reliable, and pollution-free operation of
microgrids operating in isolated areas. Commonly, the EMS approaches use
optimization and rolling-horizon predictions. However, the inclusion of very
short-term predictions increases the complexity of the optimization,
compromising its ability and reliability to operate online. In response to
this problem, this paper proposes a rule-based EMS (RB-EMS) which uses
neither optimization nor prediction horizons. Instead, the RB-EMS evaluates
historical data, and very short-term predictions to calculate the setpoints
of distributed energy resources, and schedulable loads in a cost-effective,
reliable, and sustainable manner. As a form of self-regulation, the RB-EMS
introduces the Reliability Index to calculate the maximum state of charge of
the energy storage system. Given the speed imposed by the very short-term
predictions, the RB-EMS also introduces a start-up manager for diesel units
that present a dead time in their enlistment. The isolated ESUSCON-HUATACONDO
microgrid was used as a testbed for performance validation. The work shows a
first scenario comparing the RB-EMS against a rolling horizon EMS based on
MILP optimization. A second scenario shows the energy management performance
with 1 minute predictions. The better results obtained, and the
computational simplicity of the RB-EMS allows propose it to achieve faster
and more reliable energy management in other isolated
microgrids.
Microgrids have the potential to provide security and
flexibility to power systems through the integration of a wide range of
resources, including distributed energy storage, usually in the form of
batteries. An aggregation of microgrids can enable the participation of these
resources in the main system’s energy and ancillary services market. The
traditional minimum-cost operation, however, can undermine microgrid’s
ability to hold reserve capacity for operation in islanded mode and can
rapidly degrade distributed batteries. This paper studies the impacts of
various operational strategies from distributed energy storage plants on
their revenues and on market prices, considering an array of microgrids that
act in a synchronized fashion. The operational model minimizes the entire
electric power system cost, considering transmission-connected and
distributed energy resources, and capturing capacity degradation of batteries
as part of the cost function. Additionally, microgrid-based, distributed
batteries can provide energy arbitrage and both system-level and
microgrid-level security services. Through several case studies, we
demonstrate the economic impacts of distributed energy storage providing
these services, including also capacity degradation. We also demonstrate the
benefits of providing reserve services in terms of extra revenue and battery
lifespan. Finally, we conclude that limitations in the provision of
system-level services from distributed batteries due to degradation
considerations and higher microgrid-level security requirements may,
counterintuitively, increase system-level revenues for storage owners, if
such degradation considerations and microgrid-level security requirements are
adopted, at once, by a large number of microgrids, leading to unintended,
non-strategic capacity withholding by distributed storage
owners.
M. Farrokhabadi, C. A.
Cañizares, J. W. Simpson-Porco,
E. Nasr, L. Fan, P. A.
Mendoza-Araya, R. Tonkoski, U. Tamrakar,
N. Hatziargyriou, D. Lagos,
R. W. Wies, M. Paolone,
M. Liserre, L. Meegahapola,
M. Kabalan, A. H. Hajimiragha,
D. Peralta, M. A. Elizondo,
K. P. Schneider, F. K. Tuffner, and
J. Reilly.
Microgrid stability definitions, analysis, and examples.
IEEE Transactions on Power Systems, 35(1):13–29, Jan 2020.
📄
This document is a summary of a report prepared by the IEEE PES
Task Force (TF) on Microgrid Stability Definitions, Analysis, and Modeling,
IEEE Power and Energy Society, Piscataway, NJ, USA, Tech. Rep. PES-TR66, Apr.
2018, which defines concepts and identifies relevant issues related to
stability in microgrids. In this paper, definitions and classification of
microgrid stability are presented and discussed, considering pertinent
microgrid features such as voltage-frequency dependence, unbalancing, low
inertia, and generation intermittency. A few examples are also presented,
highlighting some of the stability classes defined in this paper. Further
examples, along with discussions on microgrid components modeling and
stability analysis tools can be found in the TF report.
Energy Management Systems (EMS) are control schemes in charge of
defining the optimal scheduling of dispatchable units in a microgrid. Output
set points from the EMS could be exploited in other control loops that may
benefit from the microgrids expected behavior improving their operation. In
this context, this paper proposes a novel coupled operation of an EMS with an
Adaptive Protection System (APS), such that the information of the EMS serves
to compute the parameters of the protective devices deployed in a microgrid.
This aspect is formalized in the present proposal based on already developed
APS and EMS frameworks. To evaluate the performance of the proposal, the
microgrid installed in Huatacondo, north of Chile, was used as a test-bed.
The obtained results indicate that considering the information provided to
the APS form the EMS improves the overall performance of the microgrid in
case of failure, despite the operating conditions. This also indicates that
moving towards an integrated design of the EMS and APS might enhance the
behavior (robustness) of a microgrid (as a whole) in case of failures or
contingencies.
R. Palma-Behnke, G. A.
Jiménez-Estévez, D. Sáez,
M. Montedonico, P. Mendoza-Araya,
R. Hernández, and C. Muñoz Poblete.
Lowering electricity access barriers by means of participative processes
applied to microgrid solutions: The chilean case.
Proceedings of the IEEE, 107(9):1857–1871, Sep. 2019.
📄
Many people across Latin America still do not have access to
reliable electricity. Although Chile exhibits a comparatively high
electricity coverage, many barriers are still present for the development of
sustainable energy supply solutions exploiting local renewable energy
sources. To face this challenge, a coconstruction methodology is proposed,
which considers a flexible and participatory design with continuous
communication between the technical team of the project and the community,
thus ensuring informed decision making around the project design. In this
context, microgrid-based solutions offer an ideal opportunity to exploit the
integration of energy sources adapted to the specific local characteristics.
The coconstruction methodology allows the identification of local
requirements, less often considered for design procedures based on a
traditional approach, in a joint work with the communities so that the
technological solution is tailored for it. Consequently, different technical
solutions (design adaptations and innovations) have been proposed and
developed under this framework, such as: energy management systems, demand
response strategies, microgrid applications for Mapuche communities,
microformers, a monitoring system that includes social aspects, and vehicle
to grid for microgrids. This paper summarizes the experience of several
microgrid projects in Chile, identifies risks, impacts, control actions, and
discusses their replicability to the Latin American and the Caribbean
region.
The development of a proper protection system is essential for
the secure and reliable operation of microgrids. In this paper, a novel
adaptive protection system for microgrids is presented. The protection scheme
is based on a protective device that includes two directional elements which
are operating in an interleaved manner, namely overcurrent and undervoltage
elements. The proposed protection scheme can be implemented in
microprocessor-based relays. To define the settings of the protective device,
a robust programming approach was proposed considering a finite set of fault
scenarios. The scenarios are generated based on the predictions about the
available energy and the demand. For each decision step, a robust
optimization problem is solved online, which is based on forecasting with a
confidence band to represent the uncertainty. The system is tested and
compared using real data sets from an existing microgrid in northern Chile.
To assess the performance of the proposed protection system, fault scenarios
not considered in the optimization were taken into account. The results
obtained show that the proposed protective device is able to manage those
failure scenarios, as well as those included in the tuning of the settings.
Practical considerations are also discussed.
Abstract—The concept of a microgrid is emerging to be a
technically viable approach for meeting reliable supply of electricity with
increased availability in the presence of large-scale grid disturbances
induced by severe weather events, as well to integrate various types of
electricity sources and storage devices close to consumer loads. The existing
approaches to studying and ensuring the stability of microgrids are largely
incapable of providing the structural certainty to promote true plug-and-play
operation, particularly with changing network conditions. Thus, there is a
need and an opportunity to develop a stability criterion that can truly
promote the plug-and-play capabilities of a microgrid. This article proposes
a novel stability criterion that uses an impedance matching approach in a
microgrid environment. Analytical and simulation results show stability
boundaries that can be used in the grid-tied and islanded
cases.
J. Merino,
P. Mendoza-Araya, G. Venkataramanan, and
M. Baysal.
Islanding detection in microgrids using harmonic signatures.
IEEE Transactions on Power Delivery, 30(5):2102–2109, Oct 2015.
📄
In recent years, there has been a growing interest in
incorporating microgrids in electrical power networks. This is due to various
advantages they present, particularly the possibility of working in either
autonomous mode or grid connected, which makes them highly versatile
structures for incorporating intermittent generation and energy storage.
However, they pose safety issues in being able to support a local island in
case of utility disconnection. Thus, in the event of an unintentional island
situation, they should be able to detect the loss of mains and disconnect for
self-protection and safety reasons. Most of the anti-islanding schemes are
implemented within control of single generation devices, such as dc-ac
inverters used with solar electric systems being incompatible with the
concept of microgrids due to the variety and multiplicity of sources within
the microgrid. In this paper, a passive islanding detection method based on
the change of the 5th harmonic voltage magnitude at the point of common
coupling between grid-connected and islanded modes of operation is presented.
Hardware test results from the application of this approach to a laboratory
scale microgrid are shown. The experimental results demonstrate the validity
of the proposed method, in meeting the requirements of IEEE 1547
standards.
Isolated electrical systems lack electrical interconnection to
other networks and are usually placed in geographically isolated areas -
mainly islands or locations in developing countries. Until recently, only
diesel generators were able to assure a safe and reliable supply in exchange
for very high costs for fuel transportation and system operation.
Transmission system operators (TSOs) are increasingly seeking to replace
traditional energy models based on large groups of conventional generation
units with mixed solutions where diesel groups are held as backup generation
and important advantages are provided by renewable energy sources. The grid
codes determine the technical requirements to be fulfilled by the generators
connected in any electrical network, but regulations applied to isolated
grids are more demanding. In technical literature it is rather easy to find
and compare grid codes for interconnected electrical systems. However, the
existing literature is incomplete and sparse regarding isolated grids. This
paper aims to review the current state of isolated systems and grid codes
applicable to them, specifying points of comparison and defining the
guidelines to be followed by the upcoming regulations.
P. Mendoza-Araya, J. Munoz
Castro, J. Cotos Nolasco, and R. E.
Palma-Behnke.
Lab-scale tcr-based svc system for educational and dg applications.
IEEE Transactions on Power Systems, 26(1):3–11, Feb 2011.
📄
Motivated by the development of power semiconductor
technologies, flexible ac transmission systems (FACTS) devices and their
penetration in the field of electrical power systems, an educational
challenge in complementing theoretical knowledge with practical experience is
recognized. In this paper, the design and implementation of a lab-scale
hardware and software setup is presented. Three small-scale devices,
including a static VAr compensator (SVC) unit, a transmission line model, and
a substation, are developed. The SVC unit is validated by obtaining its
operating characteristic. The lab setup is presented as a platform to carry
out different experiments related to the SVC operation. Safety considerations
in the design are discussed. Steady-state and dynamic analysis are presented
showing the consistency between theory and practice. The potential use of
small SVC units on low-voltage distributed generation schemes is
discussed.
Publicaciones en conferencias y otras
J. Meneses and
P. Mendoza-Araya.
Small-signal stability analysis of smart grids considering high penetration of
power electronics converters and energy markets.
In 2020 22nd European Conference on Power Electronics and Applications
(EPE'20 ECCE Europe), pages P.1–P.11, Sep. 2020.
📄
Future smart grids are expected to have a high amount of
renewable energy sources as well as an advanced metering and communication
infrastructure. These communication technologies offer dynamic information
that can be sent to the utilities and used by the power system operators. The
power system operators drive the scheduling optimization of the generators
usually at a different and slower timescale. However, as the exchange of
information get closer to real-time, it is possible to turn this into a
closed-loop control-based problem, that adjusts the generator and load power
outputs constantly as system conditions change. Under this new scenario, it
is possible to observe interactions between the markets and the physical
power system. This work proposes a methodology to assess the stability of
future smart grids, with high penetration of power electronics converters and
considering the coupling between the power systems and energy markets. The
power system and energy market are modeled to form a feedback system that can
be assessed by the Nyquist stability criterion. The simulations are done in
the MATLAB/SIMULINK environment using the WSCC 3 machine 9 bus power
system.
Aramis Perez, LG Mar,
Fernando Fuentes, Patricio Mendoza,
Guillermo Jimenez, and Marcos Orchard.
Performance of photovoltaic modules after an accelerated thermal cycling
degradation test.
In Proc. Annu. Conf. PHM Soc., volume 11, pages 1–9, 2019.
📄
Typically, datasheets of photovoltaic (PV) modules state that
the guaranteed power production remains constant for a certain period of time
and after this point, a linear reduction begins reaching an estimated 80% of
the original rated power. Moreover, literature reports that the degradation
of PV modules reaches less than 1% per year. In this regard, after 20 years
of operation a typical PV module will deliver approximately 20% less energy
than a the beginning of its life. In this article, the results of an
accelerated thermal cycling degradation test are compared to its brand new
conditions. These results demonstrate that although the performance among the
PV modules is variable when new, after the cycling test the performance of
the degraded PV modules is similar. In this case, the power reduction of the
degraded module varies from 1.4% up o 7.6% when compared to the initial
condition. Furthermore, an Electrochemical Impedance Spectroscopy (EIS)
analysis demonstrates that at high frequencies the results are practically
the same regardless if the panel is new or degraded, but at low frequencies
the variation of the impedance is notorious.
Battery aging is an important issue that should be considered in
the battery modelling. This is paramount when the battery is part of an
isolated microgrid, being this a component with an important investment and
replacement cost. In this work, three published aging models are included in
a microgrid Energy Management System. The performance of these models is
compared. The results show the economic benefits of including the battery
aging model into the Energy Management System. The Energy Management System
with the Copetti and Chenlo aging model has the best performance compared to
the other aging models.
B. Blanco-Contreras,
J. Meneses-Silva, P. Mendoza-Araya, and
G. Jiménez-Estévez.
Effect of constant power load models on the stability of isolated microgrids.
In 2019 IEEE CHILEAN Conference on Electrical, Electronics Engineering,
Information and Communication Technologies (CHILECON), pages 1–6, Nov
2019.
📄
The loads that can be found in microgrids have been changing
over the years and the problems they cause have grown in complexity. For
example, some of the loads present in this type of networks behave like
Constant Power Loads (CPL), among which are the tightly regulated electronic
converters, which have a quick response and a low output fluctuation. The
problem with this type of load is its negative incremental impedance
characteristic, which may cause instabilities in the power network with
multiple power electronic converters. This work presents a study about the
influence of both a dynamic and a static CPL in an isolated microgrid. To
achieve this, the DIgSILENT Power Factory software is used to simulate the
Huatacondo microgrid located in northern Chile. The results show that, when
the load is modeled as constant power, both the voltage and frequency
response to disturbances is worsened with the use of constant-impedance type
loads. We conclude that electronic type loads, which have CPL behavior, could
bring stability issues in isolated microgrids.
M. Montes-Parra,
J. García-Hernández, J. Gordillo-Sierra,
G. Jiménez-Estévez, and P. Mendoza-Araya.
Microgrid energy management system optimization using game theory.
In 2019 IEEE CHILEAN Conference on Electrical, Electronics Engineering,
Information and Communication Technologies (CHILECON), pages 1–7, Nov
2019.
📄
This paper presents an interactive algorithm based on game
theory for optimizing an energy management system (EMS) of a microgrid. As
agents in game, load, storage and energy resources adopt an individual
strategy and through a potential game, they are able to reach a Nash
Equilibrium. Results show energy dispatch for four different agents
conditions, including exclusion of one of the energy sources to emulate plug
and play behavior. Availability and ease to change parameters for agents in
proposed algorithm allows users tune it for several different conditions,
achieving a useful tool for energy management in a
microgrid.
D. Rivera, J. Ponce,
C. Carvallo, P. Mendoza-Araya, and
G. Jiménez-Estévez.
Communication-based fault location, isolation, and service restoration for
microgrids.
In 2019 IEEE CHILEAN Conference on Electrical, Electronics Engineering,
Information and Communication Technologies (CHILECON), pages 1–6, Nov
2019.
📄
The traditional power system protection scheme is obsolete when
it comes to microgrids, since they generate bidirectional power flows due to
the presence of different sources of distributed generation. In case of
failure, these sources contribute to short-circuit currents. It is for this
reason that there are different fields of research around fault location
methodologies. In this paper we present a communication-based fault location
methodology, which uses directional fault passage indicators (FPIs)
communicated with a control center. Through the information received by the
FPIs, the location of faults and the isolation of the affected areas are
carried out. In addition, it performs the restoration of service in healthy
lines, if possible, by means of a reconfiguration of the topology of the
microgrid through sectionalizers.
C. D. B. Rodríguez,
J. A. J. Segura, M. C. C. Ruiz,
G. A. J. Estevez, and P. A. M. Araya.
Evaluating the impact of a v2g scheme on the demand curve.
In 2019 IEEE CHILEAN Conference on Electrical, Electronics Engineering,
Information and Communication Technologies (CHILECON), pages 1–6, Nov
2019.
📄
This paper evaluates how the use of V2G technology has an
important impact on the characteristic of the demand curve. Therefore, a
study case is developed based on the characteristic of Bogota's (Colombia)
demand curve and the statement of different scenarios of V2G participation.
In order to determine when the EV battery is charging or injecting, 3
parameters were considered: Availability, State of Charge (SOC) and a TOU
tariff. In addition, 4 behavior profiles were proposed for different types of
vehicle owners with the objective of analyzing the sensibility of the demand
curve in terms of number of owners with certain daily behavior. Finally, the
results were contrasted by the load factor in each case, where it was shown
that the impact on the demand curve depends mainly on the number of vehicles
incorporated to the V2G scheme, demonstrating an improvement until a maximum
number of vehicles.
T. Roje, A. Navas,
M. Urrutia, P. Mendoza-Araya, and
G. Jiménez-Estévez.
Advanced lead-acid battery models for the state-of-charge estimation in an
isolated microgrid.
In 2019 IEEE CHILEAN Conference on Electrical, Electronics Engineering,
Information and Communication Technologies (CHILECON), pages 1–6, Nov
2019.
📄
In order to compare and improve battery energy storage system
(BESS) models, this work exhibits a comparative study of the Coppeti, the
Coulomb counting, and the Thevenin based models of the State of Charge (SoC)
for lead-acid batteries. Additionally, a multi-model estimator that merges
and exploits the benefits of aforementioned models is proposed by using an
extended Kalman filter (EKF). The performance of the different SoC models are
evaluated by means of simulations in a economic dispatch problem of an
isolated microgrid with an Energy Management System (EMS). The Comparative
study of the SoC models is done using real operation data from the
Huatacondo's microgrid with an EMS based on a rolling horizon strategy. As
shown in the results, the operating costs of the microgrid are considerably
reduced when the multi-model estimator is used, showing a direct impact in
the economical costs of the system.
N. Mira-Gebauer and
P. Mendoza-Araya.
Microgrid small-signal impedance characterization considering droop controlled
inverters.
In 2019 IEEE Power Energy Society General Meeting (PESGM), pages
1–5, Aug 2019.
📄
This paper presents an analysis of the small-signal impedances
of a microgrid that considers droop-controlled inverters. Two indices that
ease the characterization of small-signal impedances are proposed. Through a
study case, the effectiveness of the indices is shown.
O. Nuñez-Mata,
R. Palma-Behnke, and P. Mendoza-Araya.
Robust coordination of overcurrent and undervoltage protection devices for
microgrids.
In 2018 IEEE 38th Central America and Panama Convention (CONCAPAN
XXXVIII), pages 1–6, Nov 2018.
📄
The development of a proper protection system is essential for
the secure and reliable operation of microgrids. In a microgrid, operating
conditions that produce limited magnitudes of fault currents will be
insufficient to activate the overcurrent protective devices. Therefore, it
will be necessary to propose new protection systems for its safe and reliable
operation. In this work, a new methodology for optimal coordination of
protection devices based in a robust optimization is proposed. This proposal
uses a protective device based on the combined action of overcurrent and
undervoltage elements, which are operating in an interleaved manner. Internal
time coordination of both protection elements is required. Once the
overcurrent element is established as the primary protection, and the
undervoltage element as the backup protection, the operating times of the
protective devices are optimized. The methodology was evaluated in the
ESUSCON microgrid, which is a low-voltage isolated microgrid located in
northern Chile. The simulation results show a better performance of the
proposed device than the existing protection system of the microgrid. The
proposed methodology proved its effectiveness by clearing all evaluated
faults in a timely and coordinated manner.
J. Diego Jiménez, S. M.
Vives, E. G. Jiménez, and A. P.
Mendoza.
Development of a methodology for planning and design of microgrids for rural
electrification.
In 2017 CHILEAN Conference on Electrical, Electronics Engineering,
Information and Communication Technologies (CHILECON), pages 1–6, Oct
2017.
📄
Rural electrification brings economic and social welfare to
communities through benefits such as power supply for medical centers,
technology access, household tasks improvement and water quality, among
others. However, due to low population density and low electricity demand,
the cost of extending an existing grid to an isolated community can be very
high, in comparison to a microgrid electrification scheme. This article
presents a methodology for planning and designing a microgrid for rural
electrification of remote off-grid locations. This methodology prioritizes
the quality of life improvements of its inhabitants taking into account
different variables such as: location, renewable energy resources
availability, equipment prices, initial budget, operation and maintenance
costs and equipment replacement costs.
N. F. Mira-Gebauer, E. F.
Rojo-Olea, and P. A. Mendoza-Araya.
Induction machine small-signal impedance for stability studies using dynamic
phasor modeling.
In 2017 CHILEAN Conference on Electrical, Electronics Engineering,
Information and Communication Technologies (CHILECON), pages 1–6, Oct
2017.
📄
The presence of both electronic-converter-based and
rotating-machine-based energy sources in microgrids poses a challenge for its
stable operation. Most of the stability studies in microgrids have been
focused on the electronic converters interfacing a renewable energy source to
an AC microgrid. However, the rotating machines are still a key component of
many microgrids. This paper presents an induction machine model that uses
dynamic phasors as an alternative to d-q modeling. The goal of this work is
to obtain the small-signal impedances of the machine, which could be further
used in stability studies. The results show that the machine model
successfully reflects the actual impedance of the machine obtained by
simulations. The process by which the practical machine impedance is obtained
is also detailed in this paper.
O. Nuñez-Mata,
P. González-Inostroza, P. Mendoza-Araya,
and G. Jiménez-Estévez.
Development of a microgrid protection laboratory experiment for the study of
overcurrent and undervoltage functions.
In 2017 CHILEAN Conference on Electrical, Electronics Engineering,
Information and Communication Technologies (CHILECON), pages 1–6, Oct
2017.
📄
Today, power systems face new challenges in different fields,
such as economic, social, environmental and technical. In the technical
field, a number of issues related to protection systems are recognized, due
to the inclusion of distributed generation and microgrids, among other
aspects. This paper presents a novel laboratory experience aimed at
university students, with the objective of understanding the operation and
limitations that traditional protection systems face today. This is part of
the learning process of the Micro-grid and Distributed Generation course, of
the Department of Electrical Engineering, University of Chile, where the
requirement of complementing the class of electrical protections with a
laboratory experience was detected. In this paper, the methodology for the
design of the experience, including all its stages, is presented. A practical
application to a group of students was included as part of the
pre-assessment, with a view to including improvements to the laboratory
guide. During the evaluation it was possible to verify the degree of
difficulty that the students had, assess their performance, and receive
comments after their completion. With all the information gathered,
improvements for future instances of the experience in the coming semesters
are proposed.
P. Ramirez-Del-Barrio,
P. Mendoza-Araya, F. Valencia,
G. León, L. Cornejo-Ponce,
M. Montedonico, and G. Jiménez-Estévez.
Sustainable development through the use of solar energy for productive
processes: The ayllu solar project.
In 2017 IEEE Global Humanitarian Technology Conference (GHTC),
pages 1–8, Oct 2017.
📄
The Ayllu Solar project's main goal is to foster the sustainable
development of rural/urban communities in Arica & Parinacota region, northern
Chile, by means of using solar energy. This is a 5-year project based on
three pillars, namely, (i) the creation of replicable and scalable energy
solutions, (ii) the development of human capital capacities for the effective
use of solar energy, and (iii) ensuring sustainability including effective
solar energy solutions, business models, support network, community
involvement and a proper institutional framework. Concerning the former, the
project follows a community participatory approach through a
“co-construction methodology”. The projects' methodology considered a
first year of information gathering and the creation of a baseline of solar
energy status, and a second year for the development of “reference
projects”, which are initiatives that will serve as examples to local
communities on how solar energy can be effectively used in their productive
processes. This paper presents the current state of progress, on the third
year of execution of the Ayllu project, of four reference projects presently
under development: (a) an alpaca fiber processing solution that includes
fiber mill and electric shearing units, in Visviri town, (b) tourism in
pre-Hispanic caravan routes, in Putre rural areas, (c) cultivation of river
shrimp through the intensive use of solar energy, in Camarones valley, and
(d) solar dehydration, packing and store systems for fruits and vegetables,
in Caleta Vítor and Chaca valley. The projects are described from the
technical, social, and cultural point of view showing the achievements
reached when integral solutions are proposed instead of the single technical
approach.
O. Núñez-Mata,
R. Palma-Behnke, F. Valencia,
P. Mendoza-Araya, and J. Cotos.
Integrated protection and monitoring system for safe operation of
photovoltaic-based isolated microgrids.
In 2017 IEEE Power Energy Society General Meeting, pages 1–5,
July 2017.
📄
The task of electrifying isolated zones involves several
requirements that must be attended. One option to fulfil this task is by
using isolated microgrids to energize zones typically disconnected from the
main grid. The high penetration of variable energy resources and their
corresponding power-electronics-based interfaces make the operating
conditions of isolated microgrids considerably different than the operating
conditions of large-scale power systems. Consequently, one of the most
important challenges of microgrids is the design of the protection system,
i.e., the traditional protection schemes should be rethought to respond
adequately to safety requirements of isolated microgrids. In this paper a
novel methodology for the protection of photovoltaic-based isolated
microgrids is presented. This scheme responds to changes in the operation
conditions, adjusting the protection devices settings to deal with fault
events and maintain a safe operation. This proposal is tested through an
experimental setup and simulations, showing better results than the other
protection schemes.
C. Sepulveda, R. Moreno,
and P. Mendoza-Araya.
Combined economic and stability analysis of a microgrid: A co-optimisation
approach.
In 2017 IEEE Manchester PowerTech, pages 1–5, June 2017.
📄
Both economics and stability analysis are critical to operate
electricity networks in an efficient and secure manner, especially in the
context of microgrids, where more complex stability phenomena may arise. In
this vein, we propose a combined economic and stability model implemented
through a hierarchical approach, where a master problem determines the
economic system dispatch regardless of stability considerations and then a
slave subproblem attempts to stabilize the master's solution through the
optimization of control gains. If the economic dispatch solution determined
by the master problem cannot be stabilized by slave's adjustments of control
gains, a feasibility cut is generated and added to the master problem to
calculate a new, more stable dispatch solution (master and slave are run
iteratively). We demonstrate that control gains can be co-optimized with
power outputs of generating units (in real time) to obtain more economically
efficient and secure dispatch solutions and therefore that economics and
stability analysis can be combined in a single framework by using advanced
optimization techniques.
P. Ramírez-Del-Barrio,
F. Valencia, A. Marconi-Vargas,
I. Polanco-Lobos, and P. Mendoza-Araya.
An alpaca fiber processing solution based on solar energy for an isolated
location in chile following a co-construction approach.
In 2017 IEEE Mexican Humanitarian Technology Conference (MHTC),
pages 130–136, March 2017.
📄
Sustainable development of rural communities requires defining
development strategies that respect human nature and the environment,
guaranteeing the involvement of the affected community. The aim of this paper
is to analyze a case study where a co-construction methodological approach
was applied to productive projects in isolated rural communities. This
project has the particularity of using local renewable energy resources to
satisfy the energy demand of the productive process. The co-construction
approach was implemented from the kick-off of the project to the operation
and evaluation stages. In this specific case, the proposed methodology
required that the community became involved in the decision-making process
from the beginning of the project. The methodology was applied in the General
Lagos region in the north of Chile, within the framework of the sustainable
development project “Ayllu Solar.” The results showed that high levels of
community engagement could be achieved through the involvement of the
community since the beginning of sustainable development
projects.
R. Sandoval and P. A.
Mendoza-Araya.
Impacts of using microwave oven transformers on micropower distribution grids.
In 2016 IEEE Global Humanitarian Technology Conference (GHTC),
pages 495–501, Oct 2016.
📄
The Microformer project aims to develop electricity distribution
systems from discarded electronic waste, by using a microwave oven
transformer (MOT) as the main component. Even though this project has seen a
few practical applications so far, and there is some knowledge on the
behavior of the lone transformer, a thorough study on the behavior of the MOT
on a larger distribution system coexisting with other transformers has not
been carried out. This paper presents a study of the impact of MOTs on
distribution grids, using a 12-bus lab-scale microgrid. The grid is populated
with MOTs and configured to show typical characteristics of a distribution
system (e.g. unbalance). Model simulations and lab-scale experiments are
carried out for the 12-bus system. The results are presented as a series of
recommendations for future grid developments using MOTs, which include
derating and modifications of MOTs depending on their use within the grid,
and technical adequacy of the Microformer solution as a function of
distribution line length, among others.
O. Núñez, F. Valencia,
P. Mendoza-Araya, R. Palma-Behnke,
G. Jiménez, and J. Cotos.
Microgrids protection schemes.
In 2015 CHILEAN Conference on Electrical, Electronics Engineering,
Information and Communication Technologies (CHILECON), pages 597–602,
Oct 2015.
📄
Microgrids have received much attention in recent years because
of its potential to deliver economic, social, technical and environmental
benefits. However, its implementation has major challenges in different areas
to make them viable, such as control, energy management, and the development
of protection schemes. The latter has several issues still to be resolved. In
fact, in literature, several authors propose methods to deal with such
issues, highlighting those aimed for a centralized protection system with an
adaptive strategy. The challenges of protection systems relate to the
incorporation of distributed generation from renewable sources and its
intermittence, as well as the ability to operate in both connected mode and
islanded mode, which involves continuous change of operation, among others.
This article reviews in detail the challenges to be addressed in developing
microgrid protection schemes, together with the analysis of a real case such
as the Huatacondo microgrid, in northern Chile.
M. John, P. A.
Mendoza-Araya, and G. Venkataramanan.
Small signal impedance measurement in droop controlled ac microgrids.
In 2014 IEEE Energy Conversion Congress and Exposition (ECCE),
pages 702–709, Sep. 2014.
📄
Stable operation of microgrids is highly influenced by
characteristics of generators due to their small size and inertia and fast
and variable dynamics. Recent work has shown that microgird stability can be
determined by analysis of small signal impedances at the point of
interconnection. The purpose of small signal impedance measurement is to
verify the analytical models of single devices and to provide measured
impedances where analytical models are not available, so that stability may
be established. Small signal impedance measurement typically involves in-situ
injection of currents or voltages superimposed upon the operating system. In
droop-controlled microgrids, since the frequency is a function of the power
demand, the injection has to be independent of the frequency. In this paper
an injection approach is proposed using a three phase buck converter.
Analytical models using dynamic phasors are compared to measurement results
obtained in a laboratory microgrid. The injection method and the incremental
phasor models of passive loads are verified and small signal impedance
measurements of an islanded and grid-connected microgrid are obtained
including a voltage source PWM converter.
P. A. Mendoza-Araya and
G. Venkataramanan.
Dynamic phasor models for ac microgrids stability studies.
In 2014 IEEE Energy Conversion Congress and Exposition (ECCE),
pages 3363–3370, Sep. 2014.
📄
This paper develops a dynamic phasor based model for
single-source microgrids aimed at studying small-signal stability. The
modeled microgrids comprise distributed generators and loads operating on a
droop-control strategy. The model provides a convenient set of variables to
represent the system dynamics which are readily compatible with phasor
representation in magnitude and phase angle coordinates. Stability of both a
grid-tied microgrid and standalone microgrid are studied. Analytical results
show interesting stability boundaries in the closed form that can be used for
design and operation of microgrids, supported by simulation results. The
model may be readily extended to include the effects of reactive power
control, power factor control, etc.
P. A. Mendoza-Araya and
G. Venkataramanan.
Impedance matching based stability criteria for ac microgrids.
In 2014 IEEE Energy Conversion Congress and Exposition (ECCE),
pages 1558–1565, Sep. 2014.
📄
Stable operation of the electrical system in the context of
microgrids is imperative to enable their large scale adoption. Even though
many analytical tools used in power systems are readily applicable to
microgrids, there are certain aspects that render them inadequate or
requiring adaptation. This work evaluates several stability criteria applied
to a microgrid environment, which comprises distributed generators and loads
operating on a droop-control strategy. Stability criteria based on impedance
matching at the point of application is proposed. Analytical and simulation
results show stability boundaries that can be used in the grid-tied and
islanded cases.
P. A. Mendoza-Araya, P. J.
Kollmeyer, and D. C. Ludois.
V2g integration and experimental demonstration on a lab-scale microgrid.
In 2013 IEEE Energy Conversion Congress and Exposition, pages
5165–5172, Sep. 2013.
📄
Electric and plug-in hybrid-electric vehicles are soon likely to
be integrated as bidirectional energy storage elements with the electric grid
or local microgrids. This paper discusses the interfacing of a plug-in
vehicle with a lab-scale microgrid, and how this integration was successfully
achieved with a power electronics converter that utilizes a power-following
droop controller. Simulations, which are verified with experimental results
obtained with two electric research vehicles and a lab-scale microgrid,
demonstrate that for both single and three-phase cases the imbalances created
by vehicle charging and discharging meet, or nearly meet the required power
quality and phase imbalance standards. The power-following droop control is
validated as an effective way of supporting the microgrid during transients
as well as maintaining, in the long term, a desired charging rate. Fast
charging is also briefly introduced as part of the future
work.
D. Ludois, J. Lee,
P. Mendoza, and G. Venkataramanan.
Reuse of post-consumer e-waste for low cost micropower distribution.
In 2011 IEEE Global Humanitarian Technology Conference, pages
137–142, Oct 2011.
📄
A novel medium voltage distribution system to electrify rural
areas in developing nations using post consumer resources is presented in
this paper. Using transformers repurposed from discarded microwave ovens to
form a medium voltage micro grid, power may be distributed over an area of a
few square kilometers while interconnecting a wide variety of generation
sources and storage at a fraction of the cost of traditional systems.
Microwave oven transformers (MOTs) are systematically characterized for
optimal performance in these cases and construction guidelines are provided.
A candidate distribution system using MOTs was constructed to deliver power
from a small wind turbine to a small building at a horticulture field
station. Results from this demonstration project are
provided.
J. Munoz, P. Mendoza,
J. Cotos, and R. Palma.
Lab-scale three-phase tcr-based svc system for educational purpose in dynamic
and steady-state analysis.
In 2007 39th North American Power Symposium, pages 636–643, Sep.
2007.
📄
Motivated by the development of power semiconductor
technologies, FACTS devices and its penetration on electrical power systems,
an educational challenge in complementing theoretical knowledge with
practical experience is recognized. In this paper, the design and
implementation of a lab-scale hardware and software setup is presented. Three
small-scale devices, including an SVC unit, a transmission line model and a
substation are developed. The SVC unit is validated by obtaining its
operating characteristic. The lab setup is presented as a platform to carry
out different experiments related to the SVC operation. Steady-state and
dynamic analysis are discussed showing the consistence between theory and
practice.
