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Optimal Design of Off-Grid Power Systems

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A special issue of Energies (ISSN 1996-1073). This special issue belongs to the section "A1: Smart Grids and Microgrids".

Deadline for manuscript submissions: closed (15 August 2022) | Viewed by 25669

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Special Issue Editors

Prof. Dr. Davide Poli

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Guest Editor

Department of Energy, Systems, Territory, and Constructions Engineering (DESTEC), University of Pisa, Largo Lucio Lazzarino, 56122 Pisa, Italy
Interests: minigrids for developing countries; optimal size and operation of storage devices; power system reliability; dynamic thermal rating; smart grids
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Dr. Davide Fioriti

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Guest Editor

Department of Energy, Systems, Territory, and Constructions Engineering (DESTEC), University of Pisa, Largo Lucio Lazzarino, 56122 Pisa, Italy
Interests: minigrids for developing countries; optimal size and operation of hybrid energy systems; power system reliability; smart grids; optimization algorithms

Special Issue Information

Dear Colleagues,

Electricity is essential for modern services, appliances, and communication devices, both in a metropolis and in a rural village of a developing country, but the quality and the reliability of this energy vector is very diverse worldwide. Off-grid systems can be cost-effective solutions to provide reliable service also in unconventional situations and remote areas.

In developed countries, most areas are served by the public grid, but some islands and rural territories can be so far from the main continental power system that the corresponding grids are weak or hard to connect to. As a result, many islands and remote communities are supplied by decentralized systems (often diesel-based), because extending the public grid to such locations would be too expensive. Furthermore, depending on the economic and social peculiarities of the context under examination, the power quality and continuity of the industrial process are serious concerns; thus, it is useful that some fractions of the power system, even when usually grid-connected, are able to temporarily operate off-grid, so that when a fault or a blackout occurs in the main network, the local process remains supplied. This means that off-grid systems can be required both for economic and technical reasons, even when a main power grid already exists.

In developing countries, rural areas are rarely electrified, and the population often lacks cheap and reliable electricity service, thus leading to significant social, economic, and healthcare inequalities, described in the Sustainable Development Goals. Due to the small economic activities and the low population density, the corresponding demand is often so limited that does not justify the investment for long transmission lines. Thus, local power systems are seen as promising cost-effective solutions for rural electrification, especially when no service is available, or the public power grid is weak and unreliable. However, accurate economic analyses are required to identify the cost effectiveness and profitability of these solutions, also accounting for the social, economic, political, and technical benefits, such as healthcare concerns, education, and local job creation, among others. Despite the potential benefits of these solutions, private companies are often hindered to enter this market due to the high relevant risks, which shall be compensated by adequate profit opportunities. This is the reason innovative business models are encouraged, considering, for example, the circular economy, the water–energy–food nexus, remote control, pre-paid metering or demand response, among others.

For off-grid systems, exploiting local energy resources, such as solar, wind, hydro or (bio-)fuel, possibly combined with cogeneration, is crucial to cut down long-term costs. The considered solution shall be tailored to the specific context to maximize the economic, environmental, and social benefits. In order to match load and renewable production curves, and their uncertainties, energy storage is then crucial, but this poses complex issues of correct sizing and operation.

Given this context, and especially considering the expected growth in off-grid systems, this Special Issue aims to collect original research and studies on the abovementioned multidisciplinary topics, including all technical, economic, policy, and social aspects related to the optimal design of off-grid power systems. Papers selected for this Special Issue will be subject to a rigorous peer review procedure, with the aim of rapid and wide dissemination of research results, developments, and applications.

We are writing to invite you to submit your original work to this Special Issue, and we look forward to receiving your outstanding research.

Prof. Dr. Davide Poli
Dr. Davide Fioriti
Guest Editors

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Keywords

Isolated hybrid energy systems
Renewable energy sources
Energy storage and batteries
Stand-alone microgrids
Power generation and distribution network sizing
Life cycle assessment (LCA)
Multiyear planning
Water–energy–food nexus
Circular economy
Demand response
Business models
Sustainable Development Goals (SDG)
Energy access
Multiobjective multicriteria approaches
Policy and regulation
Power system security and quality
Rural electrification
Reliability and security
Energy management/generation dispatching
Subsidies/grants

Published Papers (9 papers)

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Research

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20 pages, 2794 KiB

Open AccessArticle

WSPRT Methods for Improving Power System Automation Devices in the Conditions of Distributed Generation Sources Operation

by Aleksandr Kulikov, Pavel Ilyushin, Anton Loskutov, Konstantin Suslov and Sergey Filippov

Energies 2022, 15(22), 8448; https://doi.org/10.3390/en15228448 - 11 Nov 2022

Cited by 4 | Viewed by 1225

Abstract

The trend towards the decentralization and decarbonization of the energy sector stimulates the adoption of generation facilities based on renewable energy sources (RES) and distributed generation (DG) facilities that utilize secondary energy resources. Operation features of DG facilities, such as a high speed of electromechanical transient processes and significant deviations of power quality indicators from standard values, require improvement and an increase in the speed of automation devices. Modern electroautomatic devices must determine the operating regions (normal and emergency) and adapt the operation algorithms to the conditions of the current mode. The study presented proposes methods developed to use the Wald Sequential Probability Ratio Test (WSPRT) to improve the reliability and efficiency of the power system automation devices. The paper provides examples of using WSPRT in the devices of automatic frequency load shedding, automatic transformer disconnection, and power quality control. The results of mathematical modeling confirm the high performance of WSPRT in power system automation devices owing to an increase in the reliability of operating regions identification and speed of response. For example, in the automatic frequency load shedding (AFLS) algorithm for a network with DG facilities at a sampling rate that meets the requirements of the IEC 61850 (80 samples per period), the acceptance time does not exceed 1 ms. The study substantiates the need to use WSPRT in the logic blocks of automation devices employed in active distribution networks. Full article

(This article belongs to the Special Issue Optimal Design of Off-Grid Power Systems)

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25 pages, 29443 KiB

Open AccessArticle

Dimensioning Microgrids for Productive Use of Energy in the Global South—Considering Demand Side Flexibility to Reduce the Cost of Energy

by Johann Kraft and Matthias Luh

Energies 2022, 15(20), 7500; https://doi.org/10.3390/en15207500 - 12 Oct 2022

Cited by 1 | Viewed by 1474

Abstract

Microgrids using renewable energy sources play an important role in providing universal electricity access in rural areas in the Global South. Current methods of system dimensioning rely on stochastic load profile modeling, which has limitations in microgrids with industrial consumers due to high demand side uncertainties. In this paper, we propose an alternative approach considering demand side management during system design which we implemented using a genetic scheduling algorithm. The developed method is applied to a test case system on Idjwi Island, Democratic Republic of the Congo (DRC), which is to be powered by a micro hydropower plant (MHP) in combination with a photovoltaic (PV) system and a battery energy storage system (BESS). The results show that the increased flexibility of industrial consumers can significantly reduce the cost of electricity. Most importantly, the presented method quantifies the trade-off between electricity cost and consumer flexibility. This gives local stakeholders the ability to make an informed compromise and design an off-grid system that covers their electricity needs in the most cost-efficient way. Full article

(This article belongs to the Special Issue Optimal Design of Off-Grid Power Systems)

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22 pages, 3111 KiB

Open AccessArticle

Sizing of an Island Standalone Hybrid System Considering Economic and Environmental Parameters: A Case Study

by Tamal Chowdhury, Samiul Hasan, Hemal Chowdhury, Abul Hasnat, Ahmad Rashedi, M. R. M. Asyraf, Mohamad Zaki Hassan and Sadiq M. Sait

Energies 2022, 15(16), 5940; https://doi.org/10.3390/en15165940 - 16 Aug 2022

Cited by 20 | Viewed by 2108

Abstract

Due to the significance of environmental aspects, the modeling of hybrid systems should be performed with the lowest cost and environmental pollution. Therefore, an effective and optimum sizing method can ensure acceptable performance. This paper implements a “technique for order performance by similarity to the ideal solution” (TOPSIS) method combined with the “analytic hierarchy process (AHP)” method to size a standalone system based on techno-economic parameters. For this reason, a survey was conducted to collect local load data on Monpura Island, located in Bhola, Bangladesh. Visible and design faults of the existing PV/diesel mini-grid have also been identified. Five alternative hybrid configurations have been considered as to evaluate the best optimum system. Two economic and one environmental criterion was used to size the system. Two experts specialized in energy systems evaluated the criteria and proposed the suitable system. Battery, wind and PV capital cost multipliers have been considered as to perform sensitivity analysis. According to techno-economic analysis and expert opinion, PV/biogas/wind has been found to be the most appropriate system among these configurations. The system has a cost of electricity (COE) of 0.691 (USD/kWh) and emits only 4.43 kg of CO₂ per year. The net present cost of the proposed system is 18% lower than the existing microgrid, and the model has lower emissions due to high renewable penetration. It was also found that integrating wind can significantly reduce battery capacity in the mini-grid. The proposed system consumes 34% less batteries than the existing system. Implementing this optimum system can result in greater benefit to the local people. Full article

(This article belongs to the Special Issue Optimal Design of Off-Grid Power Systems)

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13 pages, 1341 KiB

Open AccessArticle

Electrification of Rural Remote Areas Using Renewable Energy Sources: Literature Review

by Dmitriy N. Karamov, Pavel V. Ilyushin and Konstantin V. Suslov

Energies 2022, 15(16), 5881; https://doi.org/10.3390/en15165881 - 13 Aug 2022

Cited by 5 | Viewed by 2325

Abstract

The current stage of development of autonomous energy systems is characterized by a rapid increase in renewable energy sources’ installed capacity. Such growth is observed both in centralized and isolated energy systems. Renewable energy sources show high efficiency in the electrification of rural remote settlements around the world. The power of such power complexes varies from several kilowatts to tens of megawatts. When solving the problems of rural remote settlements electrification, the main issues of optimizing the composition of equipment and the structure of the energy systems play an extremely important role. Moreover, depending on the specifications of the problem being solved, criteria for evaluating efficiency are used, which are different. For example, the following are used as objective functions: minimization of the levelized cost of energy and fossil fuel consumption; maximizing the standard of people living and reliability indicators; the payback period of the project and other indicators. Various combinations of objective functions and the solution to the multi-criteria optimization problem are possible. Moreover, an important stage in the development of renewable energy in remote rural areas is the availability of new mechanisms to support an environmentally friendly generation. These mechanisms can be used in solving problems of optimizing the structure and composition of energy equipment in remote power systems. The main purpose of this article is to demonstrate the world practices of optimal design of isolated energy systems. The review includes both the main questions that arise when solving such problems, and specific problems that require a more detailed analysis of the object of study. Full article

(This article belongs to the Special Issue Optimal Design of Off-Grid Power Systems)

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29 pages, 5062 KiB

Open AccessArticle

Optimization of Hybrid Renewable Energy Microgrid for Rural Agricultural Area in Southern Philippines

by Rovick Tarife, Yosuke Nakanishi, Yining Chen, Yicheng Zhou, Noel Estoperez and Anacita Tahud

Energies 2022, 15(6), 2251; https://doi.org/10.3390/en15062251 - 19 Mar 2022

Cited by 22 | Viewed by 5736

Abstract

Microgrids, or distributed systems of local energy generation, transmission, and demand, are now technologically and operationally capable of providing power to communities, especially in rural and peri-urban regions of developing nations. The reliability of the system, the cost of power generation, and the operating environmental impact are the major issues when designing and evaluating the performance of an off-grid hybrid renewable energy microgrid (HREM). This paper presents an integrated method for optimal sizing and operation of an HREM for rural agricultural communities in the Southern Philippines composed of run-of-the-river hydropower, photovoltaics (PV), diesel generator, and a battery energy storage system (BESS) using multi-objective particle swarm optimization (MOPSO) and a proposed multi-case power management strategy. The three conflicting objective functions that were simultaneously minimized were: loss of power supply probability (LPSP), levelized cost of energy (LCOE), and greenhouse gas (GHG) emissions, subject to several constraints. The optimization generated 200 non-dominated or Pareto optimal alternative solutions, 4 of which were selected as solutions of interest. Based on the results, the optimal sizes of the main components for the reliable operation of the system are 100 panels with a rating of 0.25 kW for PV, 100 kWh for BESS, and 13 kW for the diesel generator, with corresponding LCOE, LPSP, and GHG emission values of 0.1795 USD/kWh, 0.05%, and 7874 kg, respectively, for 1 year. The effectiveness of the proposed HREM design was also analyzed, and the study yielded plenty of useful findings that could aid the electrification of the area. Full article

(This article belongs to the Special Issue Optimal Design of Off-Grid Power Systems)

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17 pages, 3403 KiB

Open AccessArticle

Improving Sustainable Access to Electricity in Rural Tanzania: A System Dynamics Approach to the Matembwe Village

by Francesco Tonini, Francesco Davide Sanvito, Fabrizio Colombelli and Emanuela Colombo

Energies 2022, 15(5), 1902; https://doi.org/10.3390/en15051902 - 4 Mar 2022

Cited by 6 | Viewed by 2585

Abstract

As it emerges from the literature, electricity access in rural contexts is deeply intertwined with socioeconomic dynamics. However, the advent of a reliable and sufficient source of electricity is not the sole driver that might contribute to local development. Indeed, complementary activities might have a crucial role in sustaining the development of rural communities as well as the electricity access. The current research addresses the lack of counterfactual scenarios in which the impact of complementary activities on electrification projects can be investigated. The authors introduce the case study of Matembwe village, a rural community in the Njombe region of Tanzania. The data collection includes the electricity consumption, number of electricity connections, and number of income-generating activities in a timespan ranging from 1989 to 2015. The analysis is based on system dynamics. The study considers different scenarios representing the dynamics related to the following complementary actions: access to market measures, access to credit measures, and access to usable skills. On the one hand, the study reveals that the effectiveness of the considered complementary actions is limited except from the access to microcredit which fosters an increase in electricity connections by 17%. On the other hand, both access to microcredit and the starting up of a local cooperative by CEFA Onlus that reinvests its profits in the local market impact the socio-economic dimension by 69% and 22%, respectively. Full article

(This article belongs to the Special Issue Optimal Design of Off-Grid Power Systems)

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28 pages, 7069 KiB

Open AccessArticle

Off-Grid Multi-Carrier Microgrid Design Optimisation: The Case of Rakiura–Stewart Island, Aotearoa–New Zealand

by Soheil Mohseni, Alan C. Brent and Daniel Burmester

Energies 2021, 14(20), 6522; https://doi.org/10.3390/en14206522 - 11 Oct 2021

Cited by 16 | Viewed by 2561

Abstract

The establishment of the concept of sustainable, decentralised, multi-carrier energy systems, together with the declining costs of renewable energy technologies, has proposed changes in off-grid electrification interventions towards the development of integrated energy systems. Notwithstanding the potential benefits, the optimal capacity planning of such systems with multiple energy carriers—electricity, heating, cooling, hydrogen, biogas—is exceedingly complex due to the concurrent goals and interrelated constraints that must be relaxed. To this end, this paper puts forward an innovative new optimal capacity planning method for a first-of-its-kind stand-alone multiple energy carrier microgrid (MECM) serving the electricity, hot water, and transportation fuel demands of remote communities. The proposed off-grid MECM system is equipped with solar photovoltaic panels, wind turbines, a hydrogen-based energy storage system—including an electrolyser, a hydrogen reservoir, and a fuel cell—a hybrid super-capacitor/battery energy storage system, a hot water storage tank, a heat exchanger, an inline electric heater, a hydrogen refuelling station, and some power converters. The main objective of calculating the optimal size of the conceptualised isolated MECM’s components through minimising the associated lifetime costs is fulfilled by a specifically developed meta-heuristic-based solution algorithm subject to a set of operational and planning constraints. To evaluate the utility and effectiveness of the proposed method, as well as the technical feasibility and economic viability of the suggested grid-independent MECM layout, a numerical case study was carried out for Rakiura–Stewart Island, Aotearoa–New Zealand. Notably, the numeric simulation results highlight that the optimal solution presents a low-risk, high-yield investment opportunity, which is able to save the diesel-dependent community a significant 54% in electricity costs (including electrified space heating)—if financed as a community renewable energy project—apart from providing a cost-effective and resilient platform to serve the hot water and transportation fuel needs. Full article

(This article belongs to the Special Issue Optimal Design of Off-Grid Power Systems)

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Review

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35 pages, 2844 KiB

Open AccessReview

State-of-the-Art Literature Review of Power Flow Control Methods for Low-Voltage AC and AC-DC Microgrids

by Pavel Ilyushin, Vladislav Volnyi, Konstantin Suslov and Sergey Filippov

Energies 2023, 16(7), 3153; https://doi.org/10.3390/en16073153 - 31 Mar 2023

Cited by 10 | Viewed by 2345

Abstract

The development of AC distribution systems provides for the seamless integration of low-voltage microgrids with distributed energy resources (DERs). This poses new challenges for the control of normal, emergency, and post-emergency states of microgrids, calling for the creation and development of information and communications technology infrastructure. Power converters/inverters that are used to integrate renewable DERs lack inertia. Along with them, fossil fuel-fired generation units are also being integrated into microgrids. These include gas generator sets, diesel generator sets, and microturbines, having small (up to 1–2 s) values of mechanical inertia constants—Tj. This leads to an increase in the rate of transients by a factor of 5–10. Under these conditions, the technical requirements for the speed of automatic power flow control systems, as well as the methods they rely on, have to be reconsidered. Microgrids include DC microgrids, AC microgrids, and hybrid (AC-DC) microgrids. In the case of hybrid microgrids, DERs are connected to the DC grid and are integrated into the AC grid through a common inverter. The complexity of the task of microgrid control is due to the need to choose properly the type and extent of control actions so as to prevent the emergence and development of accidents. The employed control methods must ensure the reliable power supply to consumers and the quality of power in microgrids, as well as the reliable operation of the external distribution systems into which they are integrated. The article gives an overview of control methods for low-voltage AC and AC-DC microgrids, which allow one to tackle effectively solve the tasks. Full article

(This article belongs to the Special Issue Optimal Design of Off-Grid Power Systems)

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Other

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25 pages, 22596 KiB

Open AccessProject Report

Design Considerations for Reducing Battery Storage in Off-Grid, Stand-Alone, Photovoltaic-Powered Cold Storage in Rural Applications

by Johan Meyer and Sune von Solms

Energies 2022, 15(9), 3468; https://doi.org/10.3390/en15093468 - 9 May 2022

Cited by 2 | Viewed by 2928

Abstract

This paper presents design considerations for the design and implementation of stand-alone photovoltaic-powered containerized cold storage solutions for rural off-grid applications. The work presented is based on a case study of an off-grid photovoltaic-powered cold storage unit located in rural South Africa. Although solar-powered solutions for off-grid rural applications are very attractive and offer many benefits, including increased food security, skills development, income generation, and productivity due to the presence of solar power, the application of cold storage requires careful consideration of the design aspects to ensure that the solution is feasible and sustainable. The challenge of maintaining low temperatures inside a cold storage system in an excessively warm environment, such as that frequently encountered in most African rural settings, has stimulated discussions of design considerations for optimal efficiency. Not only are the design aspects of the PV panel mounting and tilt associated with the geographic location of the application, but the heating implications are also derived from the physical orientation of the storage unit. Results from mathematical models are substantiated with field data collected from a case deployment. The design considerations for the sizing of the electrical components in the system are presented. The paper concludes by answering the research question as to what design aspects should be considered for an off-grid, PV-powered containerized cold storage system to reduce the size of the battery storage unit. Full article

(This article belongs to the Special Issue Optimal Design of Off-Grid Power Systems)

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