Iterative Simulation-Based Design of a Multi Input Controller for a Hybrid Renewable Energy System

Sustainable energy supply is a priority need for the socioeconomic and entrepreneurial development of communities in remote areas. Especially, in a developing country like Malaysia, providing sustainable energy to these areas has become a challenging task for the government. From past records, a micro-hydro plant hardly works for more than one year continuously without having problems like stalling or breakdowns due to ecological/technical problems. Generators' fuel has been very expensive and further away from remote villagers. The enhancement of single-source standalone renewable energy to the hybrid structure will provide an alternative power supply as standby to the consumer load. The one important component to this method is the automated control units that could monitor all resources’ conditions and decide which source of power supply is on standby. The Micro-Hydro is the main source and solar photovoltaic with the other energy resources are at standby. With that, in this study, a design of an iterative sequential controller for multiple inputs, single-output power system was considered and proposed. Micro-hydro and solar photovoltaic renewable energy, energy storage, and Utility grid are used as alternative standby resources, determined by priority. The projected concept is an interactive user-friendly, flexible, visually analytical for remote standalone hybrid renewable energy station regulators. The design applies an algorithm to implement an object-oriented finite-state machines model constructed from Simulink to obtain a multiple-input single-output profile. The model-depicted curves of sequential transition trajectory contour, logic truth table, etc. in the practical selection for project work. The hybrid design of the controller improved the standalone renewable energy system sustainability and alleviate other challenges at a lower cost. Keywords: Hybrid renewable energy resource, iterative simulation-based, design Sustainability, modeling, Finite-state machine

Design and optimization of hybrid renewable energy systems for off-grid continuous operations

The mining industry accounts for a significant portion of the energy demand by the industrial sector. The rising demand for metals around the world, coupled with the depletion of readily accessible ore deposits, has led to mining operations moving to more remote locations with no grid supply of energy. As a result, the operations require transport of fuel over large distances, leading to a significant increase in the overall mining cost. Renewable energy is considered to be the most promising solution to the mining industry energy problem. This work investigates the possibility of operating remote mines on local generation from renewables. A survey of recent literature revealed that while a lot of research had been done on hybrid renewable energy systems design and sizing, little thought had been given to accounting for the stochastic nature of renewable resources in the sizing process. Previous works focused on the sizing of PV-wind-battery systems; other potential generation and storage technologies were largely ignored. The challenge of intermittency in the power output of renewable generation systems had also largely been ignored. This thesis extends the state of the art on hybrid systems sizing by developing models and methodologies to address these challenges. A novel hybrid energy system integrating thermal and electrical renewable generation options with multiple large scale energy storage options is considered in this thesis. Models are developed for the different components of the energy system, with dynamic models incorporated for the material and energy balances of the storage alternatives, leading to a system of nonlinear differential algebraic equations (DAEs). The temporal nature of the renewable resources is accounted for by considering multiple stochastic renewable input scenarios generated from probability distribution functions (PDFs) as inputs into the system model. A reliability measure to quantify the impact of weather-based variability, called the modified loss of power supply probability, is developed. A bi-criteria sizing methodology which allows for the stochastic nature of renewable resources to be accounted for is presented. The approach combines the time series approach to reliability evaluation with a stochastic simulation model. Two approaches for mitigating the impact of intermittency in power outputs of renewable generation technologies are also developed. The first approach is based on system redesign, while the second approach is based on the introduction of an instantaneous response storage option. Case studies were presented to demonstrate the various methodologies. The results show that climate-based variability can have a significant impact on the cost and performance of hybrid energy systems and should always be accounted for in the sizing process. Intermittency needs to be accounted for in some form at the design stage as it can have an impact on the choice of technologies. The integration of thermal and electrical power generation and storage options provide a way to reduce hybrid system costs. The methodologies developed in this thesis are applicable to any location and can easily be extended to incorporate other generation and storage alternatives. They provide the decision maker with necessary information for making preliminary sizing decisions

Advanced control of renewable energy microgrids with hybrid energy storage system

Renewable energy will play an important role in the transition to a new energetic model which, along with other developments of the digital age, will probably bring about the Third Industrial Revolution. However, the change to this new energetic model is subject to overcoming technological barriers, namely the sporadic nature of renewable sources. Which in turn affects both, power quality and economic competitiveness. The imbalance of active and reactive power that renewable energies introduce in the grid causes variation in the voltage supply, grid frequency, harmonics, as well as producing other power quality issues. Energy storage systems appear to be a key factor in compensating generation and demand. The lack of controllability and the penalty for deviations in the regulation market hinder the economic competitiveness of renewable energy. Energy storage systems will be the technological solution enabling controllability in renewable energies, allowing their introduction in the spot energy market. Redesigning the grid into smaller, more manageable units based on microgrids appears as a solution to the outlined problems. In these microgrids, stored energy compensates both the intermittent nature of renewable generation and the randomness of the consumer's behaviour. Traditionally, energy storage has been developed by large hydropower-regulation plants, however, these kinds of plants are subject to natural emplacements and their implementation is subject to environmental impact grades. The high energy density of hydrogen as an energy carrier will play an important role in this new energetic paradigm. However, robust performance and the transient response are the main barriers for its technological implantation and, usually, hydrogen-based systems have a useful life that is sometimes too limited to buffer the associated cost. Batteries and supercapacitors have a better transient response, however, their low energy density does not provide enough autonomy to the system. The design of a hybrid energy storage system, having advanced control systems in charge of taking advantage of each storage system and avoiding the causes of degradation and/or limitations of them, emerges as a technological solution to the problems commented. The high number of constraints and variables to be optimized increases the complexity of the associated control problem, making it necessary to deploy advanced control algorithms. In this thesis, the development of optimal controllers for renewable energy microgrids with hybrid energy storage systems is explored using Model Predictive Control (MPC). The control system is introduction on different time scales resulting in an optimal control solution for the economic dispatch and the power quality of the microgrid. Meanwhile, degradation issues of energy storage systems are analyzed and minimized, improving the longevity of the whole energy storage system

Produção e armazenamento de energia em locais remotos : estudo de caso Aldeia da Cuada, Ilha das Flores

Mestrado em Sistemas Energéticos SustentáveisEm pequenas ilhas o aproveitamento das fontes renováveis constituem uma forte alternativa aos sistemas de produção atuais, podendo-se, com algumas estratégias de produção híbrida, com investimentos aceitáveis no médio prazo, conseguir suprir as necessidades de energia num determinado local. Esta dissertação incide numa revisão bibliográfica de energias, sistemas de armazenamento, e sistemas produtores passíveis de ser aplicados de forma alternativa aos atuais sistemas de produção energética utilizados em pequenos locais remotos. Nesta dissertação é proposto um sistema híbrido, eólico-fotovoltaico, com e sem armazenamento, para a Aldeia da Cuada situada na ilha das Flores, tendo por base os seus consumos energéticos diários. Assim, no estudo apresenta-se o dimensionamento do sistema, bem como a análise económica para diferentes configurações propostas do mesmo. O dimensionamento do sistema proposto foi levado a efeito analiticamente e por recurso ao software Hybrid Optimization Model for Electric Renewable (HOMER).In small islands, the use of renewable sources is a strong alternative to current production systems. With some hybrid production strategies just as acceptable investments in the medium term can be used to supply the energy needs in a certain place. This dissertation focuses on a bibliographical review of energy sources, storage systems, and production systems that can be applied in an alternative way to current energy production systems used in small remote locations. In this dissertation a hybrid wind-photovoltaic system, with and without storage, is proposed for the Aldeia da Cuada located on the island of Flores, based on its daily energy consumption. In this way, the study presents the design of the system, as well as the economic analysis for different configurations. The design of the proposed system was carried out analytically and by resource of the software Hybrid Optimization Model for Electric Renewable (HOMER)

Modelling and optimisation of solar power plants with energy storage systems

To avoid driving climate change on a dangerous path, a substantial reduction in greenhouse gases emissions is required. Hence, a high penetration of renewable energy technologies is essential, but most renewables are either affordable or dispatchable but not both. Energy storage systems integrated into concentrating solar power (CSP) plants can enhance dispatchability and solar-to-electricity efficiency. Besides, the combination of dispatchable CSP plants with lower cost photovoltaic (PV) plants exploits synergies between the reliability of CSP with energy storage and cost of PV. However, this integration leads to complex interactions between the different technologies and requires sophisticated design guidelines to achieve low costs and high dispatchability simultaneously. In this thesis, a two-stage multi-objective optimisation framework for the design and operation of hybrid CSP-PV plants with energy storage is developed. The two-stage optimisation simultaneously optimises the design and operation of a hybrid solar power plant with respect to competing technical and financial performances. The multi-objective operational optimisation stage finds the best operational strategy of a hybrid power plant with energy storage systems. The model, written in Python, uses a typical meteorological year to optimise one-year hourly operation. The results demonstrate that the integration of an energy storage system in a concentrating solar power plant provides dispatchability and, when hybridised with photovoltaic, enhances its competitiveness with current electricity prices. The low mismatch between supply and demand, even when a fixed commitment is required throughout the year, together with high overall efficiency, indicates that the integration of energy storage in hybrid solar power plants is an opportunity to increase the penetration of solar energy in the power sector. The design of reliable and cost-competitive hybrid solar power plants requires the careful balancing of trade-offs between financial and technical performance. Hence, the design optimisation stage optimises the capacities of the main components of the hybrid power plant and handles financial and technical objectives. Different configurations are analysed as case studies throughout the thesis to analyse the impacts, interactions, and synergies of technology integration. Three locations are investigated, which present different solar resource profiles: Seville (Spain), Tonopah (USA), and the Atacama Desert (Chile). The optimisation results are used to develop some guidelines for the optimal design of dispatchable hybrid solar power plants with energy storage based on the given solar resource and required dispatchability. These guidelines provide an initial design for affordable and dispatchable hybrid solar power plants and can enable their widespread deployment. The model developed can be applied to other locations under different input parameters and demand profiles. Besides, the flexibility of the model allows it to be extended in order to evaluate different energy conversion and storage technologies to design hybrid power plants with energy storage under different configurations and requirements. Thus, the optimisation framework can provide valuable information for the integration of different technologies to support the affordable and sustainable transition to a clean energy system

Accurate Sizing of Residential Stand-Alone Photovoltaic Systems Considering System Reliability

[EN] In rural areas or in isolated communities in developing countries it is increasingly common to install micro-renewable sources, such as photovoltaic (PV) systems, by residential consumers without access to the utility distribution network. The reliability of the supply provided by these stand-alone generators is a key issue when designing the PV system. The proper system sizing for a minimum level of reliability avoids unacceptable continuity of supply (undersized system) and unnecessary costs (oversized system). This paper presents a method for the accurate sizing of stand-alone photovoltaic (SAPV) residential generation systems for a pre-established reliability level. The proposed method is based on the application of a sequential random Monte Carlo simulation to the system model. Uncertainties of solar radiation, energy demand, and component failures are simultaneously considered. The results of the case study facilitate the sizing of the main energy elements (solar panels and battery) depending on the required level of reliability, taking into account the uncertainties that affect this type of facility. The analysis carried out demonstrates that deterministic designs of SAPV systems based on average demand and radiation values or the average number of consecutive cloudy days can lead to inadequate levels of continuity of supply.This work has been supported by research funds of the Universitat Politecnica de Valencia.Quiles Cucarella, E.; Roldán-Blay, C.; Escrivá-Escrivá, G.; Roldán-Porta, C. (2020). Accurate Sizing of Residential Stand-Alone Photovoltaic Systems Considering System Reliability. Sustainability. 12(3):1-18. https://doi.org/10.3390/su12031274S118123Twaha, S., & Ramli, M. A. M. (2018). A review of optimization approaches for hybrid distributed energy generation systems: Off-grid and grid-connected systems. 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Evaluation of a hybrid solar power system as a potential replacement for urban residential and medical economic activity areas in southern Nigeria

A hybrid solar power system (HSPS) is an alternate method of supplying electricity that can reduce fuel usage while maintaining power supply security. In this study, the efficiency of HSPS, which consists of Grid Supply (GS), Diesel Power Generation (DPG), Solar-Photovoltaic (SPV), and Battery Storage (BS) systems, was evaluated in two economic activity areas (EAAs) in Southern Nigeria. The cross-sectional research design was used, and the research was based on Behera's energy-led growth theory. Urban-residential and Health were the EAAs considered and chosen using a stratified random sample technique. Southern Nigerian states of Oyo and Lagos provided the samples, which were combined and used for the study. Electricity consumption was calculated using electricity load demand for the two EAAs from 2008 to 2017. For each EAA, an Integrated Renewable Energy Mini/Microgrid Model (IREMMM) based on power load demand and solar irradiation was constructed. Levelized Cost of Electricity (LCOE) (/kWh), and Net Present Cost (NPC) (M) were calculated for one hybrid configuration, SPV-DPG-BS-GS, and two standalone configurations, DPG and SPV-BS. Configurations with SPV integrated had lower LCOEs than DPGs in both EAAs. In Southern Nigeria, solar PV combinations with battery storage provided the highest performance for a hybrid power system. In the medical contexts, a hybrid power system achieves higher overall performance

A new method to energy saving in a micro grid

Optimization of energy production systems is a relevant issue that must be considered in order to follow the fossil fuels consumption reduction policies and CO2 emission regulation. Increasing electricity production from renewable resources (e.g., photovoltaic systems and wind farms) is desirable but its unpredictability is a cause of problems for the main grid stability. A system with multiple energy sources represents an efficient solution, by realizing an interface among renewable energy sources, energy storage systems, and conventional power generators. Direct consequences of multi-energy systems are a wider energy flexibility and benefits for the electric grid, the purpose of this paper is to propose the best technology combination for electricity generation from a mix of renewable energy resources to satisfy the electrical needs. The paper identifies the optimal off-grid option and compares this with conventional grid extension, through the use of HOMER software. The solution obtained shows that a hybrid combination of renewable energy generators at an off-grid location can be a cost-effective alternative to grid extension and it is sustainable, techno-economically viable, and environmentally sound. The results show how this innovative energetic approach can provide a cost reduction in power supply and energy fees of 40% and 25%, respectively, and CO2 emission decrease attained around 18%. Furthermore, the multi-energy system taken as the case study has been optimized through the utilization of three different type of energy storage (Pb-Ac batteries, flywheels, and micro—Compressed Air Energy Storage (C.A.E.S.)