Energy Production Analysis and Optimization of Mini-Grid in Remote Areas: The Case Study of Habaswein, Kenya

Rural electrification in remote areas of developing countries has several challenges which hinder energy access to the population. For instance, the extension of the national grid to provide electricity in these areas is largely not viable. The Kenyan Government has put a target to achieve universal energy access by the year 2020. To realize this objective, the focus of the program is being shifted to establishing off-grid power stations in rural areas. Among rural areas to be electrified is Habaswein, which is a settlement in Kenya’s northeastern region without connection to the national power grid, and where Kenya Power installed a stand-alone hybrid mini-grid. Based on field observations, power generation data analysis, evaluation of the potential energy resources and simulations, this research intends to evaluate the performance of the Habaswein mini-grid and optimize the existing hybrid generation system to enhance its reliability and reduce the operation costs. The result will be a suggestion of how Kenyan rural areas could be sustainably electrified by using renewable energy based off-grid power stations. It will contribute to bridge the current research gap in this area, and it will be a vital tool to researchers, implementers and the policy makers in energy sector

Coordinated Control of Interconnected Microgrid and Energy Storage System

Several microgrids can be interconnected together to enhance the grid reliability and reduce the cost of supplying power to an island area where conventional power grid cannot be connected. Source and load demand do not properly balance always. Besides that, sometimes power and frequency fluctuation has occurred in MG at island mode. Need to design a special control for maintaining the state of charge (SoC) of energy storage system. This paper proposes a new power supply system for an island area that interconnects two microgrids with a single energy storage system (ESS). An algorithm has been proposed that control the microgrids energy storage system for spinning reserve and load power/frequency regulation purpose. The minimum loading constraints of diesel engine generator (DEG) is considered and the SOC of the ESS is properly maintained

Optimatization of hybrid renewable energy systems on isolated microgrids : a smart grid approach

Tese de doutoramento, Sistemas Sustentáveis de Energia, Universidade de Lisboa, Faculdade de Ciências, 2016The energy systems of small isolated communities face great challenges related to their autonomy and resilience, when looking for a sustainable energy future. Hybrid renewable energy systems, composed from different technologies, partially or totally renewable, potentiates a growing security of supply for these isolated micro-communities. Moreover, with a smart grid approach, the possibility to reschedule part of the electricity load is seen as a promising opportunity to delay further investments on the grid’s power capacity, enabling a better grid management, through peak load control, but also to promote a more efficient use of endogenous resources, maximizing renewable penetration. To identify the micro-communities main energy challenges, a literature review was taken, reporting the design and implementation of isolated hybrid renewable energy systems. Since electricity and heat energy vectors can be, in part, assured by endogenous resources, a methodology to optimize demand response on isolated hybrid renewable energy systems was developed, using the electric backup of solar thermal systems for domestic hot water supply as flexible loads. This approach is intended to increase energy efficiency of the energy system, reducing grid operation costs and associated CO2 emissions. A model of the electric impact of the implementation of solar thermal systems and heat pumps for domestic hot water supply was developed and tested for the Corvo Island case study, a small and isolated microgrid, located in the mid-Atlantic with around 400 inhabitants and a diesel power plant. An impact of 60% on peak load and 7% on annual electricity demand was found. In order to tackle this significant impact in the grid, a model for optimizing the economic dispatch of the island was developed, testing multiple demand response approaches to the backup loads, from heuristics to genetic algorithms, having this last one performed best to control the peak load and minimize the operation costs. Nonetheless, there was the need to compare and validate the demand response optimization strategies of this developed model with other available modeling tools, which in the end presented similar results. As the pillar of this thesis is the optimization of hybrid renewable energy systems, the influence of the uncertainties associated to renewables forecast had to be studied, in particular its impact on the demand response scheduling. Wind uncertainties demonstrated to have a greater impact on the grid than the solar ones. Finally, the methodology developed incrementally along the thesis and validated in Corvo Island, was tested on different scales and types of isolated systems. It demonstrated to be especially suitable for small systems with less than 20 MW power installed and over 25% renewable generation, with mostly residential load profiles

Optimal operation control of hybrid renewable energy systems

Thesis (D. Tech. (Electrical Engineering)) -- Central University of Technology, Free State, 2014For a sustainable and clean electricity production in isolated rural areas, renewable energies appear to be the most suitable and usable supply options. Apart from all being renewable and sustainable, each of the renewable energy sources has its specific characteristics and advantages that make it well suited for specific applications and locations. Solar photovoltaic and wind turbines are well established and are currently the mostly used renewable energy sources for electricity generation in small-scale rural applications. However, for areas in which adequate water resources are available, micro-hydro is the best supply option compared to other renewable resources in terms of cost of energy produced. Apart from being capital-cost-intensive, the other main disadvantages of the renewable energy technologies are their resource-dependent output powers and their strong reliance on weather and climatic conditions. Therefore, they cannot continuously match the fluctuating load energy requirements each and every time. Standalone diesel generators, on the other hand, have low initial capital costs and can generate electricity on demand, but their operation and maintenance costs are very high, especially when they run at partial loads. In order for the renewable sources to respond reliably to the load energy requirements, they can be combined in a hybrid energy system with back-up diesel generator and energy storage systems. The most important feature of such a hybrid system is to generate energy at any time by optimally using all available energy sources. The fact that the renewable resources available at a given site are a function of the season of the year implies that the fraction of the energy provided to the load is not constant. This means that for hybrid systems comprising diesel generator, renewable sources and battery storage in their architecture, the renewable energy fraction and the energy storage capacity are projected to have a significant impact on the diesel generator fuel consumption, depending on the complex interaction between the daily variation of renewable resources and the non-linear load demand. V This was the context on which this research was based, aiming to develop a tool to minimize the daily operation costs of standalone hybrid systems. However, the complexity of this problem is of an extremely high mathematical degree due to the non-linearity of the load demand as well as the non-linearity of the renewable resources profiles. Unlike the algorithms already developed, the objective was to develop a tool that could minimize the diesel generator control variables while maximizing the hydro, wind, solar and battery control variables resulting in saving fuel and operation costs. An innovative and powerful optimization model was then developed capable of efficiently dealing with these types of problems. The hybrid system optimal operation control model has been simulated using fmincon interior-point in MATLAB. Using realistic and actual data for several case studies, the developed model has been successfully used to analyse the complex interaction between the daily non-linear load, the non-linear renewable resources as well as the battery dynamic, and their impact on the hybrid system’s daily operation cost minimization. The model developed, as well as the solver and algorithm used in this work, have low computational requirements for achieving results within a reasonable time, therefore this can be seen as a faster and more accurate optimization tool

Metodología de Evaluación y Optimización de Sistemas Renovables Híbridos para Electrificación de Zonas Aisladas de la Red

The objective of this thesis is the definition and development of a comprehensive methodology of energy planning for areas isolated from the mains, considering not only the energy context of the country and its development towards a sustainable scenario, but also studying the potential of renewable generation in the remote area under study, the ability for demand management and the socio-economic aspects involved in the final decision on what renewable energy solution would be the most appropriate in accordance with the characteristics of the location. The research work is organized into three major phases. The first one defines the algorithm of analysis of the context energy of the country and its evolution towards a future energy scenario based on renewable energies. A second phase which analyzes the best configurations of hybrid renewable systems capable of responding to energy needs in the area, sorting them based on their net present value. And a third one introducing the method of multi-criteria analysis which allows to select, from among all possible configurations identified in the previous stage, the most appropriate to the needs and characteristics of the area to study, taking into account not only economic or technical aspects, but also sociological, political, and environmental criteria. Finally, the developed methodology is applied to a case concrete as example of its potential. An isolated community in the Democratic Republic of the Congo has been selected since 90% of the population living in areas isolated from the mains, and being one of the African countries with the greatest potential for renewable energy generation.El objetivo de esta tesis es la definición y desarrollo de una metodología integral de planificación energética para zonas aisladas de la red eléctrica que considere no solo el contexto energético del país y su desarrollo hacia un escenario sostenible, sino también el estudio del potencial de generación renovable en la zona remota a estudiar, la capacidad de gestión de la demanda y los aspectos socio-económicos que intervienen en la decisión final sobre qué solución energética renovable sería la más apropiada de acuerdo con las características de la ubicación. El trabajo de investigación se organiza en tres grandes etapas. La primera donde se define el algoritmo de análisis del contexto energético del país y su evolución hacia un escenario energético futuro basado en energías renovables. Una segunda fase donde se analizan las mejores configuraciones de sistemas renovables híbridos capaces de responder a las necesidades energéticas de la zona, clasificándolas en base a su valor neto actual. Y una tercera donde se describe el método de análisis multi-criterio que permite seleccionar, de entre todas las posibles configuraciones identificadas en la etapa anterior, la más adecuada para las necesidades y características de la zona a estudiar, teniendo en cuenta no solo aspectos económicos o técnicos, sino también criterios sociológicos, políticos y medioambientales. Finalmente, se aplica la metodología a un caso concreto en la República Democrática del Congo como ejemplo de su aplicación. Para el análisis del caso de estudio, se ha seleccionado una comunidad aislada en la República Democrática del Congo ya que el 90% de la población vive en zonas aisladas de la red eléctrica, y es uno de los países de África con mayor potencial de generación con energías renovables.L'objectiu d'aquesta tesi és la definició i desenvolupament d'una metodologia integral de planificació energètica per a zones aïllades de la xarxa elèctrica que considere no solament el context energètic del país i el seu desenvolupament cap a un escenari sostenible, sinó també l'estudi del potencial de generació renovable en la zona remota a estudiar, la capacitat de gestió de la demanda i els aspectes soci-econòmics que intervenen en la decisió final sobre quina solució energètica renovable seria la més apropiada d'acord amb les característiques de la ubicació. El treball de recerca s'organitza en tres grans etapes. La primera on es defineix l'algorisme d'anàlisi del context energètic del país i la seua evolució cap a un escenari energètic futur basat en energies renovables. Una segona fase on s'analitzen les millors configuracions de sistemes renovables híbrids capaços de respondre a les necessitats energètiques de la zona, classificant-les sobre la base del seu valor net actual. I una tercera on es descriu el mètode d'anàlisi multi-criteri que permet seleccionar, d'entre totes les possibles configuracions identificades en l'etapa anterior, la més adequada per a les necessitats i característiques de la zona a estudiar, tenint en compte no sol aspectes econòmics o tècnics, sinó també criteris sociològics, polítics i mediambientals. Finalment, s'aplica la metodologia a un cas concret en la República Democràtica del Congo com a exemple de la seua aplicació. Per a l'anàlisi del cas d'estudi, s'ha seleccionat una comunitat aïllada en la República Democràtica del Congo ja que el 90% de la població viu en zones aïllades de la xarxa elèctrica, i és un dels països d'Àfrica amb major potencial de generació amb energies renovable.Peñalvo López, E. (2017). Metodología de Evaluación y Optimización de Sistemas Renovables Híbridos para Electrificación de Zonas Aisladas de la Red [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/82308TESI

A MPC Strategy for the Optimal Management of Microgrids Based on Evolutionary Optimization

In this paper, a novel model predictive control strategy, with a 24-h prediction horizon, is proposed to reduce the operational cost of microgrids. To overcome the complexity of the optimization problems arising from the operation of the microgrid at each step, an adaptive evolutionary strategy with a satisfactory trade-off between exploration and exploitation capabilities was added to the model predictive control. The proposed strategy was evaluated using a representative microgrid that includes a wind turbine, a photovoltaic plant, a microturbine, a diesel engine, and an energy storage system. The achieved results demonstrate the validity of the proposed approach, outperforming a global scheduling planner-based on a genetic algorithm by 14.2% in terms of operational cost. In addition, the proposed approach also better manages the use of the energy storage system.Ministerio de Economía y Competitividad DPI2016-75294-C2-2-RUnión Europea (Programa Horizonte 2020) 76409

Electric Power Conversion and Micro-Grids

This edited volume is a collection of reviewed and relevant research chapters offering a comprehensive overview of recent achievements in the field of micro-grids and electric power conversion. The book comprises single chapters authored by various researchers and is edited by a group of experts in such research areas. All chapters are complete in themselves but united under a common research study topic. This publication aims at providing a thorough overview of the latest research efforts by international authors on electric power conversion, micro-grids, and their up-to-the-minute technological advances and opens new possible research paths for further novel developments

Analysis of the economic feasibility and reduction of a building’s energy consumption and emissions when integrating hybrid solar thermal/PV/micro-CHP systems

The aim of this paper is to assess the performance of several designs of hybrid systems composed of solar thermal collectors, photovoltaic panels and natural gas internal combustion engines. The software TRNSYS 17 has been used to perform all the calculations and data processing, as well as an optimisation of the tank volumes through an add-in coupled with the GENOPT® software. The study is carried out by analysing the behaviour of the designed systems and the conventional case in five different locations of Spain with diverse climatic characteristics, evaluating the same building in all cases. Regulators, manufacturers and energy service engineers are the most interested in these results. Two major contributions in this paper are the calculations of primary energy consumption and emissions and the inclusion of a Life Cycle Cost analysis. A table which shows the order of preference regarding those criteria for each considered case study is also included. This was fulfilled in the interest of comparing between the different configurations and climatic zones so as to obtain conclusions on each of them. The study also illustrates a sensibility analysis regarding energy prices. Finally, the exhaustive literature review, the novel electricity consumption profile of the building and the illustration of the influence of the cogeneration engine working hours are also valuable outputs of this paper, developed in order to address the knowledge gap and the ongoing challenges in the field of distributed generation

Modeling, Simulation and Control of Wind Diesel Power Systems

Wind diesel power systems (WDPSs) are isolated microgrids that combine diesel generators (DGs) with wind turbine generators (WTGs). Often, WDPS are the result of adding WTGs to a previous existing diesel power plant located in a remote place where there is an available wind resource. By means of power supplied by WTGs, fuel consumption and CO2 emissions are reduced. WDPSs are isolated power systems with low inertia where important system frequency and voltage variations occur. WDPS dynamic modeling and simulation allows short-term simulations to be carried out to obtain detailed electrical variable transients so that WDPS stability and power quality can be tested. This book includes papers on several subjects regarding WDPSs: the main topic of interest is WDPS dynamic modeling and simulation, but related areas such as the sizing of the different WDPS components, studies concerning the control of WDPSs or the use of energy storage systems (ESSs) in WDPSs and the benefits that ESSs provide to WDPS are also discussed. The book also deals with related AC isolated microgrids, such as wind-hydro microgrids or wind-photovoltaic-diesel microgrids