The United Nations has declared 2012 the ``International Year of Sustainable Energy for All''. A substantial portion of the world's population (some 1.3 billion people) currently live without electricity and development efforts to reach them are progressing relatively slowly. This thesis follows the development of a technology which can enable community owned and operated microgrids to emerge based solely on the local supply and demand of that community. Although this thesis ends with the technical analysis of a DC/DC converter, there is a significant amount of background to cover in order to properly understand the context in which it will be used. After providing an introduction into typical rural electrification efforts and pointing out some of the shortcomings of these projects, this thesis introduces some cutting edge efforts which combine solar home system technology with cellular technology and discusses the benefits of such a marriage of technology. Next, the research proposes some tweaks to this novel technology and provides a high-level economic demonstration of the spread of solar home systems in a community based on these modifications. It then takes this concept even further and proposes the addition of a DC/DC converter which could turn these individual solar home systems into a proper microgrid. This thesis elaborates on the development process of simulating such a microgrid in PSCAD, including the individual components of a solar home system and the specific task of designing the converter which would form the backbone of the proposed microgrid. The final simulations and analyses demonstrate a microgrid that is both technically and economically feasible for developing world applications.

Pakistan has been riddled with energy shortage crisis. Long hours of load shedding have caused major economic setbacks in urban areas and rural areas do not even make the cut. Some rural parts, which are connected to the grid, suffer major load shedding and so economic growth is minimal. Most energy is directed towards industrial demand; hence the domestic demand suffers and causes long hours of load shedding. To aid this supply-demand gap, microgrids can be helpful in relieving some of the domestic load on the grid. A microgrid may be more economical only as a support for the main grid in an area, depending on its configuration. Since microgrids are generally composed of renewable energy sources like wind or solar or a combination of both, the supply from just these sources may result in high intermittency. To allow uniform supply, a backup energy source or energy storage is included with the renewable sources. Sizing a microgrid for the targeted region is critical. Some major sizing factors include the availability of renewable resource, load profile of the region, land availability, grid availability, etc. For this thesis, a region near Gharo, a town in Thatta District in Sindh, Pakistan, is selected to deploy the microgrid with a wind farm and battery energy storage system. The microgrid is connected to the main feeder, which supplies grid electricity to a small town of 30 small homes, a school and a small hospital. Hourly wind speed data and an annual load profile is used to calculate the most economic size of the microgrid, depending on the energy dispatch philosophy. To find the most economical solution, this thesis incorporates a stochastic technique, known as the Particle Swarm Optimization (PSO), which is a powerful intelligence evolution algorithm for solving optimization problems. Over the years, PSO has gained popularity due to its simple structure and high performance in solving linear or non-linear objective functions with any number of constraints. In this case, the objective function to be minimized is the net present cost of the microgrid, which comprises of annual capital cost, annual operation and maintenance cost, annual replacement cost of all equipment involved and the annual net cost of buying/selling electricity from/to the grid, respectively.

Microgrids are turning to be one of the most important factors for future power systems. In this thesis, the considered system consists of two resourses, namely Solar and Wind energy. These renewable energy sources are generally connected parallel in Microgrid system. In order to get better performance from Microgrid, the existing system has to be modified. This thesis presents the modeling and control of PV/wind Microgrid. Selection of suitable wind turbine and AC or DC Microgrid is clearly presented in thesis.             Microgrid concept integrates large amounts of micro sources without disrupting the operation of main utility grid. This hybrid Microgrid consists of PV/wind energy sources for DC and AC networks respectively. Energy storage systems may be connected to either AC or DC Microgrids. The proposed hybrid Microgrid operates in grid-tied or isolated mode. AC sources and loads are connected to AC network, whereas DC sources and loads are connected to DC network. Uncertainty and intermittent characteristics of wind speed, solar irradiation level, ambient temperature and load are additionally considered in the system model and operation.

abstract: With ever increasing use of natural gas to generate electricity, installed natural gas fired microturbines are found in residential areas to generate electricity locally. This research work discusses a generalized methodology for assessing optimal capacity and locations for installing natural gas fired microturbines in a distribution residential network. The overall objective is to place microturbines to minimize the system power loss occurring in the electrical distribution network; in such a way that the electric feeder does not need any up-gradation. The IEEE 123 Node Test Feeder is selected as the test bed for validating the developed methodology. Three-phase unbalanced electric power flow is run in OpenDSS through COM server, and the gas distribution network is analyzed using GASWorkS. The continual sensitivity analysis methodology is developed to select multiple DG locations and annual simulation is run to minimize annual average losses. The proposed placement of microturbines must be feasible in the gas distribution network and should not result into gas pipeline reinforcement. The corresponding gas distribution network is developed in GASWorkS software, and nodal pressures of the gas system are checked for various cases to investigate if the existing gas distribution network can accommodate the penetration of selected microturbines. The results indicate the optimal locations suitable to place microturbines and capacity that can be accommodated by the system, based on the consideration of overall minimum annual average losses as well as the guarantee of nodal pressure provided by the gas distribution network. The proposed method is generalized and can be used for any IEEE test feeder or an actual residential distribution network. / Dissertation/Thesis / M.S. Electrical Engineering 2014

Cette recherche se concentre sur l'optimisation d'un micro-réseau en interaction avec le réseau électrique intelligent. Il s'agit de la recherche de solutions optimales pour la conception d'un micro-réseau afin de minimiser les coûts, d'une part, et la possibilité augmenter 1'utilisation des sources renouvelables, d'autre part. La supervision, doit traiter la prise en compte des incertitudes dans la gestion prédictive optimisée des flux de puissance. / This thesis study focuses on a DC microgrid building-integrated satisfying the power balance at the local level and supplying DC loads during both, grid-connected and isolated operation modes. Considering that energy management can be defined as a group of different control strategies and operational practices that together with the new physical equipment and software solutions aims to accomplish the objectives of energy management, the main objective of this thesis is to define the energy management strategies for the building-integrated DC microgrid, aiming to keep the bus voltage stable as well as to reduce the energy cost to the end users and the negative impact to the main grid. Therefore, this research work focuses to optimize and develop the implementation of the designed controller of building-integrated DC microgrid. The proposed DC microgrid consists of PV building-integrated sources, a storage system, a main grid connection for the grid-connected mode and a micro turbine for the off-grid or isolated mode, and a DC load (electric appliances of a tertiary building). The bidirectional connections with the main grid and the storage aim to supply the building’s DC appliances, and sell or store the energy surplus. The results validate the operation of the whole system, ensuring the capability of the proposed supervisory control to manage the energy power flow while ensuring voltage stability. Other goals concern the analyze of the proposed separation between optimization and real time power balance and the usage of the proposed load shedding/restoration algorithm in the microgrid environment are also validate. Regarding the technical contributions, the work of this thesis allowed the creation and the practical development of a test bench for microgrid based on PV sources emulator, which allows the repeatability conditions (closeness of the agreement between the results of successive measurements of the same solar irradiance and air temperature carried out under the same conditions of measurement) and reproducibility (closeness of the agreement between the results of measurements of the same solar irradiation and air temperature carried out under changed conditions of measurement). Numerous experimental tests were carried out and allowed the validation of the proposed concepts.

This report aims to evaluate if and how a microgrid could be constructed on AirSon Engineering AB:s estate. The main focus of the report is legislation, benefits with energy storage, different energy storage systems, system control and energy and power balances. A literature study and processing of data are used to answer the reports questions. The goal with this study is that the microgrid can be constructed without the need of concession. If certain exceptions are met Swedish legislation approves construction of a microgrid without concession. Additionally, the microgrid needs to fulfill the law about micro producers to get tax reduction. If possible, the current through the main fuse will not exceed 63 amperes. By reducing the production, the current can be limited to 63 amperes. Further, three energy storage systems are evaluated, lithium-ion battery, nickel metal hydride battery and hydrogen fuel cell. Lithium-ion battery is best suited when it comes to performance. From an economic perspective the size of the energy storage and charging cycles determines which system that is preferable. Variations in electricity price from night to morning gives an economic benefit from an energy storage via buying electricity night-time and using it in the morning. Furthermore, the energy storage leads to higher self-sufficiency and self-utilization. The microgrid will consist of 104,7 kilowatt peak power solar power and 3 kilowatt wind power. By collecting data from the estate and weather data from PVGIS energy and power balances are calculated. The microgrid will be a direct current grid and will be controlled by a so called EnergyHub, which is a product from Ferroamp that also balances the phases. Moreover, self-sufficiency and self-utilization are used to determine the optimal size of the energy storage system. A larger energy storage system will conclude in higher self-sufficiency and self-utilization. However, the self-sufficiency increases exceedingly little in compared to the increasement of the energy storage size.

Microgrids—miniature versions of the electrical grid are becoming increasingly more popular as advancements in technologies, renewable energy mandates, and decreased costs drive communities to adopt them. The modern microgrid has capabilities of generating, distributing, and regulating the flow of electricity, capable of operating in both grid-connected and islanded (disconnected) conditions. This paper utilizes ETAP software in the analysis, simulation, and development of the Cal Poly microgrid. Additionally, an ETAP power system protection tutorial is created to aid students entering the power industry. Microprocessor-based relays are heavily utilized in both the ETAP model and hardware implementation of the system. Case studies in this project investigate electric power system load flow, short circuit, protection coordination, and transient stability analysis of the Cal Poly microgrid.

Due to increasing changes in the power industry, Cal Poly San Luis Obispo's electrical engineering department introduced a set of initiatives to adequately equip students with the skills and knowledge to interact with new technologies. Specifically, the department proposed a microgrid and power systems protection and automation laboratory to strengthen students' knowledge of microprocessor-based relays. This paper outlines a microgrid laboratory system that fulfills the initiative's goal and proposes a collection of laboratory experiments for inclusion in a new laboratory course at Cal Poly. The experiments provide students with practical experience using Schweitzer Engineering Laboratory (SEL) relays and teach fundamental concepts in semi-automated generator synchronization and power system data acquisition. The microgrid laboratory system utilizes SEL relays and a centralized SEL controller to automate frequency regulation through load shedding, power factor correction, generator and utility synchronization, and relay protection group switching.

The need to cope with the rapid transformation of the conventional electrical grid into the future smart grid, with multiple connected microgrids, has led to the investigation of optimal smart grid architectures. The main components of the future smart grids such as generators, substations, controllers, smart meters and collector nodes are evolving; however, truly effective integration of these elements into the microgrid context to guarantee intelligent and dynamic functionality across the whole smart grid remains an open issue. Energy trading is a significant part of this integration. In microgrids, energy trading refers to the use of surplus energy in one microgrid to satisfy the demand of another microgrid or a group of microgrids that form a microgrid community. Different techniques are employed to manage the energy trading process such as optimization-based and conventional game-theoretical methods, which bring about several challenges including complexity, scalability and ability to learn dynamic environments. A common challenge among all of these methods is adapting to changing circumstances. Optimization methods, for example, show promising performance in static scenarios where the optimal solution is achieved for a specific snapshot of the system. However, to use such a technique in a dynamic environment, finding the optimal solutions for all the time slots is needed, which imposes a significant complexity. Challenges such as this can be best addressed using game theory techniques empowered with machine learning methods across grid infrastructure and microgrid communities. In this thesis, novel Bayesian coalitional game theory-based and Bayesian reinforcement learning-based coalition formation algorithms are proposed, which allow the microgrids to exchange energy with their coalition members while minimizing the associated cost and power loss. In addition, a deep reinforcement learning scheme is developed to address the problem of large convergence time resulting from the sizeable state-action space of the methods mentioned above. The proposed algorithms can ideally overcome the uncertainty in the system. The advantages of the proposed methods are highlighted by comparing them with the conventional coalitional game theory-based techniques, Q-learning-based technique, random coalition formation, as well as with the case with no coalitions. The results show the superiority of the proposed methods in terms of power loss and cost minimization in dynamic environments.

Indiana University-Purdue University Indianapolis (IUPUI) / Combining rooftop solar with energy storage for off-grid residential operation is restrictively expensive. Historically, operating off-grid requires an 'isolated self-consumption' operating strategy where any excess generation is wasted and to ensure reliability you must install costly, polluting generators or a large amount of energy storage. With the advent of Blockchain technology residents can come together and establish transactive microgrids which have two possible operating strategies: Centralized Energy Sharing (CES) and Interconnected Energy Sharing (IES). The CES strategy proposes that all systems combine their photovoltaic (PV) generation and energy storage systems (ESS) to meet their loads. IES strategy establishes an energy trading system between stand-alone systems which allows buying energy when battery capacity is empty and selling energy when battery capacity is full. Transactive microgrids have been investigated analytically by several sources, none of which consider year-round off-grid operation. A simulation tool was developed through MATLAB for comparing the three operating strategies: isolated self-consumption, CES, and IES. This simulation tool could easily be incorporated into existing software such as HOMER. The effect of several variables on total cost was tested including interconnection type, initial charge, load variability, starting month, number of stand-alone systems, geographic location, and required reliability. It was found that the CES strategy improves initial cost by 7\% to 10\% compared to the baseline (isolated self-consumption) and IES cases in every simulation. The IES case consistently saved money compared to the baseline, just by a very small amount (less than 1\%). Initial charge was investigated for March, July, and November and was only found to have an effect in November. More research should be done to show the effect of initial charge for every month of the year. Load variability had inconsistent results between the two geographic locations studied, Indianapolis and San Antonio. This result would be improved with an improved load simulation which includes peak shifting. The number of systems did not have a demonstrable effect, giving the same cost whether there were 2 systems or 50 involved in the trading strategies. It may be that only one other system is necessary to receive the benefits from a transactive microgrid. Geographic locations studied (Indianapolis, Indiana; Phoenix, Arizona; Little Rock, Arkansas; and Erie, Pennsylvania) showed a large effect on the total cost with Phoenix being considerably cheaper than any other location and Erie having the highest cost. This result was expected due to each geographic location's load and solar radiation profiles. Required reliability showed a consistent and predictable effect with cost going down as the requirement relaxed and more hours of outage were allowed. In order to accomplish off-grid operation with favorable economics it is likely that a system will need to reduce its reliability requirement, adopt energy saving consumption habits, choose a favorable geographic location, and either establish a transactive microgrid or include secondary energy generation and/or storage.