The latest tools and techniques for addressing the challenges of 21st century power generation, renewable sources and distribution systems
Renewable energy technologies and systems are advancing by leaps and bounds, and it's only a matter of time before renewables replace fossil fuel and nuclear energy sources. Written for practicing engineers, researchers and students alike, this book discusses state-of-the art mathematical and engineering tools for the modeling, simulation and control of renewable and mixed energy systems and related power electronics. Computational methods for multi-domain modeling of integrated energy systems and the solution of power electronics engineering problems are described in detail.
Chapters follow a consistent format, featuring a brief introduction to the theoretical background, a description of problems to be solved, as well as objectives to be achieved. Multiple block diagrams, electrical circuits, and mathematical analysis and/or computer code are provided throughout. And each chapter concludes with discussions of lessons learned, recommendations for further studies, and suggestions for experimental work.
Key topics covered in detail include:
* Integration of the most usual sources of electrical power and related thermal systems
* Equations for energy systems and power electronics focusing on state-space and power circuit oriented simulations
* MATLAB® and Simulink® models and functions and their interactions with real-world implementations using microprocessors and microcontrollers
* Numerical integration techniques, transfer-function modeling, harmonic analysis, and power quality performance assessment
* MATLAB®/Simulink®, Power Systems Toolbox, and PSIM for the simulation of power electronic circuits, including for renewable energy sources such as wind and solar sources
Written by distinguished experts in the field, Integration of Renewable Sources of Energy, 2nd Edition is a valuable working resource for practicing engineers interested in power electronics, power systems, power quality, and alternative or renewable energy. It is also a valuable text/reference for undergraduate and graduate electrical engineering students.
Felix A. Farret, PhD, is a Professor in the Department of Processing Energy, at the FederalUniversity of Santa Maria, Brazil. He is the Coordinator of the Center of Excellence in Energy and Power Systems (CEESP) at Federal University of Santa Maria. He has been involved with R&D for industrial electronics and alternative energy sources for more than four decades.
M. Godoy Simões, PhD, IEEE Fellow, is a Professor in the Electrical Engineering Department at Colorado School of Mines. Dr. Sim??es pioneered the application of neural networks and fuzzylogic in power electronics, motor drives and renewable energy systems.
Alternative Sources of Energy
The basic human needs to survive are air, water, food, space to live, and energy, as well as the ability to reproduce, and humans have been constantly searching for means to harvest and convert energy to hence survive. But the interrelation of energy with other needs has not been so evident as in the recent years. When the industrial revolution in Europe caused an evolution of societies and large areas of increasing population density, people realized that factors such as comfortable housing and energy would be relevant to the development of a country. Fossil fuels have become essential in modern societies, and new strategies have been developed to guarantee their uninterrupted supply. In the last 250 years, our population, and correspondingly the demands for industrial and commercial goods, has increased. We have to consider that we live on a planet of constant size and constrained resources, and increased population and their demands may have consequences: economic constraints, new frontiers, wars, international agreements, and heavy pollution [1-3]. Engineers and scientists are working toward the optimized use of resources. Humans are excavating the lands for charcoal, petroleum, gas, uranium, and other minerals, polluting the atmosphere, rivers, oceans, and food sources. Burning fossil fuels and thermal energy conversion just increase entropy and contribute to exhaustion of our planet's energy resources.
In the past the approach to generate large amounts of electrical energy was realized by means of constructing large power plants, which were considered more efficient than smaller ones on an economic scale, such as the Three Gorges Dam in China (18?GW with structure for 22.5?GW), Itaipu Binacional in Brazil (14.0?GW), Sayano-Shushenskaya Dam in Russia (6.4?MW), Churchill Falls Generating Station in Canada (5.43?GW), and Guri Dam in Venezuela (2.0?GW). However, such large power plants caused immense floods, massive power transmission lines and towers, air pollution, modified waterways, devastated forests, large population densities in cities, and wars for the dominion of energy resources. Because of these trends in development, distances to energy sources are increasing, material capacities are reaching their limits, fossil reserves are being exhausted, and pollution is becoming widespread. New alternatives must be devised if humanity is to survive today and for the centuries to come.
1.2 Renewable Sources of Energy
The Earth receives solar energy as radiation from the sun in quantity that far exceeds the needs of the entire humankind. The sun generates wind, rain, rivers, and waves by heating the plane. Along with rain and snow, sunlight is necessary for plants to grow. Biomass, the organic matter that makes up plants, in general can be used to produce electricity, transportation fuel, and chemicals. Plant photosynthesis (essentially, the chemical storage of solar energy) creates a range of biomass products, from wood fuel to rapeseed, which can be used for heat, electricity, and liquid fuels.
Hydrogen can also be extracted from many organic compounds, as can water. Hydrogen is the most abundant element on Earth, but it does not occur naturally in gas form. It is always combined with other elements, such as oxygen to form water. Once separated from another element, hydrogen can be burned as a fuel or converted into electricity.
The sun also powers the evapotranspiration cycle, which allows water to generate power in hydro schemes-the largest source of renewable electricity today. Interactions with the moon produce tidal flows, which can produce electricity.
Although humans have been tapping into renewable energy sources (such as solar, wind, biomass, geothermal, and water) for thousands of years, only a fraction of their technical and economic potential has been captured and exploited. Yet renewable energy offers safe, reliable, clean, local, and increasingly cost-effective alternatives for all our energy needs. It can dismantle the power promoted by petroleum, coal, and radioactive materials [2-6].
Research has made renewable energy more affordable today than it was 30 years ago. Wind energy has declined from 40 cents per kilowatt hour (¢/kWh) to less than 5¢. Electricity from the sun through photovoltaics (which literally means "light electricity") has dropped from more than $1/kWh in 1980 to nearly 15¢/kWh today. Ethanol fuel costs have plummeted from $4/gal in the early 1980s to $1.20 today. As a result, renewable energy resource development will result in new jobs, local power plants, and less dependence on oil and radioactive materials from foreign countries [5-7].
There are some drawbacks in developing renewable energy solutions. An example is when solar thermal energy is used, because solar rays are captured through collectors (often huge mirrors) and solar thermal generation requires large tracts of land, and affects natural environment. The environment is also affected when buildings, roads, transmission lines, and transformers are built. In addition, the fluid often used for solar thermal generation is toxic, and spills can occur. Solar or photovoltaic cells are produced using the same technologies as those used to create silicon chips for computers, and this manufacturing process also uses toxic chemicals. In addition, toxic chemicals are used in batteries that store solar electricity through nights and on cloudy days. Manufacturing this equipment also has environmental effects. Therefore, even though the renewable power plant does not release air pollution or use fossil fuels, it still has an effect on the environment.
Wind power has also some drawbacks, involving primarily land use. For example, the average wind farm requires 17 acres to produce 1?MW of electricity (about enough electricity for 750-1000 homes). However, farmers and ranchers can use the land beneath wind turbines. Wind farms can cause erosion in desert areas, and they affect natural views because they tend to be located on or just below ridgelines. Bird deaths also result from collisions with wind turbines and wires. This is the subject of ongoing research. Ultimately, combined with energy efficiency, renewable energy can provide everything fossil fuels offer in terms of energy services: from heating and cooling to electricity, transportation, chemicals, illumination, and food drying.
Energy has always existed and has been used and transformed in one form or another. For example, the energy in a flashlight's battery becomes light energy when the flashlight is turned on. Food, the most natural stored chemical energy, resides in fat tissues and cells as potential energy. When the body uses that stored energy to do work, it becomes kinetic energy. Telephones transform a voice into electrical energy variations, which flow over wires or are transmitted through air. Other telephones change this electrical energy into sound energy through speakers. Cars use stored chemical energy in fuel to move, and they change chemical energy into heat and kinetic energy. Toasters change electrical energy into heat. Computers, television sets, and DVD players change electrical energy into coordinated types of mechanical movement and image and sound energy to reproduce the ambient of life. That means that as soon human beings are awake in the morning, they begin to use more energy than that keeping them alive to switch lights on, for a bath, morning cooking, heaters on, car on, going to work, and so on.
In all such transformations of energy, intermediary transformations are involved. For example, consider the case for a home computer. Electricity allows self-organization of the main processor, according to a preestablished program, to convert ventilator movement to the cooling process for the main processing unit and the motherboard. The alternating current (ac) source power after being distributed to all houses is converted into integrated direct current (dc) power to feed peripheral plates. After many electric processes, the monitor produces a luminous energy on screen. Many processes and intermediary sources are integrated into a simple computer. They produce heat, light, movement, and circulation of electrical current to make it an impressively organized machine. This diversity of energy forms is an example of the changes happening in power systems since the primary source conversion.
1.3 Renewable Energy versus Alternative Energy
All forms of energy are renewable after a lapse of time. For example, coal can be renewed in nature after millions, perhaps billions, of years. Sugar cane would take no more than one year to be replanted. Therefore, a source of energy is considered renewable if the time it takes to be recovered is referred to human life duration. Furthermore, a renewable energy source cannot run out and causes so little damage to the environment that its use does not need to be restricted. On the other hand, no energy system based on mineral resources is renewable because, one day, the mineral deposits will be used up. This is true for fossil fuels and uranium. The debate about when a particular mineral resource will run out becomes irrelevant in this context. A renewable energy source is replenished continuously.
Renewable energy sources-solar, wind, biomass (under specific conditions), and tides-are based directly or indirectly on solar energy. Hydroelectric power is not necessarily a renewable energy source because large-scale projects can cause ecological damage and...