Abstract
Content
- Introduction
- 1. Theme urgency
- 2. Goal and tasks of the research
- 3. Basic advantages and disadvantages of photovoltaic systems
- Conclusion
- References
Introduction
The last 25–30 years have seen increased attention to the search for and development of alternative energy sources that are different from fossil organic resources for its huge inventory, meaning that they are virtually inexhaustible or are periodically renewed. Among the unconventional sources include Solar, wind, annually renewable organic mass (biomass), energy, focus ocean in the form of sea waves, currents and tides, the heated surface layers, the energy of rivers. The impetus for the application of new technologies in the transformation of energy non–conventional sources served by two factors: the energy crisis of the early 70–ies and the increasing demands for environmental protection. The international community became aware of the reserves of fossil fuels are not limitless. According to forecasts, by freezing energy at the present level of oil will be exhausted in 80 years, natural gas will last for 150 years, and coal for 500 years [1].
It should be noted and disadvantages of new energy sources. First of all, this low density of energy flow, forcing the pre-concentrate the energy flows from large areas and to create bulky structures for their mutual transformations. Further, based on non–traditional sources are natural phenomena, the intensity of which is subject to strong fluctuations depending on the region, season, time of day. As a result of complicated energy conversion system, increases their cost [2].
1. Theme urgency
The main objective of the electric power system (EPS) is to produce electricity and deliver it to consumers to cover their load. Existing EPS were formed as a centralized system with the features depending on the fuel and energy power plants. Centralization means that the electricity production is done on large power plants, from which the power is transmitted to the consumers. The advantage of this system is relatively simple coordination of many large generating units, maintains a well–controlled balance between generation and consumption and, consequently, the frequency stability [2].
The reduction of reserves of natural fuels leads to the development of EPS in increasing the use of renewable energy such as wind or solar energy, which in many countries constitute the majority of distributed generation. These changes in the structure of the EPS are as a result of three main requirements:
– the reduction of greenhouse gases (Kyoto Protocol);
– the growing use of renewable energy resources – ware (European Directive ware);
– improving energy efficiency (European Directive on the use of the combined production of electricity and heat (Combined Heat and Power – CHP)).
The development of distributed generation has many advantages, such as:
– the reduction of CO2 emissions by improving energy efficiency and reducing the use of coal as fuel for power plants;
– minimization of losses in the transmission network;
– partial implementation of investments in infrastructure.
Traditional EPS (Fig. 1) has a vertically integrated structure with centralized generation, distributed consumption, limited their interaction and regulatory requirements it does not provide mutual benefits to all parties of this process [3].
Figure 1 – The structure of the traditional power system
Traditional power system can be characterized by such features as:
– large conventional power plants;
– technically optimized scheme for providing for regional energy needs;
– centralized management;
– limited inter–regional cooperation;
– old technology, known for about 100 years.
The concept of a smart grid is the idea of the future EPS. In General, the Smart Grid is a power grid, in which the transmission and distribution electric network is used for two–way communications between power stations, consumers and control centers for the purpose of optimization of the electricity supply and consumption to improve their effectiveness (Fig. 2). The infrastructure of a smart grid is based on the principles of interoperability, open standards and implemented using protocols of the Internet [4].
The concept of a smart grid has the following objectives:
– providing consumers with opportunities for automated control of energy use and minimize their costs of electricity;
– self–healing system in the event of an accident;
– the use of high quality energy resources, including renewables;
– improving power quality and reliability of electricity supply.
Figure 2 – The Concept Of The Smart Grid
2. Goal and tasks of the research
The main goal of this work is the study of Autonomous power supply systems based on renewable energy sources, their modes of operation, the performance evaluation and their application in the energy market.
Solar energy is the radiant energy of the Sun. The sun is the source of life on Earth and the source of almost all types of renewable energy.
The atmosphere of the Sun consists of 71 % hydrogen, a 26.5% helium and 2.5% of other gases. The sun acts like a giant nuclear reactor
, every second of the hydrogen atoms combine
forming a helium atom and energy of radiation in the process of nuclear fusion.
During this reaction extremely high temperature and pressure of the Sun causes the splitting of atoms of hydrogen and nuclear fusion.
Four hydrogen nuclei to form one helium atom. The mass of the helium atom is less than four hydrogen atoms,
and while nuclear fusion is some matter is released into the space in the form of radiation energy [5].
Energy from the Sun's core to the surface of the Sun is millions of years old, and only 8 minutes it takes to cover the distance to the Earth is 150 million kilometers. Solar energy is moving to the surface of the Earth at the speed of light. Not the heat of the sun penetrates to the Ground, and instead the light is converted into heat when absorbed by molecules in the Earth's atmosphere [6].
Figure 3 – the Photovoltaic solar energy potential in Europe
Photovoltaic modules
One photoelectric Converter generates up to 2 watts of power, which is not sufficient even to power a pocket calculator. To increase energy production a large number of solar cells together to form photovoltaic modules, which are then joined in massive amounts (Fig. 4). The modular structure of solar cells allows to build various PV system depending on the production of energy for various applications. Thus, the photovoltaic element is an element in PV systems [7].
Figure 4 – Photovoltaic cell, module and array solar cells
Serial modules behave like consumers: they heat up in the flow of current and can be damaged. To use reverse protection diodes (as shown in Fig. 5).
Figure 5 – Serial connection of solar modules with reverse diodes
For parallel connection of the shaded element can be powered by energy from other solar cells. To protect apply in each branch locking diodes (Fig. 6).
Figure 6 – the Location of the locking diodes in parallel connection
In Fig. 7 shows a diagram of a combined photovoltaic module with locking and reverse diodes.
Figure 7 – Photovoltaic generator with reverse and locking diodes
Electric scheme, dubbed the model of a single diode
, displays the solar battery element.
This model consists of a current generator, which is connected in parallel with a diode and a shunt resistor Rsh.
In addition, one terminal of the generator current in the series connection resistance Rs.
The total equivalent circuit model takes the form shown in figure 8.
Figure 8 – Electrical model of the solar battery
(animation: 9 slides, 5 cycles of repetition, of 104.5 KB)
Iph – pathogentically current [A],
Id – diode current [A],
Ud – diode voltage [V],
I – output current [A],
U – the voltage on clemo [V],
Ish – shunt current [A],
Rsh – parallel resistance [Ohm],
Rs – series resistance [A].
3. Basic advantages and disadvantages of photovoltaic systems
The advantages of solar power. (Dignity SES)
– The General availability and inexhaustibility of the source.
– Theoretically, it is absolutely safe for the environment, although there is a possibility that the widespread adoption of solar energy can change albedo (characteristic reflectance (scattering) ability) of the earth's surface and lead to climate change (however, at the present level of energy consumption is extremely unlikely).
Disadvantages of solar power plants. (Disadvantages SES)
– Dependence on weather and time of day.
– As a consequence the need for energy storage.
– In industrial production – the need for duplication solar ES maneuverable ES of comparable capacity.
– High construction costs associated with the use of rare elements (e.g., indium and tellurium).
– The need for periodic cleaning of the reflecting surface from dust.
– Heating of the atmosphere above the power plant [8].
Conclusion
Renewable energy is energy produced by natural sources which can be replenished, such as wind, solar fotovoltaica energy concentrator solar energy, water energy, ocean energy and geothermal energy. Climate change, along with the exhaustion of natural resources leads to increased use of renewable energy sources (RES) with clean energy [9].
Many countries around the world apply their scientific knowledge and expertise for the study and development of renewable energy sources. Thanks to the Kyoto Protocol (1997) and growing awareness of the need to maintain the environment is expected to increase production of renewable energy in the near future [10].
This master's work is not completed yet. Final completion: December 2016. The full text of the work and materials on the topic can be obtained from the author or his head after this date.
References
- Лосюк Ю. Нетрадиционные источники энергии / Минск, 2005. – 233 pp.
- Стычинский З., Воропай Н. Возобновляемые источники энергии/ Магдебург – Иркутск 2010. – 200 с.
- Styczynski Z. Alternative Energie / Magdeburg, 2006. – 236 с.
- Фолькер К. Системы возобновляемых источников энергии/ Folliant, 2013. – 430 с.
- Hau E. Wind Turbines / Munich. – 2008. 886 c.
- Магомедов А. Нетрадиционные возобновляемые источники энергии / Махачкала, 1996. – 245с.
- Chao Zhang, Matthias Meier, Wendi Zhang,.Influence of Interface Textures on Light Management in Thin-Film Silicon Solar Cells With Intermediate Reflector/ – М.: Наука, 2015. – 7 с.
- Хахалева Л. Нетрадиционные и возобновляемые источники энергии / Ульяновск, . – 2008. 33с.
- Eduardo F. Camacho, Tariq Samad, Mario Garcia-Sanz. Control for Renewable Energy and Smart Grids / From: The Impact of Control Technology, 2011. – 20 с.
- Зайцева М. Нетрадиционные возобновляемые источники энергии / Нижний Новгород, 2012. – 8 с.