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Introduction

Scientific and technical progress is impossible without energy development, electrification. To increase productivity is paramount to the mechanization and automation of production processes, replacing human labor by machine. But the vast majority of the technical means of mechanization and automation (equipment, devices, computer) has an electrical basis. Especially the wide application of electric energy to drive the electric motors. The power of the electrical machines (depending on their purpose) are different from fractions of a watt (micro-motors used in many branches of engineering and in household products) to large values, in excess of one million kilowatts (power generators). [1].

It is difficult to imagine everyday life without using electricity.. However, in recent years the energy problem is increasingly concerned at the progressive mankind.

Disturbing as the fact that mineral resources will soon be exhausted, and that the intensive energy consumption can lead to environmental disaster, which will transform the Earth into a planet completely unsuitable for life. Therefore, the development of new methods of energy production and study of the already known is of great research interest[2].

One of the main technological problems of industrial energy is the inequality in the consumption of electricity, which leads to the aggravation already mentioned above: the intensive use of primary resources and environmental issues..

One of the perspective directions of energy at the moment is the development and application of the device of accumulation of electricity.

Issues to be addressed:

  1. Consumption of primary energy resources.
  2. Emissions to the atmosphere. Environmental problems.
  3. The Irregularity of the load curve
  4. Accumulation of electricity.

1. The relevance of the topic

The production of electricity at power stations and its consumption by different receivers represent processes that are interrelated in such a way that because of the physical laws of the power consumption at any time must be equal to the generated power [3].

Under ideal uniform consumption of electricity must occur even work a certain number of power plants. In fact, most of the individual power consumers is uneven and the total consumption is also uneven. You can cite many examples of the uneven operation of devices that consume electricity. The plant, operating one or two shifts, uneven consumes electrical energy during the day. Night time power consumption close to zero. The street and apartment lights only during certain hours of the day. The work of home appliances, fans, vacuum cleaners, electric ovens, heating devices, televisions, radios, electric shavers are also uneven. In the morning and evening communal load is greatest.

The load curve of a district or city representing the time variation of the total power of all consumers, has dips and highs. This means that in some hours of the day require a large total power generators, and other hours part _ generators or power plants should be disabled or should work with a reduced load. The number of power plants and their capacity are determined by relatively short maximum load of consumers. This leads to underutilization of equipment and more expensive energy systems. So, reducing the number of hours of use of installed capacity of large thermal power plant with 6000 to 4000 hours per year leads to an increase in the cost of electricity generated by 30-35%. [4].

2. The purpose and objectives of the study

Conserving energy of all types – this task becomes more and more relevant in the modern world. Energy-saving technology considered a priority at the level of the state of domestic politics in many States and in Russia in particular. Energy-saving technology developed on the basis of innovative solutions. These technologies should also be environmentally safe and not to change the course of life of society in General and the usual stock cases each person individually.

The main goal of this work is the study of systems and devices for energy storage that will allow to align the load chart.

Analysis of trends in the consumption of electric energy shows that in the future the uneven consumption will increase with the growth of welfare of the population and the associated increase in domestic load, increasing electromagneti work. The reduction in the number of working days in a week also contributes to the uneven energy consumption. This situation is typical not only for our region. In most countries in Western Europe, the unevenness in the consumption of electricity is such that within the hour the variation of the load reaches 30% of maximum power in the future is also expected to increase in unevenness. To radically change the nature of the electricity consumption is very difficult, as it depends on the steady rhythm of people's lives and a number does not depend on " people's objective circumstances. For example, you cannot change the fact that electric lighting is necessary in the evening hours after dark. [5].

The main task of the energy to take action for the equalization of the graph the total load of consumers. So, you enter the scaled value of the electricity depending on what time period it is consumed. If electricity is consumed in the moments of maximum load, and the cost is set higher. This increases consumer interest in such restructuring work, which could contribute to a decrease in the electrical load at the moments of maximum consumption in the power system. In General, the possibility of aligning the consumption of electricity is small. Therefore, the power system must be sufficiently agile, able to quickly change the capacity of the power plants. [6].

3. Batteries

Through solar panels or wind turbines to produce electricity. But it is still necessary to keep to obtain light and heat at night or when there is no wind. That is the necessary devices for the accumulation and conservation of energy — storage batteries.

The efficiency of solar and wind installations depends on the mode of operation. It is preferable that they worked in "basic" mode, that is, when there is sun and wind. This requirement may not coincide with the regime of electricity consumption. Therefore there is a need of its accumulation.

Solar panels and wind turbines give energy unevenly. The battery allows you to use the excess electricity generated by these sources in the period of high values and to store energy for a long time (tens of days), and the stored electricity at any time can be transferred to the load, wherein the discharge current can provide power to the load, the capacity of which greatly exceeds the installed capacity of the solar battery, a thermoelectric generator or a wind power plant.

The battery in the power supply system should have the following properties: long life, many cycles [7].

Under the accumulation (accumulation) of energy refers to the input any kind of energy into the device, equipment, installation or construction – in battery (storage) of energy to this energy there then, at consumption time again in the same or in a modified form to back. To charge the battery with energy sometimes need more the energy in the charging process may experience a loss of energy. After charging the battery can remain in the ready state (in charged state), but in this state, part of energy can be lost for arbitrary scattering, leakage, discharge or other similar phenomena. When impact energy from the battery may also have it losses; in addition, it is sometimes impossible to get back the full accumulated energy. Some of the batteries are arranged so that they should be some residual energy. Condition battery when the power consumption, during preparedness, return energy after the impact is schematically represented.

However, energy can be accumulated (pooled) and independent from the will or actions of man – as the result of physical processes occurring in nature or in artificial devices. As the example in Fig. 2 shows some of the processes of accumulation energy in nature. In addition to them, it should be noted a very large amount of heat contained in the hot fluid inner layers of the Earth, kinetic energy of rotation of the Earth around the Sun and around its axis, the kinetic energy of wind, water flow and moving items chemical energy stored in living things.

Artificial energy storage can be the following objectives:

Figure 1 — The use of the energy accumulator (A) to produce an energy pulse of increased power

Figure 2 — An example of the application of a battery of energy in a re-sold energy consumer. 1 charging the battery from a stationary power source (E), 2 using the accumulated energy.

Figure 3 — 1 aligning the daily load graph by accumulating Win energy during the night minimum load and using the accumulated energy Wex to cover the peak load peaks; 2 obtained in the ideal case of a uniform load graph

Any battery can be described using several parameters:

It is necessary to say at once that it is impossible to identify the "best" type of battery. Each of them has its pros and cons, which make the battery optimal for some applications and unacceptable for others. [10].

In modern technology there are five basic types of batteries that differ in their chemical composition:

  1. Nickel-cadmium (NiCd). Well established and studied technology, but has a low energy density. Used where durability is important, the ability to provide high load current and low cost.
  2. Nickel-metal hydride (NiMH). Compared to NiCd batteries have higher energy density but lower life time. NiMH batteries do not contain toxic materials.
  3. . Lithium-ion (Li-ion). The most rapidly developing technology. Are used where need high energy density and low weight. Li-ion more than all other batteries. The user must strictly observe the regimes charge and discharge specified by the manufacturer, for safety reasons.
  4. Lithium polymer (Li-polymer). Conceived as a cheaper version of Li-ion batteries. This type of chemistry in the energy density similar to Li-ion . This allows you to make Li-polymer batteries are very compact.
  5. . Sealed lead acid (SLA). Used where higher performance is required and weight doesn't matter. Typical applications - fixed medical equipment, electric vehicles, emergency power supply systems, UPS.

3.1 Nickel-cadmium batteries.

Nickel-cadmium batteries are the oldest used. The technology of their production are well studied and worked out.

Unlike other types of chemistry, NiCd perfectly withstands high currents. NiCd batteries are better than others are designed to operate in extreme temperature ranges. Nedorazvedany constant charging of NiCd batteries is bad for their health. Periodica full charge is very important as it prevents the formation of large crystal formations on the electrodes of the battery cells. The process of formation of these formations is called the memory effect. As a result, the battery gradually deteriorates its parameters.

The advantages and disadvantages of NiCd batteries.

Dignity:

  1. Great resource. Being maintained properly, NiCd batteries provide 1000 - 1500 cycles charge/discharge.
  2. Very good load capacity. NiCd batteries provide a large current load.
  3. A long service life.
  4. Easy storage and transport. Most airlines allow the transport of NiCd batteries without special precautions.
  5. NiCd batteries are well suited for operation at low temperatures modes of charge and discharge.

Disadvantages:

  1. Low enough, in comparison with new types of batteries, the energy density.
  2. The memory effect. The need for periodic training for its prevention.
  3. NiCd batteries contain toxic materials.
  4. A sufficiently large current discharge. NiCd batteries require a charge after storage.

3.2 Nickel-metal hydride batteries.

Designed as a replacement for NiCd batteries, Nickel-metal hydride (NiMH) have two significant advantages: high energy density and environmental safety. Modern NiMH batteries have 40% more energy density compared to NiCd. This allows you to make batteries of higher capacity in the same dimensions. However, for these advantages had to pay a high-discharge current: NiMH batteries it is 1.5 times higher than that of NiCd.

The advantages and disadvantages of NiMH batteries.

Dignity:

  1. Capacity, 30-40% greater than NiCd batteries, with the potential of creating a NiMH battery more capacity is not exhausted.
  2. Memory effect in NiMH batteries is much less pronounced than in NiCd.
  3. Easy storage and transport no special requirements.
  4. Environmental safety.

Disadvantages:

  1. A relatively small resource. If during each cycle the battery is discharged completely, then significant deterioration of the parameters starts after 200 to 300 cycles charge/discharge. For NiMH battery partial discharge is more preferable than complete.
  2. Limited discharge current. Optimal load current is 0.2 C-0.5 C.
  3. More complex charging algorithms. Due to the fact that NiMH battery in the charge process is heated much stronger than NiCd, charge time increases.
  4. Large self-discharge.

3.3 Lithium-ion batteries.

Now batteries based on lithium are the most rapidly developing technology. The energy density of Li-ion battery is twice that of NiCd, and the potential of the technology will in the future greatly increase this parameter. In addition to high capacity, Li-ion batteries have good load characteristics similar to the characteristics of the NiCd. If the battery discharges from its voltage varies in a very small range, which simplifies the design of the equipment. The low internal resistance of lithium batteries allows you to transfer the load of considerable power. Along with indisputable advantages, lithium-ion batteries have their drawbacks. In connection with the explosion, Li-ion batteries require an electronic protection circuits. Such schemes are embedded in each battery and limit the peak voltage on the cell in the charge process, do not allow the cell to discharge below an acceptable level, limit the current and control the temperature. The use of protection circuits is practically eliminated danger of explosion battery. The effect of aging is also a weak point of lithium ion batteries. Using two, maximum three, years of storage, the battery becomes unserviceable. It should be mentioned that any other type of battery chemistry also subject to aging. NiMH especially, when stored in elevated temperatures. Storing batteries in a cool place slows the aging process of Li-ion batteries (also, this is true for other types of chemistry). Manufacturers recommend storing batteries at 15°C. in addition, Li-ion batteries should not be fully discharged. Li-ion batteries long-term storage is not recommended.[13].

The advantages and disadvantages of Li-ion batteries.

Dignity:

  1. High energy density, and the potential for its increase has not been exhausted.
  2. Low-discharge current. Less than half of the value of self-discharge NiCd batteries.
  3. Not require periodic maintenance.

Disadvantages:

  1. The need for special protection schemes to limit the current and voltage.
  2. Subject to aging, regardless of the mode of operation. Storage in a cool place can reduce the aging rate by 40%.
  3. The limited load current.
  4. The high cost of production. 40% higher than the production of NiCd.

3.4 Li-polymer batteries.

The fundamental difference between polymer batteries from all other types of chemistry lies in the absence of any liquid or gel electrolyte. These batteries use a dry electrolyte polymer that replaces the porous separator soaked with liquid or gel. Polymer electrolyte has electrical conductivity, but allows ion exchange. Plus this type of chemistry is that the battery cell can be made absolutely arbitrary shape, which leaves complete freedom to the developers of the battery case. The minimum thickness of the cell is less than a millimeter. The disadvantages of this technology include the fact that the polymer batteries have very high internal resistance and are not capable of providing large transient currents. Acceptable parameters of the battery becomes when heated to a temperature of 60°C. the Potential of technology is great. Resource polymer battery promises to be no less than 1000 cycles, and the energy density is higher than Li-ion. Polymer batteries is a hybrid polymer and lithium-ion batteries that use gel electrolyte to increase the conductivity. [14].

The advantages and disadvantages of polymer batteries.

Dignity:

  1. Very thin cells. The thickness of the battery may be less than 1mm.
  2. Plasticity. The cell can be shaped in any form convenient to the manufacturer.
  3. Light weight.
  4. Security. Polymer batteries are resistant to overcharge. No leaking of electrolyte.

Disadvantages:

  1. At this point, lower density of energy and resource, compared to Li-ion. However, the potential for development exists.
  2. An expensive production.

3.5 Lead-acid batteries.

Historically, lead-acid batteries were the first rechargeable energy sources launched into commercial use. Since then, they have undergone significant changes. The liquid electrolyte was replaced by the electrolyte impregnated with the separator or gelled electrolyte batteries are hermetically sealed and do not require periodic addition of electrolyte. Recombination of gases occurs in the pores of the separator or gel electrolyte. As a precaution in sealed batteries are used the safety valves through which stravlivaya the excess pressure, if the charge process, the battery gases do not have time to recombine. In comparison with other types of chemicals, lead acid batteries, SLA, have the lowest energy density, but the highest capacity. Therefore they are used where higher performance is required, but do not play a decisive role of weight and dimensions. Basically, it's the uninterruptible power supply, biomedical equipment. A great advantage of this type of chemistry is a very small self-discharge. If a NiCd battery loses 40% of stored energy in three months, the SLA battery it will take a year. Weaknesses of this type of chemistry are the load characteristics. SLA batteries do not like high current load and deep discharge. When operating in intense modes, quickly comes aging, which is expressed in loss of capacity. Also, the service life of SLA batteries is strongly influenced by operating temperature. Depending on the mode of operation, the resource SLA battery is 200-300 cycles charge/discharge.

The advantages and disadvantages of SLA batteries.

Dignity:

  1. These batteries are cheap and easy to manufacture.
  2. A well-established technology. Subject to the rules of operation, SLA batteries are very reliable.
  3. Self-discharge is the smallest among all types of batteries.
  4. Batteries require less maintenance. The memory effect and the need to refill the electrolyte is absent.

Disadvantages:

  1. The inability to store batteries in a discharged condition are easily damaged.
  2. Low energy density that restricts the field of application.
  3. More complex charging algorithms. Due to the fact that NiMH battery in the charge process is heated much stronger than NiCd, charge time increases.
  4. Allow a very limited number of full discharge cycles.
  5. Contain environmentally harmful materials.
  6. A strong temperature dependence.

Conclusion

Thus, after analyzing the 5 types of batteries, it can be concluded that the best option for all features - battery, lead acid SLA, as it has the lowest energy density, but the highest capacity. Therefore they are used where higher performance is required, but do not play a decisive role of weight and dimensions. All of the above characteristics as a whole are suitable and meet the goals and objectives in this master thesis.

When writing this abstract master's work is not yet complete. Final completion: may 2018. Full text works and materials on the subject can be obtained from author or his supervisor after the specified date.

References

  1. Кириллин В. А. Энергетика. Главные проблемы: В вопросах и ответах. – М.: Знание, 1997. – 128 с.
  2. Кларка Р. Оптимистический взгляд на будущее энергетики мира: Пер. с англ. – М.: Энергоатомиздат, 1994. – 215 с.
  3. Юдасин Л. С. Энергетика: проблемы и надежды. – М.: Просвещение, 1990. – 207с.
  4. Старшикова Ю. Н. Мировая энергетика: прогноз развития до 2020 г. – М.: Энергия, 1990. – 256 с.
  5. Непорожнего П. С. Попкова В. И. Энергетические ресурсы мира – М.: Энергоатомиздат, 1995. – 232 с.
  6. Ивашутин А. Г. Нетрадиционные источники энергии. – М.: Знание, 1982. – 120 с.
  7. Хрусталев Д. А. «Аккумуляторы» Изумруд, 2003 год, 224 стр.
  8. Курзуков Н. И. Ягнятинский В.М., Аккумуляторные батареи. Краткий справочник. - М.: ЗАО «КЖИ «За рулем»», 2008. - 88 с.
  9. Боровский Ю. И. Старостин А.К., Чиксков Ю.П. Стартерные аккумуляторные батареи. - М.: Фонд: За экономическую грамотность, 1997
  10. Владимир Васильев. «Литий-ионные и литий-полимерные аккумуляторы»
  11. Лаврус В. С. «Источники энергии» Изд. «Наука и техника», 1997 г.
  12. Коровин Н. В. «Электрохимическая энергетика» М.:Энергоатомиздат, 1991.
  13. Вайнел Д. В. «Аккумуляторные батареи» пер. с англ., 4 изд., М. — Л., 1960.
  14. Дьякова А. Ф. Энергетика сегодня и завтра. – М.: Энергоатомиздат, 1990. – 344 с.