The article analyzes the main characteristics of the electricity generators to use them as a part of small hydroelectric power plants. It is shown, that contactless asynchronous generators in comparison with synchronous generators and DC generators have improved their operational and technical characteristics, and above all, their reliability and performance efficiency. We have shown graphic dependences of the cost and the weight of power generators. It is proposed using direct frequency converter as a stabilizer of parameters of asynchronous generator of electricity, used as a source of electricity for small hydropower plants. The article explains the features of the work and the choice of parameters for generators, working together with the direct frequency converters. The authors have revealed some aspects of the work of direct frequency converters with natural commutation and with adjustable phase angle, including their advantages and disadvantages. The article also presents block diagrams for small hydroelectric power plants, made with the help of asynchronous generators and direct frequency converters
The article deals with the basic methods of stabilizing voltage generators for small hydroelectric power plants. It shows a block diagram of the implementation and analysis of the characteristics of the work; it reveals the advantages and disadvantages. The authors explain the features of the work of the functional circuits voltage regulators with discrete ballast, with phase control and management of the load current. It is shown, that to improve the performance of small hydroelectric power plants considerably we have to use contactless generators in their construction: asynchronous generators with capacitive excitation and synchronous generators with permanent magnets. The functional scheme of the voltage regulator, the construction of which has an additional field winding, simplifies the system voltage stabilization of the synchronous generator with permanent magnets, as well as a functional scheme of an asynchronous generator voltage regulator, made using step-up transformers, which significantly reduces the weight of the capacitors providing excitation of the generator and compensation of reactive power load. We have discussed the methods and devices for stabilization of voltage generators which will improve the effectiveness of pre-design work on the creation of new devices of stabilization of parameters of electric power generators for small hydroelectric power plants with improved operational and technical specifications
The article shows that to improve the performance of autonomous systems we need new methods and principles of their design, associated with both the use of renewable sources and the application of new technical solutions of electromechanical generators and static stabilizers and inverters electric power settings. We have disclosed modern requirements for generators of electric power, as well as features of calculating the parameters of contactless electrical power generators: asynchronous generators capacitive excitation and asynchronous generators with permanent magnets. The article presents some analytical expressions for calculating the electrical losses and the efficiency of the generators, specific weight and power. It is shown, that expedient to designing contactless electrical power generators to carry out as part of the autonomous electricity supply systems, as it is sometimes advantageous to understate the main criteria of efficiency of generators, in order to improve, for example, weight and overall dimensions of static converters. The conclusion is made that in order to improve the efficiency of designing contactless electrical power generators in the early stages of designing it is necessary to carry out a preliminary assessment of the main criteria of efficiency of contactless electrical machines. We have also discussed analytical expressions, which might be used for preliminary evaluation of application features for various types of contactless generators in the stand-alone electricity supply systems taking into account the conditions of use
The article shows the main advantages and disadvantages of renewable energy sources. It is shown, that in general, the use of renewable energy in the world has acquired real momentum and stable growth trend. An interesting fact is that the greatest application was currently the most mutable and unstable form of energy - wind. The total global installed capacity of large wind turbines, according to various estimates, is approximately 20 GW. This is because the specific investment in wind power is lower than with most other forms of renewable energy. The article presents features of the design and operation of modern wind power stations. It is shown that when choosing wind power plants and stations we must take into account the following main parameters and factors: the average value of amount of electricity consumed by power consumers on a monthly basis; power generator; uptime in the absence wind or when weak wind. The study shows block-circuit solutions of different options of energy systems made using wind power plants. We have also disclosed prospects of development wind energy and considered the advantages and the features of the choice of the main functional units of wind power stations which will increase the effectiveness of predesign work on the creation of high-performance systems of electrosupply with combined power supply systems based on renewable energy sources
Due to strict economical factors, determining a
service life of the structural components of a tracked
timber-harvesting machine (TTHM), including the
support rollers becomes a key issue for the
manufacturers and customers. With that, optimum
relationship between the original cost of the support
rollers and their life cycle cost for maintenance and
repair during the entire service life shall be observed.
The timber harvesting machines are operated under
severe environmental and production conditions. In
the course of operation, they meet variable obstacle,
including stubs, stones, fallen trees, etc., which in
their turn affect negatively the service life of the
support rollers. This article offers a research of the
service life of the tracked timber harvesting machine
support rollers. It describes main defects of the
support rollers, including operational, mechanical
and thermal ones, as well as embedded flaws and
dynamic defects. It also presents the factors affecting
the support rollers' wear. The article presents a
service life-determining model where the following
principle can be generally applied. Service life of a
support roller is determined by its admissible
operational wear-out divided by actual factor for this
support roller and operational conditions
One can see some density irregularity within the roll
in the baler with a chamber of constant volume. We
have found out that the maximum density of hay roll
width (the baler width) is observed in the middle part.
This is due to the shape of the hay roll entering the
baler. To even the hay rolls they have mounted some
rotating disks having some inclined spring pins above
the baler. To improve the roller distribution the disks
above the baler have been pushed forward forming a
tapering gap. The evening discs rotating above the
moving roll will cause some relative motion of hay
particles. The interaction of the evening disks with
the hay roll in the vertical plane will be determined
by the elasticity of the hay roll and the weight of the
frame with the disks. We have studied the trajectories
of hay particles motion with the help of MathCad
program. We have had the following initial
parameters: the degree of compaction (decrease of the
roll height when evening), the friction coefficient, the
angle rate of the evening disks, the number of pins and the speed of the hay roll. As a result we have got
the trajectories of the hay particles motion when the
evening disks functioning. The analysis of the
trajectories has allowed to establish some basic
parameters of the evening device such as the distance
of 0.15…0.2 m between the pins; the degree of
compression while evening 20...25 %, the angle rate
of the evening discs 23...30 rad / s and the diameter
of the evening disc 0.74 m. The application of the
evening device in the form of the disks with pins
provides a uniform distribution of hay particles
edgewise of the baler ensuring preliminary hay roll
seal press before passing to the baler pressure
chamber that contributes to getting the rolls with
larger mass and a uniform distribution of hay density
inside the roll
Researches of fine-grained concrete testify the
possibility of using mineral mechanically activated and
nano-additives in a complex with the anti-frost
additives providing the organization of production of
concrete works at negative air temperatures that is
especially important for the Arctic regions
The article deals with the models and the methods of
the market of the proposed sub-systems and
equipment, based on the analysis of the requirements
for security to choose the best solution for the
synthesis of the integrated security system
The NP-problem of discrete optimization of consumption of non-renewable resources is considered in the article. It is offered to use transitions of NP-system conditions on the complete graph with number of vertexes, equal to quantity of discrete resources, for the problem decision. The purpose of such system is construction of a chain of the predetermined length and the minimum weight on the complete graph. The length of a chain defines quantity of the consumed resources. The problem factor is factorial growth of number of variants of chains on graph at linear growth of quantity of resources. The main idea consists in a finding of statistical regularities of ranks of transitions of NP-system at construction of chains with the minimum weight on graphs of the small size. Use of ranks allows to abstract from concrete weights of transitions, which are variables for each problem of optimization, and to find the patrimonial feature of all optimum decisions. It is offered to use the found regularities to solve the problems of the big dimension. As a result of researches, it has been defined that probabilities of ranks of transitions are described by geometric distribution. In the article, the algorithm of definition of parameter of geometrical distribution for a rank of each transition depending on the initial and consumed quantity of resources is presented. Realization of a method of generating of suboptimum chains is based on use of generators of the pseudo-random numbers setting values of each rank of transition of NP-system according to geometrical distribution of probabilities. It is offered two variants of generators of ranks of chains to use. Computer experiment has shown useful effect of an offered method at the decision of problems of small and average dimension
This article presents the issues related to the
application of electrical ozonation to enhance seed
germination. The calculations confirming the
theoretical conclusions were made