Substantiation of the choice of the replacement scheme of line for mathematical modeling of 20 kV power supplies.

In the current global economic crisis and acute shortage of energy resources, increasing importance is attached to energy saving measures, economical and careful consumption of raw materials, materials, electricity and heat, environmental safety of industrial production. During the reconstruction of existing power supply systems of industrial enterprises, modern progressive solutions should be considered and implemented, morally and physically obsolete electrical equipment should be replaced, namely the introduction of new electrical equipment for transition from 6/10 kV to 20 kV in Ukrainian power systems. It is also necessary to pay attention to the improvement of power supply circuits and distribution networks, the implementation of complex automation of complex technological processes, rational compensation of reactive power at all levels of power supply systems. In the power system, the main transport link is the power line. Power lines (transmission lines) are long conductors suspended at a safe distance from the ground overhead lines (overhead lines) or cable lines (overhead lines) in which conductors are insulated from each other and from the environment and protected by insulation and armor electricity. Power lines are the most massive elements of the power supply system, they connect the individual nodes of its circuit. Longitudinal and transverse parameters are distinguished in alternative schemes. The load current flows through the longitudinal parameters, voltage is applied to the transverse ones. The replacement circuit of the electrical network consists of replacement circuits of the following elements: power lines, transformers, reactors, capacitors, loads, power sources. Calculating the steady-state modes of power systems, the substitution schemes of the elements are given in a single-line design, because the parameters of all phases are symmetrical. In local and local electrical networks with a relatively short length and low rated voltage, the conduction currents are small compared to load currents. Therefore, in typical electrical calculations of these networks, the capacitive conductivity of the lines is not taken into account. However, for these networks, the accounting of capacitive conductivities is necessary when considering some modes, the existence of which in itself is due only to the presence of capacitive conductivities. For example, the mode of single-phase ground fault in a network with isolated or compensated neutral or analysis of the modes of operation of neutrals of electrical networks of different voltage classes cannot be performed without taking into account the capacitive conductivity of these networks. When switching the power system of Ukraine to the nominal voltage of 20 kV, it should be taken into account that the transmission line will be replaced in the sections of both the overhead power line and cable power line, namely 35, 10, 6 kV. The replacement scheme must describe all the characteristics and properties of the elements of cable and overhead lines in accordance with real conditions. Thus, it is not expedient to use simplified substitution circuits that neglect energy parameters and properties of conductors to study the parameters of transmission lines. The use of a complete "P" -shaped scheme for the analysis of the parameters of transmission lines and transmission lines for a voltage of 20 kV is the basis of mathematical modeling of the transmission system in the distribution networks of our country.

USE OF THERMAL PROCESSES TO OBTAIN ELECTRICITY

As a result of the analysis of the research results, it is easy to see that the voltage at the output of our electrothermal generator increases with increasing temperature difference between the surface of the heating system pipe and the aluminum air cooling radiator, between which are Peltier elements. However, the efficiency of such a generation is much lower than the efficiency indicated in the development guides of the corresponding model of the Peltier element (Appendix B). The reason for this is, obviously, the negative impact of the applied structural elements of the created model, which reduce the efficiency of heat transfer between the source of the temperature difference and the Peltier element. The step-up voltage converter used in the created model allows to receive necessary for power supply of useful devices of 5 V of a voltage on an output of the generator, but according to the parameters, this device needs a certain (though rather small) voltage on the input. In the study without load, we were able to obtain at the output of the converter 5 V standard voltage at a temperature difference ΔT = 16.1 ° C. Instead, in the second study, when the output of the converter was used as a source for the cooling fan, the required 5 V was achieved only at ΔТ = 23.2 ° С. This temperature difference is easily achieved by the surface of the heating radiator and the air of the living space during the heating season. That is, a generator based on four Peltier elements TPP 1 - 12706 will really be able to produce the required amount of electricity to power useful devices and charge mobile devices. Of particular interest is the result of a study of the efficiency of active air cooling, powered by the output of our generator. As we can see, the voltage at the Peltier elements under the conditions of the current at the generator output (Fig. 4, dependence 4) is noticeably lower than that in the case of the no-load experiment (Fig. 4, dependence 1). But only until the step-up converter can provide a voltage of 5 V (Fig. 4, dependence 3 has a jump near ΔT = 23.2 ° C) to power the fan active cooling radiator! After that, the active cooling fan is switched on and the generation efficiency becomes higher than that during the idling study. This means that the use of active cooling of the radiator makes sense in such devices. The scientific novelty of the work is to confirm the possibility of creating a heat generator using as a source of energy available in everyday life temperature difference, in particular, obtained the characteristics of the modern Peltier element. The practical significance of the work lies in the possibility of using the device at home when using a heated battery to obtain electricity that can be used to connect a flashlight, humidifier, charge the fitness bracelet.

Methods of analysis of possible states of the object diagnosis.

The development of new methods of technical diagnostics is an important task aimed at improving the efficiency and safety of the operation of industrial equipment. Such methods are complexes of jointly used methods for obtaining diagnostic information, methods for extracting from it the actual data on the technical state of the diagnosed objects, and methods for organizing diagnostic processes. Complex technical systems are characterized by complex nonlinear interactions between their constituent elements, complex scenarios of causal relationships between hazardous, probabilistic events and processes occurring during their operation. These scenarios can be implemented in complex scenario trees. Features of technical diagnostics of complex technical systems are determined by the distinctive properties of failures in such systems and scenarios. The technical diagnostics system is an information-measuring system and contains sensors of controlled parameters, communication lines with an information collection unit, executive devices, devices for interfacing with other information-measuring and control systems. Methods of technical diagnostics serve as the basis for constructing such a system. The current level and prospects for the development of diagnostic tools, flaw detection and automated control open real possibilities of using methods of maintenance and repair of equipment by a technical condition. The greatest effect from the use of such a system is achieved when operating complex equipment, preventive repair of which is associated with high costs, and emergency repair.

Study of the solar power plant power generation forecasting model.

The question of determining the possible capacity of a photovoltaic power plant is very acute due to the growing demand for renewable energy, coupled with the fact that during the day we have limited time to generate energy from such a source. Thus, based on the obtained analytical data, which allows to predict weather conditions, it is possible to regulate the amount of energy supplied to the network in a certain way due to more maneuverable power plants. In previous years, electrical engineering scientists and researchers from different countries have developed and implemented methods for determining weather conditions, such as clouds, air temperature, atmospheric dust and others, as well as their impact on the energy output of a solar power plant. A photovoltaic panel is a complex nonlinear object with many variables. In addition to the structural features of the module, the output is most affected by solar radiation and panel temperature. When researching the prediction of the amount of energy produced, it is important to find sufficiently reliable and consistent data. At the forefront of these issues are US universities and research centers. For example, the University of Nevada in Las Vegas, in 2006 put into operation a set of measurements of weather conditions: the level of sunlight, ambient temperature, wind speed, humidity and others. When calculating the power generated by the panels, it is assumed that the system operates at the point of maximum power. The scheme works as follows: we set the values of temperature (Temperature) and irradiation (Irradiance); we apply voltage to the output terminals of the array by changing its value from 0 to Voc. We take current readings at each point, we find the power for each point, we find the maximum among the obtained array of points. Repeat over the entire range of input values. Thus, we obtain a graph of the output power of Figs. 4 pre-considering the losses in the inverter.

Search for the optimal topology of artificial neural networks based on multidimensional Legendre polynomials.

Earlier in [1], it was concluded that it is necessary to improve the learning algorithms of neural networks operating in systems that generate electricity using renewable energy sources. This article is intended to acquaint the reader with a new type of activation functions of artificial neural networks (ANN), namely - the use of Legendre polynomials, as well as a new method of learning ANN, when this process is not sequential, as usual, but in parallel. The accepted statements made it possible to make sure that the new, designed neural network has better properties (such as training time and less value of learning error) than the standard ones. The relevance of this topic lies in the following provisions: - improving the interaction between the solar station and artificial intelligence systems, through increased productivity; - taking into account the transients in the electrical network by means of intelligent control, through the use of neural networks of the proposed architecture. The developed neural networks have found their application in the work of a photovoltaic station. Their main purpose is to fulfill the forecast in the electrical networks of the amount of generated power. To successfully complete the task, the following goals were set and solved: to analyze and compare standard activation functions and algorithms for ANN training, to show methods and describe the improvement of networks, to demonstrate the application of developed ANN in photovoltaic problems. This article was designed to acquaint with the new method of building neural networks, which is based on seeing the transmission of signals in a non-sequential way, such as parallel, with certain features of the connection with which it was given in the text. The paper also demonstrates the use of the Legendre polynomial using qualitative neural network activation functions that work with solar panels. For confirmation in the article the answers to calculations are given. In future materials it is planned to streamline in more detail the process of modeling and compiling a mathematical calculation for the construction of neural networks.

Simulation of a hybrid photovoltaic system with a storage battery for a local object in the case of energy management using forecast.

The issues of increasing the efficiency of a hybrid photovoltaic system with a storage battery for a local object by improving energy management by forecasting with simulation of energy processes in the system are considered. It is proposed to combine the functions of ensuring the auxiliary needs of the object with the planned generation of energy to the grid for the day ahead during peak hours. In the absence of generation to the grid in the case of sufficient energy from the photovoltaic and storage batteries, the system operates in an autonomous mode. To reduce energy consumption from the network, it is proposed to switch to work with the grid with predicting the degree of battery charge and correcting the load power when the voltage decreases within acceptable limits. To study the efficiency of energy management according to the forecast, simulation modeling of energy processes in the daily cycle was used. The developed model with a block for predicting the degree of battery charge allows you to investigate the operation of the system under various weather conditions with an estimate of the cost of paying for electricity from the grid at multi- zone billing. In this case, the archived data of the forecast of the generation of a photovoltaic battery from open web resources were used. The simulation results confirm the efficiency of the proposed solutions and the possibility of reducing costs even in the absence of generation to the grid. The solutions obtained are the basis for the design of software control complexes for photovoltaic systems with batteries with improved energy efficiency.

Higher harmonics of zero sequence current and voltage as a source of information for single-phase earth fault protection.

Single-phase earth faults in networks with ungrounded neutral are common and belong to a wider class of high-impedance damage. The problem of protection against such damage is quite complex and has been actively studied around the world in recent decades. In this article, it is proposed to use the information contained in the high-frequency components of the current and voltage of the zero-sequence during the transient process of insulation damage for targeted protection. The method of selection of high-frequency components is considered. The possibility of using a Petersen coil in the network is considered, as well as the probable deviation from the resonant tuning of the Petersen coil. The peculiarities of the transient process depending on the instantaneous voltage at the moment of a short circuit are investigated. Simulation of single-phase short circuits with different active resistance in the short circuit place is carried out. The spectral composition of zero-sequence currents and voltages during the transient process is analyzed. The dependence of the power of high-frequency components on the quality of Petersen coil tuning, instantaneous voltage at the time of short circuit, and active resistance at the time of short circuit is investigated. The principle of protection is based on determining the direction of the total reactive power of the higher harmonics of currents and voltages of zero sequence and the numerically found derivatives. The results of mathematical modeling showed that at the moment when the phase is closed to the ground, due to the recharging of the capacitance of the phase conductors in currents and voltages of zero sequence, higher harmonics occur. The power of the harmonics from the second to the tenth can be compared with the power of the first harmonic and they should be used for protection. Positive results of work of the offered way of protection at mathematical modeling and at tests on a laboratory stand are received.

Efficiency of electricity use by mine drainage plants.

The experience of operating mine drainage plants indicates significant consumption of electricity consumed by pump electric motors. This situation of mine drainage is not always justified. Sometimes this can be caused by the operation of the components of the pumping unit (pump, electric motor, pipeline, electrical network) with underestimated efficiency. The article describes the methodology and provides methods for monitoring the efficiency of the use of electricity both as a whole by the drainage system and its constituent elements. The most vulnerable of the components of the drainage system is the pumping units themselves. This is primarily due to the complexity of the design of the pumps, the presence of moving parts and significant pressures during their operation. It is generally recommended to use a pressure gauge on the discharge line, a vacuum gauge on the water inlet side, and a flow meter to measure the pump flow to monitor the pump unit. In addition to these devices, for the diagnosis of unsatisfactory pump operation, it is recommended to additionally install a manometer that measures the pressure in the unloading chamber, a manometer that measures the pressure behind the unloading disc and a flow meter that measures the water flow in the unloader. The indicators of the proposed three control devices make it possible to determine by calculation such important pump parameters as the value of the axial force and the dimensions of the end and annular clearances of the unloading unit. This technique can be used as the basis for technical diagnostics and rational organization of the operation of existing installations. This allows you to control and promptly eliminate malfunctions that occur during the operation of drainage, save valuable equipment and eliminate wasteful energy costs.

EQUALIZING BUILDING LOAD DIAGRAM BY THE METHOD OF RANDOM COMPONENT COMPENSATION WHEN CONNECTING A GROUP OF KINETIC ENERGY STORAGES TO POWER SUPPLY SYSTEM

The article presents the results of a theoretical study of the process of regulating the load diagram while compensating its random component by connecting a group of kinetic energy storages devices to the power supply system of the administrative building. Daily load diagrams of the administrative building are presented in the form of an additive model. The definition of the law of load distribution is validated. The structure of group of kinetic power storages connecting to the power supply system of administrative building has been developed to compensate the random component of the load diagram. A method of load diagrams equalizing by random component compensating is proposed. Application of the proposed method of load equalizing will allow controlling effectively the capacity of load in the building’s internal power supply system.

Investigation of overvoltage in electrical networks.

The paper considers the processes that occur in power lines and power transformers at atmospheric and switching overvoltages. Atmospheric overvoltages are divided into two types: direct, which occur due to a direct lightning strike; and induction - occur at any switching. Direct overvoltages reach values sufficient to cover the insulation of any voltage class. Protection of power transmission lines from them - suspension of grounded lightning protection cables, protection of substation equipment - installation of lightning rods. It is important to study the wave processes in power lines that occur when switching, which occurs when the power supply is turned on, when disconnected from the power supply, in the event of short circuits, when power lines are struck by lightning. In addition, it is important to study the wave processes in power transformers, the effect of the pulse corona, the effect of overvoltage on the transformer windings. In a more detailed analysis of the processes, the following conclusions were made: 1) under the condition of the same mains voltage, the voltage wave will be higher in the cable transmission line than in the air, due to the difference in impedance. 2) in the XX mode, the load current will drop to zero, and the load voltage will double. The voltage of the reflected wave will keep the sign. In short-circuit mode, the load voltage will drop to zero and the load current will double. The voltage of the reflected wave will change the sign. Thus, when the substation equipment is under a voltage close to XX, there is a probability of equipment damage during atmospheric overvoltages. 3) For substations that are powered by overhead power lines, it is advisable to use a tank to smooth the slope of the refracted wave, and for substations that are powered by cable transmission lines, it is advisable to use inductance to smooth the slope of the refracted wave. 4) Inductance and capacitance can have a significant effect on the amplitude of the voltage wave, provided that. 5) Capacitance performs protective functions in all directions, both refracted and reflected wave, and inductance only smooths the refracted wave. The obtained relations can be used to study the overvoltage in the connection nodes of node substations.