Power Supply Systems Of Enterprises Research Articles

Power supply reactive power factor control as a function of consumer power and losses in transformers

The system of automatic control of the reactive power factor of the enterprise's power supply system is considered, in which one part of the transformer substations is equipped with adjustable capacitor units, and the second is not. Its advantage in comparison with the power factor control system is shown, firstly, lower requirements for its error and, secondly, the calculation of the consumer with the supplier for electricity is made taking into account the ratio of reactive energy to active energy. An estimate of the error of regulation of the reactive power factor on the higher voltage side of the transformers of the main step-down substation, where settlement meters are installed, is given, with stabilization of the reactive power factor on the low voltage side of these transformers. The synthesis of the system of automatic control of the reactive power factor, built as a function of the power of consumers and power losses in transformers, and the estimation of its error are considered. The proposed control system is intended for power supply systems with a combined load, the use of which will allow the consumer to avoid penalty coefficients to the tariff for active electricity, and ultimately reduce losses in the transmission of electricity and increase the transmission capacity of the electrical network.

ЭФФЕКТИВНОСТЬ ПРИМЕНЕНИЯ АВТОМАТИЧЕСКИХ УСТАНОВОК КОМПЕНСАЦИИ РЕАКТИВНОЙ МОЩНОСТИ В НЕФТЕПРОМЫСЛОВЫХ ЭЛЕКТРИЧЕСКИХ СЕТЯХ

The relevance One of the key directions of innovative development of the electric power industry until 2035 is the transition to digital active-adaptive networks with a distributed intelligent automation and control system. In this regard, in conditions of increasing demands for improving the quality of electricity and reducing losses in networks, it is necessary to improve the voltage and reactive power regulation system in electric networks, which should be based on the widespread use of modern means of regulating voltage and reactive power, as well as automatic control systems, including centralized ones. The main effect of reducing technical losses in electric networks, as shown by the energy survey of FGC UES JSC, the experience of foreign electric grid companies and the analysis of the modes of operation of the Unified National Electric Grid, can be obtained by optimizing the established modes of operation of the electric grid in terms of reactive power and voltage levels in automatic mode, provided that the condition of regulating devices is constantly monitored. The absence of a system for remote monitoring of the parameters of power factor correction devices in the power supply systems of enterprises leads to untimely detection and elimination of failures in the operation and operation of the network without power factor correction. Aim of research To analyze the energy parameters of the power supply system of oil production facilities, to identify deviations of voltage values and power factor from regulatory requirements. To investigate the effectiveness of the use of low-voltage automatic power factor correction units in the power supply system of an oil-producing enterprise. Research methods The study of scientific literature, field research at oil pumping facilities, energy surveys, computer modeling. In order to identify the technical and economic efficiency of the use of low-voltage automatic power factor correction units, pilot field tests were conducted in one of the oil and gas producing enterprises of the Tatneft PJSC. Results Energy surveys of in-field pumping facilities, oil treatment and reservoir pressure maintenance of Tatneft PJSC have shown that the value of reactive power in the networks of power supply systems of these enterprises significantly exceeds the standard. As a result of pilot field tests, it was revealed that the use of automatic power factor correction units in automatic mode ensures the stabilization of the power factor at the level of standard values, excluding under-compensation or overcompensation of reactive power, while reducing electricity consumption by an average of 2.4 %. The remote monitoring system allows you to monitor the operating mode and technical condition of all elements of the capacitor plant, timely perform maintenance of contactors to ensure the operability of the installation.

Improving the efficiency of emergency control systems for future-oriented connection of sources of distributed generation

Improvement of energy-intensive technological processes of industrial enterprises requires increasing the reliability and efficiency of power supply of consumers. In this regard, one of the priority areas associated with introduction of the sources of distributed generation is mainstreamed in energy industry. This trend has both beneficial and negative impacts. It makes difficult to control normal, emergency, and post-emergency modes of power supply systems of enterprises of ferrous metallurgy. When new sources of distributed generation are introduced under the conditions of complex closed-loop power supply system, it is necessary to assess the level of short-circuit currents to check the electrical equipment and residual voltages across the busbars of the consumers of ferrous metallurgy. Also, it is necessary to determine the critical time of generators dropping and evaluate the stability in case of isolated operation. An algorithm has been developed for automated search of a dividing point in case of an emergency and isolated operation depending on the power balance to maintain stability. It is based on a combination of the method of successive network reduction and step-by-step method. To improve the reliability of essential consumers, the authors have developed an algorithm for automatic search for the dividing point during operation of emergency control system depending on the power balance to maintain stability. The authors have developed proprietary software to assess the effectiveness of emergency automation equipment of multi-level complex closed-loop power supply system of metallurgical enterprise. Performed calculations and analysis of emergency and post-emergency modes are designed to develop a comprehensive approach of a set of measures to ensure the reliability and stability of essential consumers in the mode of automatic search.

APPLICATION OF SOME MODELS OF POWER SUPPLY SYSTEMS WITH AN EXAMPLE OF TAKING INTO ACCOUNT THEIR RELIABILITY FOR INDUSTRIAL ENTERPRISES IN PRACTICE

The publication presents the most common and promising models and schemes for replacing the power supply system of industrial enterprises, and an example of their use in practice for power supply to sewage treatment plants of a chemical enterprise. Various types of models are considered (in tabular form, in the form of an electrical replacement circuit or in the form of a finite-state machine), as well as a logical-probabilistic approach to the representation of the power supply system. The use of automation systems in power supply systems of industrial enterprises can reduce the total number of accidents, prevent their development, reduce the time of disconnections of electrical installations and downtime of mechanisms, and also allows to transfer to work without constant maintenance a significant number of electrical installations of substations, which, in turn, leads to a reduction in the number of service personnel, increase labor productivity and reduce maintenance costs. One of the main tasks on the way to automating the power supply system of enterprises is to present it in the form of a model. The list of replacement models and schemes that can be used to represent the power supply system of enterprises is quite large, and choosing the appropriate model, for that best meets the requirements of the final goal is quite a complex scientific task. The purpose of this article is to analyze the most common and promising models and schemes for replacing the power supply system and provide recommendations on their application in practice for power supply to sewage treatment plants of a chemical enterprise. Presenting the power supply system in the form of a table allows you to simplify and visually perform certification of electrical equipment, identify problem and weak points in the power supply system of industrial enterprises. Such a table proves that a large amount of electrical equipment at lower levels depends on a single electrical device at higher levels. The representation of the power supply system in the form of a three-phase symmetric replacement circuit can be used to calculate short-circuit currents in symmetric and unbalanced modes in the MatLab program and similar. Using the model of the power supply system in the form of a finite-state machine allows you to visually check the reliability of power supply to consumers, simplify the design of the power supply system of an industrial enterprise, select the state of switching devices in the power supply system and take into account the advantages and disadvantages of each state. It is advisable to use the methods discussed in this article to represent the power supply system (in tabular form, in the form of a finite-state machine or a three-phase symmetric replacement scheme) and their further application and use in automated power supply systems of industrial enterprises. The logical-probabilistic method allows us to consider the issue of power supply reliability based on the theory of logical algebra.

Improving the quality of electricity in the power supply systems of the mineral resource complex with hybrid filter-compensating devices

The urgency and necessity of choosing and justifying the structures of hybrid filter-compensating devices based on series and parallel active filters to improve the quality of electricity in the power supply systems of enterprises of the mineral resource complex is shown. Mathematical models of hybrid filter compensating devices based on parallel and series active filters have been developed. Based on these mathematical models, computer simulation models of the indicated hybrid structures have been developed. The results of simulation showed the effectiveness of the correction of power quality indicators in terms of reducing the level of higher harmonics of current and voltage, as well as voltage deviations. The degree of influence of filter-compensating devices on the power quality indicators, which determine the continuity and stability of the technological process at the enterprises of the mineral resource complex, have been revealed. It has been established that a hybrid filter-compensating device based on a parallel active filter can reduce the level of higher harmonics of current and voltage by more than 90 and 70 %, respectively, and based on a series active filter, it can reduce the level of higher harmonics of voltage by more than 80 %. Based on the simulation results, the possibility of compensating for the reactive power of a hybrid structure based on parallel active and passive filters has been revealed. The possibility of integrating hybrid filter-compensating devices into more complex multifunctional electrical systems for the automated improvement of the quality of electricity is substantiated, as well as the expediency and prospects of their use in combined power supply systems based on the parallel operation of centralized and autonomous sources of distributed generation.

Problems of Power Factor Correction in Power Supply Systems with Higher Harmonics Sources

In this paper, on the basis of simulation modeling, an algorithm for studying the current resonance that occurs in the power supply system with a chaotic change of the load power and variation of reactive power compensation degree, in the presence of consumers with a nonlinear current-voltage characteristic is proposed. It is shown that overloading of capacitor banks can occur in a wide frequency range, close to the resonant frequency. The proposed algorithm determines all possible frequencies at which an increase of currents in capacitor banks can occur above the permissible values in parallel resonance. The purpose of the proposed work: to show in what operating modes of the enterprise power supply system an overload of capacitors by currents of higher harmonics can occur when the load power changes and the degree of reactive power compensation varies.

Анализ сенсорных элементов схемы и выявление слабых мест в сетях генераторного напряжения

Large industrial enterprises use own electrical and thermal energy sources in addition to external power systems. Therefore, ensuring the stable operation of both the auxiliary power plants supply mechanisms and the main technological equipment of an enterprise is an important task in the electric networks design and reconstruction. The reliability of the power supply system can be carried out in various ways, one of which is the identification and analysis of sensory (sensitive) circuit elements in order to further eliminate weak units. Thus, the paper considers a complex generator voltage network of an industrial enterprise that is connected to the system through high and extra high voltage substations. This network features thermal power plants with auxi­liary and high-voltage industrial consumers of the enterprise and pumping stations. A series of electromechanical transients calculations was performed in the simulation of short circuits in the network using KATRAN 10.0 software package to identify the sensory elements of the circuit. Based on the results of the calculation, the stability of synchronous and asynchronous motors is estimated by determining the level of their operational parameters deviation. Based on the calculation results, it is concluded that the power plant mechanisms of auxiliary needs have the highest sensitivity, and the maximum deviation of the mode parameters is achieved during short circuits at high voltage levels. Analyzing the sensor elements of the system allows for the higher reliability of the industrial enterprise power supply system with strong disturbances in the network.

Assessment of the consumers’ contribution to the deterioration of the electrical power quality

The article presents the rationale for the further development of the methods that uniquely identify consumers making a major contribution to the deterioration of the quality of electricity in power supply systems of enterprises. A new method that gives an unambiguous result is proposed. This feature is a significant difference from the known methods. The given statements are confirmed by the results of computer simulation that are presented in the article. The method is based on the principle of changing the input resistance of the system implemented by varying the impedance of the transformer windings. An on load tap changer can be used for this purpose. The prospects for applying the method to determine the contribution of individual consumers to the changes in the quality of electric power of the enterprises supply systems in terms of percentage are shown.

ОСОБЛИВОСТІ ЕЛЕКТРОПОСТАЧАННЯ ЗАЛІЗОРУДНИХ ПІДПРИЄМСТВ ПРИ ВПРОВАДЖЕННІ РОЗОСЕРЕДЖЕНОЇ ГЕНЕРАЦІЇ

Urgency of the research. Ukraine has powerful dispersed generation resources. At the same time, one of the four measures proposed by the International Energy Agency for improving energy efficiency in the countries of the world is increasing the use of renewable energy sources in the total electricity production, including not the last role given to dispersed generation. Meanwhile, the consequence of the natural decrease in the levels of iron ore extraction in our country, at depths exceeding 1000-1500 m, that is, towards the projected ones, which already increases the energy intensity of its extraction and the decline of the con-capita ability on the world market. Target setting. The main purpose of this work is to synthesize the features of the electric power supply of iron ore enterprises, provided that they are introduced into the system of their electricity supply of distributed generation sources and analysis of the specifics of their operation. Actual scientific researches and issues analysis. Thus, the actual scientific-practical task is to study the peculiarities of the operation of systems of electricity supply of iron ore enterprises with the use of sources of dispersed generation in their distribution networks. Uninvestigated parts of general matters defining. Previously, it was proposed to install power plants at the crosscutting overheads, on dumps of quarries and other possible places of installation in the conditions of iron ore enterprises. However, the principles of the implementation of intelligent power supply management systems for the enterprises under consideration, especially when reconfiguring these systems, are not yet definitively defined. The research objective. The purpose of this work is to synthesize the features of the electricity supply of iron ore enterprises, provided that the sources of distributed generation are introduced into their electricity supply system. The statement of basic materials. In a number of previous studies, the authors justify the positive effect of the introduction of dispersed generation into the structure of the power supply systems of enterprises. The application of artificial neural networks in control systems and determination of electrical energy parameters of power supply systems of iron ore enterprises is proposed, which will allow multifactorial management and analysis of energy parameters in the implementation of distributed generation sources. The proposed approach for the implementation of artificial neural networks for modeling the reliability of the power supply system of iron ore enterprises with the introduction of dispersed generation can be presented with the help of artificial neural networks, which will improve predictability of generated electricity by dispersed generation in time. Conclusions. The model of reliability of the power supply system of the field-view enterprises in the implementation of dispersed generation can be represented using artificial neural networks, which will improve predictability of generated electricity by dispersed generation in time.

Models for predicting damage due to accidents at energy objects and in energy systems of enterprises

Achieving energy security by preventing and timely eliminating the consequences of accidents at energy facilities and in energy supply systems of enterprises is one of the important tasks of energy management. The basis for planning appropriate energy security measures is the prediction of damage from these accidents. The purpose of forecasting is to assess the possibility of an accident occurring at some point in time and leading to a particular damage, and to assess the magnitude of this damage. The article proposed methodological approaches to the construction of mathematical models of such prediction. In this case, as an indicator of damage, the economic losses caused by these accidents are taken. The simulation is based on the representation of this indicator in the form of a step change function of the magnitude of losses in the event of an accident. Depending on the amount of information available in the period prior to forecasting, the mathematical representation of the forecasting problem is reduced to the construction of conditionally determined or stochastic models. Conditionally determined models allow obtaining acceptable damage estimates with a short period of retrospection and small amounts of information, and stochastic models with significantly large amounts. At the same time, the principle of “maximum uncertainty” formalized in the form of maximum entropy is the basis for removing uncertainty in the construction of both conditionally determined and stochastic models. Its use has allowed increasing the objectivity of forecasts by minimizing the subjective information used in modeling. The proposed approaches to the construction of mathematical models for predicting accidents at energy facilities and power supply systems of enterprises are the basis for creating specific techniques for solving relevant energy management tasks both at the micro level at the scale of individual enterprises and at the macro level at the scale of industries, regions and the state as a whole.

Результаты измерений показателей качества электроэнергии в системах электроснабжения предприятий и организаций

Результаты измерений показателей качества электроэнергии в системах электроснабжения предприятий и организаций

The algorithm of selection of non-traditional renewable sources of electric energy in the local power supply system of enterprises of mining complex

The article suggests the adoption of local energy systems (LES) in complex supply of the enterprises of the domestic mining complex (DMC) on the basis of renewable sources of electric energy (RSEE). The features of the use of LES and the urgency of development and implementation in practice of work of the enterprises DMC RSEE as an additional power supply is composed of power supply system, with the aim of providing conditions of continuity and reliability of power supply of consumers and decrease the cost of mining. For implementation of a local power enterprises of DMC and reasonably proposed for the practical implementation of the selection algorithm RSEE to LES enterprises DMC. Referense 7, Figures 2.

THE DIAGNOSIS TECHNIQUE OF ABNORMAL HEATING OF POWER CAPACITORS

The existing system of protection and diagnostics are not able to detect abnormal heating of the power capacitors caused by its internal malfunction formation. The paper contains a proposal of a technique that enables to detect such heat at its early study. This technique consists of a hardware and an algorithms. The hardware consists of a microprocessor-based instrument developed by the author, of measuring transformers of current and of temperature sensors. This equipment must be connected to the condenser unit with a rated voltage of 380 V. In operation, the device performs continuous measurement of the surface temperature of the casing of each condenser, the temperature of the external environment, voltage and current from the power source. The measured values are used in the mathematical model of thermal processes that enables to calculate the temperature of the hottest point of each capacitor in real-time. Then the calculation of the intrinsic difference ΔΘ1° between the average temperature values of the dielectric and the base average value of this temperatures during the second day from the start of the measurements. If the Dq1 value exceeds the value of the absolute error of simulation, diagnostic signals of abnormal levels of heating, viz. low, medium, high and very high, are generated. It is also necessary to calculate the rate of change of ΔΘ1° and to consider the values obtained in the formation of hazard levels. For the low level and the average level of hazard the operation of diagnostic system with a visual signal is recommended, while for the high level of hazard it is recommended to use both visual and sound signals, and for the very high hazard level the capacitor ought to be turned off from the source. The algorithms have been developed heuristically. The final formation of the algorithms is possible only after the long-term operation of the proposed diagnosis system on real objects. The implementation of the developed system will reduce the probability of sudden failure of capacitor units and, correspondingly, will increase the reliability of power supply system of enterprise.

Modeling of an industrial enterprise power supply system using direct current

Modern technological equipment driven by three-phase electric asynchronous motors, with a view to simplifying the kinematic scheme, improving performance characteristics, and extending capabilities, is as a rule equipped with a variable-frequency drive, which permits one to smoothly and in a wide range adjust the rotational speed of the motor shaft and the shaft torque. Widespread frequency control is leading to a significant change in the structural composition of consumers of electrical energy and confronting manufacturers, suppliers, and consumers of electrical energy with new problems. A frequency converter is usually constructed according to a two-stage scheme. The first stage is an ac to dc converter. The direct voltage is then converted into alternating (usually three-phase) current of required frequency and amplitude. A converter of industrial three-phase voltage to direct voltage represents a load of fundamentally different nonlinear nature, and moreover the parameters of these nonlinearities change over time. With wide use of frequency converters for power supply of electric motors of different machines, problems appear that are related to the strong distortion of the frequency composition of the supply voltage. These distortions are much more difficult to compensate for than the usual problems of increasing the power factor. Overloading of generating equipment and power lines with the harmonics of high multiplicity is not less dangerous than overloading with the reactive power, and methods of dealing with these phenomena are much more energy-intense. It is clear that, at this stage of development of the power industry, the structure of intrashop power supply consisting of a centralized powerful converter of industrial three-phase current to the direct current and intrashop power system of direct current and individual converters of direct current into alternating is becoming economically more profitable. In this paper, a part of the dc system of power supply to group consumers of an industrial enterprise is described containing two converting–distributing gears (CDGs) with a capacity of 3 kW each with an intelligent control system. The converting–distributing gear should provide conversion of three-phase alternating current 380/220 V 50 Hz to direct 220/440 V with the capability of parallel operation on dc buses to ten hierarchically arranged devices in the modes of the master, slave, and mode of proportional load distribution. The computer modeling proves the operating capability of the experimental sample of the part of the dc system of power supply.

Оптимизация системы электроснабжения промышленного предприятия при ее реконструкции

В статье представлен методический подход к решению задачи оптимальной реконструкции системы электроснабжения промышленного предприятия в условиях неопределенности исходной информации и многокритериальности. На примере конкретного предприятия получены рекомендации по реконструкции его системы электроснабжения при разных возможностях финансирования.