scholarly journals Predicting the influence of the non-sinusoidal network mode on power transformers

2019 ◽  
Vol 114 ◽  
pp. 04005
Author(s):  
Ngo Van Cuong ◽  
Lidiia I. Kovernikova
Keyword(s):  
Service Life ◽  
Electric Power ◽  
Power Quality ◽  
Electrical Equipment ◽  
Operating Conditions ◽  
Transformer Oil ◽  
Power Transformers ◽  
Electrical Network ◽  
Electrical Networks ◽  
Current Harmonics

The parameters of electrical network modes often do not meet the requirements of Russian GOST 32144-2013 and the guidelines of Vietnam. In the actual operating conditions while there is the non-sinusoidal mode in electrical networks voltage and current harmonics are present. Harmonics result in overheating and damage of power transformers since they cause additional active power losses. Additional losses lead to the additional heat release, accelerating the process of insulating paper, transformer oil and magnetic structure deterioration consequently shortening the service life of a power transformer. In this regard there arises a need to develop certain scientific methods that would help demonstrate that low power quality, for instance could lead to a decrease in the electrical equipment service life. Currently we see a development of automated systems for continuous monitoring of power quality indices and mode parameters of electrical networks. These systems could be supplemented by characteristics calculating programs that give out a warning upon detection of the adverse influence of voltage and current harmonics on various electrical equipment of both electric power providers and electric power consumers. A software program presented in the article may be used to predict the influence of voltage and current harmonics on power transformers.

scholarly journals Nonlinear load modeling for analysis of non-sinusoidal conditions in electrical networks based on measurements of harmonic parameters

2021 ◽  
pp. 5-20
Author(s):  
L. Kovernikova ◽  
V.C. Luong
Keyword(s):  
Electrical Equipment ◽  
Distribution Functions ◽  
Operating Conditions ◽  
Electrical Network ◽  
Electrical Networks ◽  
Nonlinear Loads ◽  
Nonlinear Load ◽  
Current Harmonics ◽  
Load Models ◽  
Nonlinear Devices

Non-sinusoidal conditions in electrical networks need to be calculated for their control and development of technical measures to maintain harmonic parameters according to the requirements of regulatory documents. These calculations are impossible without electrical network and nonlinear load models that adequately reflect them in computational programs. Nonlinear load models have been developed for a long time. Some studies present general modeling principles and models of various nonlinear devices. Others consider some nonlinear devices as equivalent nonlinear loads connected to low and medium voltage networks. A whole host of high-power nonlinear electrical equipment is connected to high voltage networks. Modeling nonlinear loads connected to these networks is a problem. Research of measured parameters of harmonic conditions in electrical networks has shown that they are random values. The probabilistic nature is determined by the network configuration, a range of network components, the number of nonlinear loads, wave and frequency properties of the network, harmonic source phase currents, voltage at terminals of nonlinear electrical equipment, changes in operating conditions and load power, and many other factors. Nonlinear loads can only be modeled based on the measurements of parameters of harmonic conditions due to their unpredictability. The paper presents an overview of existing methods for modeling nonlinear loads, a methodological approach to modeling nonlinear loads based on measured parameters, an algorithm for modeling harmonics of active and reactive currents, a computational program algorithm designed to identify distribution functions of measured current harmonics, and modeling results for current harmonics of railway transformers supplying power to electric locomotives.

scholarly journals Evaluation of the Influence of Non-sinusoidal Conditions on Power Transformers

2018 ◽  
Vol 58 ◽  
pp. 03012
Author(s):  
Lidiia Kovernikova ◽  
Ngo Van Cuong
Keyword(s):  
Cost Effective ◽  
Electrical Equipment ◽  
Power Transformers ◽  
Electrical Network ◽  
Operating Parameters ◽  
Electrical Networks ◽  
Equipment Operation ◽  
Traction Substation ◽  
Operation Conditions ◽  
Railway Traction

The electrical equipment operation is cost-effective and reliable when operating parameters of the electrical network correspond to the rated data of the equipment. The real operation conditions, however, differ from those required for electrical equipment, which negatively affects its efficiency. The non-sinusoidal conditions in electrical networks are currently very common. The paper provides an overview of the characteristics obtained from an analysis of publications, which are used to evaluate the effect of the non-sinusoidal conditions on power transformers. The results of the calculation of these characteristics for a transformer installed at a railway traction substation are presented. Parameters of the non-sinusoidal conditions are obtained as a result of measurements.

scholarly journals On the influence of electric power quality on the decimation of currents and voltages of utility frequency

2021 ◽  
Vol 288 ◽  
pp. 01022
Author(s):  
Gennady Vagin ◽  
Alexander Kulikov ◽  
Alexander Sevostyanov ◽  
Anatoly Fitasov
Keyword(s):  
Electric Power ◽  
Power Quality ◽  
Harmonic Component ◽  
Electric Power Industry ◽  
Digital Signal ◽  
Electrical Energy ◽  
Sampling Frequency ◽  
Electrical Network ◽  
Electrical Networks ◽  
Electric Power Quality

The electric power industry cannot develop without analyzing the factors that affect the shape of currents and voltages when determining the parameters of the electric network mode in the context of the introduction of modern means of intellectualization into the structure of power supply systems. The share of equipment affecting the electric power quality reaches 90% in modern electrical networks. This leads to the appearance of noise in the network that reduces the quality of electrical energy, voltage distortion by higher harmonic components in particular, and affects the adequacy of the parameters of the electrical network adopted by automatic control devices. The article presents the results of digital signal processing containing distortions in the form of a harmonic component with a decrease in the sampling frequency. It is shown that a decrease in the sampling frequency does not exclude the effect of higher harmonics on the result of processing signals, including high-frequency distortions.

scholarly journals Analysis of the influence of non-sinusoidal and unbalanced network modes on induction motors

2021 ◽  
Vol 289 ◽  
pp. 01002
Author(s):  
Ngo Van Cuong ◽  
Lidiia I. Kovernikova
Keyword(s):  
Power Systems ◽  
Power Quality ◽  
Induction Motors ◽  
Electrical Power ◽  
Electrical Energy ◽  
Operating Conditions ◽  
Premature Aging ◽  
Electrical Network ◽  
Electrical Networks ◽  
Electrical Power Systems

The parameters of electrical network modes do not correspond the requirements GOST 32144-2013 of Russian and the National technical regulation of Vietnam. In real operating conditions in electrical networks in non-sinusoidal and unbalanced modes there are harmonic components of voltages and currents as well as voltages and currents of negative sequence. They cause additional losses of active power, which leads to additional heating and causes premature aging of the insulation, and as the result, the reduction in the service life of induction motors. Currently, we see that the process of formation of intelligent electrical power systems is underway. Systems for continuous monitoring of power quality indices and parameters of electrical systems modes are being developed. These systems can be supplemented with programs for calculating characteristics that issue the warning when the unfavorable influence of the parameters of non-sinusoidal and unbalanced modes is detected on various electrical equipment of both electrical power systems and consumers of electrical energy. The paper provides an overview of the characteristics used to analyze, assess and predict the influence of poor power quality associated with non-sinusoidal and unbalanced of currents and voltages on induction motors. A computer program was developed to calculate these characteristics. The program was used to study the influence of non-sinusoidal and unbalanced modes on the induction motors of the coal sorting plant of the Vietnamese company “Cua Ong-Vinacomin”.

Approach to the location of distributed generation sources in the structure of electrical networks

2021 ◽  
pp. 75-86
Author(s):  
A. Gai ◽  
◽  
V. Gulevich ◽  
Keyword(s):  
Electric Power ◽  
Quality Indicators ◽  
Distributed Generation ◽  
Power Supply ◽  
Alternative Energy ◽  
Electric Power Industry ◽  
Energy System ◽  
Electrical Network ◽  
Electrical Networks

Today, the electricity supplier is not able to declare the possible level of quality of electricity supply, and the consumer simply does not have the opportunity to buy such "high-quality" electricity. In such conditions, a differentiated approach to tariff formation is inevitable, which has been implemented in practice today, albeit in its infancy. Further improvement of the tariff-forming mechanism is impossible without creating a "flexible" dependence of the tariff on the quality indicators of the consumer's power supply. Quality indicators, in turn, are based, on the one hand, on the methods and approaches for their determination, and on the other, on statistically reliable data on the elements that make up the equipment in the "generation-consumer" chain. In recent years, there has been a tendency to change the concept of development of the electric power industry, since preference is given to the development of sources of distributed generation. Distributed generation is understood as a source of electrical energy directly connected to the distribution electrical network or connected to it by consumers. Ensuring the socio-economic stability of society and a decent quality of life for the population largely depends on the reliability and efficiency of the functioning of the infrastructure for the supply of fuel and energy resources, in particular, electricity. Excessive losses of electricity during its production, transportation and distribution, as well as an unacceptable level of harmful emissions into the atmosphere, are the cause of interruptions in power supply to consumers and even the threat of systemic accidents in the United Energy System (UPS) of the country. The introduction of alternative energy sources in electric power systems, in addition to reducing the harmful impact on the environment and solving the problems associated with waste pollution during electric power generation, will reduce the use of natural resources and relieve the backbone and distribution power lines. As part of the scientific search, an approach was proposed, which is the basis for calculations to determine the optimal installation locations for sources of distributed generation of an average overhead line. The results obtained are presented in the framework of a joint technical meeting of leading specialists of operating enterprises, the customer and the staff of the Department of Power Supply named after V.M. Sinkova NULES of Ukraine.

scholarly journals Influence of Oil-Filled Transformers Overload Capacity on the Throughput Capacity of the Electrical Network

2018 ◽  
Vol 61 (4) ◽  
pp. 310-320
Author(s):  
V. A. Anishchenko ◽  
I. V. Gorokhovik
Keyword(s):  
Service Life ◽  
Power System ◽  
Electric Power ◽  
Power Supply ◽  
Electric Power System ◽  
Throughput Capacity ◽  
Electrical Network ◽  
Economic Losses ◽  
Insulation Material ◽  
Overload Capacity

During the operation of the electric power system, there is often a need to overload its individual elements (generators, power transformers, overhead and cable power lines, switching electric devices) for a period lasting from several dozens of minutes to a day. The overloads can be caused by intentional disconnection of parallel elements of the system because of scheduled preventive repairs, post-accident disconnections, as well as an unexpected increase in electricity consumption due to the impact of various factors. The overload capacity of the system elements makes it possible to increase operational reliability of power supply to consumers without additional expenditures while maintaining, in most cases, the almost normal service life of electrical equipment. Oil-filled transformers have the greatest potential overload capacity power, which makes it possible to consider them as a significant source of increasing the capacity of the transmission and distribution networks of the electric power system. Excessive over-current of power oil-filled transformers significantly reduces reliability and reduces their normal service life. This is due to the accelerated process of wear of the insulation material of the transfer windings as a result of overheating of the transformer oil, that causes structural changes and, as a consequence, to mechanical damage to the insulation of the windings; the latter can cause an electrical puncture. On the other hand, underestimation of the permissible overload of transformers might result in economic losses due to under-produced products when the functioning of the part of the transformers connected in parallel are ceased for scheduled preventive maintenance or as a result of forced emergency shutdowns. Therefore, there is a need to assess the potential of reasonable increase in the throughput capacity of the electrical network and, accordingly, the reliability of the power supply system, taking into account the requirements for the permissible loads of transformers when the electrical network and various operating modes are being designed.

scholarly journals Improvement of the gas chromatographic method for diagnosing developing defects in oil-filled electrical equipment based on the analysis of furan compounds

2021 ◽  
Vol 288 ◽  
pp. 01080
Author(s):  
Ngoc Dan Vu ◽  
Alina Vyacheslavovna Taneeva ◽  
Vyacheslav Fedorovich Novikov
Keyword(s):  
Furfuryl Alcohol ◽  
Dipole Moments ◽  
Electrical Equipment ◽  
Selectivity Coefficient ◽  
Transformer Oil ◽  
Effect Of Temperature ◽  
Electrical Networks ◽  
Organic Extractants ◽  
Gas Chromatographic Method ◽  
Paper Insulation

During the operation of oil-filled electrical equipment under the influence of temperature, humidity and other negative factors, the destruction of paper insulation occurs. As a result of this destruction, furan compounds are formed, which get into the transformer oil. To identify the process of destruction of paper insulation, control of furan compounds in transformer oil is carried out by instrumental methods. Of these methods, the most widely used is gas chromatography using packed chromatographic columns, on the basis of which guidelines have been developed. To improve gas chromatographic methods for monitoring furan compounds, we used a highly efficient quartz capillary column filled with a polar stationary phase based on polyethylene glycol. The sample was injected into the injector of the chromatograph Chromos-GC1000 using an automated dosing system with a vial for 23 samples. Used transformer oil of the GK-1 brand of Almetyevsk electrical networks was taken as the object of research; The optimal retention characteristics of standard sorbates were preliminary determined, which were used as organic extractants of transformer oil and furan compounds. The effect of temperature on the process of chromatographic analysis of furfuryl alcohol and organic extractants was determined, on the basis of which it was established that the selectivity of separation is determined by the nature of intermolecular interactions in the sorbate-sorbent system, in particular, the formation of a hydrogen bond. It has been shown that the selectivity coefficient for the separation of furfuryl alcohol depends on the physicochemical nature of organic extractants, their boiling points and dipole moments and has the highest values for the analyzed pair of components: furfuryl alcohol - ethanol.

The problem of determining the antioxidant additive in transformer oil by chromatographic methods

2020 ◽  
Vol 22 (5) ◽  
pp. 107-115
Author(s):  
Duy Hung Nguyen ◽  
V. F. Novikov
Keyword(s):  
Liquid Phase ◽  
Sample Preparation ◽  
Ethyl Alcohol ◽  
High Voltage ◽  
Electrical Equipment ◽  
Operating Conditions ◽  
Transformer Oil ◽  
Phase Extraction ◽  
Antioxidant Additive ◽  
Negative Effect

THE PURPOSE. Transformer oil is widely used in high-voltage electrical equipment and acts as a dielectric and also as a cooling medium. It consists of a complex mixture of hydrocarbon compositions with various impurity compounds. During the operation of oil -filled electrical equipment under the influence of the technological operating conditions of high -voltage devices, aging of both transformer oil and solid insulation occurs. In this case, the dielectric properties deteriorate, which can damage the transformer equipme nt. METHODS. To increase the service life of oil-filled electrical equipment, an antioxidant additive is introduced into the transformer oil at the stage of its manufacture, which is most often used as ionol, the concentration of which must be constantly controlled by various instrumental methods. To determine the antioxidant additive in transformer oil, a sample preparation system is used based on liquid-phase extraction with selective solvents, which are used as aliphatic alcohols of various physical and chemical nature. RESULTS. It has been established that ethyl alcohol, which is widely used in the sample preparation system for liquid extraction of ionol, contains a significant amount of water, which has a negative effect on the process of ionol extracti on from transformer oil. In addition, the composition of ethyl alcohol contains impurity substances that can have a negative effect on the process of liquid-phase extraction of ionol from transformer oil. The generalized data on the physicochemical properties of extractants used to extract ionol from transformer oil are presented. CONLUSION. It has been shown that butanol is the most promising organic solvent for the extraction of ionol, which has a higher boiling point compared to ethyl alcohol and contains a small amount of water. It was found that the selectivity of the chromatographic separation of butanol components with an elevated column temperature increases. At the same time, the separation efficiency increases as the number of theoretical plates per meter of chromatographic column increases. As the temperature of the capillary column increases, the symmetry of the chromatographic peaks of the separated components also increases.

Study Results of the Electrical Parameters of the High-Power "Ladle-Furnace" Unit and its Impact on the Power Supply Network

2021 ◽  
Vol 3 (3) ◽  
pp. 33-43
Author(s):  
Ivan N. APRELKOV ◽  
Keyword(s):  
Electric Power ◽  
Power Quality ◽  
Power Supply ◽  
Electric Arc ◽  
Furnace Unit ◽  
Operating Conditions ◽  
Ladle Furnace ◽  
Supply Network ◽  
Study Results ◽  
Electric Power Quality

The steel refinement and its chemical composition and temperature finalization processes in a pouring ladle carried out by heating the metal with electric arc have received wide use at modern metallurgical enterprises. The article considers the electrical operating conditions of the ladle furnace unit (LFU) equipped with a 40 MVA electric furnace transformer. It was expected that the LFU load would vary insignificantly, because the electric arc burns between the electrodes and the surface of already molten metal, without the occurrence of short circuits. However, the accomplished studies testify that the LFU load is abruptly variable and nonlinear in nature, and gives rise to significant voltage fluctuations and harmonic distortions in the power supply network. The flicker intensity (severity) factor has been estimated, and the level of current harmonic components generated due to LFU operation has been determined. By using the obtained results, it becomes possible to predict the influence of LFU electric operating conditions on the levels of electric power quality indicators in changing the power supply network parameters, and to adopt circuit engineering solutions for assuring the electric power quality in the plant electric power supply system.

scholarly journals ON THE SIMULATION OF MODES ОF ELECTRIC POWER SYSTEMS WITH FACTS

2017 ◽  
Vol 60 (4) ◽  
pp. 341-351
Author(s):  
E. D. Halilov
Keyword(s):  
Power Systems ◽  
Power System ◽  
Electric Power ◽  
Power Flow ◽  
Power Transmission ◽  
Electric Power Systems ◽  
Active Power ◽  
Operating Conditions ◽  
Electrical Networks ◽  
Facts Devices

Power flow control is an important task of development of electric power systems. It is necessary to reduce the power loss, improve the reliability and quality of power supply and increase the power transmission. Currently, on the basis of modern power electronics effective FАСТS devices for flexible control of power system operation modes have been developed. FАСТS devices are able to simultaneously influence the voltage, the reactance, the angle between the voltages. As it is known, the calculations of the established modes of electric systems are the most frequently performed tasks at all the territorial and time levels of control and planning operations. These calculations are significant by themselves, being also an integral part of software systems of calculation of losses of power and energy in electrical networks, calculation of optimal modes and also sustainability. The need for multiple mode calculation imposes high requirements to the methods of calculation of the established modes in real time in terms of performance and reliability of the results of the solution being obtained under operating conditions of electric power systems. In traditional calculations of the established modes of electrical networks, shunt reactors, current-limiting reactors, capacitor banks, longitudinal compensation devices were accounted in the simulation as passive elements. In regard with the introduction of FACTS devices in power systems, there is an arising need to develop appropriate algorithms and implement them in the form of software for analyzing and controlling the established modes of power systems. The methodology and software for calculation of the established modes of electric networks with consideration of FACTS devices have been developed. The software makes it possible to obtain practically acceptable solutions in three outer iterations. Based on the results of numerical simulation of modes of the power system of the “Azerenergy” JSC it was determined that the application of FACTS devices can significantly increase the transmission line active power, improve voltage levels and reduce losses of active power. The dependences of flows and power losses on the control parameter of FACTS devices have been derived. 

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