scholarly journals PROPERTIES OF THE REACTIVE POWER OF THE ASYNCHRONOUS MACHINE AS A LOAD OF THE ELECTRIC NETWORK

2021 ◽  
Vol 2 (37) ◽  
pp. 28-33
Author(s):  
O. Klyuyev ◽  
E. Khmelnitsky
Keyword(s):  
Power Supply ◽  
Reactive Power ◽  
Supply Voltage ◽  
Power Supply Unit ◽  
Minimum Point ◽  
Electrical Network ◽  
Electrical Networks ◽  
Asynchronous Machines ◽  
Load Unit ◽  
Main Consumer

It is known that the voltage mode of the electrical network is associated with the balance of reactive power and directly affects the operation of production equipment. A typical static characteristic of a power supply unit in terms of reactive power, obtained for a load composition characteristic of electrical networks, is an extreme function with a minimum point. It is the presence of a minimum point in the dependence of reactive power on voltage that makes it possible to develop this type of instability as a voltage avalanche. This mode is especially dangerous for industrial units with abruptly variable loads, which can create significant fluctuations in the supply voltage, which significantly affects the operation of powerful asynchronous motors. Therefore, the issues of the relationship between the parameters mode of the electrical network and the properties of electrical loads are always important, especially asynchronous machines as the main consumer of electricity, which largely determines the properties of the generalized reactive power curve of the entire load unit. Literary sources do not explain in detail why the curve of the dependence of the reactive power of the power supply unit on voltage has a minimum. The article sets out this issue in sufficient detail for asynchronous machines as the main consumer of reactive power in electrical networks. The task is to obtain the dependence of the reactive power of an induction machine with a squirrel-cage rotor on the voltage of the supply network, as well as to determine the criteria for controlling reactive power flows in order to inadmissibly reduce the voltage in the load unit. As a result, based on the system of equations of an asynchronous machine, the dependence of its reactive power on the supply voltage of the network was derived. The mathematical properties of this function are investigated with a physical justification of its unimodality and the presence of a minimum point. The obtained expressions make it possible to determine the magnitude of the control action on the high-speed reactive power compensation devices to stabilize the voltage level in the power supply unit.

scholarly journals On the Mutual Influence of Voltage Control Modes and the Compensation of Reactive Power in the Electrical Networks of Industrial Enterprises

2021 ◽  
Vol 64 (3) ◽  
pp. 239-249
Author(s):  
V. P. Schasny ◽  
A. I. Zhukouski
Keyword(s):  
Power Supply ◽  
Reactive Power ◽  
Mutual Influence ◽  
Voltage Control ◽  
Reactive Power Compensation ◽  
Electrical Network ◽  
Electrical Networks ◽  
Industrial Enterprises ◽  
Technical Requirements

The efficiency of an enterprise’s power supply system depends on the quality of electricity and the losses of the latter in electrical networks; both being largely determined by the modes of voltage control and reactive power compensation. In practice, the problems of voltage control and reactive power compensation in power supply systems of industrial enterprises, including electric networks with a voltage of up to 1 kV, as well as 6, 10 kV and higher, are often solved separately. It triggers an irrational use of existing voltage control devices, underutilization of the installed capacity of compensating devices, and affects the voltage control in the electrical networks of the power supply organization. Since voltage management and compensation modes of reactive power are inseparable, they can be correctly determined only with the use of an integrated approach based on technical and economic criteria and taking into account technical requirements and local conditions. This article analyzes the mutual influence of voltage control and reactive power compensation modes in the electrical networks of industrial enterprises from the point of view of ensuring the quality of electricity and minimizing load power losses. The method and results of calculations (on the example of a specific industrial facility) for determining voltage deviations and losses in the electrical network as well as for selecting parameters for voltage control and reactive power compensation are presented. Due to the close relationship of these modes that affect all voltage levels, the effectiveness of measures cannot be ensured without the use of multifunctional devices for controlling the equipment of transformer substations.

Study of the influence of overvoltage on the quality of electricity in energy systems.

2020 ◽  
Vol 23 (2) ◽  
pp. 52-58
Author(s):  
S. SKRYPNYK ◽  
Keyword(s):  
Power Supply ◽  
Fire Hazard ◽  
Lightning Discharge ◽  
Quality Standard ◽  
Normal Operation ◽  
Electrical Network ◽  
Modern World ◽  
Electrical Networks ◽  
The World

Our world with its high technologies has long been deeply dependent on the quality of electricity supply. In most countries of the world there are national power grids that combine the entire set of generating capacity and loads. This network provides the operation of household appliances, lighting, heating, refrigeration, air conditioning and transport, as well as the functioning of the state apparatus, industry, finance, trade, health services and utilities across the country. Without this utility, namely electricity, the modern world simply could not live at its current pace. Sophisticated technological improvements are firmly rooted in our lives and workplaces, and with the advent of e-commerce began the process of continuous transformation of the way individuals interact with the rest of the world. But with the achievement of intelligent technologies, an uninterrupted power supply is required, the parameters of which exactly meet the established standards. These standards maintain our energy security and create a reliable power system, that is maintaining the system in a trouble-free state. Overvoltage is the deviation of the rated voltage from the value of the corresponding quality standard (frequency, sinusoidal voltage and compliance of harmonics). Overvoltage in terms of fire hazard is one of the most dangerous emergency modes of electrical equipment, which causes conditions that in most cases are sufficient for the occurrence of fire hazards (exceeding the allowable voltage leads to disruption of normal operation or possible ignition). Against the background of deteriorating engineering systems, increased power consumption and poor maintenance, power supply of electrical installations, the main causes of overvoltage in electrical networks are thunderstorms (atmospheric overvoltage), switching switches, uneven phase load in electrical networks, etc. The physical picture of internal overvoltage is due to oscillatory transients from the initial to the established voltage distributions in the conductive sections due to the different situation in the electrical circuit. In the conditions of operation of electric networks planned, mode or emergency situations are possible. Therefore, the ranges of overvoltage are determined by the range from several hundred volts to tens and hundreds of kilovolts, and depend on the types of overvoltage. Atmospheric overvoltage is considered to be one of the most dangerous types of emergency modes of operation of the electrical network. This overvoltage occurs as a result of lightning discharge during precipitation by concentrating electricity on the surface of the object, the introduction of potential through engineering networks and

scholarly journals ELECTRIC SUPPLY OF UNDERGROUND CONSUMERS OF DEEP ENERGY-INTENSIVE MINES

2018 ◽  
pp. 25-46
Author(s):  
F. P. Shkrabets
Keyword(s):  
Power Supply ◽  
Supply Voltage ◽  
Maximum Load ◽  
Electrical Equipment ◽  
Transport Systems ◽  
Local Power ◽  
Electrical Networks ◽  
Electric Networks ◽  
Supply Networks ◽  
Technical And Economic Indicators

The increase in the capacity of cleaning and construction vehicles for highcapacity and energy-intensive mines calls for an increase in the  supply voltage of cleaning and tunneling combines, as well as  transport systems: from a voltage of 660 V switched to 1140 V, and  now to 3300 V. This allows improving technical and economic  indicators for clearing and access areas, as well as improving the reliability of local Power Supply Systems (PSS). However, this  trend prevents the supply of underground electric networks with a  voltage of 6 kV, in connection with which the problem arises of  increasing the voltage of supply networks. To date, it has become  possible to apply the 10 kV voltage to the operation, which is most  acceptable for the use of electrical equipment for electrical networks  and protection devices. Leading educational, research and design  organizations were engaged in research on this issue. An analysis of the results of the research showed that switching to 10 kV voltage is  justified and timely. At the same time, 35 kV voltage is not removed  from the agenda, which is technically feasible and economically  justified, but there are problems with the safety of its operation in  underground workings, which requires appropriate refinement. This  level of voltage will improve the quality of electricity.Conclusions: 1. Application of 35 kV voltage in the underground power supply system of coal and ore mines is advisable at a depth of more than 1000 m with a maximum load of at least 1000 kVA at the  level of the stem cables.2. Application of 35 kV voltage in underground electrical networks will allow to significantly improve the quality indicators of voltage,  reliability, and economy of the system due to the current unloading  of the most important element of SES, such as stem cables.3. Analysis of the main parameters and characteristics of electrical mine electrical equipment gives reason to believe that it allows  implementing a trend of 35 kV deep input to deep horizons of mines  (mines) and placement of 35/6 kV substations on working horizons.

scholarly journals Development of Optimum Repair Schedule of Electrical Network Equipment to Improve the Reliability of its Functioning

2019 ◽  
pp. 4-11
Author(s):  
Sergey V. Belyaev ◽  
Aleksey V. Malafeev ◽  
Evgeniy Ya. Omelchenko
Keyword(s):  
Power Supply ◽  
Technical Condition ◽  
Electrical Network ◽  
Steady Increase ◽  
Electrical Networks ◽  
Number Of Factors ◽  
Network Equipment ◽  
Long Time ◽  
Planning Algorithm ◽  
Labor Resources

To ensure uninterrupted power supply to consumers, maintenance of the electrical networks in a working condition is today carried out through the use of a system of preventive maintenance. In the general case such a system allows building equipment repair schedules based on repair cycles for a long time predetermining the list of necessary material and labor resources in advance. However, in practice, the use of this system is rather difficult and not always effective. This is due to the need to change the repair schedule for emergency or urgent repairs taking into account the seasonality of work performed and the organizational structure of the production department of electrical networks and related departments as well as taking into account the specific features of the operation of specific equipment. Taking into account the current pace of development of electrical networks with a steady increase in the number of consumers (which also leads to a complication of the configuration of electrical networks) this is impossible without the use of appropriate mathematics and software that automates the planning processes for the maintenance and repair of electrical networks with a large number of factors. The minimum equipment downtime was taken as the main criterion for optimality, as a factor that largely determines the reliability of power supply. A planning algorithm has been developed that takes into account the ranking of works in order of importance, the possibility of their shift in time and the likely adjustment of the schedule based on the results of assessing the technical condition of the equipment. A method for minimizing the downtime of repair crews by using them in adjacent areas as well as a technique for identifying a set of equipment that may be under repair in the same period of time are proposed.

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 Timely determination of static stability margins in power supply systems equipped with distributed generation installations

2021 ◽  
Vol 25 (1) ◽  
pp. 31-43
Author(s):  
Yu. N. Bulatov ◽  
A. V. Kryukov ◽  
К. V. Suslov ◽  
A. V. Cherepanov
Keyword(s):  
Distributed Generation ◽  
Power Supply ◽  
Computer Modelling ◽  
Dynamic Modelling ◽  
Electrical Network ◽  
Electrical Networks ◽  
Stability Margins ◽  
Emergency Control ◽  
Supply Systems

The article aims to develop a methodology to ensure timely determination of the margins of static aperiodic stability in power supply systems, at the nodal points of which distributed generation units are installed. The authors used mathematical methods and algorithms based on the application of limiting regime equations. Transitional processes were analysed for various points in the space of controlled mode parameters according to the simulation modelling in Matlab using the Simulink and SimPowerSystems packages. On the basis of the obtained results, an effective technique for analysing stability margins in electrical networks with distributed generation units was implemented. This method is applicable in design problems, as well as in operational and emergency control. The conducted theoretical analysis and computer modelling showed the effectiveness of the proposed methodology for calculating stability margins; the nondegeneracy of the Jacobi matrix of limiting regime equations at the solution point ensures the guaranteed reliability of the results. It was shown that an alternative approach to solving the problem of timely determination of aperiodic stability margins can be implemented on the basis of limiting regime equation with increased nonlinearity. Dynamic modelling of an electrical network with distributed generation units confirmed the correctness of determining the stability margins calculated using limiting regime equations. The developed technique can be recommended for practical use in the design of power supply systems or in operational control of synchronous generators. In particular, the presented methodology can be used to implement a multi-agent emergency control system for distributed generation installations located in generalpurpose distribution electrical networks. 

scholarly journals КОМПЛЕКСНЕ ОЦІНЮВАННЯ ЕФЕКТИВНОСТІ ВСТАНОВЛЕННЯ ДОДАТКОВИХ ДЖЕРЕЛ РЕАКТИВНОЇ ПОТУЖНОСТІ У РОЗПОДІЛЬНИХ ЕЛЕКТРИЧНИХ МЕРЕЖАХ

2018 ◽  
Vol 124 (4) ◽  
pp. 103-111
Author(s):  
В. В. Кулик ◽  
О. Б. Бурикін ◽  
В. М. Пірняк
Keyword(s):  
Reactive Power ◽  
Comprehensive Evaluation ◽  
Efficiency Index ◽  
Electrical Network ◽  
Electrical Networks ◽  
Power Sources ◽  
Search Area ◽  
Electrical Grids ◽  
Monitoring Devices

To develop a method for assessing the effectiveness of reactive power sources (RPS) in electrical grids. The efficiency indicator was obtained as a result of combining the method of assessing the quality of the functioning of electrical grids on the basis of Markov networks and the method of interval analysis of energy losses. The efficiency index improves the formulation of the problem of optimizing the connection of the RPS to electrical networks. It improves the quality of this task. A new method of forming an indicator of the guaranteed effectiveness of the installing the RPS is obtained. It provides an unambiguous comprehensive evaluation of efficiency, takes into account the reliability of the electrical network, the quality of the voltage in its nodes, the accuracy of calculating the released and lost electricity. The method makes it possible to construct more efficient algorithms for optimizing the connection of RPS. They allow excluding from the search area optimal solutions "indefinite" fragments of the network without the help of an analyst. Estimation of the real effect is difficult or impossible for such fragments due to frequent failures or lack of monitoring devices. This correction of the search area improves the quality of the solution.

scholarly journals DEVELOPMENT OF AN ALGORITHM FOR CREATING A THREE-DIMENSIONAL GRAPH OF THE TOTAL HARMONIC OF VOLTAGE COMPONENTS RATIO

2021 ◽  
pp. 56-67
Author(s):  
Nadezhda M. Drey ◽  
Ayrat G. Ziganshin ◽  
Georgi M. Mikheev
Keyword(s):  
Power Supply ◽  
Power Supply System ◽  
Reactive Power ◽  
Short Circuit ◽  
Three Dimensional ◽  
Supply System ◽  
Electrical Network ◽  
Industrial Enterprises ◽  
Harmonic Components ◽  
Dimensional Graph

In the power supply system of industrial enterprises with low installed capacity, a battery of cosine capacitors is used as reactive power compensation devices in most cases. However, in certain modes of operation in such a network due to the presence of electrical receivers, which generate the highest harmonics, there may be resonance phenomena. Therefore, in such a network you should know both the presence of harmonic components and their percentage. It is known that according to GOST 32144-2013 it is necessary to take into account not only the individual harmonic components of the voltage of about 40 harmonics, but also the total ratio of these components. For this reason, the calculation of this parameter in the power supply system of consumers is an urgent task. In this paper the principle of structure of the three-dimensional graph of the total factor of harmonic components of voltage is revealed. The arguments for the dependence of this factor on the most important parameters of the electrical network, such as system short-circuit power, capacitor bank, load consumption are given. The authors have developed an algorithm for creating a three-dimensional graph of the total harmonic voltage components coefficient with the disclosure of the principles of its construction. As an example, the paper presents graphical dependencies: kU = f(SКZ , QBK ); kU = f(SКZ , PNG ); kU = f(QBK , PNG).

scholarly journals Impact of the hybrid reactive power compensator on the power grid used a fuzzy PI regulator

2021 ◽  
Vol 12 (1) ◽  
pp. 170
Author(s):  
Abdelkader Rahmouni
Keyword(s):  
Energy Transport ◽  
Reactive Power ◽  
Electrical Energy ◽  
Voltage Regulation ◽  
Electrical Network ◽  
Electrical Networks ◽  
Pi Regulator ◽  
Voltage Distortion ◽  
The Face ◽  
Reactive Power Compensator

The work presented in this article is a contribution to the problem of controlling reactive powers and voltages in an electrical network. Among these control tools, the static reactive power compensator (SVC) was chosen because of its simplicity of control. SVC is one of the Alternative Flexible Current Transmission Systems (FACTS) devices which help to solve the problems encountered in the operation of electrical networks, either on the distribution side or on the transport side. To increase its compensation efficiency in the face of harmonic currents which cause voltage distortion, we have introduced a three-phase harmonic filter. This new hybrid SVC is used to control the reactive power, the voltage and in addition to reduce the voltage distortion and the correction of the power factor in the electrical energy transport network. In order to improve its efficiency, two voltage regulation systems have been chosen in the control system for this compensator, the fuzzy PI regulator and the PIP regulator.

scholarly journals DETERMINATION OF THE MAXIMUM VOLTAGE AT THE PHOTOVOLTAIC POWER PLANT CONNECTION POINT

2021 ◽  
pp. 10-15
Author(s):  
Mykola Volodymyrovych Bazylevych
Keyword(s):  
Power Plant ◽  
Power Supply ◽  
Power Plants ◽  
Reactive Power ◽  
Voltage Drop ◽  
Mode Of Delivery ◽  
Distribution Networks ◽  
Electrical Network ◽  
Successive Approximations ◽  
Photovoltaic Power

The modes of the electrical network have not been calculated for the photovoltaic power plants if they are used for small and medium-sized applications. It is known that the voltage at the point of installation of a photovoltaics power plant may exceed the critical limit voltage and as a result it may cause the emergency with the electrical equipment. According to the existing methods, it is possible to find the voltage only by full electrical network modes calculating. In practice such calculation is not convenient, especially for 0.4 kV distribution networks. The suggestion is to find the most probable limit voltage at the point of installation of a photovoltaic power plant without calculating the mode of the electrical network using instead the information about the voltage value in the power supply centre. The voltage at the installation point of the photovoltaic power plant mainly depends on the generated power of the photovoltaics power plant, line resistance, load power connected to a voltage of 0.4 kV and bus voltages of 0.4 kV of the power supply. The voltage hardly depends on the power of the power transformer, the parameters of 10 kV lines and the parameters of 0.4 kV lines, except for the line "power centre–photovoltaic power plant". The highest voltage at the point of installation of the photovoltaics power plant will be in the case when the load on the line is absent. The suggested methods allow finding analytically the maximum value of voltage at the point of installation of a photovoltaic power plant without using of the successive approximations methods. As a rule the photovoltaics power plant operates in the mode of delivery of the maximum active power. By the range of various analytical formulas, the value of voltage at the point of installation of a photovoltaic power plant has been determined. The accuracy of finding the voltage by different formulas has also been determined. It is established that in order to achieve the required accuracy, the dependence of the current at the output of the photovoltaics power plant on the voltage at the connection point should be taken into account. Modification of formulas for the purpose of simplification of their application is considered. The conditions for finding the maximum possible voltage value at the point of installation of a photovoltaics power plant are considered. This requires that the argument of the voltage drop vector on the line be equal to the argument of the voltage vector on the busbars of the power supply. This is achieved by the fact that the photovoltaic power plant generates active and reactive power in a certain ratio. It is shown the inexpediency of finding the maximum possible voltage value at the point of installation of a photovoltaic power plant due to a small difference with the most possible voltage value with a significant complication of calculations.

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