Quality Of Electrical Energy Research Articles

Исследование помехоэмиссии в электрических сетях 10/0,4 кВ

At modern enterprises, there is a decrease in the quality of electricity. This fact is due not only to an increase in electrical losses, but also to a large spread of loads whose volt-ampere or Weber-ampere characteristics are nonlinear. This article describes the main problems and prospects of using frequency converters in terms of generating high-frequency harmonics of current and voltage in the network. Data on the generation of current and voltage harmonics by frequency converters were obtained experimentally. To measure the main indicators of frequency harmonic components of current and voltage, a three-phase analyzer of electrical network parameters was used. The main problems in the case of frequency converters are identified: a decrease in the quality of electrical energy and the occurrence of interference; a high degree of increasing the number of emergency shutdowns and failure of electronic equipment probability, as a result, there is a need to develop and take additional measures to install devices for compensating current harmonics.

Harmonic minimisation in direct torque controlled induction motor using neural network controller

In a conventional direct torque control (DTC) method, hysteresis controllers are used to process the flux and torque errors influencing space voltage vector selection to obtain direct torque control of induction motor resulting in harmonics. The scope of the paper is to apply neural network controller technology for direct torque controlled induction motor drives suitable for high performance application. Then the flux and torque errors are processed through hysteresis controllers along with neural network controllers in order to improve voltage space vector selection strategy and achieve reduction in current harmonics and improve quality of electrical energy. Finally, the Simulink models of direct torque controlled induction motor with and without neural controller are tested in MATLAB/Simulink for different operating conditions with favourable results.

Study of the state of the issue of increasing the quality of electric energy in the power supply systems

This article examines the importance of ensuring the quality of electricity and considers the possibility of using a system for monitoring the quality of electricity in the power supply system. Based on the results of the study, it was found that the use of contactless switching devices as switches of sections of windings of power transformers allows you to abandon current-limiting reactors and resistors. This is achieved by the fact that the switching of the windings occurs at the moment the load current passes through zero.

Researching and modelling of unbalanced regimes in systems of household electric power consumers

The modelling of the operation modes of the 0.38/0.22 kV power supply systems by the Monte Carlo method using the Electronics Workbench computer program is considered, and statistical processing of simulation results and testing of the Pearson distribution law hypothesis using the Mathcad program are carried out. An analysis of existing power supply systems has been carried out and an alternative, economically feasible version of the power supply system is proposed, where consumers are powered by low power transformers mounted on supports. The performed studies showed that the variation of the load currents in the segments and the losses of electric energy in an asymmetrically loaded network of 0.38/0.22 kV are subject to the normal distribution law and that the consumers who feed on the traditional power supply system have unsatisfactory quality of electrical energy.

On the power quality of electrical energy supplied to joint stock company “Aleksandrovsky mine”

Joint Stock Company (JSC) “Mine Aleksandrovsky” is located in the Mogochinsky district of the Trans-Baikal Territory. “Mine Aleksandrovsky” concluded an energy supply agreement with JSC “Chitaenergosbyt” for the purchase of electric energy from it. In accordance with the contract, the electric energy supplier undertakes to supply electric energy that meets the requirements of the current legislation of the Russian Federation. The power quality in the Trans-Baikal Territory in most regions does not meet the requirements of State Standard 32144-2013. Suppliers and the network organization are responsible to consumers for the reliability of its electric energy supply and its quality within the boundaries of their electric networks. Despite the obligations of the contract, the electric energy supplied to “Mine Alexandrovsky” does not meet the requirements. In 2017 the ball mill engine in the shredding department of the gold recovery factory failed as a result of power outages and the supply of low power quality through the 6 kV line. The article provides information on interruptions in power supply over the years of operation of the enterprise, the results of analysis of the power quality, information on damage to electrical equipment caused by low power quality, and economic damage.

Оценка влияния статических характеристик нагрузки на уровень частоты сети при раздельной работе с энергосистемой

ue to the requirements for the quality of electrical energy becoming stricter, it is now relevant to assess the impact of various factors on the main quality indicators: voltage and frequency deviations of the network. One of these factors is the static characteristics of various loads, which under certain conditions can have a significant impact on the parameters of the power system. In this article, it is proposed to evaluate the influence of static characteristics on the network’s frequency level when it enters separate operation with the power system and with various changes in the steady-state mode, and also to investigate the relationship between the coef­ficients of the load regulating effect and the value of the short-circuit power or the length of the supply cable. Separate operation was considered because in this mode, the influence of the regulating effect of a powerful load on the mode parameters becomes more pronounced. The scientific novelty of this study consists in an algorithm that allows refining the frequency deviation of an isolated electric power system, taking into account and without taking into account the static load characteristics when changing the length of the supply cable in the KATRAN software package. The main result of this study is the almost direct relationship revealed between the influence of static load characteristics on the network frequency and the distance of the load with a large proportion of synchronous motors from the power source in an autonomous electric power system. We also evaluated the feasibility of taking the regulatory effect of the load into account when calculating electrical modes depending on the type of load and the calculated value of the short-circuit power.

Loss Counter in Power Double Winding Transformers Implementing the Method of Conditionally Constant Coefficients in Online Mode Using the Information Platform

The article describes the developed loss counter in power double-winding transformers of distribution net-works. The principle of operation of the proposed measuring unit of the loss counter is considered on the exam-ple of one channel for measuring current and voltage in accordance with the above functional scheme. The ap-pearance and main characteristics of the loss counter are given. The main characteristics of the developed loss counter are confirmed by the adjustment Protocol based on the results of measurements in the FBU «Rostov CSM» and are at the level of existing characteristics of electric energy quality analyzers. The data measured and calculated by the microcontroller of the loss counter, necessary for the implementation of the method of conditionally constant coefficients, are transmitted over the USB bus to a single-Board computer. Using the de-veloped software written in the high-level General-purpose programming language Python, the formation and sending of data to the information platform Yandex.Cloud. The approbation of the operation of the loss coun-ter on the developed physical model «power transformer-asymmetric and non-sinusoidal load» and operating substations is shown. Thus, the developed loss counter can be used to calculate losses from higher harmonic components in power transformers by the method of conditionally constant coefficients in the online mode us-ing the resources of the information platform Yandex.Cloud.

Energy characteristics of induction water heater

Many agricultural facilities do not have the ability to connect to gas supply networks; at such facilities electric water heaters are used as sources of thermal energy for heating and hot water systems. The issue of the use of induction heating as one of the most effective at such facilities is relevant. The aim of this work is to study energy characteristics of an induction water heater, such as efficiency and power factor. In order to determine the estimated efficiency and power factor the energy balance method was used. The experimental values of the efficiency and power factor are determined by the calorimetric method and with the help of an electric energy quality analyzer. The obtained value of the efficiency and power factor of the induction water heater corresponds to the calculated value with an accuracy of ±1%.

Assessment of the energy efficiency potential of mining enterprises

The paper studies the problematic issues of assessing the potential and improving the energy efficiency at mining enterprises. The necessity of developing a methodology for determining the unreasonable losses of energy resources and introducing the fast-payback options is substantiated. In order to solve this problem, a systematic approach has been used, which is based on experimental data and accounting the global economic situation. An experimental-mathematical approach is proposed for determining the main components of technologically unreasonable losses of electrical energy resources, such as the modes of transformers and pumps operation, an impact of electrical energy quality on energy consumption. The methodology was approbated at the “Mineral” mining enterprise. The proposed solutions are able to reduce energy consumption by 10% of the total with an average payback period of up to two years.

Scientific substantiation and normative support of systems automatic regulation hydrogenerating installations energy-efficient modes operation

The article shows the advantages of the combined method of generating electrical and thermal energy that are not implemented currently completely because of inconsistencies of energy and economic sides combined. Fundamental difficulties associated with the separation of fuel costs among manufactured products, without which it is impossible to determine their cost. It is shown that the distribution of the expenditure incurred on fuel, and the separation of the fuel consumption in fact it is one and the same problem. Ignorance of the real costs does not allow to generate reasonable rates of products which leads to lower competitiveness of the combined production and does not contribute to technical improvement. It is proved that the problems that occur in the combined use of thermal energy caused by the imperfection of the theoretical foundations of Economics of the power system. In particular, it refers to the establishment of cost of thermal energy after the partial implementation of it in the form of work. Apply in the heat of the preconditions for establishing the value of joules of heat energy, is ambiguous and not justified. It is based on the regulations of thermodynamics and are not related to the economy of production. Based on these assumptions the methods of separation of fuel (physical, energetic, regulatory, etc) can not be used when establishing the cost of energy products produced by the combined method. The proposed economic approach to the division of costs for fuel and scientifically grounded method of separation of expenditure incurred on fuel, which can be used in the calculation of cost of electrical and thermal energy generated by the combined method. The issues associated with providing the required quality of electric energy produced in hydroelectric power plants, improving the accuracy of regulation of frequency and power generating units. Performed parametric synthesis of astatic regulator of the system of automatic regulation of frequency of rotation of the turbine based on the solution of the inverse problem of dynamics. An analysis of existing normative-methodological support of automatic control systems of hydraulic units.

COMPREHENSIVE METHODOLOGY FOR DETERMINING THE PARTIAL PARTICIPATION OF CONSUMERS IN THE RESPONSIBILITY FOR VIOLATION OF ELECTRICITY QUALITY INDICATORS

In the power industry, one of the most important aspects of energy conservation and environmental friendliness is to improve the quality of electricity and ensure electromagnetic compatibility. The quality of electricity is directly related to the efficiency of production, distribution and consumption of electric energy. In a market economy, the grid company and the consumer act as equal commercial partners, subjects of a single process of distribution and consumption of electric energy. To ensure interest in improving the quality of electricity, it is necessary to ensure conditions under which the losses incurred by the subjects of the process of electric energy distribution are paid by the true culprits. In international practice, the definition of responsibility for violation of the quality of electricity is dominated by two principles for determining the admissibility of a consumer connecting to the network in case of violation of the requirements for indicators of quality of electricity, which can be expressed in logical formulas: "pays the last" and "everyone pays his share". For Ukraine, a country with developed electric grids in which measures to comply with the quality of electric power are world practice of operating electric grids. According to this principle, each subject of the electric energy distribution process has the right to introduce its own share of distortions, but it is obliged to compensate for losses from the reduction in the quality of electricity, according to this share. It is advisable to assign an objective assessment of equity participation in compensation for damage to deterministic calculations, without the factor of influence on their result from the supplier or consumers of electric energy. A methodology for the comprehensive definition of liability for violation of the quality of electric energy is proposed. The methodology for determining the weighted coefficient of responsibility allows us to take into account: the possibility of simultaneous distortion of several indicators of electric power quality, such as steady-state voltage deviation, voltage unbalance, voltage non-sinusoidality, by one subject, the possibility of simultaneous distortion of one electric power quality indicator by different entities, the possibility of simultaneous distortion by several entities of various electric power quality indicators.

Повышение качества электроэнергии путем регулирования вентильных генераторов

Повышение качества электроэнергии путем регулирования вентильных генераторов

Improving the efficiency of power supply systems through the combined effect of voltage distortion

In most cases, any abnormal mode in the distribution electrical network is eliminated by the action of relay protection and automation devices (RPA), i.e. - there is a shutdown of the damaged item. It is much more difficult to constantly maintain the normal key indicators of the quality of electrical energy in the network. With the advent of controlled voltage converters based on transistors IGCT and IGBT, static synchronous compensators STATCOM were developed. The main disadvantage of this kind of device is that the control output generated by them is static. Under conditions of increased likelihood of abnormal conditions, their dynamic compensation will be much more effective. In the process of research, the methods of dynamic continuous action of voltage on a sinusoid in a distribution electric network were used. The development of a theoretical approach was accompanied by constant monitoring of existing and developed technical solutions associated with the task set in the work. The object of the study was the distribution electrical network of industrial enterprises with a sharply alternating nature of negative network perturbations. A method has been developed for dynamic suppression of amplitude-phase voltage distortions on the basis of restoring the voltage curve due to the continuous introduction of a compensation voltage curve into the network via a booster transformer. A faster formation of the control action in comparison with analogues allows us to more effectively respond to negative network perturbations in distribution networks, especially if the nature of their occurrence changes dramatically. The proposed method is designed to maintain the quality of electricity within acceptable limits in accordance with the requirements of Russian State Standard 32144-2013.

Renewable energies and storage in small insular systems: Potential, perspectives and a case study

Insular electricity systems are of importance, as the security of supply, the competitiveness and the sustainability of the islands’ populations depend on non- or weakly interconnected electrical systems. For this reason, they have until now been treated with a good degree of conservatism in relation to both the power generation technologies used and the regulatory framework applied. This, however, results in power generation costs significantly higher than those of the interconnected systems, whilst it is also linked with high local environmental burdens.However, developments in the fields of renewable energy systems technologies, of weather prediction models and of grids and micro-grids management allow today for a much more responsive and adaptive management of the insular systems than was possible only ten years ago. This is further enhanced by the progress made in electrical energy storage, which makes the autonomy of islands a realistic goal, and also a feasible one, especially for small and very small islands.It is against this background that the regulatory framework has also to be re-considered, in order to enable a fair valuation and charging of storage, of load curtailment and eventually of ensured supply and quality of electrical energy. All this needs to be part of the new modus operandi towards decarbonized and sustainable insular communities.

Распределение мощности между обмотками тяговых трансформаторов на основе цифровой фильтрации

The purpose of the paper is to present an improved method of active power equalization on the secondary windings of the Scott traction transformer in the power supply systems of AC railways located in the proximity to the facilities of the agroindustrial complex, gas supply systems, etc. Active power distribution using automatically controlled thyristor bridges with pulse width modulation and capacitive storage devices allows to reduce the asymmetry and unsinusoidality of currents and voltages in the primary three-phase network almost to zero at suddenly appearing and disappearing mobile traction loads, such as high-speed electric trains. To control the currents and voltages in the windings, digital filtering algorithms have been applied, which form the required number of voltage levels at a given frequency of pulse width modulation. The efficiency of these algorithms is confirmed by computer simulation in the Matlab environment. It is proposed to improve the method of power equalization on the secondary windings of the Scott traction transformer with the use of digital filtering-based automatic control algorithms. The power equalization device together with the Scott transformer ensure high quality of electric energy in the primary three-phase network in terms of asymmetry and unsinusoidality of currents and voltages, due to which electromagnetic compatibility of the traction power supply system and the power supply system of various agricultural facilities, oil and gas complex, and others located in the proximity of railways is provided.

Development of the wave method of calculation operational parameters of a double-circuit power transmission line with known values of output voltages and currents at the end of the line

Electrical energy from the place of its generation is transmitted to consumers of various capacities. The distance from the source of electrical energy to the consumer can vary from several meters to several thousand kilometers. In this regard, the accurate determination of the operating parameters of the power transmission line (PTL) is a mandatory and necessary condition for the PTL normal functioning. In the current-carrying parts of the double-circuit PTL there are six incident and six reflected waves of the electromagnetic field. They determine voltages and currents. A scheme is proposed for the distribution of these waves along linear wires of a homogeneous section of a double-circuit PTL. This scheme shows that the current-carrying parts of the adjacent wires have a significant impact on voltages and currents in one wire. This scheme illustrates the distribution of the amplitude values of electromagnetic field waves, defined as the integration constant. Using the integration constants, the propagation constants of electromagnetic waves along the linear wires of the PTL and the corresponding wave impedances, one can obtain the amplitude values of the incident and reflected waves at any point of the double- circuit PTL, and hence the currents and voltages in the double-circuit PTL. The article presents a method for determining the currents and voltages in a double-circuit PTL according to the load. The proposed method will allow determining the qualitative and quantitative indicators of electrical energy (induced voltage) appearing from each wire separately and provide the possibility of their elimination, which will improve the quality of electrical energy.

A hybrid deep learning model for short-term PV power forecasting

The integration of PV power brings great economic and environmental benefits. However, the high penetration of PV power may challenge the planning and operation of the existing power system owing to the intermittence and randomicity of PV power generation. Achieving accurate forecasting for PV power generation is important for providing high quality electric energy for end-consumers and for enhancing the reliability of power system operation. Motivated by recent advancements in deep learning methods and their satisfactory performance in the energy sector, a hybrid deep learning model combining wavelet packet decomposition (WPD) and long short-term memory (LSTM) networks is proposed in this study. The hybrid deep learning model is utilized for one-hour-ahead PV power forecasting with five-minute intervals. WPD is first used to decompose the original PV power series into sub-series. Next, four independent LSTM networks are developed for these sub-series. Finally, the results predicted by each LSTM network are reconstructed and a linear weighting method is employed to obtain the final forecasting results. The performance of the proposed method is demonstrated with a case study using an actual dataset collected from Alice Springs, Australia. Comparisons with individual LSTM, recurrent neural network (RNN), gated recurrent (GRU), and multi-layer perceptron (MLP) models are also presented. The values of three performance evaluation indicators, MBE, MAPE, and RMSE, show that the proposed hybrid deep learning model exhibits superior performance in both forecasting accuracy and stability.

Numerical-field evaluation of an efficiency of a shortening of a three-phase stator winding of a cylindrical magnetic field inductor

The article proposes the implementation of the on-board battery system of energy accumulation of the DC rail - a reinforcing point that provides regulated parameters for the quality of electrical energy in the contact network. The expediency of using a matching converter, which provides the principle of separate commutation, in order to minimize the loss of switching of the power keys of the converter, is shown. The location of the reinforcement point in the immediate vicinity of the consumer - directly on the rolling stock - on a locomotive or in a special trailer car is substantiated. The energy and mass parameters of the system are estimated. The calculations are made to make the choice of specific power keys of the converter. The optimal frequency of switching of the power keys of the converter is determined, which provides a compromise between the overall properties of the magnetic elements and the losses in the magnetic material. The necessary value of transformer scattering inductance, mass of magnetic elements and batteries is estimated.

MULTIPLE AGENT MANAGEMENT BY DISTRIBUTION ELECTRIC NETWORKS OPTIMAL DISPATCH

Solving the problem of management intellectualization is complicated by the large dimensionality and branching distribution network, low monitoring of its regime and limited set of adaptive management measures. Introduction the SmartGrid concept in modern distribution power networks makes it unnecessary to solve the problem of adaptation the topology of the working scheme to the electricity transmission mode current conditions in real time. The paper substantiates the special urgency of the problem of closing closed circuits in modern heterogeneous electrical networks, which are maintained by operators of electric networks of different hierarchical levels. Known methods of optimization disconnection of electrical networks provide a centralized approach to the relevant control systems that practically impossible to implement optimal commutation switching in real time. Therefore, it is expedient to use a decentralized approach, based on the principles of multi-agent management of the distribution grid. Obviously, operative optimization of the places of unplugging of distributive electric networks will cause the improvement of the quality of electric energy by voltage deviation. This situation has fallen to the basis of the developed mathematical apparatus supporting decisions by the multi-agent system of operational reconfiguration of distribution electrical networks. The proposed approach to the formation of a multi-agent control system for the configuration of distribution electrical networks is illustrated in the scheme of heterogeneous electrical networks 110-750 kV of the Southern power grid of UPS Ukraine. It is stated that the opening of circuits 110 (150) kV will result in decrease of active power losses by 9.5%, and energy losses during the year is approximately 8%. The operational adaptation of the working circuit of distribution networks further reduces energy losses by 3-5% during the year.

The influence of mixed load with complex waveform current supply on the electrical energy quality

The joint work of heating tape and a dark infrared radiator at different electrical modes for getting positive technological and energy effects and indicators of electrical energy quality in the network have been investigated.