Reliability Of Electrical Equipment Research Articles

A hybrid network of NARX and DS-attention applied for the state estimation of lithium-ion batteries

Monitoring the state of the battery, including the state of charge (SOC) and state of health (SOH), is crucial for ensuring the safety and reliability of electrical equipment. The paper presents a novel hybrid network that combines nonlinear autoregressive model with exogenous inputs (NARX) and DS-attention. The proposed DS-attention method establishes a robust mapping relationship between inputs and outputs, it is a specialized method of the recurrent neural network that enhances the estimation performance by incorporating division function and self-adaptive function into the attention mechanism. The division function is designed to efficiently differentiate between exogenous inputs and state outputs, thereby minimizing the potential for cross-interference between them, and the self-adaptive function optimizes the query features within the attention mechanism. The results demonstrate that the hybrid method of NARX and DS-attention achieves higher prediction accuracy for SOH and SOC estimation of lithium-ion batteries. Specifically, compared with the best-performing similar methods, the proposed hybrid method enhanced the prediction accuracy by 22.9%, 60.7%, and 51.2% across three different SOH datasets, respectively. In terms of long sequence SOC forecasting, the improvements in prediction accuracy under two different working conditions are 82.5% and 60.5%, respectively. The proposed algorithm optimizes the attention mechanism based on the characteristics of the NARX, resulting in higher estimation accuracy for predicting the state of lithium batteries.

NEURAL NETWORK PROCESSING OF ELECTROMAGNETIC ACOUSTIC SIGNALS TO IDENTIFY THE STRESS-STRAIN STATE AND DAMAGE OF POWER EQUIPMENT

The purpose of the study is to develop and train an artificial neural network to identify the stress-strain state and damage to the metal of power equipment based on the values of the parameters of the harmonic components of the electromagnetic-acoustic transducer signal.
 
 Materials and methods. Experimental study of the relationship between the parameters of the harmonic components of the signal of an electromagnetic-acoustic transducer with the stress-strain state and damage to the structure of standard metal samples, development of an artificial neural network and methods for its training to identify the stress-strain state and damage to the structure of the metal according to the loading diagram.
 
 Results. Analysis of changes in the microstructure and frequency models of standard steel samples used in power engineering confirmed the possibility of identifying the stress-strain state and damage to the structure of metals based on the values of the parameters of the harmonic components of the electromagnetic-acoustic transducer signal. To solve this problem, an artificial neural network has been developed and trained. After training, the effectiveness of the network in identifying the stress-strain state and damage to the structure of metals reached 92.16%, which is acceptable for the tasks of recognizing the technical condition of metal structural elements of electrical installation equipment.
 
 Conclusions. The use of an artificial neural network to identify the stress-strain state and damage to metal structures based on the harmonic parameters of the electromagnetic-acoustic transducer signal enables to identify areas of concentration of mechanical stress and damage to the metal structure at the early stage of development, thereby increasing reliability and safety operation of electrical equipment.

Results of a statistical study of types of single-phase faults in low-voltage ship electrical networks

The increase in the power supply of ships is manifested in growth of ship power plants' capacity, the total length of cable lines, and the number of electrified mechanisms. With the development of marine technology, the severity of the consequences of damage to ship electrical equipment and the costs of its maintenance and repair increase. The search for ways to improve the reliability and safety of electrical equipment should be based on design and technological solutions at the stages of its development and production, as well as an analysis of various factors that may appear during the operation of marine equipment and affect the condition of ship electrical systems. During studying these factors, it has been revealed that one of the common types of damage to electrical equipment of marine equipment is single-phase short circuits, the causes of which are varied. Preventing short circuits is labour intensive and in some cases impracticable. However, understanding the characteristics of this type of damage to low-voltage equipment is necessary to improve the reliability and safety of ship electrical systems. The conducted research is based on a survey of ship electrical mechanics. The results of the surveys have made it possible to analyze the frequency of occurrence of single-phase insulation faults, the duration of their existence, to identify the most likely places of occurrence of short circuits and equipment that is more susceptible to such damage compared to other elements of the electrical power system.

Methods for assessing the reliability of in-shop power supply

Research activities in the field of development of electrical power and electrical equipment include the development of new approaches to assessing the reliability indicators of electrical equipment elements and in-house power supply systems in general. The study has examined methods for assessing the reliability of electrical equipment in intra-shop power supply systems using the example of a workshop network section, including its main elements: power transformer, low-voltage cable lines, distribution points, circuit breakers, magnetic starters, contactors, switches. The reliability parameters of the circuit are calculated relative to the distribution cabinet of the power (DCp) and the distribution point of the power (DPp); regarding each connection of DCp and DPp. The methods under consideration are recommended to be used to clarify the frequency and timing of maintenance and repairs of electrical equipment of the in-shop power supply system, as well as to analyze the reliability of operation and identify the least reliable sections of network diagrams. The presented calculation using the logical-probabilistic method by constructing a fault tree is advisable to use to estimate the frequency of power loss of DCp and DPp, as well as individual connections. For the studied circuits, graphical dependences of the probability of failure-free operation of electrical equipment and the occurrence of a failure over time have been constructed.

Lithium Battery State-of-Health Estimation Based on Sample Data Generation and Temporal Convolutional Neural Network

Accurate estimation of battery health is an effective means of improving the safety and reliability of electrical equipment. However, developing data-driven models to estimate battery state of health (SOH) is challenging when the amount of data is restricted. In this regard, this study proposes a method for estimating the SOH of lithium batteries based on sample data generation and a temporal convolutional neural network. First, we analyzed the charge/discharge curves of the batteries, from which we extracted features that were highly correlated with the SOH decay. Then, we used a Variational Auto-Encoder (VAE) to learn the features and distributions of the sample data to generate highly similar data and enrich the number of samples. Finally, a temporal convolutional neural network (TCN) was built to mine the nonlinear relationship between features and SOH by combining the source and extended domain data to realize SOH estimation. The experimental results show that the proposed method in this study has less than 2% error in SOH estimation, which improves the accuracy by 64.9% based on its baseline model. The feasibility of using data-driven models for battery health management in data-constrained application scenarios is demonstrated.

Power Quality Improvement using Shunt Active Power Filter: An Industrial Zone Case Study

Power quality (PQ) improvement using active power filters (APF) is a topic of growing interest. APFs are effective in reducing harmonic distortion and improving power factor. They can be used in a variety of applications to improve the performance and reliability of electrical equipment. To address concerns with PQ improvement, this study offers an application of shunt APF in an industrial zone smart grid. the non-linear loads and unpredictable harmonics produced by on-grid PV inverters that represent the architecture of an industrial smart grid. Utilizing the MATLAB/SIMULINK software suite, a detailed design of the APF and associated hysteresis current control technique is provided. The findings demonstrate that APF is a useful tool for reducing total harmonic distortion (THD) and has a quick dynamic reaction to control grid voltage and power factor.

Dynamic Cross-Linked Polyethylene Networks with High Energy Storage and Electrical Damage Self-Healability.

Dielectric polymers that exhibit high energy density Ue, low dielectric loss, and thermal resistance are ideal materials for next-generation electrical equipment. The most widely utilized approach to improving Ue involves augmenting the polarization through increasing the dielectric constant εr or the breakdown strength Eb. However, as a conflicting parameter, the dielectric loss also increases inevitably at the same time. In addition, due to the long-term work under a strong electric field or high potential, dielectric materials often produce electrical damage (electrical tree), which is one of the main factors affecting the reliability and service life of electrical equipment. To address these problems, we herein develop dynamic cross-linked polyethylene materials (PE-MA-Epo) by polyethylene-graft-maleic anhydride (PE-MA) and polar epoxy monomers, which showed high εr (>7), low dielectric loss (<0.02), high Ue (5.16 J/cm3 at 425 MV/m), and outstanding discharge efficiency (97%). The performances of the materials are adequate to rival biaxially oriented polypropylene (BOPP) films. Moreover, the excellent self-healing capability of PE-MA-Epo enables the total recovery of εr and tan δ after electrical tree healing. After two cycles of electrical breakdown healing, Eb remained at 80%, which improves the durability and reliability of dielectric polymers. Therefore, PE-MA-Epo shows great potential for applications in advanced electronic power devices.

Analytical method of identifying the type of defect of oil-filled equipment according to the results of analysis of gases dissolved in oil

Purpose. Development of a method for recognizing the type of defect of oil-filled equipment based on the results of the analysis of gases dissolved in oil. Methodology. Analysis of gas ratio values in oil-filled equipment with various types of defects, synthesis of a method for recognizing the type of defects. Findings. A description of the analytical method for recognising the type of defects in oil-filled equipment based on the results of the dissolved gases analysis is given. To recognise the type of defect, the values of three ratios are used: CH4/H2, C2H4/C2H6, and C2H2/C2H4. Using these ratios, 40 different types of defects and their combinations can be recognised. These defects correspond to 25 different ranges of gas ratios obtained as a result of gas content studies for 3715 units of oil-filled equipment The type of defect is determined by analysing the obtained gas ratio values and classifying them according to the ranges of gas ratios for each fault. In the case when the obtained ratio values correspond to several types of faults in the same range, characteristic nomograms of defects and recommendations according to the key gas method are used to clarify the type of fault. A comparative analysis of the reliability of fault type recognition using the developed method and some well-known methods for interpreting the results of dissolved in oil gases analysis was performed. Originality. An analytical method for recognising the type of faults in oil-filled equipment of electrical networks based on the results of the dissolved gases analysis is proposed. This method differs from the existing ones in that, when using three known gas ratios, it allows recognising a larger number of defects of different types (40), including those for which the known methods do not allow establishing a diagnosis. This result is ensured by the use of 25 ranges of gas ratios obtained from the results of gas content studies for 3715 units of oil-filled equipment. Practical value. The use of the developed method for recognising the type of faults in oil-filled equipment of electrical networks allows increasing the reliability of defect recognition based on the results of dissolved gases analysis. This, in turn, makes it possible to increase the operational reliability of electric power equipment and extend the service life of this equipment.

DEVELOPMENT OF A COMPREHENSIVE APPROACH TO DIAGNOSING THE OVERHEAD LINE FAULTS LOCATION IN SINGLE-PHASE GROUND FAULTS BASED ON A DIGITAL SUBSTATION DATA PROCESSING ALGORITHM

Link for citation: Sushkov V.V., Sukhachev I.S., Sidorov S.V. Development of a comprehensive approach to diagnosing the overhead line faults location in single-phase ground faults based on a digital substation data processing algorithm. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 7, рр. 66-77. In Rus. Relevance. Emergency of electric complex of outgoing transmission lines is associated with the occurrence of damage to the line isolation and the resulting transients, marked by the presence of higher harmonic components of currents and voltage, which reduce the reliability and energy efficiency of electrical equipment of oil and gas companies: degrade the mechanical characteristics and efficiency of electric motors, accelerate aging of their isolation, disrupt the operation of control systems and emergency automatics, fault diagnostics systems. One of the reasons of high-level emergency situations, outages and emergency repairs in electric complexes of outgoing transmission lines of oil and gas companies is appearance of phase-to-ground faults. A large number of changing factors are known to influence the reliability of phase-to-ground fault location methods: parameters of transmission line operating mode, its structural and electrical parameters, fault type, transient resistance value, ground resistance and others. Inclusion in the transmission line fault location algorithms of averaged values of a number of the factors listed above independent of changes of humidity of soil and air, its temperature and other factors causes an error of methods of fault location up to 30 %. Accordingly, the research to develop a fault location method for overhead transmission lines with isolated neutral points during phase-to-ground faults based on a digital substation data processing algorithm, accounting for tower parameters and natural-climatic factors, is relevant. Objective: improving the reliability of power grids and providing consumers with power of the required standard by applying a digital fault location system to the outgoing transmission lines electrical complex. Methods: mathematical analysis of a power transmission line, taking into account its design features and natural-climatic factors on the basis of the method of mirror images; mathematical analysis of steady-state and transient modes of transmission line operation considering self and mutual parameters terms of wires; transmission line currents and voltages Fourier analysis; validation of developed method of phase-to-ground fault location in power grid of Tyumen region energy company. Results. The authors have developed the phase-to-ground faults location method for transmission lines in power grids with isolated neutral points, which differs in the following – first the faulty overhead line feeder branch is identified by correspondences between the negative sequence voltage values of the phase voltages at the transformer substation inputs, and then the distance to the location of the single-phase ground fault is determined along the branch line based on the resonant frequencies of the line taking into account its design features and natural and climatic factors.

Mathematical Analysis of the Reliability of Modern Trolleybuses and Electric Buses

The rhythmic and stable operation of trolleybuses and autonomous trolleybuses or urban electric buses, depends to a large extent on the reliability of the equipment installed on the trolleybus. The actual operational reliability of trolleybus electrical equipment (EE) depends on its technical condition. Under the influence of external factors and specific operating modes, the technical condition of the equipment is continuously deteriorating, reliability indicators are decreasing, and the number of failures is increasing. Using the mathematical theory of reliability, probability theory and mathematical statistics, numerical methods of solving nonlinear and transcendental equations, this article defines the conditions of diagnostics depending on the intensity of failures and the given probability of failure-free operation of the equipment. Additionally, the inverse problem of determining the current reliability of electrical engineering systems depends on the terms of diagnostics and the intensity of failures being solved. As a result of the processing of statistical information on failures it is established that for the electrical equipment of a trolleybus, after a number of repair measures, the maximum density of failures occurs at a lower mileage, and the probability of failure-free operation can vary depending on the degree of wear of the equipment, i.e., on the number of previous failures. It is theoretically substantiated and experimentally confirmed that the reliability of trolleybus electrical equipment changes according to the exponential law of distribution of a random variable. It has been established that the real averaged diagnostic terms regulated by instructions are not optimal in most cases and differ several times from those defined in this paper. The dependence of switching equipment run-in on time has been clarified, which served as a prerequisite for specifying the inter-repair period for various types of trolleybus electrical equipment. A method of adjustment of the inter-repair time for the electrical equipment of trolleybuses is proposed.

АЛГОРИТМ РАСЧЁТА ПАРАМЕТРОВ НАДЁЖНОСТИ СИСТЕМЫ ЭЛЕКТРОСНАБЖЕНИЯ, РАБОТАЮЩЕЙ В АГРЕССИВНОЙ СРЕДЕ

The issue of improving the reliability of electrical equipment of the power supply system of industrial enterprises with aggressive environments is considered

Improvement of surface insulating performance for polytetrafluoroethylene film by atmospheric pressure plasma deposition

The surface flashover phenomenon across a vacuum-dielectric interface severely limits the service life and operational reliability of high voltage electrical equipment. Surface modification by atmospheric pressure plasma treatment is a promising method to improve the surface insulating performance of polymers. In order to explore the mechanism of plasma processing on the vacuum flashover characteristics of polymer materials, atmospheric pressure plasma deposition was used to treat polytetrafluoroethylene (PTFE) film. The surface parameters under different processing conditions, such as surface chemical composition, surface resistivity, surface charge decay and trap distribution, were tested and analyzed. The space charge distribution of PTFE and the flashover voltage in vacuum were measured. The results show that Si–O–Si and Si–OH groups are introduced on the surface of PTFE, and the characteristic peaks of PTFE are gradually weakened with the increase of processing time. The surface trap density increases and more traps with lower energy level arise with longer processing time. The plasma deposition changes the space charge distribution in PTFE body, and leads to positive charge accumulation inside the sample. The flashover field strength respectively increases by 15% and 70% in direct current (DC) voltage and microsecond pulse voltage after plasma deposition. The rapid dissipation of surface charge is the main reason for pulse flashover voltage enhancement, while the increase of surface leakage current due to lower surface resistivity and space charge accumulation in PTFE body make the DC flashover voltage reach the saturation point. Therefore the surface insulating and body performance of polymer materials after plasma modification processing should be considered comprehensively based on different applications.

Measures to increase the technical resource of electrical equipment of powerful irrigation pump stations

RELEVANCE. At present, unstressed systems for launching high-voltage electric motors have been increasingly used. These systems limit the values of starting currents as well as eliminate alternating oscillations of engine electromagnetic torque. THE PURPOSE. Development of measures to improve the technical resource of electrical equipment of powerful irrigation pumping stations based on the use of soft start systems for high-voltage electric motors. METHODS. In the course of the study, methods for analyzing the technological processes of a pumping station, methods for mathematical and computer modeling of an electric drive were used. RESULTS. Computer models have been developed to study the regime characteristics of asynchronous and synchronous electric drives of pumping stations with direct and soft start of electric motors. A shockless start-up system for high-voltage electric motors of irrigation pumping stations of the first lift based on a current inverter is proposed. CONCLUSION. The reliability and durability of electrical equipment depends primarily on the technical resource, which is determined by a number of factors. The main factors influencing the technical life of the electrical equipment of large irrigation pumping stations are the transient modes that occur when the pumping units are started. The soft start system of high-voltage electric motors of irrigation pumping stations proposed in this article makes it possible to eliminate the negative impact of transient conditions on the operation of electrical equipment and, thereby, increase the technical resource and reliability of the power supply system of the pumping station as a whole.

GIS-Based Electric Service Resource Management System

&lt;p&gt;With the increasing investment in railway construction, China’s railway transport network is now very sound, the number of operating miles is growing, and the operating speed has also made a qualitative leap. At the same time, the safety and reliability of the operation of railway signal cables and other electrical equipment has also put forward higher requirements. At the present stage, the management of railway electrical services equipment mainly relies on manual management, which is cumbersome, inefficient and unsuitable for multi-user sharing. At the same time, the structure of railway electrical equipment is complex, and the components of the equipment are prone to aging, which can easily cause equipment failure. How to professionally manage electrical service equipment and improve the safety and reliability of electrical service equipment has become an urgent problem for railway electrical service departments. Geographic Information System (GIS) architecture uses spatial data layering technology to achieve multi-level and proportional display of equipment and facilities, which can provide visual display of professional facilities such as railway engineering, electricity and power supply, and carry out multi-source and multi-temporal intelligent analysis of data, provide geographical information service interface for various professions of engineering and electricity to meet their own functional requirements. Knowledge mapping is a key technology for acquiring knowledge and building a knowledge database in the era of big data. In order to explore the hidden information between railway electrical resources, integrate seemingly independent data into the knowledge base and apply them. In this paper, we design a GIS-based electric service resource management system in combination with knowledge mapping that can make data complete and well-structured after processing scattered and redundant information, and analyze and discuss the system’s architecture, functional requirements, key technologies and development prospects.&lt;/p&gt; &lt;p&gt;&amp;nbsp;&lt;/p&gt;

FUZZY MODELING OF SWITCHING EQUIPMENT FOR TASKS OF ASSESSING THE RISK OF EMERGENCY SITUATIONS IN THE EPS IN CASE OF ELECTRICAL EQUIPMENT FAILURES

Today in the electric power industry of Ukraine the issue of assessing the risk of EPS operation due to failures of electrical equipment is particularly important. Failures are associated with significant level of aging and low replacement rates of electrical equipment, also with the possible simultaneous emergency decommissioning of several elements as a result of terrorist attacks.&#x0D; Based on the analysis of the operating conditions of high-voltage switching equipment, standards and operational documentation method of diagnosing the technical condition of SF6 circuit breakers is proposed. This method is based on the use of fuzzy set theory.&#x0D; To assess the risk of power outages in the EPS in case of electrical equipment failures, a linguistic model is proposed for determining the total residual life and the probability of failure of SF6 high-voltage circuit breakers of various types. Which is based on the aggregation of information on the technical condition of individual functional units.&#x0D; An approach is proposed to take into account the importance of individual units of the circuit breaker in terms of the impact on the total residual life by weight coefficients determined due to failure statistics. The result of determining the total residual life is the ability to estimate the probability of failure on the observation time interval.&#x0D; Tuning and adaptation of the developed linguistic model of the SF6 circuit breaker to real operating conditions is provided by adjusting the parameters of the membership functions of the terms of the input linguistic variables using weighting coefficients and fuzzy inference with weighted average truth.&#x0D; The developed linguistic mathematical model for assessing the technical condition and probability of failure of SF6 circuit breakers can be used as a component of the complex of risk analysis programs in the EPS. And the formation of preventive actions to ensure the operational reliability of electrical equipment and regime reliability of the EPS in case of emergency equipment failures.

Стратегия обеспечения надежности эксплуатации электрооборудования АПК, с целью организации надзорной деятельности за безопасностью работ

The article proposes a process for ensuring the reliability of the operation of electrical equipment at an agro-industrial complex enterprise in order to organize the activities of the labor protection service to ensure the safety of work. Ensuring the reliability of electrical equipment is a laborious process that involves a large number of personnel and various equipment. The organizational foundations of the problem posed are considered, and at the same time, technical issues also affect the provision of labor safety and require further study and detail, which makes it possible for the labor protection service to develop not only organizational, but also technical measures for labor protection, to prevent injuries while ensuring reliability operation of electrical equipment at agribusiness enterprises. Keywords: RELIABILITY, OPERATION OF ELECTRICAL EQUIPMENT, SUPERVISION, SAFETY, AGRO-INDUSTRIAL COMPLEX, SPECIALIST IN LABOR SAFETY, PERSONNEL, ELECTRICAL INSTALLATION WORKS, DIAGNOSTICS OF ELECTRICAL INSTALLATIONS

Munich Exhibition of Oscar von Miller. Part 2. A Remarkable Result (On the 140th Anniversary of the Misbach-Munich Power Transmission of M. Depre)

The article is devoted to the history of the first power transmissions over a long distance. In 1873, the French engineer H. Fontaine transferred electrical energy between a dynamo and a DC motor over a kilometer distance. The efficiency of this power transmission was rather poor, but the experiment became widely known and interested many scientists. However, a low level to which the electrical engineering had been developed by that time, lack of electricity consumers, high cost, and poor reliability of electrical equipment did not allow the problems of power transmission efficiency to be solved within a short period of time. After the advent in 1876 of P.N. Yablochkov’s lighting system and the electrical market, the issue of constructing power transmission lines was becoming increasingly more urgent. Theoretical studies of a number of electrical engineers: D.A. Lachinov, O. Froelich, M. Deprez, and others showed ways to increase the power transmission efficiency, the value of which could be higher than 50%. These works faced incomprehension from many eminent electrical engineers of that time. Practical proof was required. The article describes the central event of the Munich Exhibition in 1882 - the transmission of electrical energy over a distance of 57 km from Miesbach to Munich, implemented by Marcel Despres and Oscar von Miller. In fact, this was the first experience of creating a high-voltage DC power line in history. A bold power transmission experiment over such a considerable distance was of great importance for the development of electric power industry and served as impetus for accelerating work in this field.

ОПРЕДЕЛЕНИЕ ДИАГНОСТИЧЕСКОГО СИГНАЛА ДЛЯ МОНИТОРИНГА СИНХРОННЫХ ДВИГАТЕЛЕЙ С ПОСТОЯННЫМИ МАГНИТАМИ

Relevance Nowadays, it is possible to achieve a significant increase in the technical and economic indicators of enterprises by improving the reliability of electrical and mechanical equipment. In this case, the time between current and overhaul repairs is increased and operating costs and, together with them, material and other resources are significantly reduced. Metallurgical production is the most expensive in terms of electrical consumption and a significant number of electric drives are concentrated there. For more than a hundred years, asynchronous electric machines have occupied key positions in regulated AC electric drives. Along with them, new types of electric machines have been actively developed in recent decades, which structurally in the active part do not contain windings on the rotor, the rotor is asymmetrical in magnetic relation, the stator can have one or two windings. Such machines include synchronous reactive and inductor electromechanical converters. All studies are of a private nature and do not cover the whole class of electric machines as a whole. There are no unified analytical dependencies for electromagnetic torque, active and reactive powers, power factor, methods of engineering calculations of machines, optimization methods, unified approaches to the synthesis of control actions on stator windings, calculation of losses, the peculiarities of synthesis of such machines for specific production mechanisms are not considered, taking into account the nature of load and speed diagrams and modes of operation in an extended range of speeds and load torques. In connection with the above-mentioned, a comprehensive study of permanent magnet synchronous motor (PMSM) is relevant, and there is a need to determine the diagnostic signs of faults both incipient and manifested. Aim of research The article is devoted to the issues of obtaining diagnostic information in the generator mode of PMSM. It is shown that the generator mode is an effective mode for obtaining a diagnostic signal, allowing to fully implement the methods of mathematical analysis of signals, without introducing errors in the form of spectral components from the work of converters. Research methods The methods of theoretical and experimental research were applied in the work. To conduct theoretical studies used software packages Excel and MathCad; software package MatLab for wavelet analysis and Fourier analysis; software package Elcut to develop a computer model and simulation modeling; the basics of wavelet theory. Results The generator mode is an effective mode of obtaining the diagnostic signal, which allows to fully implement the methods of mathematical analysis of signals without introducing errors in the form of spectral components, which inevitably occur during the operation of converters of any type. The use of the generator mode in PMSM diagnostic systems allows obtaining a much cleaner diagnostic signal, which increases the diagnostic accuracy, reduces the number of false diagnoses and minimizes the masking effect. This mode does not require any changes in the structure of the control system, because during the operation of any PMSM, one way or another, when the speed is reduced or stopped, the motors briefly operates in generator mode.

The results of the production tests of the method for diagnosing the eccentricity of the rotor of an asynchronous electric motor

Ensuring the reliability of electrical equipment in agriculture remains an urgent problem, since rugged operating conditions and aggressive environment hinder its rational use. The high accident incidence rate of asynchronous motors in most cases is invariably caused by the failure of the inter-turn insulation and interphase short circuit or short circuits to the housing. The probability of an emergency situation increases with an increase in the radial clearance in the bearings and, consequently, the occurrence of static eccentricity of the rotor. The developed method for diagnosing the static eccentricity of the rotor of an asynchronous motor is based on the analysis of the rotor speed; the amplitude of the rotor speed change was used as a diagnostic parameter. The paper presents the change in the rotation frequency depending on the difference in the amplitudes, resulted from the study conducted for different values of static eccentricity. The test results have shown that with an increase in the eccentricity of the rotor, the amplitude of the speed fluctuations increases.

Development of a method for recognizing the type of defect based on the results of dissolved gas analysis using a set of diagnostic criteria

Ensuring a reliable supply of electricity to both the households and industry is the main task of the power industry. One of the factors that affects the operational reliability of electric power equipment is the ageing of equipment, which is observed in every country. The most used among non-destructive methods of diagnosing the condition of high-voltage oil-filled equipment is the dissolved gas analysis. Using the values of gas ratios, gas percentages, as well as the values of gas ratios to the gas with the maximum content, most methods of interpreting the results of dissolved gas analysis can recognize electrical and thermal type defects, and some methods allow to recognize also combined type defects. However, the reliability of defect recognition by different methods for the same data is significantly different. The use of only one of the diagnostic criteria to recognize defects of different types does not always allow to make the correct diagnosis. Thus, the issue of developing a method for recognizing the type of defect based on the results of the dissolved gas analysis with the simultaneous use of a set of diagnostic criteria is relevant and has practical significance. Since the values of diagnostic criteria in the diagnostic space differ for different types of defects, it is advisable to use deterministic recognition methods, in particular distance recognition methods. To recognize the type of defect, it is proposed to use the method of minimum distance to the set, which allows not only to recognize the type of defect, but also to identify the same type of object with the closest gas content and with known causes of the defect. For the practical implementation of the method, an algorithm has been developed based on the joint use of the key gas method and the ratios of characteristic gases. The given example of practical use of the developed method showed its high efficiency in comparison with the existing methods of interpreting the results of the dissolved gas analysis.