High-voltage Motor Research Articles

Determination of converter parameters for high-voltage electromechanical systems of stationary installations of industrial fans

Purpose. To study the electromagnetic processes in the circuit of the phase rotor of a high-voltage induction motor connected to the network through a step-up converter, to determine the parameters of the converter and their relationship with the voltage gain to ensure the optimal level of energy efficiency of the electromechanical system. Methodology. Methods of theoretical electrical engineering for the construction of a rotor circuit replacement scheme for an induction motor with a step-up converter, methods for solving a system of first-order differential equations, analytical methods. Findings. The expediency of using a converter that combines the rotor circuit of a high-voltage induction motor with the power supply network and provides regulation of the rotor EMF with the recovery of the slip energy of the induction motor rotor to the power supply network has been proved. This will ensure speed control of powerful high-voltage induction motors on the rotor side with an EMF of up to 600 V and significantly reduce the cost of a high-voltage electromechanical system. A methodology for determining the converter gain and the parameters of the rotor circuit of the electromechanical system is proposed, which allows determining the transformation ratio of the matching transformer at the optimal value of the voltage gain. The conditions of trouble-free operation of the inverter at the moment of start-up of the electromechanical system are determined. Achieving these conditions is ensured by determining the delay of the control signal to the power keys of the inverter of a step-up converter. The correlation between the voltage gain and the equivalent resistance of the rotor circuit of the electromechanical system is established. Originality. The ratio of the voltage gain to the equivalent resistance of the rotor circuit of the electromechanical system is established, which will ensure the matching of the rotor EMF with the voltage of the power supply network while maintaining a high level of energy efficiency. Practical value. A methodology for determining the gain and parameters of a step-up converter is proposed, which allows determining the transformation ratio of a matching transformer at the optimal value of the voltage gain. The proposed methodology can be applied to the modelling of complex powerful high-voltage electromechanical systems, especially for stationary installations of industrial fans.

Метод обработки сигналов токов статора асинхронного двигателя для диагностики обрыва стержня ротора

The study is relevant due to high requirements to the reliability of the operation of auxiliary mechanisms of thermal power plants (TPP). The main source of mechanical power of auxiliary mechanisms of TPPs is high-voltage induction motor with squirrel cage rotor (IMSC). One of the most difficult causes of emergency shutdown to detect early is a broken rotor bar. The breakage of IMSC rotor bar is of latent character. It can be for a long time without considerable influence on the machine operation mode. Nevertheless, the fact of the breakage can be considered as an emergency condition of IMSC, and the consequences of leaving the groove of the magnetic core are irreversible. Scientifically, early diagnostics of IMSC rotor bars breakage of TPP auxiliary needs is both a difficult and extremely urgent task. The existing methods of diagnostics of such damage are based on measurement and analysis of vibration and acoustic physical quantities. The most common electrical parameter, used as a source of information, as a rule, is current consumption. And most of methods are based on Fourier analysis. The purpose of the study is to develop a mathematical algorithm to process digitized curves of stator phase currents to diagnose high-voltage IMSC. The theory of electric machines, the method of analytical approximation of experimental data, the method of regression analysis have been used to solve the problem. Experimental data is obtained, and testing of the algorithm is conducted on an experimental installation with a 0,4 kV induction motor with a modified design of the active part of the rotor developed for physical simulation of IMSC broken rotor bar. This paper proposes a new method of digital processing of stator current signals based on the regression analysis method for diagnostics of IMSC rotor winding. The authors have developed an algorithm for mathematical processing of digitized stator current curves based on regression analysis in the cosine-sine basis to identify the diagnostic sign of failure of one rotor bar of IMSC rotor. The authors have determined the number of harmonic components that best describe the initial signal from the point of view of the balance between saving computational resources and accuracy of approximation. A mathematical algorithm to detect the rotor bar breakage of an induction motor based on regression analysis of stator currents has been obtained and tested. It allows to detect rotor circuit damage with 97 % accuracy. At the same time the diagnostic sign changes its level when one bar breaks by 5 %. It is recommended to adapt the algorithm to the programming languages of microprocessor relay protection units.

Analysis of Transition Cause of Partial Discharge Patterns in High Voltage Motor Stator Windings

Analysis of Transition Cause of Partial Discharge Patterns in High Voltage Motor Stator Windings

Analysis of Insulation Breakdown in Slot End of Stator Windings of High Voltage Motor

Analysis of Insulation Breakdown in Slot End of Stator Windings of High Voltage Motor

Исследование сигнала внешнего магнитного поля асинхронного электродвигателя в режиме выбега

Currently, one of the important scientific tasks is the development and improvement of methods for non-destructive testing of asynchronous electric motors during operation. One of the promising areas of diagnostics is the use of an external magnetic field signal. However, its study in the run-down mode is not given due attention by the authors of scientific publications, despite a number of advantages of this signal. Therefore, the aim of this research is to confirm the possibility to record and study the signal of the radial component of the induction of the external magnetic field in the run-down mode of an asynchronous motor. So, the aim is relevant. The research is carried out using several test benches, real low-voltage and high-voltage asynchronous motors and a simulation model of an asynchronous electric motor designed in the Ansys software package. To process the signals, namely, to construct the frequency-time spectra of the external magnetic field in the run-down mode, the authors have used a program based on the Short Time Fourier Transform using the Flat-top window as a window function to more accurately determine the amplitudes of the harmonic components. During the research conducted on test benches, it has been found that the external magnetic field of the motor in the run-down mode will exist due to the phenomenon of residual magnetization. The possibility of modeling asynchronous motors considering residual magnetization has been proven and the reliability of the resulting model has been confirmed. The spectra of external magnetic field signals on real motors and simulation models in the run-down mode are presented. The external magnetic field signal in the run-down mode can be recorded both on simulation models and on real low-voltage and high-voltage asynchronous electric motors. During further research, it is planned to analyze the possibility of identifying faults in asynchronous motors using this signal.

The influence of ITSF on vibration of high voltage Line-Start permanent magnet synchronous motor

PurposeThe purpose of this paper is to present the influence of inter-turn short circuit faults (ITSF) on electromagnetic vibration in high-voltage line-starting permanent magnet synchronous motor (HVLSPMSMS).Design/methodology/approachIn this paper, the ampere–conductor wave model of HVLSPMSM after ITSF is established. Second, a mathematical model of the magnetic field after ITSF is established, and the influence law of the ITSF on the air-gap magnetic field is analyzed. Further, the mathematical expression of the electromagnetic force density is established based on the Maxwell tensor method. The impact of HVLSPMSM torque ripple frequency, radial electromagnetic force spatial–temporal distribution and rotor unbalanced magnetic tension force by ITSF is revealed. Finally, the electromagnetic–mechanical coupling model of HVLSPMSM is established, and the vibration spectra of the motor with different degrees of ITSF are solved by numerical calculation.FindingsIn this study, it is found that the 2np order flux density harmonics and (2 N + 1) p order electromagnetic forces are not generated when ITSF occurs in HVLSPMSM.Originality/valueBy analyzing the multi-harmonics of HVLSPMSM after ITSF, this paper provides a reliable method for troubleshooting from the perspective of vibration and torque fluctuation and rotor unbalanced electromagnetic force.

Iron loss calculation model of high‐voltage multi‐pole asynchronous motors considering high harmonic flux density

AbstractA variable coefficient segmented iron loss calculation model is proposed for high‐voltage multi‐pole asynchronous motors, which fully considers the influence of high‐order harmonic magnetic density on such motors. This model introduces additional hysteresis loss, improved eddy current loss coefficients, and rotation magnetisation coefficients to account for changes in losses due to small hysteresis loops and skin effect, as well as rotation magnetisation losses. A 710 kW 10‐pole asynchronous motor is used as the research object. A full‐domain iron loss calculation model considering stator and rotor tooth top surface losses is developed. The model can be used to accurately calculate the overall and local harmonic iron losses in the stator and rotor cores of high‐voltage multi‐pole asynchronous motors. And quantitatively analyse the distribution pattern of any harmonic iron loss at any location in the motor core. It realises the refinement calculation and analysis of iron losses in the whole domain of high‐voltage multi‐pole asynchronous motor. Finally, no‐load and load tests were conducted on the 710 kW 10‐pole asynchronous motor. The iron losses of the 710 kW 10‐pole asynchronous motor at no load and load are calculated using the above mentioned model and the classical trinomial constant factor model. The results are compared with the measured iron loss values. It is proved that the iron loss model is more accurate in calculating the iron loss of high‐voltage multi‐pole asynchronous motor. The result helps researchers to calculate the iron loss distribution of high voltage motors more accurately. Thus, the design and operating parameters of the motor can be optimised to improve the efficiency and performance of the motor. It provides the necessary technical support and key basis for the reduction of loss and energy saving of high‐voltage motors and the optimisation of their core structure.

Study on the method of evaluating the failure of stator bar insulation materials based on mechanical damage characteristics

The damage impact of mechanical shocks on stator bar insulation is a key factor in high-voltage motor accidents. This study conducted electrical aging acceleration and breakdown experiments on damaged stator insulating materials to understand failure causes and evaluation methods. The relationship between sample defect area and depth and electrical properties was analyzed, along with the morphology of the damaged surface using a scanning electron microscope. Results show that the defect area correlates with impact mode but does not directly impact electrical performance. Effective insulation thickness is positively linked to electrical performance. This study serves as a valuable reference for evaluating mechanical impact faults in high-voltage motors.

Application of cascaded H-bridge multilevel inverter in the speed regulation of medium- and high-voltage asynchronous motor

Application of cascaded H-bridge multilevel inverter in the speed regulation of medium- and high-voltage asynchronous motor

Electromagnetic converter of reactive power and monitoring of high-voltage induction motors

In this paper, the control and monitoring of reactive power in an over-voltage induction motor are elucidated through a comparative analysis of theoretical and practical research findings. These results are based on structural principles, research models, and the static, dynamic, metrological, and technical characteristics of three-phase electromagnetic current converters, evaluated against established criteria. The effectiveness of employing current converters with straightforward design, high sensitivity, speed, and reliability, along with simple switching elements that transform the primary input stator current into a secondary voltage output signal, is emphasized. Utilizing a graph model, the static characteristics of the stator current to secondary voltage converter, essential for regulating and monitoring the reactive power of an asynchronous motor, are delineated, and a research algorithm is developed.

Overshoot level studies of PD Exposure in High Voltage Motor Isolation

Overshoot level studies of PD Exposure in High Voltage Motor Isolation

New Approach Towards Sustainability – The Global Efficiency Concept (GEff)

In the actual economical environment, business sustainability requires high-efficiency technological processes and new innovative developments. That is why the efficiency concept has to be present at all levels of industrial and financial activities. The proposed concepts in this paper could be further developed as a model for improving companies’ corporate energy policies.
 Nowadays, some purchase decisions for equipment are still driven predominately by the purchase price, and the full consequences of energy efficiency and the impact on the environment are not always considered.
 In general relatively “low value equipment” purchase policy is still driven by purchase price only, in spite of the evidence that such price represents a maximum of 5 % to 7 % of the total expenses related to the total costs of ownership. In the minerals industry “low value equipment”, like low-voltage motors (up to 1100 volts, 50/60 Hz), are found many times and in very large numbers, their efficiency and reliability influencing dramatically specific costs of technological processes.
 Although with “major equipment” energy savings are considered more in the purchase decision, every growing importance on the environment of “Green House Gas” (GHG) emissions is still not a major factor when selecting equipment. Often more traditional equipment is purchased at the expense of new innovative technologies that in addition to providing energy savings can also be used as a tool for trading Carbon Credits in the financial marketplace. An example of such a technology is the IsaMill™ comminution machine, which is becoming more widely used in gold and general mining operations in South Africa and throughout the world. Comminution in the mining industry is one of the most energy intensive activities in the world, and the innovative use of “major equipment” saving power can also have a positive effect on the environment.
 The paper presents descriptions of the essentials of the Global Efficiency (GEff) concept that has been promoted over the last years in South Africa. Price-efficiency criteria (as a corollary of GEff) are investigated for applications incorporating equipments that are driven by low and high voltage motors.
 The paper presents theoretical and technical aspects analysing the economic and environmental impact, by reducing total cost of ownership with energy savings, for one “low value equipment” in typical applications largely used in mineral processing in the gold mining industry, and one “major equipment” purchase at a current operating gold mine where the innovative IsaMill™ comminution technology was installed as an alternative to traditional older technologies.
 Besides the impact of energy savings with high-efficiency technological processes and new innovative developments, this paper suggests the general impacts of:
 
 Technical and economical performance improvements and competitiveness of mining corporations to international standards;
 Defusing incipient energy crisis in the gold mining sector;
 Improving environmental conditions;
 Creating new job opportunities in the gold mining sector.

Альтернативная ресурсосберегающая дифференциальная защита электродвигателей

The author presents the principle of operation of alternative resource-saving differential protection for high-voltage electric motors, made with adjustable selection of settings, without the use of measuring current transformers (CT) and current relays with ferromagnetic cores, which have significant weight and dimensional parameters and high cost. The result is the creation of resource-saving protection for the protection of electric motors, made on inductive coils and reed switches. Protections with their application can be used as an alternative to the traditional protections of electric motors made on electromechanical, semiconductor and microprocessor bases and at the same time by their characteristics are not inferior to them. The scientific novelty is that this protection has the effect of resource saving of used materials, thus allowing to realize significant savings of copper and steel, and represents a new approach in realization of differential protection for electric motors. All structural elements of the presented protection are made of heat-resistant, durable and lightweight plastic, type «PLA», printed on a 3D printer. The resource-saving of these protections is in the use of inductance coils and reed switches, which are, both in terms of their cost and weight and dimensional parameters, an order of magnitude cheaper and smaller in size and weight than the above-mentioned measuring CTs. The use of the presented protection increases the reliability of relay protection, both the cell itself, where it is installed, and the electrical installation, which is an electric motor connected to it. The proposed differential protection is made in the form of a structure with the installation of its elements inside the cell of complete (closed) switchgear voltage 6-35kV and in the electric motor

Improved thermal conductivity of anticorona insulation paint for high-voltage motor application

Improved thermal conductivity of anticorona insulation paint for high-voltage motor application

ACTUAL PROBLEMS AND SOLUTIONS FOR THE 6-10 KV POWER GRIDS

The features of operation of the 6-10 kV distribution power grids, which are commonly utilized in the power supply systems of industrial enterprises and cities, are considered and analyzed. It is shown that cabling, high-voltage motors and instrument voltage transformers are very vulnerable to overvoltages. It is noted that the existing systems for limiting overvoltages and protecting against ground faults, using surge arresters, RC-dampers, arc suppressing reactors, the neutral resistors of power grids and relay protection, are characterized by a number of advantages, but are ineffective when used separately. The advantage of the combined system of overvoltage and ground fault protection for power grids is proven and shown, and the results of operational testing are the basis for practical use.

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.

Development of Intelligent Painting System for UAV in Ultra-high Voltage Environment

Aiming at the problems of high-altitude painting, an intelligent painting unmanned aerial vehicle (UAV) system, including hardware design and software implementation, has been developed. The hardware design of the system mainly includes three parts: drawer-type modular power supply, UAV intelligent painting control system, and high airflow ultra-high-speed motor drive system. The software realization mainly includes two parts: the control thread of the high-voltage main motor and the control thread of the solenoid valve for opening and closing. Besides, the target recognition processing scheme has been designed. To evaluate the accuracy and practicability of this technique, the UAV system has been applied for an intelligent painting experiment in an ultra-high voltage environment, successfully illustrating the feasibility of uninterrupted power supply intelligent painting by UAV.

Is repair of energy using products environmentally beneficial? The case of high voltage electric motors

Repair is advocated as a circular strategy to improve the environmental performance of products. Whether this holds for very long-lived and energy intensive products has not been addressed. This study compares environmental impacts of two high voltage motors of different energy efficiency and assesses their use extension by repair with life cycle assessment (LCA). Due to high energy use, long lifetime and intensive use, the use phase dominates all environmental impacts, even resource depletion. Therefore, a higher energy efficiency is more beneficial than extending the use by repair, and if the energy efficiency is slightly reduced, the repair is not beneficial. Therefore, product requirements and users and manufacturers of such products should ensure designs with high energy efficiency rather than making the product repairable. Finally, the results highlight the importance of including resource use from electricity production and transmission in LCA of the use extension of energy using products.

A STRUCTURED RELIABILITY AND MAINTAINABILITY ASSESSMENT MODEL: AN APPLICATION TO HIGH VOLTAGE MOTORS

Motors are one of the vital equipment and generally the higher in numbers in oil and gas processing facilities. The primary function is to drive the process equipment such as compressors, fans, pumps etc. Unreliability of the motors is a threat to safety but also to production loss and high operating expenditure. Motors experience higher failure rates and maintenance costs with age due to lower focus during useful life periods. In order to properly address the long-term reliability and maintainability of the motors and associated subsystems, this paper aims to propose a structured methodology and set of tools to ensure effective assessment. The proposed model mainly consists of data collection, analysis, assessment, financial analysis and later developed actions to properly address the concerns. Equipment failure and repair data is a challenge to any reliability assessment; hence, proposed methodology was introduced to collect, verify and validate the data. Later, multiple tools such as Pareto Analysis, Failure Mode and Effect Analysis and Root Cause Analysis were used to perform a detailed assessment. Weibull analysis was also explored to understand the failure modes, which ultimately helped in improving the availability of the motors. The proposed methodology has been applied to high-voltage motors to observe the effectiveness of the tools and proposed model in addressing reliability and maintainability. The results show significant reliability improvements of 12% (from 58% to 70%) and prove that the structured method can be effectively used in complex process facilities with significant benefits.

Fluid-thermal characteristics of high-voltage line-start permanent magnet synchronous motor based on bidirectional hydraulic-thermal network coupling

This paper concerns the fluid-thermal characteristics of a high-voltage line-start permanent magnet synchronous motor (LSPMSM). A bidirectional hydraulic-thermal network coupling methodology is proposed and applied to the fluid-thermal characteristics calculation. The proposed method can fully account for fluid-thermal interactions to achieve an accurate prediction. According to the structural features of the motor with axial and radial mixed ventilation cooling, the global hydraulic network is established by connecting the local indenter elements and hydraulic resistances. The global thermal network is established based on heat source distribution and heat transfer paths. The temperature rise of the motor ranges from 45.8 K to 84.9 K. The hotspot appears at the lower end-winding on the drive side, and the lowest temperature rise occurs on the nondrive side of the shaft. Moreover, the experimental platform is built to verify the accuracy of the proposed method, and the relative error is 2.2% and 2.9%.