Power Industrial Applications Research Articles

DEVELOPMENT OF SOME ACCOMPANYING TECHNOLOGIES OF IV GENERATION NUCLEAR REACTORS WITH COOLANT GAS

High-temperature nuclear reactors with coolant gas have several advantages for application in power generation and industry. For the design and implementation of reactor facilities of this type, the development of accompanying technologies is necessary. Such technologies include the production of nuclear-grade graphite, pyrocarbon protective coatings of nuclear microfuel, production of helium.The Gas Institute of the National Academy of Sciences of Ukraine conducted a series of research and development works in this field. The research results allow to create energy-efficient and environmentally safe technology for purification of natural graphite to high levels of purity. Research of application of pyrocarbon coating on nuclear microfuel model was carried out in reactors with electrothermal fluidized bed. As a result, material with a wide spectrum of pyrocarbon content (from 2 to 97 % wt.) was obtained. Сryogenic technology for the production of helium concentrate from natural gas was developed. To continue research in the development of accompanying technologies for nuclear reactors with coolant gas, international consortium for participation in EURATOM and Horizon 2020 grant programs is being set up.

DeepPAR and DeepDPA: Privacy Preserving and Asynchronous Deep Learning for Industrial IoT

Industrial Internet of Things (IIoT) is significant of building powerful industrial systems and applications. Deep learning has provided a promising opportunity to extract useful knowledge by utilizing vast amounts of data in IIoT. However, lacking of massive public datasets will lead to low performance and overfitting of the learned model. Therefore, the federated deep learning over distributed datasets has been proposed. Whereas, it inevitably introduces some new security challenges, i.e., disclosing participant's data privacy. However, existing methods cannot guarantee each participant's data privacy in a learning group. In this article, we propose two privacy-preserving asynchronous deep learning schemes [privacy-preserving and asynchronous deep learning via re-encryption (DeepPAR) and dynamic privacy-preserving and asynchronous deep learning (DeepDPA)]. Compared to the state-of-the-art work, DeepPAR protects each participant's input privacy while preserving dynamic update secrecy inherently. Meanwhile, DeepDPA enables to guarantee backward secrecy of group participants in a lightweight manner. Security analysis and performance evaluations on real dataset show that our proposed schemes are secure, efficient, and effective.

Magnetic-Integrated Multipulse Rectifier Transformer With a Tight Impedance Equalizing Strategy for Power Quality Improvement of DC Traction Power Supply System

To improve the power quality of dc traction power supply system (DC-TPSS), a magnetic-integrated multipulse rectifier transformer (MI-MPRT) with a tight impedance equalizing strategy is proposed in this article. The configuration and winding-arrangement of MI-MPRT are introduced, and by integrating multiple windings on a same iron core, the volume and cost of the proposed transformer can be decreased significantly. Cooperated with the staggered winding-arrangement, a tight impedance equalizing strategy is proposed to optimize the winding thickness and insulation distance comprehensively, and MI-MPRT would be designed in a minimum axial dimension, with equalizing short-circuit impedance of each winding. A high-power prototype is manufactured, and the efficiency of prototype is verified by the transformer standard test. In addition, the DC-TPSS based MI-MPRT is implemented, and the experiment results validate that the power quality of new system can be improved significantly by harmonic elimination, circulation-currents suppression, and dc-voltage ripple restraint. Both the theoretical and experimental results indicate that the proposed MI-MPRT is suitable for power quality improvement and industrial application in DC-TPSS.

Temperature Influence on Dielectric Response of Rotating Machine Insulation and Its Correction

Insulation condition is an essential aspect for the operational reliability of high voltage rotating machines in power plants and industrial applications. Insulation resistance (IR) and line-frequency dissipation-factor / power-factor (tanδ) measurement are often performed for the assessment of stator insulation condition. These measured values need to be normalized to a reference temperature (e.g. 40 °C) for comparison and trending and this is traditionally achieved by multiplying the results with a certain factor. However, this correction could be subject to error for an individual device since the correction factors recommended by various standards are average values of a certain number of machines at different conditions. In addition to that, insulation condition also has some influence on the temperature dependent property.With the introduction of Dielectric Frequency Response, DFR and Polarization/Depolarization Current, PDC as more advanced insulation diagnostic methods, with proper modelling, temperature correction can be done based on the insulation condition of an individual device and thus accuracy is considerably improved. In this paper, the background of DFR and its superiority in temperature correction are introduced. After that, the numerical Fourier and Inverse Fourier Transformation algorithm is applied to correct the time domain measurement (IR and PDC).

Toward Fast Calculation of Probabilistic Optimal Power Flow

With the rapid growth of renewables, probabilistic optimal power flow (POPF) has become an important tool to analyze uncertainties in power systems. However, POPF calculation involves repeatedly solving the optimization problem. The computational efficiency has been a major bottleneck for its practical application in power industries. This letter proposes a novel method to significantly improve the efficiency of POPF calculation while maintaining the desired accuracy. The IEEE 30-bus, IEEE 118-bus, and practical utility 661-bus systems are used to demonstrate the effectiveness of the proposed method.

A free-standing superhydrophobic film for highly efficient removal of water from turbine oil

A free-standing superhydrophobic film is prepared by sequentially dip-coating a commercially available filter paper with nano SiO2 suspension, epoxy emulsion, and octyltrimethoxysilane solution. A surface with micro- or nano-roughness is formed because SiO2 nanoparticles are uniformly and firmly adhered on the backbone of the filter paper by the cured epoxy resin. Furthermore, the surface energy is significantly reduced because of introducing octytrimethoxysilane. Such a surface structure makes the prepared film a superhydrophobic material. Due to its free-standing nature, this superhydrophobic film can be used to remove water from turbine oil by filtration. The efficiency of water removal is high (up to 94.1%), and the filtration process is driven solely by gravity without extra energy consumption. Because of the facile fabrication process and the high efficiency of water removal, this free-standing superhydrophobic film may find application in power industry.

CMC-Jacketed Piping for High-Temperature Applications: Concept, Laboratory Tests and Large-Scale Application Test

The increasing market share of highly volatile electricity generated from renewable sources like wind or solar energy, leads to enormous challenges in the energy sector. Since large-scale storage systems are neither currently nor in the near future available, the gap between electricity from renewable sources and current electricity demand has to be closed with flexibly operated conventional power plants. In order to be a viable, cost-effective option in tomorrow’s energy market future power plants must be highly efficient while having low CO2 emissions. Furthermore, they have to be highly reactive to counter instabilities in the electrical grid due to fluctuations in renewable sources. Current materials used in power plants are only within limits suited to experience extreme changes in operational loads. However, extreme changes of operational loads will become increasingly severe with a growing share of renewables. Our project team has developed a new concept for CMC-jacketed pipes to alleviate these issues. Recently, this concept was further developed and tested in laboratory as well as a large-scale application test at Grosskraftwerk Mannheim (GKM). All tests are still ongoing. Additionally, to the use in modern highly efficient power plants such CMC-jacketed piping is also suitable for other high-temperature applications, like e.g. solar power plants or industrial chemical applications.

NEW ASYMMETRIC 21-LEVEL INVERTER WITH REDUCED NUMBER OF SWITCHES

Multilevel inverter plays an important role in the field of modern power electronics and is widely being used for many high voltage and high power industrial and commercial applications. The objective of this paper is to design and simulate the modified asymmetric multilevel inverter topology with reduced number of switches. The proposed inverter topology synthesizes 21-level output voltage during symmetric operation using three DC voltage sources and twelve switches 8 main switches and 4 auxiliary switches. The different methods of calculating the switching angles are presented in this paper. The MATLAB/Simulink software is used to simulate the proposed inverter. The performance of the proposed inverter is analyzed and the corresponding simulation results are presented in this paper.

Principle of block chain technology and its application in electric power industry

Block chain is an important sub-concept of Bitcoin, which is essentially a comprehensive database without intermediary structure. Block chain technology, as a distributed data storage database technology, has broad application prospects in the power industry. Starting from the basic conceptual structure characteristics of block chain technology, this paper explains the principle and core technology of block chain technology, and explores the application of block chain technology in power transmission, power terminal services and energy fields.

A Test Method for the Chlorine Content of Phosphate Ester Fire-Resistant Oils by Energy-Dispersive X-Ray Fluorescence Spectrometry

The concentration of the chlorine in phosphate ester fire-resistant oils needs to be controlled strictly, because it is crucially related to the corrosion of debug system and it is considered as an important indicator to find the hidden faults. It is confirmed that the chlorine content can be tested accurately and conveniently using energy dispersive X-ray fluorescence (EDXRF) spectrometry, due to many advantageous features of this method, namely, rapid response, high sensitivity and good measure precision. The preparation of standard samples and the optimization of analytical conditions are discussed in this paper; then a series of experiments is performed to verify the accuracy of this method. Test results of the samples with chlorine content more than 10mg•kg-1 show that the precision of the proposed measurement method is above 89%, and its repeatability is above 97%. This work not only can provide a feasible method for the rapid detection of chlorine content in phosphate ester fire-resistant oils, but also gives a promising application in power industry

Investigation on SVM-Backstepping sensorless control of five-phase open-end winding induction motor based on model reference adaptive system and parameter estimation

This paper deals with a new control technique applied to five-phase induction motor under open-end stator winding (FPIM-OESW) topology using the backstepping nonlinear control. The main objective is to improve the dynamics of this kind of machine, which is intended to be used in high power industrial application, where the maintenance is difficult and the fault tolerant is needed to ensure the continuous motor operating mode with minimized number of interruption. This control technique is combined with the Space Vector Pulse Width Modulation (SVPWM) to maintain a fixed switching frequency. In addition, the Model Reference Adaptive System (MRAS) concept is used for the estimation of the load torque, the rotor flux and the rotor speed to overcome the main drawbacks presented with the previous sensorless systems concepts. However, the great sensitivity to the changes of the motor internal parameters and it operating instability problems, especially in low-speed operating region, that causes an estimation error of the rotor speed, is the most disadvantage of the MRAS technique. Therefore, to solve this problem, an estimation method of the motor internal parameters such as the rotor resistance, the stator resistance and the magnetizing inductance, is proposed in this paper. Where, the main aim is to improve furthermore the control performance, to reduce the computational complexity and to minimize the rotor speed estimation error. The obtained simulation results confirm the enhanced performance and the clear efficacy of the proposed control technique under a variety of cases of different operating conditions.

Current issues of information technologies application in electric power industry

The article considers the problems of IT development in the power industry. During the studies the analysis of the competitive advantages of information technologies was carried out and the following functional features of information systems were revealed: Material Requirements Planning (MRP), Manufacturing resource planning (MRP II), Enterprise Resource Planning (ERP), Enterprise Resource & Relationship Processing (ERP II), Customer Relationship Management (CRM), Supply Chain Management (SCM). The authors also justify the incentives for the development of intelligent technologies in the electric power industry. The main purpose of the study was to substantiate that management capabilities based on IT create the conditions for innovative development of the industry. The digitalization of the energy sector, intelligent metering and distribution systems for the electric power present new requirements for the training of IT specialists. Analysis of the main current IT trends in the power sector helps to justify the need for the use of the Internet services during laboratory work in the educational process.

Guest Editorial: Special Section on Predictive Control in Power Electronics, Electrical Drives and Industrial Applications

The features and potential of predictive control techniques in power electronics applications have been demonstrated and widely studied during the last 15 years. The most remarkable advantages are the intuitive control scheme, great flexibility to cover a variety of degrees of freedom, and the straight-forward incorporation of nonlinear variables and constraints. Although this proposal with very attractive characteristics dates back to the 1970s, the experimental validation has only been possible recently, thanks to the development of modern digital controllers due to the relatively high computational burden associated with this method. The great effort of the researchers enabled a large number of publications in journals and dedicated conferences that has positioned this strategy as a viable alternative to the classical controllers. Thus, implementations based on this approach in proposals such as variable-speed drives, current, voltage, and power regulation, renewable energy generation systems, microgrids, energy storage, or electric vehicles (EVs) can be found in the literature. It is expected that the pace of developments with the predictive control keeps the current trend, because of the great opportunities in the research and industrial fields.

Analysis and Control of the Permanent Magnet Synchronous Motor With Auxiliary Modular Design

U-shape core permanent magnet synchronous motor (PMSM) has the features of small size, simple and robust construction, generally working in the low power and low cost industry applications [1], [2]. Due to the simple structure and the self-starting ability, single-phase PMSM with U-shape core got more attentions in early research and application, however, its development was limited by motor large torque ripple and low efficiency. As one effective way to solve the problem, the PMSM with auxiliary modular design comes out [2], which can obtain a smooth operation feature with shifted magnets array and supply the opportunity for fault tolerant control. Based on the two-phase PMSM with auxiliary modular design, the motor mathematical model and the fault tolerant control configuration are presented in this paper to illustrate motor characteristics and achieve the fault-tolerant ability. Finally, the motor prototype is tested and the experimental results are used to verify the proposed steady operation and the fault-tolerant strategy.

Dual-fuel operation of gasoline and natural gas in a turbocharged engine

Natural gas is a high-octane fuel that produces lower CO2 emissions per kilowatt hour than liquid transport fuels, with essentially zero sulfur emissions. Historically, natural gas has mostly been used in power generation and industrial applications. However, there has been a recent shift towards employing natural gas in the transport sector. In many regions, vehicles are retrofitted with compressed natural gas (CNG) systems, enabling operation on both gasoline and natural gas (and theoretical mixtures thereof). This work examines the effect of leveraging the secondary natural gas fuel system on the performance, efficiency and broader environmental impact of a high specific output gasoline engine. Firstly, mixture sweeps are presented for varying gasoline/natural gas ratios (100% gasoline to 100% natural gas) at wide open throttle (WOT) with both fixed and variable spark timing. This baseline information is then used to optimize the engine calibration for varying gasoline/natural gas ratios over a wider range of operating conditions. Finally, the CO2-equivalent emissions are computed to investigate the broader environmental impact of an optimized gasoline/natural gas vehicle.

Chemical-looping combustion: Status and research needs

Chemical-Looping Combustion (CLC) has emerged in recent years as a very promising combustion technology for power plants and industrial applications with inherent CO2 capture, which circumvent the energy penalty imposed on other competing technologies. The process is based on the use of a metal oxide to transport the oxygen needed for combustion in order to prevent direct contact between the fuel and air. CLC is performed in two interconnected reactors, and the CO2 separation inherent to the process practically eliminates the energy penalty associated with gas separation. The CLC process was initially developed for gaseous fuels, and its application was subsequently extended to solid fuels. The process has been demonstrated in units of different size, from bench scale to MW-scale pilot plants, burning natural gas, syngas, coal and biomass, and using ores and synthetic materials as oxygen-carriers.An overview of the status of the process, starting with the fundamentals and considering the main experimental results and characteristics of process performance, is made both for gaseous and solid fuels. Process modelling of the system for solid and gaseous fuels is also analysed. The main research needs and challenges both for gaseous and solid fuel are highlighted.

Measurement and analysis of SiC-MOSFET threshold voltage shift

Silicon carbide power MOSFETs are used in numerous studies to improve the efficiency or the performance of power electronic converters. However, the gate-oxide technology weakness is a main reliability issue of silicon carbide MOSFET transistors. The threshold voltage shift is a critical phenomenon that addresses the reliability of industrial power applications. It is important to have a better understanding of the phenomena implied in the gate threshold voltage shift. In this context, a static ageing test based on JEDEC standard is proposed and the resulting gate oxide stress is studied and discussed in this paper. Complementary testing was performed with dynamic reliability and gate oxide characterizations, such as the charge pumping technique. The results obtained are used to add insight to the current discussion of SiC MOSFET robustness. Additionally test benches and measurement protocols established on 1.7 kV 45 mΩ are detailed, which will be useful for the next generation of SiC MOSFET.

The effect of Co and Sn on Zr-Nb alloys for high temperature application

AbstractZirconium has attracted a lot of attention recently due to its distinctive properties that make it suitable for extensive applications in the nuclear power and chemical industry. Zirconium and its alloys are undergoing long-term development as promising materials for the nuclear industry and power engineering. Recently, advanced Zr-based alloys are aimed for service in more severe operating conditions such as higher burn-up, increased operation temperature, and high-PH operation. In this work we observe the temperature dependence of Zr50Nb50, Zr78Nb22, Zr78Nb19Co3 and Zr50Nb49Sn1. It was observed that ternary additions with small atomic percentages of Co and Sn have significant impact on Zr-Nb alloy; and their elastic properties showed a possible enhancement on high temperature applications and physical strength.

Fiber-Optic Current Sensor Tolerant to Imperfections of Polarization-Maintaining Fiber Connectors

We investigate the effect of polarization cross-coupling at polarization-maintaining (PM) fiber connectors on the accuracy of an interferometric fiber-optic current sensor. The sensor uses the Faraday effect in a fiber coil operated in reflection mode and an interrogator based on nonreciprocal phase modulation. PM connectors in the fiber link between the sensor's opto-electronic module and the fiber coil give rise to signal instability due to a limited and insufficiently stable polarization extinction ratio (typically <;25-30 dB). As a result the accuracy of the sensor can be well outside the allowed tolerances of applications in the electric power industry which often demands accuracy to within ±0.2%. We demonstrate that by means of a modified optical circuit the disturbing effects of polarization cross-coupling can be largely eliminated. The modified circuit introduces group delays for the cross-coupled light waves relative to the undisturbed waves much larger than the coherence length of the broadband light source. We theoretically and experimentally show that connector extinction ratios well below 20 dB are still uncritical. Furthermore, we verify the superiority of the modified circuit at changing connector temperature (and hence changing temperature-induced stress in the connector ferrules) and at repeated connector open-close operations.

Statistics based method for partial discharge identification in oil paper insulation systems

An original partial discharge generated in oil insulation identification methodology based on simultaneously conducted measurements using electrical method, ultra high frequency method and acoustic emission method is presented in the paper. Three different partial discharge model sources as well as measuring instruments commonly applied for partial discharge detection in electrical power transformers are yielded within a laboratory research. Total of 45 scenarios, including proposed spark gap configurations, selected supply voltage levels and UHF frequencies are analyzed during measurements series. Furthermore, form among total of 93 descriptors assigned for every applied partial discharge model source configuration there are 24 proposed as potentially useful for partial discharge identification applications with their 95% confidence bounds. Attempt of discriminative descriptors selection for partial discharge source analysis in on-site transformer applications as well as a proposal of unique descriptors according to every selected spark gap configuration that could be potentially useful for partial discharge identification purposes are the main purpose of the presented paper. The proposed methodology verification on a real life transformer with particular consideration of the selected descriptors potential utility in the fields of partial discharge detection and identification in electrical power industry applications confirmed a proposed methodology usefulness.