Electric Power Unit Research Articles

Vertical steam generators for VVER NPPs

Steam generators for NPPs are the important large-sized metal consuming equipment of nuclear power installations. Efficiency of steam generator operation determines the overall service life of the whole nuclear facility. The main aim of the current study is to analyze advantages and shortcomings of horizontal and vertical types of steam generator design. This analysis is aimed at the development of recommendations for designing advanced steam generators for future Russian units of NPPs with VVER reactors of increased power. Design solutions and fifty-year experience of operation of 400 steam generators of horizontal type accepted in Russia and of vertical type applied by Westinghouse, Combustion Engineering, Siemens, Mitsubishi, Doosan were analyzed within the framework of the present study. Advantages and drawbacks of both types of equipment determining the development of conditions of the operating processes were also identified and systematized. Currently NPPs equipped with VVER are characterized with extended surface area of containment shells due to the application of four-loop design configuration and horizontal-type steam generators. It was established that steam generator equipment of horizontal type is characterized by such inherent disadvantages of design, technological and operational nature as the following: 1) small height and volume of the vapor space above the evaporation surface reducing separation capabilities and the capacity of the equipment as a whole; 2) impossibility of organizing separate single-phase pre-boiling section. Because of the above, horizontal steam generators with dimensions permissible for railroad transportation and, for VVER-1200 with reactor vessel diameter equal to 5 m, by water transport as well, have exhausted the possibilities for further significant increase of the per unit electric power. The demonstrated advantages of vertical-type steam generators were as follows: 1) absence of stagnant zones within the second cooling circuit, and, consequently, of hold-ups in them; 2) uniformity of heat absorption efficiency of the heating surface ensuring, as well, improved conditions for moisture separation; 3) high degree of moisture removal from steam-water mixture due to the combination of moisture separating elements of chevron and swirl-vane types; 4) increased temperature drop with parameters of generated steam elevated by 0.3 – 0.4 MPa. Conclusion was made on the advisability of introduction of steam generators with vertical-type layout in the Russian nuclear power generation. Practical tasks that need to be addressed in order to ensure introduction of vertical steam generators at NPPs with high-power VVER reactors were formulated.

Electromagnetic Signal Preprocessing and Feature Extraction

The electromagnetic wave can lead to electrical equipment failure, which is really a serious problem to electrical power unit, which not only destroy the circuits but also may lead to fire. Therefore, This research focused on electromagnetic signal preprocessing and feature extraction based on wavelet transform. After building the model of electromagnetic waveform, the collecting signals of electrical spark affected by noise signals were processed, wavelet transform was used to filter the noise interference so that the features of electromagnetic waveform can be extracted. The result shows that the preprocessing of electromagnetic signal can achieve accurate feature parameter information and after extracting the features, which provide convenience to the further processing of electromagnetic signals.

Day-ahead stochastic multi-objective economic/emission operational scheduling of a large scale virtual power plant

The reduction of global greenhouse gas emissions is one of the key steps towards sustainable development. The integration of Distributed Energy Resources (DERs) in power systems will help with emissions reduction. Virtual Power Plants (VPPs) can overcome barriers to participation of DERs in system operation. In this paper, a model is proposed for the energy management of a VPP including PhotoVoltaic (PV) modules, wind turbines, Electrical Energy Storage (EES) systems, Combined Heat and Power (CHP) units, and heat-only units. The multi-objective operational scheduling of DERs in the VPP focuses on maximizing the expected day-ahead profit of the VPP and minimizing the expected day-ahead emissions. The uncertainty of wind speed, solar radiation, market price, and electrical load is modeled using scenario based approach. Also, two-stage stochastic programming is implemented for modeling the VPP energy management. Three cases have been investigated for evaluating the proposed method: single-objective scheduling of VPP to maximize profit, single-objective scheduling of VPP to minimize emission and multi-objective economic/emission scheduling of VPP. The results indicate the appropriate economic and environmental performance of the proposed method, which provides the possibility of selecting a compromise solution for the VPP operator in accordance with environmental restrictions and economic constraints.

The Use of Machine Learning in Situational Management in Relation to the Tasks of the Power Industry

The article discusses the application possibilities of machine learning methods (artificial neural networks (ANN) and genetic algorithms (GA) to form management actions when applying the concept of situational management for intelligent support of strategic decision-making on the development of energy. At the first stage, the application of ANN to classify extreme situations in the energy sector, to select the most effective management actions (preventive measures) in order to prevent a critical situation from developing into an emergency. Genetic algorithms are proposed to be used to determine the weighting coefficients for training ANN. An algorithm for constructing a classifier based on a neural network and a demonstration task using data on generation and consumption of the United Electric Power System of Siberia are presented.

Prospective Life Cycle Assessment Based on System Dynamics Approach: A Case Study on the Large-Scale Centrifugal Compressor

The deficiency of temporal information in life cycle assessment (LCA) may misrepresent the environmental impacts of products throughout the life cycle or at a particular time in the future. For the environmental assessment of energy-consuming products, background data obtained from the LCA database fail to incorporate emissions or extractions reflecting the future situation. To overcome this knowledge gap, we developed a system dynamics (SD) model to predict the evolution of energy structure in China till 2030 and further determined the time-varying emissions of unit electric power combined with the ecoinvent 3.1 database. Additionally, dynamic characterization factors (CFs) of global warming potential (GWP) were integrated into the life cycle impact assessment (LCIA). This study took the PCL803 large-scale centrifugal compressor as an illustrative example in which the temporal-dependent electricity was included in the dynamic life cycle inventory and the dynamic CFs of GWP were included in the LCIA. Environmental impacts were quantified and compared using the traditional and prospective LCA. Results indicated that the environmental burdens under the electricity variation were approximately 13% less than those of conventional LCA, and the GWP under dynamic CFs would be further reduced by 14.5%. The results confirmed that, when socio-economic progress, technical improvement, and dynamic CFs are not considered, the environmental assessment will lead to an overestimation of environmental loads. Therefore, the relevant time-varying parameters should be considered for accurate assessment.

Енергозберігаюча система обробітку грунту на базі електрифікованого мотоблоку

Small-sized mobile aggregates in the form of motoblocks with internal combustion engines with the capacity of 1-7 kW domestic and foreign production were widely used to increase the efficiency of production of vegetables in protected ground soils. During the work of mobile units with internal combustion engines in greenhouses and greenhouses, noise and gas pollution increase, which negatively affects not only people but also plants. More promising for work in protected soil structures are mobile aggregates with traction electric motors, which are called electric motors, as ecologically clean aggregates that do not have the named drawbacks. The purpose of the research is to substantiate and elaborate the structural and electromechanical scheme of an energy-saving soil cultivation system based on an electrified motor block, to obtain a balance of capacities, and to create a mode of control of the DC motor by successive excitation along the maximum of efficiency in the main sections of its mechanical characteristics. The electric power unit receives power with a flexible cable, which is supplied with electricity from the AC network. The gate converter converts the electric energy of an alternating current into the electric power of a direct current necessary for further electromechanical transformation in a traction electric motor. The structural and electromechanical schemes of the energy-saving soil tillage system based on the electrified motor block are substantiated. The obtained control characteristics provide the control of the DPS at the maximum efficiency and the set value of the load factor. In a relatively large zone, the change in the load factor of the engine efficiency is close to the maximum value with a loading coefficient of 0.7-0.9. This significantly simplifies the practical implementation of the modes of control of the DPS with the use of simple design of the gate transducers in the form of thyristor voltage regulators.

Having CHPP involved in frequency control related to starting Belarusian NPP

The policy of restructuring the generating capacities of the energy system of the Republic of Belarus assumes the introduction of the the Belarusian nuclear power plant (NPP) in the coming years. The presence of external and internal factors affecting the sale of electricity from NPP will require solving a number of problems, including power redundancy and frequency control through involvement of internal power generating facilities. These include steam-turbine state power plants and combined heat and power plants (CHPP), combined-cycle power units, special mobile electric power units, the commissioning of electric boilers and accumulator tanks. The latter is a new technical solution for the Belarusian energy system that requires careful analysis to identify the optimal system for coordinated operation of co-generation power units with electric boilers and accumulator tanks. At the same time, the heating and non-heating seasons of the CHPP operation are considered. The function of the accumulator tanks with minimum and maximum power consumption is shown. At charging of the accumulator tanks, the generation of electricity by co-generation power units with thermal regulation is increased. The operation of electric boilers and accumulator tanks is considered through the example of Grodno CHPP-2. The expediency of including electric boilers in the scheme of the CHPP as the most effective means of using co-generation turbine units in the cycling mode with unloading them by electric power during the night hours is determined, which ensures the maximum reduction of the electric power output to the power system from the Belarusian NPP.A similar approach at other industrial CHPP of the power system will, to some extent, ensure stable power supply from the Belarusian NPP. Reconstruction of the CHPP with installation of accumulator tanks will make it possible to create a flexible heat supply scheme for consumers in the conditions of night electrical unloading when the NPP power units are put into operation.

Spring-Assisted Motorized Transmission for Efficient Hover by Four Flapping Wings

Elastic storage has been reported to help flying insects save inertial power when flapping their wings. This motivates recent research and development of elastic storage for flapping-wing micro air vehicles (fwMAVs) and their ground (tethered) flight tests. The previous designs of spring-loaded transmissions are relatively heavy or bulky; they have not yet been adopted by freely hovering prototypes of fwMAVs, especially those with four flapping wings. It is not clear if partial elastic storage can still help save power for flapping flight while not overloading the motorized transmission. Here, we developed ultralight and compact film hinges as elastic storage for four flapping wings. This spring-assisted transmission was motor driven such that the wing beat frequency was higher than the natural frequency of elastically hinged wings. Our experiments show that spring recoil helps accelerate wing closing thus generating more thrust. When powered by a 3.18 g brushless motor, this 13.4 g fwMAV prototype with spring-assisted transmission can take off by beating four flexible wings (of 240 mm span) with up to 21–22 g thrust generation at 22–23 Hz. Due to lower disk loading and high-speed reduction, indirect drive of the four elastically hinged wings can produce a thrust per unit of electrical power of up to 4.6 g/W. This electrical-power-specific thrust is comparable to that generated by direct drive of a propeller, which was recommended by the motor (AP-03 7000kv) manufacturer.

Review of the actual state of the market for autonomous energy supply systems

In connection with the strongest energy dependence of modern mankind and regular accidents in the world's power systems, the use of alternative sources of electricity remains relevant. The article reviews the dynamics of the market of systems of autonomous power supply with electric generators for the last 10 years. The data on import and production of electric generators in the territory of the Russian Federation are presented. The main domestic producers of electric generating sets are given. The main exporting countries in Russia are electric power units. The positive impact of the policy of import substitution on the production of power units in the territory of the Russian Federation was noted. The tendency to growth of manufacture and import of gas manufacture of gas electric generating sets is established.Subject: the subject of the study is the state of the market of autonomous power supply systems with electric generators (EA) designed for professional long-term operation based on primary multi-cylinder engines using diesel fuel and gas. Objectives: the purpose of the study is to analyze the current state of the market of autonomous power supply systems.Materials and methods: in the course of work, a retrospective of the market of autonomous power supply systems with power units was given, dynamics of import and production of electric power units on the territory of the Russian Federation is presented.Results: the article reviews the dynamics of the market of autonomous power supply systems with electric power generators for the last 10 years. The data on import and production of electric generators in the territory of the Russian Federation are presented. The main domestic producers of electric generating sets are given. The main exporting countries in Russia are electric power units. The positive impact of the policy of import substitution on the production of power units in the territory of the Russian Federation was noted. The tendency to growth of manufacture and import of gas manufacture of gas electric generating sets is established. The need for the growth of the market of electric generating sets distribution of producers.Conclusions: forecasts are made on the future of power plants in the Russian Federation.

Power packet transferability via symbol propagation matrix.

A power packet is a unit of electric power composed of a power pulse and an information tag. In Shannon's information theory, messages are represented by symbol sequences in a digitized manner. Referring to this formulation, we define symbols in power packetization as a minimum unit of power transferred by a tagged pulse. Here, power is digitized and quantized. In this paper, we consider packetized power in networks for a finite duration, giving symbols and their energies to the networks. A network structure is defined using a graph whose nodes represent routers, sources and destinations. First, we introduce the concept of a symbol propagation matrix (SPM) in which symbols are transferred at links during unit times. Packetized power is described as a network flow in a spatio-temporal structure. Then, we study the problem of selecting an SPM in terms of transferability, that is, the possibility to represent given energies at sources and destinations during the finite duration. To select an SPM, we consider a network flow problem of packetized power. The problem is formulated as an M-convex submodular flow problem which is a solvable generalization of the minimum cost flow problem. Finally, through examples, we verify that this formulation provides reasonable packetized power.

Development of a Procedure for Analysis of Failure Chains in Complex Mechatronic Systems to Improve Sustainability

The increasing blurring of system boundaries in complex and mechanical products hinders to identify cause-and-effect-relations of failure chains regarding quality and sustainability. Therefore, it is necessary to develop an approach, which can analyse interactions between all system elements and their failures along the product lifecycle. To examine this certain problem of understanding the complexity of a system to prevent potential failures, a systematic and model-based analysis with the utilization of different and problem-oriented methods is needed.But how can failure chains be represented and analyzed transparently in the system model? Are there any possibilities to combine determined failure chains with established methods of different disciplines for a holistic analysis like FMECA? This crucial questions form the essential part of this article and will be demonstrated by using the example of an alternative electrical power unit for public transport busses.

Анализ параметров синхронного генератора со сверхпроводящими обмотками для автономной электроустановки

The article considers the possibility of using synchronous generators with liquid nitrogen cooled superconducting windings on the stator and rotor in self-contained electric power units with a voltage level up to 1000 V. High efficiency of such generators is demonstrated, and the basic correlations for estimating their main parameters are given. It follows from the obtained correlations that with the specified geometrical sizes and the rotor and stator winding data, the superconducting synchronous generator output power proportional to the rotor rotation frequency is determined by the following parameters: (i) the inductor geometrical sizes and the square of the excitation winding MMF; (ii) the air gap width, the volume of which must be proportional to the generator power capacity; and (iii) the permissible armature current load, the value of which will make it possible to obtain the design power output at the specified voltage level. Fulfilling of these requirements is the necessary condition for developing a synchronous generator with the specified power with superconducting windings on the stator and rotor for self-contained power installations.

Efficient drying and oxygen-containing functional groups characteristics of lignite during microwave irradiation process

ABSTRACTTo remove the high moisture of ZhaoTong lignite, the efficient drying characteristics and oxygen-containing functional groups changes in lignite during microwave irradiation process were highlighted in this study. As the microwave absorbers, lignite char and NaNO3 were added to microwave drying of ZhaoTong lignite. The minimum chemical oxygen demand of waste water generated from microwave drying process of lignite was 99.89 mg O2 L−1. The effects of microwave power, lignite mass, the weight ratio of lignite char to lignite and NaNO3 content on the drying rate, and moisture diffusion coefficient of lignite were investigated during lignite microwave irradiation process. It was found that the drying rate and moisture diffusion coefficient of lignite increased with increasing microwave power, the weight ratio of lignite char to lignite and NaNO3 content, but decreased with increasing lignite mass. Lignite char and NaNO3 were mixed with lignite that can enhance the instantaneous surface temperature of lignite sample under microwave irradiation. Compared with addition of lignite char to lignite, the addition of NaNO3 to lignite can decrease the unit electric power consumption of moisture evaporating. And the minimum unit electric power consumption of moisture evaporating was 9.44 Wh g−1. The FTIR technology was used to investigate the oxygen-containing functional groups changes in lignite during microwave drying process. The oxygen-containing functional groups of lignite were effectively removed with increasing microwave power.

Optimization of the design, operating conditions, and coupling configuration of combined cycle power plants and CO2 capture processes by minimizing the mitigation cost

This paper deals with the optimization of the coupling between a natural gas combined cycle (NGCC) plant and a post-combustion CO2 capture process by minimizing the mitigation cost – defined as the ratio between the cost of electric power generation and the amount of CO2 emitted per unit of total net electric power generated – while satisfying the design specifications: electric power generation capacity and CO2capture level. Three candidate coupling configurations, which differ in the place where the steam is extracted from, are optimized using detailed and rigorous models for both the NGCC and the CO2 capture plants. By comparing the mitigation cost of each configuration, the optimal integration configuration and the corresponding optimal sizes and operating conditions of all process units (steam turbines, gas turbines, heat recovery steam generators HRSGs, absorption and regeneration columns, reboilers and condensers, and pumps) are provided. In the computed optimal solution, the steam required by the CO2 capture plant is extracted from both the steam turbine and the HRSG (evaporator operating at low pressure), and the mitigation cost is 90.88$/t CO2. The optimal solution is compared with suboptimal solutions corresponding to the other two candidate coupling schemes. These solutions are compared in detail regarding capital investment and operating costs, HRSG configuration, process unit sizes, and operating conditions.

Facilities introduction planning of a microgrid with CO2 heat pump heating for cold regions

Fulfilling heating requirements in cold regions using fossil fuels can create problems in terms of excessive greenhouse gas emissions, making the replacement of conventional heating systems with electric heat pumps powered by renewable energy sources a desirable goal. To help address this issue, this paper examines the introduction of independent microgrids consisting of natural gas combined cycle and large-scale photovoltaic (L-PV) generating sources accompanied by electric heat pump capacity. These results help to clarify the optimal output rate of L-PV to the overall output of such a microgrid. Furthermore, this paper examine a dynamic-characteristics model of a CO2 split cycle heat pump in terms of the error of the supply-and-demand balance. This paper show that introduction of the proposed microgrid can significantly reduce the environmental and economic impact. This study clarified the environmental capability and economical efficiency of the microgrid for cold regions under management of electric power quality. When an electric power unit price and CO2 emissions of the proposal microgrid are referred to the domestic price based on official announcements of the Japanese government, the amount of CO2 reduction and electric power unit price of the proposal system can expect 48% and 30% reduction in Sapporo, respectively.

Effects of light quality on growth and development of cucumber seedlings in controlled environment

Abstract: Conventional light sources have been successfully used to cultivate a wide variety of horticultural crops. However, they are of limited use due to uncontrollability of spectra and energy inefficiency. Light-emitting diodes (LEDs) emerged with tremendous potential in controlled environment agriculture due to their energy efficiency, longevity, and spectral specificity, but the effects of different types of LEDs on plant growth and development must be examined. In this study, cucumber (Cucumis sativus L. cv. Zhongnong 26) seedlings were grown under four different lighting treatments that each delivered a photosynthetic photon flux density of 200 µmol/m2•s at plant canopy including triphosphate fluorescent lamps (TF), high-frequency fluorescent lamps (HF), white LEDs (WL), and red and blue LEDs (RBL). Cucumber seedlings were grown in a growth chamber at (25.0±1.5)°C with 12-hour light and 12-hour dark for 30 days after sowing, and data were subsequently collected. Seedlings grown under the WL were 45%, 12%, and 40% taller than those grown under the TF, HF and RBL, respectively. The leaf area was 23% smaller under the TF than under the HF. The shoot dry weight was 16%-22% lower under the TF than under the other lighting treatments. The transplants grown under the RBL had the lowest root dry weight and root to shoot ratio. The seedling quality index was similar among all the lighting treatments. The LEDs treatment yielded more total dry weight with unit electric power compared to the fluorescent lamps. The chlorophyll content was 13%-15% higher in plants grown under the HF and WL than that under the TF and RBL. Plants grown under the WL and RBL had greater photosynthetic rate, transpiration rate, and stomatal conductance than those grown under the TF and HF. It was concluded that high quality cucumber seedlings can be efficiently produced under the broad-spectrum WL that emit a reasonable amount of blue, green and red light, and the lack of green light and/or high ratio of red to blue light under the RBL may cause undesired plant attributes. Keywords: blue light, chlorophyll, cucumber seedlings, controlled environment, gas exchange, green light, light-emitting diode, red light DOI: 10.3965/j.ijabe.20171003.2299 Citation: Song J X, Meng Q W, Du W F, He D X. Effects of light quality on growth and development of cucumber seedlings in controlled environment. Int J Agric & Biol Eng, 2017; 10(3): 312–318.

Research on the Status of Water Conservation in the Thermal Power Industry in China

Abstract Based on the present situation of water consumption, this paper analyzes the factors affecting the selection of water technologies in the thermal power industry in China. Based on the water consumption standards and water conservation indicators in 345 thermal power plants nationwide, analysis showed the water consumption of thermal power plants would still have some water conservation potential, and the water required for generating one unit of electric power differs in different regions. Based on analysis of the water conservation technologies widely adopted in the thermal power industry currently, we selected 18 types of water conservation techniques within 6 categories and recommended their nationwide promotion. To ensure the sustainability of regional water resources and energy, we analyzed the future trends of development of water conservation technologies in the domestic thermal power industry and proposed relevant policy recommendations for the development of the thermal power industry and the management of water conservation techniques.

Vibration Analysis of High Pressure Cylinder Steam Inlet Pipes During Turbine Startup in Nuclear Power Plant

Vibration and dynamic strain measurement of high pressure cylinder (HPC) steam inlet pipes(SIP) is carried out during turbine startup in a nuclear power plant. The operation state of the pipes was analyzed and evaluated combined with the unit electric power, the turbine speed and the opening of control valves. The result shows that the pipe vibration velocity exceeds the allowable limit during the turbine startup and low electric power platform. And pipe vibration is synchronous to the control valves quick operation. The alternating stress is lower than the allowable value during the whole process. Pipe vibration is mainly caused by the steam flow excitation when the control valves operate quickly

Rapid localized heating of graphene coating on a silicon mold by induction for precision molding of polymer optics.

In compression molding of polymer optical components with micro/nanoscale surface features, rapid heating of the mold surface is critical for the implementation of this technology for large-scale applications. In this Letter, a novel method of a localized rapid heating process is reported. This process is based on induction heating of a thin conductive coating deposited on a silicon mold. Since the graphene coating is very thin (∼45 nm), a high heating rate of 10∼20°C/s can be achieved by employing a 1200 W 30 kHz electrical power unit. Under this condition, the graphene-coated surface and the polymer substrate can be heated above the polymer's glass transition temperature within 30 s and subsequently cooled down to room temperature within several tens of seconds after molding, resulting in an overall thermal cycle of about 3 min or shorter. The feasibility of this process was validated by fabrication of optical gratings, micropillar matrices, and microlens arrays on polymethylmethacrylate (PMMA) substrates with very high precision. The uniformity and surface geometries of the replicated optical elements are evaluated using an optical profilometer, a diffraction test setup, and a Shack-Hartmann wavefront sensor built with a molded PMMA microlens array. Compared with the conventional bulk heating molding process, this novel rapid localized induction heating process could improve replication efficiency with better geometrical fidelity.

Monolithic optical link in silicon-on-insulator CMOS technology.

This work presents a monolithic laterally-coupled wide-spectrum (350 nm < λ < 1270 nm) optical link in a silicon-on-insulator CMOS technology. The link consists of a silicon (Si) light-emitting diode (LED) as the optical source and a Si photodiode (PD) as the detector; both realized by vertical abrupt n+p junctions, separated by a shallow trench isolation composed of silicon dioxide. Medium trench isolation around the devices along with the buried oxide layer provides galvanic isolation. Optical coupling in both avalanche-mode and forward-mode operation of the LED are analyzed for various designs and bias conditions. From both DC and pulsed transient measurements, it is further shown that heating in the avalanche-mode LED leads to a slow thermal coupling to the PD with time constants in the ms range. An integrated heat sink in the same technology leads to a ∼ 6 times reduction in the change in PD junction temperature per unit electrical power dissipated in the avalanche-mode LED. The analysis paves way for wide-spectrum optical links integrated in smart power technologies.