Reliability Of Power Plants Research Articles

Model-oriented decision-making support system for the safe operation of the ship electric power plant improvement

A model-based decision support system is proposed to increase the reliability of the ship electric power plant. This system consists of a modeling unit and a unit for evaluating simulation results. The developed system can be implemented as part of control systems, both on the basis of programmable logic controllers, and on the basis of a separate programmable logic controller. The mathematical model of the ship electric power installation is given. The criteria used to evaluate the results of modeling and possible consequences are considered. A computer program for the implementation of this system presented. The results of modeling various emergency situations are given. Considered the possibility of using this system for training.

Numerical optimization of a finned tube bundle heat exchanger arrangement for passive spent fuel pool cooling to ambient air

The passive cooling of nuclear spent fuel pools is a promising alternative to active cooling. Since such systems work even in safety-critical situations, e.g. station blackout, the reliability of nuclear power plants would be enhanced. As in such systems heat needs to be transfer to the environment, the heat exchanger to air has a crucial influence on the system performance. This paper describes investigations of the Nusselt number, the achievable efficiency and the volumetric heat transfer coefficient of the tube bundle heat exchangers for a passive cooling system located at the bottom of a chimney. The effect of tube bundle configuration, tube shape, longitudinal tube pitch, transversal tube pitch and tube row number on natural convection heat transfer was numerically studied. These parameters were varied to optimize the heat transfer performance of the heat exchanger. It was found, that the staggered configuration performs better than the inline arrangement, since the flow mixing is higher. Furthermore circular tube shape and an oval tube shape with the aspect ratio of 1:2.1 were optimum for the inline and staggered configuration respectively. The longitudinal and transversal tube pitches of 63mm and 65mm performed best, since higher values reduced heat transfer. A tube row number greater than 5 did not improve the heat transfer and therefore a tube row number of 5 is recommended. The Nusselt number and volumetric heat transfer coefficient of the optimized tube bundle arrangement enhanced by 15.4% and 47.8% respectively at a temperature difference of 40K compared to the initial design.

MINERAL INSULATORS FOR KOMPTON DETECTORS OF NEUTRONS WITH A METAL HAFNIUM EMITTER

One of the priority tasks of nuclear power industry is to increase the reliability and safety of nuclear power plants. In this regard, traditional detectors for measuring the neutron flux in the reactor core are being improved and new ones are developed. This work is dedicated to one of the tasks of creating a compton self-powered neutron detector, namely, the formation of an insulator of magnesium oxide on an emitter of metallic hafnium. The effect of three types of magnesium oxide of different purity and structural state, as well as annealing temperature on the electrical resistance of the insulator between the collector and the emitter of the detector, is studied. The detector prototypes were manufactured by filling with magnesium oxidepowders or by applying liquid-phase mixturesthereof.

Early Warning of Critical Blockage in Coal Mills Based on Stacked Denoising Autoencoders

Coal mills have a significant influence on the reliability, efficiency, and safe operation of a coal-fired power plant. Coal blockage is one of the main reasons for coal mill malfunction. It is highly essential to accurately detect the critical blockage in coal mills to ensure a safe and stable operation of the unit. Taking advantage of unsupervised learning methods and historical process data from distributed control systems (DCS), a stacked denoising autoencoder (SDAE) network–based approach for monitoring critical blockage in a coal mill is proposed in this work. The SDAE model with optimized parameters is applied to reconstruct the operating data during normal operating conditions. The intrinsic relationship between all input variables was captured by training a multilayer network model. The monitoring indicator was obtained from the reconstruction errors, and the threshold for monitoring indicators was obtained using kernel density estimation (KDE) during normal operation. The proposed network is independent of fault data, requires a reduced on-line calculation, and demonstrates a better real-time performance compared to conventional methods. The abnormal variables analysis may provide a theoretical evidence for critical blockage. The effectiveness of the proposed method is validated using operating data collected from an actual coal-fired power plant in China. The results demonstrated that the proposed method can effectively detect critical blockage in a coal mill and issue a timely warning, which allows operators to detect potential faults.

Modernization of Power-Generating Units with RBMK-1000 Reactors

A nuclear power plant is a complex technological facility. The introduction of new standards and experience gained in the operation of domestic and foreign nuclear power plants requires the introduction of changes in the operating organization of existing nuclear power plants and improvements in their equipment. A general survey of the modernization of existing nuclear power plants with RBMK-1000 type reactors is presented. Measures for modernization of the power-generating units of nuclear power plants carried out following the accident at the Chernobyl nuclear power plant and at the present time are discussed. Because of modernization, the safety, reliability and economic efficiency of nuclear power plants have improved. The principal focus is on modernization of the reactor plant.

Методика определения времени безопасной эксплуатации оборудования и трубопроводов на основе результатов неразрушающего контроля

The reliability of nuclear power plants (NPPs) has an influence on power generation safety and stability. The reliability of NPP equipment and pipelines (E&P), and the frequency of in-service inspections are directly linked with damage mechanisms and their development rates. Flow accelerated corrosion (FAC) is one of significant factors causing damages to E&P because these components experience the influence of high pressure, temperature, and high flow velocity of the inner medium. The majority of feed and steam path components made of pearlitic steels are prone to this kind of wear. The tube elements used in the coils of high pressure heaters (HPH) operating in the secondary coolant circuit of nuclear power plants equipped with a VVER-1000 reactor plant were taken as the subject of the study. The time dependences of changes in the wall thickness in HPH tube elements are studied proceeding from an analysis of statistical data of in-service nondestructive tests. A method for determining the initial state of the E&P metal wall thickness before the commencement of operation is proposed. The article presents a procedure for predicting the distribution of examined objects' wall thicknesses at different times of operation with determining the occurrence probability of damages caused by flow accelerated corrosion to calculate the time of safe operation until reaching a critical state. A function that determines the boundary of permissible values of the HPH wall thickness distributions is obtained, and it is shown that the intervals of in-service inspections can be increased from 6 years (the actual frequency of inspections) to 9 years, and the next in-service inspection is recommended to be carried out after 7.5 years of operation. A method for determining the existence of FAC-induced local thinning in the examined object has been developed. The developed approaches and obtained study results can be adapted for any pipelines prone to wall thinning to determine the frequency of in-service inspections (including an express analysis based on the results of a single nondestructive in-service test), the safe operation time, and quantitative assessment of the critical value reaching probability.

Performance analysis of the SPRHRS for the 1000 MWe class PWR in coping with station black out

In order to improve the safety and reliability of the Chinese nuclear power plants (NPP), an innovative passive nuclear safety design, the secondary passive residual heat removal system (SPRHRS) is proposed for the light water reactors in China. Previous research work has shown that under design-basis accidents, SPRHRS can mitigate the results by partially or completely replacing the traditional emergency water cooling system. However, the Fukushima Daiichi nuclear power plant accident implies necessity of further assessments of NPPs capability to withstand threats resulting from accidents beyond design-basis accidents. In this study, the nodalization of a 1000 MW class PWR with the SPRHRS design was conducted using RELAP5/MOD3.4. Responses of the PWR under the loss of heat sink accident caused by the station blackout (SBO) was analyzed. The results showed that the residual heat can be effectively removed by the SPRHRS under SBO. In addition, sensitivity studies about the effects of the coolant tank volume and the isolation valve opening condition of the SPRHRS on its residual heat removal capability were also performed. The results indicate that these two main design elements have significant influence on the operation characteristics of SPRHRS. For the SPRHRS design in this study, the appropriate value of the coolant tank volume is 400 m3 and the appropriate valve opening signal is set to be triggered when the SG shell side collapsed liquid level drops lower than 20% of its full value. The present work would be instructive for the design of passive safety systems of Chinese NPPs.

The formation of the maintenance program and its impact on the increased level of power plants reliability

The paper emphasizes the basic attitudes of complex technical system maintenance programming. Particularly it is performed an analysis and a selection of strategies for condition-based maintenance. The assessment of the established maintenance program varieties effectiveness was carried out by comparison with their basic indicators of effectiveness (for corrective and preventive maintenance).

A study into the modes of the VVER-1000 RCP starting in an earlier inoperative loop

To simulate the mode of the RCP starting in an earlier inoperative loop, KORSAR/GP, a code supporting coupled numerical modeling of neutronic and thermal-hydraulic transients in a VVER reactor plant in operating and emergency conditions, was chosen as the computational tool. Studying these modes using thermal-hydraulic codes makes it possible to analyze the course of transients and certain emergency processes without using commercial test procedures, which contributes to laying the groundwork for addressing the issues involved in ensuring the reliability, operating safety and efficiency of nuclear power plants. Increased requirements to the safety of NPPs identify the need for avoiding excessive conservatism in the analysis based on which requirements to safety systems are formulated, as well as for enhancing the knowledge of the regularities of thermal-hydraulic transients based on advanced computer programs (or codes) designed for improved computational analysis of non-stationary thermal hydraulics in the water-cooled reactor circulation circuits in emergency and transient modes relying on inhomogeneous non-equilibrium mathematical models of two-phase flows and on a detailed description of the physical transient regularities. The purpose of the study is to analyze computationally the starting of a VVER-1000 RCP in an earlier inoperative loop at different reactor plant power values. To do this, one requires to develop the VVER-1000 reactor primary circuit computational pattern to model the transient taking place as one RCP is started, to conduct a further analysis, and to compare the key monitored reactor coolant and core parameters (power, temperature, flow rate, etc.).

Comparison of predictive performance and measurement of off-grid 15 kWp solar power generation in Aceh Tamiang

In 2015, the Government, through a special allocation fund, has finished constructing an off-grid 15 KWp off-grid solar power plant in Paya Tampah Village, Aceh Tamiang district. The long-term reliability of solar power plants is highly reliant on on-site measurements because of the vagueness in some of the constantly-changing variables such as irradiation, drought rate, which possibly lead to cause significant power losses and which turn out to also affect the estimated cost of PV (kWh). With the aim of upgrading capabilities in off-grid solar power plant planning especially in the province of Aceh, this paper outlining detailed comparison of the results of calculating the performance of off-grid 15 KWp off-grid solar power among system performance measurement results after 2 years of operation. Performance calculations performed with the assistant of PVsyst software. The measurement results characterize the total power generated by the off-grid solar power plant is 15 kWp and used by 38 households. The result of this investigation is expected to be used by local governments to be a benchmark on the future planned off-grid solar power plant planning.

An integrated reactive power control strategy for improving low voltage ride-through capability

Among all renewable energies, wind power is rapidly growing, whereby it has the most participation to supply power. Doubly fed induction generator (DFIG) is the most popular wind turbine, as it can play a very significant role to enhance low voltage ride through (LVRT) capability. Ancillary services such as voltage control and reactive power capability are the main topics in wind power control systems that should be handled profoundly and carefully. The lack of reactive power during fault period can result in instability in generators and/or disconnection of the wind turbine from the power system. The main aims of this study are to illustrate the most effective approaches subject to improve the efficiency, stability, and reliability of wind power plant associated with LVRT capability enhancement. This effectiveness and efficiency are demonstrated by, firstly, comparison between all types of wind turbines, focusing on the ancillary services, after the existing advanced control strategies. According to the literature, there is a consensus that modifying converter-based control topology is the most effective approach to enhance LVRT capability in DFIG-based wind turbine (WT). Therefore, an advanced integrated control strategy is designed by considering the effect of the rotor side converter (RSC) and the grid side converter (GSC). A model of the wind power plant is presented based on the control objectives. MATLAB/Simulink is also used to illustrate the effectiveness of the designed algorithm.

Dynamic simulation and techno-economic analysis of a concentrated solar power (CSP) plant hybridized with both thermal energy storage and natural gas

The addition of thermal energy storage and natural gas as a complementary energy source improves the flexibility, reliability, and value of concentrated solar power (CSP) plants. Nevertheless, due to the transient nature of solar energy, transitions from solar-only mode and natural-gas mode to hybrid solar-natural gas mode is quite challenging, especially when the plant is equipped with thermal storage. Thus, it is important to develop proper dynamic modeling and control schemes to accurately simulate such transitions. The objective of this study is to address this subject by demonstrating a dynamic model with reliable control schemes for a highly integrated hybrid parabolic trough-natural gas plant equipped with thermal energy storage. The specific goal is to study the dynamics of adding thermal storage to the hybrid plant. It is found that the developed control schemes assist smooth transitions between different operational modes and effective utilization of thermal storage and natural gas to maintain steady power production and steam mass flow rates under different solar conditions. The results demonstrate that the integration of storage regulates power production by solar energy and natural gas during the day time. It also enables an increase in the solar fraction of the hybrid plant while it causes a small decrease in thermodynamic efficiency. The analysis shows that the hybrid plant with the storage has a substantially lower specific CO2 emission (0.320 tonne/MWh) than single natural gas plant (0.413 tonne/MWh) although it has a higher levelized cost of electricity ($86.32/MWh against $74.92/MWh). The hybrid plant with storage demonstrates a promising potential for reliable and clean production of electricity, although research and development should be conducted to lower its cost.

RESEARCH OF LOW FREQUENCY GAS PRESSURE OSCILLATIONS IN DUST SYSTEMS OF POWER PLANTS USING PROGRAM PROVISION

Vibration and related with it mechanical noise of power plants and joining mechanical systems are the factors negatively impacted not only to the health of workers, but also to the durability, reliability, productivity and other parameters of power plants. Significant input into generation of vibration and of low frequency noise are bringing pressure oscillations in ducts. Some approaches and results of program provision development for calculation of low frequency gas pressure oscillations in ducts of power plants are described. Results of program provision approbation are presented. Using of suggested program provision may be useful for calculation and design of duct systems of power plants and allows increase the efficiency of low frequency oscillations reduction in ducts of power plants systems and noise and vibration negative impact.

Capacity Credit Algorithm and Index of the New Energy of Wind Energy and Solar Energy based on Big Data

Since twenty-first century, many countries have accelerated their development, and the energy on the earth has been gradually consumed, which not only has caused the lack of energy, but also the environmental pollution. Therefore, people have paid much attention to the related problems. Based on the research of big data theory, the credibility algorithm of new energy was established in this paper. And through the establishment of wind farm power generation model, its reliability and indicators were analyzed. Thus, the feasibility of replacing old energy with new energy sources was explored. And through the analysis of the data, the reliability of wind farms and photovoltaic power plants was evaluated.

양수발전소의 수력학적 과도현상에 관한 연구(Ⅱ)

This study performed a field test for the occurrence of a water hammer in a pump storage power plant and compared and analyzed the conducted numerical analyses. The pump storage power plant had the capacity of 1000 MW, had four pump turbines with a capacity of 250 MW, and had an available head of 817 m. A numerical analysis was performed on the water hammer that occurred in a simultaneous emergency stop and in a simultaneous load rejection during an operation of the four 250 MW parallel pump turbines. Furthermore, a study related to hydraulic transients was also conducted to secure the reliability and safety of the pump storage power plant, pump turbines, penstock, and other equipment. The results of the numerical analysis on the water hammer are then analyzed. These results show that an abrupt load rejection occurred when the four turbines failed under the occurrence of the maximum pressure of the penstock and the minimum pressure of the draft tube when the lower reservoir was at a high level and the lower reservoir was at a low level. Moreover, the minimum pressure of the penstock and the maximum pressure of the draft tube occurred when the upper reservoir was at a low level; the lower reservoir was at a high level; and four pumps had an emergency shutdown.

Analysis on operation reliability of hydropower units in China

With the rapid development of hydropower in China, in just a few years installed capacity has leapt to the world’s first, in addition to thermal power outside the development of the second largest electricity supply. However, the equivalent availability level of hydropower units in China is lower than that of conventional fossil energy thermal power units, and the cost of unit engineering is higher, especially the unplanned shutdown coefficient of pumped storage units in China is much higher than the world level. Therefore, it is urgent to carry out the research on the operation reliability of generator sets. Based on the analysis and summary of the basic situation, operation situation, planned outage and unplanned shutdown of hydropower units in China, this paper puts forward the main problems of reliability of hydropower units and hydroelectric power plants, which are used for reference and exchange by professional and technical personnel engaged in hydropower industry.

СОКРАЩЕНИЕ ВЫБРОСОВ ДВИГАТЕЛЯ ВНУТРЕННЕГО СГОРАНИЯ ПРИ СЖИГАНИИ ВОДОТОПЛИВНЫХ ЭМУЛЬСИЙ C ИСПОЛЬЗАНИЕМ ЭФФЕКТА "МИКРОВЗРЫВОВ"

The requirements of international organizations in the field of environmental protection, reduction of heat losses and thermal emissions from the burning of organic fuels, increasing the efficiency and reliability of operation both stationary and ship's power plants (SPP) acutely raise the question of the development of complex cleaning technologies. The study aims to develop a system for complex exhaust gas cleaning of the internal combustion engine (ICE). For performing tasks in the technology of the proposed method were envisaged 6 stages of a technological process. It was established that the primary and decisive factor for solving the tasks in development a complex system for improving environmental indicators, reducing corrosion and heat emissions is the organization of the water-fuel emulsion (WFE) combustion process in the ICE based on sulfur fuels with water content of about 30% and using the effect of "microexplosions" drops of water. The conducted experimental studies have shown that when WFE is burned with water content Wr = 30 %, an equimolar (or almost this) NO2: NO ratio necessary for activating the absorption properties of exhaust gases is created in gases. The results of studies have shown that under these conditions, passivation of the metal surface with a temperature below of dew point temperature of H2SO4 vapors takes place and therefore it becomes possible to significantly reduce the low-temperature corrosion of the condensation surface. This made it possible to install a low-temperature condensing heating surface with a surface temperature below the dew point of sulfuric acid vapor at the outlet of exhaust gas boiler after the ICE. Analysis of the experimental dates shows that: 1 m2 of condensing surface absorbs 3.4 mg/m3 of NOx and 0.89 mg/m3 of SO2, which makes it possible to decrease the NOx concentration by 1.55 times and SO2 - in 1.5 times. There is a process of precipitation of toxic solid ash and soot particles: from 150...170 mg/m3 (at the outlet of ICE when WFE is burnt with Wr = 30 %) to 70...90 mg/m3 after the condensing surface. Consumption of water with alkaline properties decreases when NOx, SO2, CO2 concentration is reduced in front of scrubbers. Reducing pollution of heating surfaces increases the cleaning period of EGB in 2.5 times. The developed complex system can be used to clean the ICE gases to the level recommended by IMO.

ПЕРЕХОДНЫЕ ПРОЦЕССЫ РЕАКТИВНО-ВЕНТИЛЬНОГО ЭЛЕКТРОПРИВОДА В ЭЛЕКТРОТЕХНИЧЕСКОЙ СИСТЕМЕ СОЛНЕЧНЫХ БАТАРЕЙ НА БОРТУ СУДНА

The article describes using small off-line solar power plants transforming solar energy into electric energy on shipboard for domestic needs: heating, lighting, pumping etc. It has been stated that in solving problems of increasing the reliability and efficiency of installing solar panels, as well as reducing the consumed electric power, electric solar power systems with jet-valve electric drives seem very promising. Using gearless electric drives in solar power plants contributes to increased accuracy of precision automatic control systems. In the researches related to jet valve machines there is found a lack in the description of a method for calculating engine parameters for a solar power system depending on the real area and panel size. For studying the characteristics of the drive transients a mathematical model is analyzed and its algorithm is presented, in which the end-to-end calculation method is used. According to this method, the initial parameters of the engine are set first, then the main dimensions and parameters of the magnetic circuit are calculated, and in the end the operating characteristics of the electric drive are determined. The dependences of the motor torque on the angle of rotation, current and inductance are calculated, as well as the flux linkage of the switched reluctance motor. The drive transient simulation has been performed. An increase of the mathematical model performance was achieved by introducing an angle identifier into the tracking system. The problem of using the rotor position sensors, which is not always possible, was solved by applying methods of indirect determining the position of angle of the rotor. It has been stated that the electrotechnical system with switched reluctance motor used in the tracking system (as well as in other types of electric drive) is widely popular due to high reliability of the solar power plant, simplicity of its design and low cost, as well as accurate positioning in the process of solar panel alignment.

ОБЕСПЕЧЕНИЕ НАДЕЖНОЙ РАБОТЫ ЭРГАТЕХНИЧЕСКОЙ СИСТЕМЫ: НАДЕЖНОСТЬ СУДОВОЙ ЭНЕРГЕТИЧЕСКОЙ УСТАНОВКИ И ЕЕ ОПЕРАТОРА

The article highlights the ergotechnical system as a complex including two major components: a technical component and a human operator. It is a quite common event for many engineering devices, including different types of transport. Today studying the reliability of the system operation is quite important. The results of the experiment conducted to study the reliability of ship power plants (SPP) and their elements on ships have been presented. The study was aimed at revealing psycho-physiological characteristics of a mechanical engineer on watch, who was identified as a subject of labor. The possible methods for diagnosing the psycho-physiological functions of a SPP operator have been listed. The quantitative assessment of the qualitative parameters of interacting between the human operator and the technical environment (SPP complex) has been made. The operator’s reliability is defined as a probability of successful completion of a task. Definitions of professional and functional reliability are given. The functional reliability is stated to play a primary role in ensuring professional reliability. Special attention is paid to the analysis of operator’s errors and the error sources. The probability of errors can be avoided or reduced by considering the individual psychological and physiological characteristics of the operators while training and selection. As a result of the study, the relation between factors affecting the reliability of the ergotechnical system of the power plant as a whole has been found. The most important criteria for optimizing the work of a human operator as a subject of activity are stated the experience and qualification along with a high level of voluntary attention. The study is related to the interdisciplinary researches, it was attended by specialists of different profiles.

An Innovative Adaptive Automated Complex for Protection Against Out-of-Step Conditions in a Power Plant

An analysis of the influence of changes in the power industry of Russia as well as throughout the world on the risk of out-of-step conditions accompanied by a qualitative assessment of their negative consequences is presented. The problem of preventing and eliminating out-of-step conditions is greatly complicated today because of large-scale construction and commissioning of distributed electrical generation plants along with the use of modern small-scale generating plants and the development of large industrial plants with their own internal sources of electrical energy. Features in the use of automated devices for eliminating out-of-step conditions under these new conditions are considered. The feasibility of creating an innovative adaptive complex to protect against out-of-step conditions at power engineering plants is evaluated. The basic principles in the construction of an automatic engine for adaptive out-of-step protection with the use of synchronized vector measurement algorithms are presented. The structural and functional designs of an adaptive out-of-step protection complex are presented. Recommendations for the use of an adaptive automatic complex for protection against out-of-step conditions to increase the operating reliability of power plants are presented.