Turbine Unit Research Articles

Similarity tests used to analyze field tests of state-of-the-art gas turbine engines: introducing power parameter

BACKGROUND: With the increasing complexity of gas turbine units, processing of gas turbine engine (GTE) test results have become a frequent practice. However, the methods are mostly based on mathematical GTE models and climatic reference maps rather than the principles of similarity. In this case, it is believed that that methods based on the specified parameters are outdated or their application is limited to only the simplest gas turbine engine designs. This paper shows that the similarity theory of modes can be successfully applied to solve some real-life engineering problems for state-of-the-art gas turbine units. AIM: To consider application of similarity theory methods to process test results and analyze the operation of state-of-the-art gas turbine units and to propose advanced dimensionless groups. METHODS: To analyze the possible use of the reduced gas turbine unit (GTU) parameters, we calculated the corresponding variable modes using a thermodynamic GTU model with a free power turbine developed and verified based on field tests at various outside air temperatures. RESULTS: Calculations of variable modes based on a mathematical GTU model were used to analyze the applicability of existing standard reduced GTU parameters and the corresponding dimensionless groups. The authors propose an advanced dimensionless group (a power parameter) and show its possible engineering applications. CONCLUSIONS: Variant calculations based on a mathematical GTU model show that it is possible to present the outcomes of tests in arbitrary conditions in a convenient representable form based on the power parameter, even if the conventional similarity of modes is not achieved. The power parameter allows for continuous testing of the rated GTU power in any actual operating mode for continuous monitoring of its status.

Analysis of the District Heating Steam Turbine Unit at CHPP Based on Energy and Exergy Indicators

A 20 MW district heating and condensing steam turbine unit (STU), consisting of the parts of high, medium and low pressure, which is operated at one of the CHPPs in Kharkiv, has been analyzed. According to the scheme, steam from two district heating recovery regulated extraction units is supplied to two network heating units. During the reconstruction of the CHPP, the heaters of the STU regeneration system were dismantled due to their degradation. It has been decided to focus on increasing heat recovery at the CHP plant, so no new high-pressure heaters were installed. In addition, instead of a cooling tower, it was decided to use water from the network for hot water supply in the condenser cooling circuit. An analytical review of the thermal scheme of a district heating STU in terms of energy and exergy indicators is given in the paper, which allowed to identify elements with high exergy cost, which is an indicator of their efficiency. Analytical tables with the exergy parameters of the original scheme element by element and analytical graphs were compiled during the analysis of the options of the thermal scheme of STU. According to the exergy analysis, the highest exergy cost is observed in the energy boiler, but it is known that it can be reduced by reducing exergy destruction in other elements. Therefore, a network heater that is heated by high-pressure steam from the first medium-pressure part of the first extraction was chosen as the element with the greatest potential for increasing the efficiency of the STU. Respectively, the first network heater, which is heated by low-pressure steam from the second low-pressure section, is selected as the second element. We also considered options of the thermal scheme of STU, in which the steam parameters in the turbine extractions (pressure, flow) were varied. It is shown that with a decrease in pressure and a decrease in steam flow in the first extraction, as well as a decrease in steam pressure and an increase in steam flow in the second extraction, the cost of exergy flows in network heaters decreases by almost 5%, the exergy efficiency of the STU increases by 2%, and the electrical efficiency of the unit increases by 2.16% compared to the original scheme.

Сведение материального и энергетического балансов при расчете фактических показателей тепловой экономичности ГТУ с учетом неопределенности результатов измерения теплотехнических параметров теплоносителей

To calculate actual indicators of thermal efficiency in respect to gas turbine units, scalar and vector formulations of the problem of regularization of material flows are used. They are based on the concept of Tikhonov's regularization when solving ill-posed problems. Analytical and numerical solutions of the problem have been obtained. It allows us to take into account the limitations on the range of permissible values of coolant flow rates, due to the metrological characteristics of the measuring instruments used. However, in the cases mentioned, the coolants enthalpy, depending on their thermophysical parameters, in particular pressure and temperature, are considered to be given. Taking into account the uncertainty of the results of measuring thermophysical parameters will make it possible to further increase the degree of validity of the results of simultaneous equations of the material and energy balances of gas turbine units. The problem of simultaneous equations of material and energy balances of a gas turbine unit taking into account the uncertainty of the results of measuring the thermal and physical parameters of coolants is set within the framework of Tikhonov's regularization concept. The statistical programming method is used for the numerical solution of the problem. The results have been tested using operational data on the GTX-100 gas turbine unit. The solutions to the problem of simultaneous equations of material and energy balances of a gas turbine unit have been obtained, taking into account the limitations on the range of permissible values of flow rates and heat engineering parameters of coolants and electric power, determined by the metrological characteristics of the measuring instruments. The authors have studied various options for setting and solving the problem and their influence on the results of calculating the thermal efficiency indicators of gas turbine units. The proposed simultaneous equations method allows us to further increase the degree of reliability of the results of calculating the actual indicators of thermal efficiency of gas turbine units in comparison with the scalar and vector formulation of the problem at constant values of the thermal physical parameters of coolants. The method is applicable both to develop output performance standards of equipment, including processing the results of thermal balance tests, and to monitor operating units.

Повышение энергетической эффективности ГТУ газоперекачивающего агрегата ГПА-Ц-16/76 за счет комплексного использования вторичных энергоресурсов

Russia has the largest reserves of natural gas in the world. In our country, trunk gas pipelines are traditionally used to deliver natural gas from the extraction site to consumers. The construction, maintenance and operation of trunk gas pipelines require considerable financial resources, so reducing the costs of pumping natural gas by increasing the energy efficiency of gas turbine units due to integrated use of secondary energy resources is of considerable interest. The conducted studies have been carried out using available methods of thermodynamic calculation of the internal combustion engine cycle, determination of the components of its thermal balance and thermal calculation of equipment for the utilization of secondary thermal energy resources. After the integrated use of secondary energy resources, an analysis of the expenditure part of the energy balance of the gas turbine unit has been carried out. It has shown that 16,000 kW (41,7 %) of the thermal energy of the incoming part of the energy balance is used to drive the gas compressor, 9,899 kW (25,8 %) is used to drive the low- and high-pressure compressors, 11,311 kW (29,4 %) is discharged with combustion products, and external heat losses amount to 1,152 kW (3 %). Compared with the basic gas turbine unit, heat losses with combustion products have decreased by 65 %. The energy-saving measures to use secondary energy resources have allowed us to reduce the consumption of natural gas during the operation of the gas turbine unit in the nominal mode compared with the basic gas turbine unit by 23 %. Considering the generation of electric energy due to the use of energy of excess pressure of the flue gas and heat during heating of the network water of the heat supply system of the gas pumping station, 35420 kW or 92,2 % of the supplied energy has been used beneficially.

Application of artificial neural networks for detecting compressor fouling in industrial gas turbines: a case study of an aero-derivative unit at an oil and gas facility in the Niger Delta, Nigeria

This study investigates the application of artificial neural networks for the detection of compressors fouling degradation in industrial gas turbines during operation to mitigate the loss in engine performance. An Artificial Neural Network (ANN)-based model was developed to monitor and predict compressor fouling degradation in an aero-derivative gas turbine derived from the Siemens SGT 400 class of gas turbines. Performance data from a Siemens SGT 400 gas turbine unit were obtained and used for the investigation. The obtained engine data represent all faults indicative of compressor performance. For the baseline, data were collected after maintenance actions had taken place, while the degraded case covers historical engine performance from 01 January 2013 to 28 February 2013, accounting for approximately 1,392 Equivalent Operating Hours (EOH). The dataset, encompassing variables such as temperature, pressure, gas flow, power, compressor discharge temperature, and compressor discharge pressure, was processed to eliminate irrelevant and redundant parameters before usage. A Multi-Layer Perceptron (MLP) was chosen as the architecture for the ANN. The outcomes of the training phase showed that the ANN achieved a classification accuracy of 96.2 % in proficiently distinguishing between “fouling” and "other factors" conditions. Additionally, the validation performance plot demonstrates that the network achieved its best performance with a value of 0.077507 at 18 epochs out of 24 training iterations. Finally, the confusion matrix demonstrates the model's capability to predict both fouling and non-fouling scenarios with a minimal rate of misclassification.

Availability Optimization and Maintenance Priorities of a Ramjet Engine Using Genetic Algorithm

The objective of this research is to improve the accessibility of ramjet engines to the aerospace industry by identifying critical elements of the system and to improve operational efficiency across the industry by optimizing endurance and performance. The compressor, gearbox, combustor, turbine, ram burner, and fuel injector are all essential components of an engine. Redundancy in compressor and turbine units is used to improve the overall performance of the system. This problem requires the use of an advanced genetic algorithm optimizer-driven design technique. This optimizer integrates system performance prediction methods to create an integrated design strategy. This study employs arbitrary repair rates, availability, and failure rates that follow an exponential distribution to establish a novel mathematical model. This model employs Markov processes and the Chapman–Kolmogorov equations to achieve generalization. Evaluating component performance involves a thorough examination of the availability values failure rates and repair rates of various subsystems in the decision matrix. It ensures continuous care of the system by making maintenance recommendations for all subsystems. Potential future research avenues may include incorporating real-time data and sophisticated machine-learning algorithms to enhance predictive maintenance processes. This study presents its findings for engine management. Innovations increase the efficiency of engines, making them applicable in real-world situations.

Power Oscillation Emergency Support Strategy for Wind Power Clusters Based on Doubly Fed Variable-Speed Pumped Storage Power Support

Single-phase short-circuit faults are severe asymmetrical fault modes in high renewable energy power systems. They can easily cause large-scale renewable energy to enter the low-voltage ride-through (LVRT) state. When such symmetrical or asymmetrical faults occur in the transmission channels of high-proportion wind power clusters, they may trigger the tripping of thermal power units and a transient voltage drop in most wind turbines in the high-proportion wind power area. This causes an instantaneous active power deficiency and poses a low-frequency oscillation risk. To address the deficiencies of wind turbine units in fault ride-through (FRT) and active frequency regulation capabilities, a power emergency support scheme for wind power clusters based on doubly fed variable-speed pumped storage dynamic excitation is proposed. A dual-channel energy control model for variable-speed pumped storage units is established via AC excitation control. This model provides inertia support and FRT energy simultaneously through AC excitation control of variable-speed pumped storage units. Considering the transient stability of the power network in the wind power cluster transmission system, this scheme prioritizes offering dynamic reactive power to support voltage recovery and suppresses power oscillations caused by power deficiency during LVRT. The electromagnetic torque completed the power regulation within 0.4 s. Finally, the effectiveness of the proposed strategy is verified through modeling and analysis based on the actual power network of a certain region in Northeast China.

Enhancing the Efficiency of Steam Turbine Cycles Through the Application of Physical Fields to the Working Fluid

Introduction. Increasing the efficiency of thermal power plants (TPPs) and combined heat and power plants(CHPs) remains a key research focus worldwide. Various approaches have been explored, including the integration of advanced cycles such as steam-gas and gas-steam systems, increasing steam parameters to ultra-supercritical conditions, and employing alternative working fluids optimized for thermodynamic performance, such astho se used in the Organic Rankine Cycle.Problem Statement. The identification of novel methods to deliberately modify the physicochemical and thermodynamic properties of the working fluid in steam turbine power plants has the potential to enhance their efficiency without necessitating major modifi cations to system components or substantial capital investment.Purpose. This study aims to develop a method for improving the efficiency, reliability, environmental sustainability, and resource efficiency of thermal energy systems by altering the physical, chemical, and thermophysical properties of the working fluid through exposure to physical fields.Materials and Methods. The research has employed water and steam as working fluids, comprehensive literature analysis, and experimental studies on the effects of physical fields on water. These experiments have been conducted using a thermodynamic test bench developed at the IPMash NASU. Analytical methods based on classical thermodynamics and turbomachinery theory have been applied to evaluate the impact. Results. The study has established that the structural rearrangement of water clusters under the influence of physical fields leads to measurable changes in its physicochemical and thermophysical properties. A conceptual framework has been developed to optimize the technological cycle of steam turbine units at various operational stages. Specific physical fields suitable for application at each stage have been identified.Conclusions. The proposed concept offers multiple advantages, including enhanced performance of heat engineering equipment and evaporative cooling systems, an estimated 5–7% increase in steam turbine cycle efficiency, significant improvements in water treatment processes, and a 90% reduction in the use of chemical reagents, thereby improving environmental sustainability.

Optimized design and development of a vehicle-mounted vertical axis wind turbine for defense cut-off locations and its performance analysis

This paper presents a vehicle-mounted vertical-axis wind turbine (VAWT) designed to generate power in motion and at cut-off locations. Particularly, its application to military vehicles is explored to provide uninterrupted electrical power for radio communication equipment and lighting needs in remote areas. The design uses a helical wind turbine for its compactness, lightweight, and suitability for vehicle mounting without heavy support structures. These turbines have low starting wind speeds, minimal vibration, portability, affordability, and low maintenance requirements. Utilizing fiberglass blades, the turbine unit measures 103 mm in height and 27.5 mm in diameter, achieving optimal rpm and torque for given wind speeds. Operating within the wind speed range of 10 km/h to 40 km/h, the VAWT produces an output voltage ranging from 5 V to 55 V, with a maximum wind turbine power output of 1120 watts at a wind speed of 12 m/s. The final generator output power obtained with the above wind turbine output of 1120 watts is 352 watts. A prototype unit has been tested and mounted on an all-terrain vehicle for evaluation. The paper provides detailed design steps, calculations, and insights for optimizing performance and facilitating large-scale implementation in the future.

Axial auxiliary fluid injection on the internal flow of the draft tube of Francis turbine

With the gradual increase in the proportion of clean energy, the demand for load regulation in hydro-generator units is growing. Taking a real Francis turbine unit as the research object, this paper conducts a numerical study by employing auxiliary fluid injection (water and air injection) through the main shaft's central hole when the unit operates at 40%, 60%, 80%, and 100% of the rated load. The results show that both water and air injection through the central hole can effectively suppress draft tube cavitation, reduce airfoil cavitation, and create more uniform streamlines in the straight conical section. These methods also contribute to reducing draft tube losses and improving turbine efficiency. Both injection types suppress pressure pulsation at 0.2 times the natural frequency (fn, the rotation frequency). Comprehensive analysis of turbine efficiency, output, cavitation, and draft tube losses suggests that under the conditions of 80% and 100% of the rated load where the flow pattern quality is inherently good, the injection volume for both fluids should not exceed 0.02 times the rated flow rate (Q). Furthermore, under the conditions of 40% and 60% of the rated load with relatively small flow rates, an injection range of 0.02Q to 0.03Q is recommended to balance efficiency enhancement with effective cavitation and loss control, thereby optimizing the overall unit performance.

System Modeling and Performance Simulation of a Full-Spectrum Solar-Biomass Combined Electricity-Heating-Cooling Multi-Generation System

The reliance on fossil fuels poses significant challenges to the environment and sustainable development. To address the heating requirements of the pyrolysis process in a biomass gasification-based multi-generation system, this study explored the use of low-grade solar energy across the full solar spectrum to supply the necessary energy for biomass pyrolysis while leveraging high-grade solar energy in the short-wavelength spectrum for power generation. The proposed multi-generation system integrates the full solar spectrum, biomass gasification, gas turbine, and waste heat recovery unit to produce power, cooling, and heating. A detailed thermodynamic model of this integrated system was developed, and the energy and exergy efficiencies of each subsystem were evaluated. Furthermore, the system’s performance was assessed on both monthly and annual timescales by employing the hourly weather data for Hohhot in 2023. The results showed that the solar subsystem achieved its highest power output of around 2.5 MWh in July and the lowest of 0.7 MWh in December. The annual electrical output peaked at 10 MWh, occurring around noon in July and August, while the winter peak was typically 2–3 MWh. For the wind power subsystem, the power output was maximized in April at 5.17 MWh and minimized in August at 0.7 MWh. Additionally, considering the overall multi-generation system performance, the highest power output of 14.9 MWh was observed in April, with lower outputs of 10.9, 11.3, and 11.4 MWh from August to October, respectively. Overall, the system demonstrated impressive annual average energy and exergy efficiencies of 74.05% and 52.13%, respectively.

Development of a New Unit Commitment Method With Quantum Predator Prey Brain Storm Optimization

ABSTRACTThis paper proposes a new method for unit commitment (UC) with Quantum Predator Prey Brain Storm Optimization (QPPBSO). The UC problems may be expressed as a mixed integer nonlinear programming problem in which binary variables mean on/off conditions of units and continuous ones imply their output. Recently, Evolutionary Computation (EC) has been applied to the UC problems due to the existence of indifferentiable cost functions such as large‐scale steam turbine units, etc. However, there is still room for improvement in EC because the UC problems have high nonlinear features. This paper focuses on the integration of EC with Quantum Computing (QC) that is promising in power systems. Specifically, this paper combines QC with Predator Prey Brain Storm Optimization (PPBSO) of high‐performance EC. The effectiveness of the proposed method is demonstrated in the New England 39‐node system.

Combined-cycle power plant with double intermediate superheating of steam in a single-circuit heat recovery boiler

One of the priority tasks of improving combined-cycle gas recovery plants is to determine the optimal parameters of the gas turbine unit (GTU) cycle and the rational degree of complexity of the technological scheme of the combined plant. The most promising options in terms of thermal efficiency are binary combined-cycle gas turbines (CCGTs) of the recycling type, which include one or two GTUs with heat recovery boilers and a steam turbine. At the same time, it is important to enhance the reliability and efficiency of the steam turbine unit operating in the CCGT cycle, as the turbine efficiency does not exceed 33–36% due to low initial steam parameters, the absence of a regeneration system and the intermediate superheating of steam that has partially passed through the turbine. Equally significant is the task of increasing the efficiency of the heat recovery boiler. To improve the reliability and efficiency of a combined-cycle gas recovery unit, it is proposed to replace the low-pressure circuit in a two-circuit recovery boiler with a two-stage intermediate superheater for the secondary superheating of steam that has been spent in the turbine's high-pressure cylinder (HPC) and low-pressure cylinder (LPC). In this configuration, the steam turbine is designed with three cylinders, and additional heat exchange surface for preheating the source (or mains) water is placed in the tail section of the recovery boiler. An analysis of the operation of the PGU-200 combined-cycle gas unit at the Syzran thermal power plant was conducted, comparing performance with and without the use of two-stage intermediate superheating of steam. Additionally, the study analyzed the impact of changes in the temperature of the outside air and the pressure of the steam spent in the turbine’s HPC and LPC and discharged to intermediate overheating on the main performance indicators of a combined-cycle gas installation. Calculations indicate that double intermediate superheating of steam can increase the power and reliability of the steam turbine by improving the efficiency and dryness of the steam exiting the turbine, while also reducing the specific consumption of conventional fuel for electricity generation by 1.16% (from 231.99 to 229.29 g/(kW·h).

Resource Characteristics of the Shafting of the K-1000-60/3000 Turbine Unit After Partial Restoration of the Rotor

The Ukrainian unified energy system is operated in an extremely difficult condition. A significant share of damaged or inaccessible power units causes a significant shortage of production capacity in the power system. Thus, the decommissioning of a powerful power unit that provides the basic part of the load schedule for long-term overhaul is undesirable. On one of the K-1000-60/3000 LMZ turbo units, the fifth stage of the high-pressure cylinder was damaged. In order to completely restore this damage, it is necessary to involve the production capacities of the manufacturers of this turbine unit, and the repair work will cause a long downtime of the powerful power unit, which covers the basic part of the electrical load schedule. In the article [1], a version of a high-pressure cylinder without working vanes of this degree is proposed. However, in the power industry, there is no experience of operating the power unit K-1000-60/3000 without working blades of one of the stages. Therefore, in this work, a study of the level of metal damage that occurs during the asynchronous inclusion of the turbogenerator in the power system, for a standard shafting and a shafting after restoration. The simulation results showed that asynchronous switching on leads to the appearance of torsional vibrations of the entire shafting. In the case of 30 attempts to connect the turbine generator to the network, damage from torsional vibrations occurs at the level of 2.1 % for the standard shafting and 2 % for the restored shafting.

Определение поправок к показателям тепловой экономичности ГТУ при разработке нормативных энергетических характеристик по данным эксплуатационных наблюдений

When developing standard energy characteristics of thermal power plant equipment, both load initial-nominal characteristics of thermal efficiency indicators, and correction data of the deviation of external factor values of fixed conditions must be determined. For the equipment of traditional steam-power cycle, correction data are usually taken based on typical energy characteristics or calculated according to methods approved by governing documents. For gas turbine units, typical energy characteristics as well as corresponding standard methods to calculate correction data are absent. Therefore, practically, correction data for gas turbine units are usually taken based on thermal balance test data, and in case of their absence correction data are taken according to the manufacturer data, which is the result of an approximate calculation. The latter leads to errors during the analysis of thermal efficiency indicators of the equipment in operation. Since most of correction data applied to gas turbine units can be considered linear in the first approximation, a method based on the multiple linear regression model can be proposed for their determination. In this case, it is necessary to have a large volume of operational observation data. For gas turbine units it is usually ensured due to the relatively high level of the applied automated process control systems. The proposed method to determine the correction data has been tested on the basis of actual data on the operation of the SGT-800 gas turbine unit. The authors have proposed a method to determine the correction data of the thermal efficiency indicators of gas turbine units during the development of standard energy characteristics based on operational observations data. The developed method has been tested in relation to a gas turbine unit in operation. The developed method can be recommended to develop standard energy characteristics of gas turbine units in the absence of results of thermal balance tests and typical energy characteristics. The method is also applicable for verification of mathematical models of gas turbine units based on the energy characteristics of equipment and used in systems for optimization of the operation modes of equipment at thermal power plants.

HYDRODYNAMIC LEVELING SYSTEMS: MEASUREMENT METHODS AND AUTOMATION POSSIBILITIES

The results of laboratory tests of hydrodynamic leveling systems of the SGDN and USGDN brands created by the Yerevan Polytechnic Institute in 1973-84 and the data of production tests of the USGDN-20D system on the vertical displacements of turbine units No. 1-5 of the Rovno NPP are presented. The shortcomings that emerged during the testing of the USGDN-20D system in the conditions of the turbulent situation and the measures taken to eliminate them, and the replacement of some structures with new ones are given. The results are given by the team of the Geodesy Problem Laboratory named after Academician R. H. Movsisyan of the RA Academy of Geodesy in 2012-23. on testing 3 automated prototypes of the HFMS created with new technologies and assessing the degree of accuracy of their measurements. A new HFMS system designed by the author is also presented, which will provide higher accuracy in determining the overshoots compared to the previous three HFMS prototypes, since here the working fluid does not encounter any resistance during movement, except for the frictional resistance. In addition, the advantage of the HFMS system is that the flow of the working fluid is provided by a 27-volt battery-powered DC electric motor, which makes it possible to install it in any place where there is no DC power source.

Influence of the experimental setup parameters on the deviation of the similarity criteria in the experimental study of the model boundary conditions from the similarity criteria of the full-scale combustion chamber

This study investigates the combustion processes of methane in an oxygen and carbon dioxide environment within oxygen-fuel energy complexes (OFC). The unique operating conditions, characterized by high pressures (up to 300 atm) and the use of CO2 as a diluent, necessitate a thorough understanding of the combustion dynamics, which differ significantly from traditional gas turbine units (GTU). An experimental setup, inspired by existing literature, is proposed to evaluate the combustion characteristics of methane under these conditions. Key objectives include establishing similarity criteria for hydrodynamic, thermal, and mass transfer processes to ensure the validity of experimental results. The analysis identifies critical parameters such as Reynolds, Euler, Boltzmann, Prandtl, and Damköhler numbers, which serve as benchmarks for achieving operational similarity between model and natural combustion scenarios. The findings indicate that while complete similarity across all criteria is unattainable, satisfactory levels can be achieved for specific processes under controlled conditions. The proposed experimental stand is designed to replicate the conditions of OFC combustion chambers, incorporating advanced measurement systems for accurate monitoring of temperature, pressure, and flow rates. The study emphasizes the importance of conducting separate tests for mass transfer processes to ensure comprehensive evaluations of combustion dynamics. This research provides valuable insights for the design and optimization of burner devices in OFC applications, contributing to the advancement of cleaner and more efficient energy production technologies. The established methodologies and criteria can guide future experimental studies, enhancing the understanding of combustion processes in high-pressure environments.

Study on the modal characteristics of runner with cracked blade for Francis turbine under the effect of fluid

Abstract The cracks in hydro-turbine runner blades impact turbine unit reliability and stability. The vibration monitoring based on natural frequency variation of hydro-turbine is an accurate and potential online monitoring method. In this paper, the modal characteristics of runner blades with different cracks under flow-induced vibration are studied numerically in different modes. The results indicate that the presence of cracks in the blade leads to a decrease in the natural frequency compared to healthy blades. Furthermore, the natural frequency of the wet mode experiences a significant decrease compared to the dry mode and the prestressed mode. The analysis reveals that cracked blade lead to large frequency difference (f d) of the natural frequencies of the runner mainly at the 4th–12th orders in the prestressed mode. For the wet mode, cracks cause large f d of the natural frequencies of the runner mainly at the 3rd–20th orders, but the most significant ones are at the 3rd–10th orders. The frequency-doubling (f fd) values of runner blade with crack under the 4th–12th orders in the prestressed mode or under the 3rd–10th orders in the wet mode are concentrate on 0.3–1.0. The results of modal analysis can provide a valuable reference for the crack detection of turbine runner.

Simulation Modeling of 140 MW CCGT Quality Indicators Based on DIN-VDI 4661 Standard Using Ebsilon® Professional Software

The operational efficiency of mid-capacity (140 MW) Combined Cycle Gas and Steam Power Plants (CCGT) remains underexplored concerning the DIN-VDI 4661 standard, which defines key quality metrics for energy systems. Addressing this gap is crucial for establishing standardized benchmarks to optimize performance and reduce energy losses. Existing studies mainly focus on Combined Cycle Gas Turbine (CCGT) units outside the 100–180 MW range and often do not explicitly follow DIN-VDI 4661, limiting efficiency comparisons and hindering targeted optimizations. This study simulates a 140 MW CCGT using Ebsilon® Professional software, incorporating DIN-VDI 4661 guidelines to assess eight quality indicators, including thermal efficiency, fuel utilization, and power-to-heat ratio. The model integrates gas and steam turbines, heat recovery, and auxiliary components, with input parameters validated against industry data. Energy balance analysis and sensitivity tests identified loss points. Results show a gas turbine thermal efficiency of 31.39%, steam turbine efficiency of 39.59%, and total system efficiency of 48.42%. However, significant energy losses (52% of input energy) were observed, mainly in gas turbines (87,000 kW) and steam turbines (56,000 kW). These findings highlight the need for design optimizations, such as improving heat recovery and turbine efficiency, to meet DIN-VDI 4661 benchmarks.

Optimizing wind turbine early fault identification: a multi-sensor approach with an enhanced DBSCAN algorithm

Abstract To address the limitations of single-sensor data in accurately detecting early abnormal states of wind turbine units, particularly considering the difficulty of obtaining labeled data and the distribution differences in datasets caused by changes in operating conditions, this study employs multi-sensor signal fusion and unsupervised learning methods to enhance fault identification from two aspects. First, the WA-VMD-CC framework (Signal Decomposition and Fusion module) synchronizes multi-sensor signal frequencies using the window average method, applies the Variational Mode Decomposition (VMD) algorithm to decompose signals, and utilizes the correlation coefficient (CC) method to select modal signals for fusion. Second, a local cluster optimization algorithm based on cluster center density differences is proposed to improve the clustering performance of the DBSCAN algorithm for different turbine samples. Experimental results demonstrate that the proposed method significantly outperforms HDBSCAN and other clustering algorithms in evaluation metrics such as the Silhouette Coefficient, achieving a maximum performance improvement of 41.70% over HDBSCAN. This indicates superior clustering compactness and separability, ensuring the reliability and robustness of the wind turbine status early warning system. This enhancement aligns with the practical engineering requirements of unsupervised learning in fault diagnosis applications.