Large Turbine Generators Research Articles

A Comparative Study on Coupled Fluid–Thermal Field of a Large Nuclear Turbine Generator with Radial and Composited Radial–Axial–Radial Ventilation Systems

With the continuous growth of energy demand, the advantages of nuclear power, such as high energy density, low emissions, and cleanliness, are gradually highlighted. However, the increasing capacity of the turbine generator in nuclear power plants has led to greater losses and critical heating issues. Designing an effective cooling system plays an important role in improving the rotor’s heat dissipation ability, especially under the condition of limited rotor space. In this study, the cooling effects of the rotor using a radial straight-type cooling structure and a composited radial–axial–radial cooling structure are compared and analyzed for a 1555 MVA hydrogen-cooled nuclear turbine generator. Three-dimensional fluid thermal coupled models of the rotor with both cooling structures are established, and corresponding boundary conditions are provided. The models are solved using the finite volume method. The flow law of cooling hydrogen gas inside the rotor and the temperature distribution of various parts of the rotor are studied in detail. Compared with the radial straight-type cooling structure, adopting the composited radial–axial–radial cooling structure can reduce the average temperature of the rotor field windings by 4.5 °C. The research results provide a reference for the design and optimization of the rotor cooling system for large-capacity nuclear turbine generators.

Study on Dynamic Response Characteristics of Circular Extended Foundation of Large Wind Turbine Generator

In order to study the dynamic response characteristics of circular extended foundation of wind turbine in mountainous areas, a 1:10 scaled model test was carried out on the circular extended foundation of 2MW wind turbine, and the deformation characteristics of wind turbine foundation under random wind load were analyzed by ABAQUS numerical calculation. The results show that: (1) The wind turbine foundation has different stress types on the windward side and the leeward side. The components of the windward side foundation are subjected to tensile stress, while the components of the wind turbine leeward side foundation are subjected to compressive stress. (2) The strain of the foundation bolt, the strain of the foundation ring, and the strain of the foundation plate are within the allowable range of material deformation, but the relative deformation of the windward side and the leeward side is quite different. (3) The numerical calculation results of wind turbine foundation under strong wind load are compared with the failure results of scale model experiment, which shows that the overall overturning failure of foundation is a dynamic response mode of wind turbine foundation. In the design and construction, it is necessary to strengthen the research on the windward side and the leeward side and strengthen the anti-overturning design of the wind turbine expansion foundation.

Real-time monitoring system for rotor temperature of a large turbogenerator based on SmartMesh IP wireless network communication technology

In this study, a real-time rotor temperature monitoring system for large turbogenerators using SmartMesh IP wireless network communication technology was designed and tested. The system is capable of providing comprehensive, accurate, continuous, and reliable real-time temperature monitoring for turbogenerators. Additionally, it has demonstrated satisfactory results in a real-time monitoring test of the rotor temperature of various famous large-scale turbogenerators and giant nuclear power half-speed turbogenerators designed and manufactured in China. The development and application of this wireless temperature measurement system would aid in improving the intelligent operation quality, safety, and stability of China's large turbine generators and even the entire power system.

An Active Disturbance Rejection Control of Large Wind Turbine Pitch Angle Based on Extremum-Seeking Algorithm

This paper proposes the analysis and design of the linear active disturbance rejection controller (LADRC) for the pitch angle model of a large wind turbine generator (WTG). Since the transfer function of the pitch control system exhibits nonminimum-phase characteristics, the parameters of LADRC are difficult to tune using the conventional bandwidth method. On the basis of PI controller parameters to first-order LADRC parameters, an optimization problem is proposed in this paper to find the parameters of an LADRC for the pitch control system under the constraint of robustness measure, and the extremum-seeking (ES) algorithm is used to solve the problem. Simulation results show that LADRC can achieve better tracking and disturbance rejection performance than traditional PI control without loss of robustness against time delay.

Power loss reduction for tilt pad journal bearings utilizing pad pockets and steps

Tilting Pad Journal Bearing (TPJB) are ubiquitous in turbomachinery from small high speed compressors to large turbine generator sets. The TPJB's power losses increase with machine size and speed, reaching as high as 1–2 MW loss (equivalent power for about 1000 homes) per bearing, in a large turbine generator. This study presents a novel power loss reduction technique, inserting a pocket and step in the pads, to activate cavitation in the pocket while maintaining pad stability. The benefits are demonstrated via Thermo-Elasto-Hydrodynamic (TEHD) CFD simulations comparing results with and without these modifications. The novel approach shows power loss reductions up to −27% without a load capacity loss, while reducing required supply oil flow, and peak pad temperature.

Open-Circuit Core Loss of Large Turbine Generators Considering the Influence of Key Bar Design

To provide power to electrical power distribution systems cost effectively, it is necessary to understand the efficiency of large turbine generators. Stator cores, which account for 10%–15% of total generator losses, are supported by a either a dovetail key bar or a square key bar. The dovetail key bar, mainly used in large turbine generators, has a shallow depth of penetration into the stator core; consequently, the need for research related to core loss has been limited in the case of dovetail key bars. By contrast, the square key bar, which is attracting attention owing to its ease of assembly, deeply penetrates the stator core, and thus has a greater effect on core loss than the dovetail key bar. However, core losses due to the key bar design have not been examined quantitatively in the literature. This paper analyzes the core-loss changes due to the key bar. Using electromagnetic finite-element analysis, we calculate the differences in core loss between the two aforenoted key bar types, which are commonly used in large turbine generators. In addition, we propose points for consideration when designing key bars for large-capacity generators.

A Mobile Robotic 3-D Measurement Method Based on Point Clouds Alignment for Large-Scale Complex Surfaces

Large-scale complex surfaces are the core components of large aircraft, ships, and wind turbine generators. High-accuracy manufacturing of the components is very crucial for its performance. Automated and high-accuracy large-scale 3-D measurement is an effective means for the manufacturing accuracy control of these components. This article proposes an automated mobile robotic profile measurement method for large-scale complex surfaces, and it also proposes a high-accuracy point clouds alignment algorithm to improve the measurement accuracy. A fringe projection scanner, integrated on the end of a mobile robot, is utilized to scan the surface and obtain the local scanning point clouds. The local scanning point clouds' coarse alignment is implemented using the robot's joint data and the laser sensor's positioning data. After that, a fine alignment algorithm combining the fruit fly optimization algorithm (FOA) with the improved iterative closest point (IICP) algorithm is proposed for point clouds' fine alignment. Practical measurement was performed on a sectional wind turbine blade, and a broad region of 4.6 m ×2.6 m was measured. An accuracy evaluation method based on point-to-plane distance was adopted to evaluate the measurement error. The result that the mean distance error is less than 0.4 mm shows the proposed mobile robotic measurement system and the aligning method are of high accuracy.

The depth utilization method of condensate system’s energy-storage to improve large turbine generator units’ load response characteristic

Load response characteristics of high thermal power units are critical to a safe and efficient grid-connected utilization of large-scale renewable energy with strong randomness. A condensate throttling regulation was reported to improve the units variable load rate. However, it is not verified by tests in different types of units. In the paper, the influence of the storage capacity of the steam generator’s condensate system on the load response characteristics is studied for four subcritical 330 MW heating units by simulation and an experimental test. The result shows the feasibility of the condensate throttling regulation, which is of great value to the practical engineering application in the future. In addition, this paper obtains the condensate regulation potential of units under different power generation load conditions through simulation and actual tests. These real data will help other units of the same type to carry out similar modifications or tests.

Alignment capabilities of big data’s value creation in the context of service delivery processes

PurposeWhile big data creates business value, knowledge on how value is created remains limited and research is needed to discover big data’s value mechanism. The purpose of this paper is to explore value creation capabilities of big data through an alignment perspective.Design/methodology/approachThe paper is based on a single case study of a service division of a large Danish wind turbine generator manufacturer based on 18 semi-structured interviews.FindingsA strategic alignment framework comprising human, information technology, organization, performance, process and strategic practices are used as a basis to identify 15 types of alignment capabilities and their inter-dependent variables fostering the value creation of big data. The alignment framework is accompanied by seven propositions to obtain alignment of big data in service processes.Research limitations/implicationsThe study demonstrates empirical anchoring of how alignment capabilities affect a company’s ability to create value from big data as identified in a service supply chain.Practical implicationsService supply chains and big data are complex matters. Therefore, understanding how alignment affects a company’s ability to create value of big data may help the company to overcome challenges of big data.Originality/valueThe study demonstrates how value from big data can be created following an alignment logic. By this, both critical and complementary alignment capabilities have been identified.

Heat transfer coefficient distribution in inner surface of stator ventilation duct for large capacity air-cooled turbine generator

The stator ventilation duct is the main path for fluid flowing to cool the stator bar and the core. Considering the complexity of the ventilation system, the investigation on the relationship between the air motion law in the ventilation duct and its surface heat transfer coefficient is crucial for the accurate calculation of the temperature field. Therefore, this paper takes the 150 MW air-cooled turbo-generator as a research object. Firstly, a new calculation model of the stator taking the air gap under rotor rotation state, and the yoke back into account is proposed to calculate the heat transfer coefficient in inner surface of stator ventilation duct. The relationship among the velocity vector, temperature of fluid and heat transfer coefficient in the ventilation duct is analyzed. Secondly, the temperature field of the new model calculated by finite volume method is compared with the measured values to verify the accuracy of calculation method. Finally, the influence of the varied rotational velocity on the heat transfer coefficient is investigated. The correction coefficient of the heat transfer coefficient related to the velocity is proposed. The calculation of the heat transfer coefficient and the correction of the fitting formula can provide theoretical guidance for the ventilation design of generators.

Diesel Generator Model Parameterization for Microgrid Simulation Using Hybrid Box-Constrained Levenberg-Marquardt Algorithm

Existing generator parameterization methods, typically developed for large turbine generator units, are difficult to apply to small kW-level diesel generators in microgrid applications. This article presents a model parameterization method that estimates a complete set of kW-level diesel generator parameters simultaneously using only load-step-change tests with limited measurement points. This method provides a more cost-efficient and robust approach to achieve high-fidelity modeling of diesel generators for microgrid dynamic simulation. A two-stage hybrid box-constrained Levenberg-Marquardt (H-BCLM) algorithm is developed to search the optimal parameter set given the parameter bounds. A heuristic algorithm, namely Generalized Opposition-based Learning Genetic Algorithm (GOL-GA), is applied to identify proper initial estimates at the first stage, followed by a modified Levenberg-Marquardt algorithm designed to fine tune the solution based on the first-stage result. The proposed method is validated against dynamic simulation of a diesel generator model and field measurements from a 16kW diesel generator unit.

Influence of Extension Length of Rotor End Windings on the Three-Dimensional Electromagnetic Field and Temperature Rise in the Large Turbine Generator End Zone With Magnetic Screen

Leakage magnetic field from the rotor end windings affects obviously the electromagnetic losses and temperature of end components in the turbine generator end zone with magnetic screen. As the capacity of turbine generator increases, this effect of rotor end windings has become more prominent. To investigate influence of the extension length of rotor end windings on the electromagnetic and thermal fields in the turbine generator end zone with magnetic screen, three-dimensional transient electromagnetic field model of 1250 MW turbine generator end zone is given. Leakage magnetic field and losses of end components are compared and studied in the end zone under the different extension lengths of rotor end windings. Based on the calculation results of electromagnetic losses (heat sources) and flow network (boundary conditions), three-dimensional fluid-thermal coupling field is calculated in the turbine generator end zone with magnetic screen. Distribution of complex fluid velocity in the end zone is obtained. Influence of the different extension lengths of rotor end windings on the stator-end copper coil, screen plate, finger plate, press plate, magnetic screen, and stator end core is researched in the turbine generator end zone. The accuracy of calculation results is validated by experimental values.

Numerical investigation of influence of different underexcited operations on temperature distribution in the large turbine generator end domain with copper screen

Overheating of the complex end parts has become one of the main problems affecting safe and stable turbine generator operation under the underexcited operation. In order to study the temperature distribution in the large turbine generator end domain with copper screen under the different underexcited operations, a 330 MW turbine generator is studied. Three-dimensional fluid-thermal coupling model for the end domain of turbine generator is established. Three-dimensional transient magnetic field of the large turbine generator end domain with copper screen is calculated with 0.85 pf underexcited operation and 0.9 pf underexcited operation. Loss values of the end metal parts from the three-dimensional transient magnetic field are applied to end domain as heat source with 0.85 pf underexcited operation and 0.9 pf underexcited operation. Outlet-pressure values and fan inlet velocity from flow network calculations are applied to the end domain as boundary conditions in the fluid and thermal coupling analysis. The three-dimensional fluid and thermal fields in the turbine generator end domain are calculated with 0.85 pf underexcited operation and 0.9 pf underexcited operation. Distribution of the radial fluid velocity component around the stator winding is determined. Temperature distribution of the end metal parts in the large turbine generator end domain with copper screen is studied with 0.85 pf underexcited operation and 0.9 pf underexcited operation. Temperature calculation results of the copper screen are compared with measured values. Calculation results are in good agreement with measured values.

Computer Modeling of the Eddy Current Losses of Metal Fasteners in Rotor Slots of a Large Nuclear Steam Turbine Generator Based on Finite-Element Method and Deep Gaussian Process Regression

Eddy current analysis is a key issue for large turbine generators. The finite-element method (FEM) is a computational tool for obtaining the electromagnetic characteristics of electrical machines. In this article, we propose a computer model of the eddy current losses of metal fasteners in the rotor slots of a large turbine generator. The electromagnetic properties of the rotor fasteners and the outer diameter of the rotor are taken as the input, and the eddy current loss of the rotor fasteners is taken as the output. A prediction model is constructed using the FEM and deep learning. The analysis results show that compared with the independent finite-element analysis, this method reduces the design cycle time and improves the design efficiency for a large-capacity turbine generator. Compared with other machine learning models, the error is smaller and the accuracy is higher. This method provides a new way to accurately predict the eddy current loss of a generator under complex nonlinear conditions.

Flange with the Groove Shape to Improve the Efficiency of Large Turbine Generator

This paper presents a new design technique to improve the efficiency of the large turbine generator. The leakage magnetic flux at the generator end region causes the eddy current loss. The eddy current loss also occurs in the flange which supports the stator cores and outside space block at both ends of the generator. We propose a flange with the groove shape to reduce eddy current loss by decreasing the incident area of magnetic flux on the flange. The results of the three-dimensional finite-element analysis show that the proposed method can improve the generator efficiency.

Optimization of Generator Stator End Winding Structure Based on Improved PSO and SVM

The selection of parameters in the support vector machine (SVM) approximation model plays an important role in the performance of the model. Therefore, the support vector machine parameters need to be optimized. Because the particle swarm algorithm is easy to be premature and easy to fall into the local optimal solution, the improved particle swarm optimization algorithm is used to optimize the parameters, and the support vector machine approximation model with optimal parameters is established. Finally, the support vector machine approximation model of optimal parameters and particle swarm optimization algorithm are combined and used in the optimization of stator end winding structure of large steam turbine generator. The validity of the method is verified by the analysis of the results, and good optimization results are obtained.

Performance comparison of 1X versus 4X HTS tapes toward the design a 10‐MW direct drive HTS generator for wind turbine applications

AbstractWith current developments underway at the University of Houston, 4× high‐temperature superconducting (HTS) yttrium barium copper oxide (YBCO) tapes are expected to reach a fourfold critical current density improvement at 30 K and 3 T as part of an Advanced Research Projects Agency‐Energy (ARPA‐E)‐sponsored project. The impetus for this project is to develop and deploy cost‐effective direct drive HTS generators for large offshore wind turbine generators. The improved conductor performance of 4× tapes over 1× tapes is projected to allow for a significant reduction in the amount of HTS tapes required to generate the excitation field and, thus, lead to a reduction of the overall generator cost. It was, however, deduced from simulation results that conventional methods of rotor field enhancement using rotor iron makes 1× conductor competitive enough compared with 4× conductors; hence, commercially available YBCO tapes can provide all the energy density requirements to make wind turbines a competitive energy resource based on energy forecasts. This paper is a presentation of design and optimization work to find the best generator topology from the point of view of both machine design and electricity supply. The generators are numerically modeled and simulated using 1× and 4× YBCO HTS conductors on either or of both the rotor and stator side of the generators.

Power System Reliability Evaluation Including Capacity Credit Considering Wind Energy with Energy Storage Systems in China

Abstract This paper is based on power system reliability evaluation on a power system. This research focuse on finding the best case of using large scale wind turbine generator (WTG) with multi-energy storage systems (multi-ESSs). By the way, calculate the capacity credit (C.C.) and effective load carrying capability (ELCC). In the future, renewable energy will occupy a large part of the electricity market. However, the reliability of power system can be influenced by the large scale WTG installed in the system. Multi-ESSs can be installed with the WTG used to decrease the fluctuation of power system reliability caused by the uncontrollable wind resource. The purpose of this paper is analyze the power system reliability in power system by the index of ELCC and C.C. by using multi-ESSs coordinated to the power system with renewable energy generators (REG). Monte Carlo simulation (MCS) method is employed to evaluation the reliability of power system with WTG and multi-ESSs operating strategies.

The Technical to Realize Variable Speed Constant Frequency Operation of Large Wind Turbine Generator

In this paper, through the introduction of the existing various mainstream wind turbine model, understand all kinds of operation mode and control method of wind turbines, contrast to put forward all kinds of wind turbine operation mode and control methods of the advantages and disadvantages, comprehensive put forward more effective technology of large wind turbines to realize variable speed constant frequency operation method, as well as for large wind turbines to realize variable speed constant frequency technology methods of the future.

Three-Stage Fuzzy Coordinator for Dynamic Stability Enhancement of Multi-Machine Power System Considering Various Penetration Levels of Wind Turbines

Disconnection of large wind turbine generators (WTGs) in renewable-integrated power systems has been well-recognized as one of the main origins of system instability. The ongoing study aims at establishing a three-stage fuzzy coordinator (TSFC) intended to enhance the power system stability encountering with major outages of large WTGs. The new TSFC employs wide area measurement system (WAMS) for a global coordination in multi-machine power system. The proposed TSFC founds a fuzzy logic coordination basis for tuning the interactions of multiple control devices. To this end, the WAMS-based TSFC is devised to end in performance harmonization of multiple control devices including automatic voltage regulator (AVR), power system stabilizer (PSS), and static var compensator (SVC). The TSFC receives the normalized voltage and rotor angle deviations of all machines and also the penetration level of wind farms as the input signals. The penetration level as the input signal determines the coordination strategy in three stages. In the sequel, based on the expert knowledge and analyzing the established rules, the TSFC generates output control signals broadcasted to the AVR, PSS, and SVC concurrently. Considering different penetration levels of WTGs, extensive numerical studies have been conducted to evaluate performance of the new coordinator.