scholarly journals Nonlinear Modeling of Dynamic Characteristics of Pump-Turbine

Energies ◽  
2022 ◽  
Vol 15 (1) ◽  
pp. 297
Author(s):  
Liying Wang ◽  
Kaidi Zhang ◽  
Weiguo Zhao
Keyword(s):  
Linear Model ◽  
Nonlinear Model ◽  
Dynamic Characteristics ◽  
Clean Energy ◽  
Energy Development ◽  
Stable Operation ◽  
Storage Unit ◽  
Pump Turbine ◽  
Characteristic Model ◽  
Pumped Storage

Hydropower is a kind of clean energy, which can effectively reduce the consumption of fossil energy and is one of the main fields of new energy development. Pumped storage power station not only provides a solution for storing electric energy and generating excess, but also is a clean, efficient, economical and safe power system regulation method with high quality. Accurate modeling of a pump-turbine, as the core equipment of a pumped storage unit, is the key to safe and stable operation of the pumped storage unit. At present, a method of simplifying the external characteristics of a pump-turbine into a first-order linear model is widely used, which cannot effectively and accurately reveal the nonlinear dynamic characteristics of the unit in transition process. In order to meet the demand of high-precision simulation of the unit, a new method of identifying Taylor series expansion considering nonlinearity based on the torque characteristic formula and the flow characteristic formula is proposed, which is applied to the pump-turbine external characteristic model, and retains the second derivative term, making the model a second-order nonlinear model, and thus, the pump-turbine model becomes a nonlinear model. The nonlinear model established is used to simulate the load increase and load rejection of the unit, and the results are compared with those for the linear model. The comparison shows that the nonlinear model established for the pump-turbine can reveal the dynamic response of the unit more effectively and accurately than the linear model, and provide a further guarantee for the safe and stable operation of pumped-storage units, which is of great significance to hydropower energy development.

scholarly journals Axial Force Analysis of the Support Bracket of Pumped Storage Unit

2021 ◽  
Author(s):  
Buchao Xu ◽  
Weiqiang Zhao ◽  
Wenhua Lin ◽  
Zhongyu Mao ◽  
Ran Tao ◽  
...  
Keyword(s):  
Structural Analysis ◽  
Axial Force ◽  
Cfd Simulation ◽  
Operating Conditions ◽  
Stable Operation ◽  
Axial Loads ◽  
Storage Unit ◽  
Maximum Deformation ◽  
Pumped Storage ◽  
Variation Rule

During operation, the support bracket is the main part to withstand the axial loads of the pumped storage unit. Moreover, the effects of axial loads including the hydraulic thrust of runner flow and the weight of runner body may cause the support bracket deformation and fatigue damage. For the safe and stable operation, the simulation of the axial force and the structural analysis of the support bracket of a pumped storage unit was carried out in this paper. The CFD simulation result has revealed the variation rule of the axial force in different operating conditions. Using ANSYS Mechanical, the static stresses and deformation of support bracket with axial loads were calculated. The results release the location and variations of maximum stress and maximum deformation caused by the axial loads. By comparing the predicted maximum axial force with the admission force calculated by the structural analysis, it is found that the axial force of the researched machine is within the safe range. This study provides the reference for the safety and stable operation of the pumped storage unit.

Transient thermo-elasto-hydrodynamic analysis of a bidirectional thrust bearing in start-up and shutdown processes

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Jingwei Cao ◽  
Liming Zhai ◽  
Yongyao Luo ◽  
Soo-Hwang Ahn ◽  
Zhengwei Wang ◽  
...  
Keyword(s):  
Thrust Bearing ◽  
Stable Operation ◽  
Thermal Interaction ◽  
Lubrication Mechanism ◽  
Interaction Method ◽  
Storage Unit ◽  
Content Type ◽  
Start Up ◽  
Lubrication Characteristics ◽  
Pumped Storage

PurposeThe purpose of this paper is to reveal the transient thermo-elasto-hydrodynamic lubrication mechanism of a bidirectional thrust bearing in a pumped-storage unit, and to propose the transient simulation method of two-way fluid-solid-thermal interaction of thrust bearing.Design/methodology/approachThe transient fluid-solid-thermal interaction method is used to simulate the three-dimensional lubrication of the thrust bearing, during the start-up and shutdown process of a pumped storage unit. A pad including an oil hole is modelled to analyze the temporal variation of lubrication characteristics, such as the film pressure, thickness and temperature, during the transient operation process.FindingsThe injection of the high-pressure oil sufficiently affects the lubrication characteristics on film, in which the hysteresis phenomena were found between the start-up and shutdown possess.Originality/valueThis paper reveals the transient lubrication mechanism of tilting pad in a thrust bearing, by means of transient fluid-solid-thermal interaction method. Lubrication characteristics are simulated without assuming the temperature relationship between the oil film inlet and the outlet and the heat transfer on the pad free surface. This paper provides a theoretical basis for the safe design and stable operation of thrust bearings.

scholarly journals Control of the Variable-Speed Pumped Storage Unit-Wind Integrated System

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Yifeng Shi ◽  
Xiangjian Shi ◽  
Chuanbao Yi ◽  
Xufeng Song ◽  
Xiaogang Chen
Keyword(s):  
Wind Power ◽  
Power Flow ◽  
Significant Contribution ◽  
Control Method ◽  
Integrated System ◽  
Stable Operation ◽  
Variable Speed ◽  
Storage Unit ◽  
Active Power Flow ◽  
Pumped Storage

The integration of variable-speed pumped storage unit (VS-PSU) guarantees an efficient peak regulation and frequency modulation of the power grid. The present research analyzes the active power flow of the VS-PSU under synchronous, subsynchronous, and supersynchronous speed in both generation and pumping modes. The control strategy of the VS-PSU is realized by the dq-axis vector control method. Furthermore, the control of the VS-PSU integrated with wind power has been conducted using DIgSILENT platform with the VS-PSU of 300 kW capacity. Results show that the fluctuation of the power output of the wind power plant can be reduced effectively. The safe, economical, and stable operation of power system integrated with wind power can be achieved by the significant contribution of the VS-PSU.

scholarly journals Analysis of Rotor-Stator Interaction of a Pump-Turbine with Splitter Blades in a Pump Mode

Mathematics ◽  
2020 ◽  
Vol 8 (9) ◽  
pp. 1465 ◽  
Author(s):  
Haiqin Song ◽  
Jinfeng Zhang ◽  
Ping Huang ◽  
Haikun Cai ◽  
Puyu Cao ◽  
...  
Keyword(s):  
Radial Force ◽  
Stable Operation ◽  
Power Station ◽  
Pump Turbine ◽  
Main Frequency ◽  
Pulsation Amplitude ◽  
Depth Analysis ◽  
Rotor Stator Interaction ◽  
Guide Blade ◽  
Pumped Storage

The pump-turbine is the core component of a pumped storage power station. This paper considers an in-depth analysis of the rotor-stator interaction characteristics under computational fluid dynamics (CFD) and experimental measurements of pump-turbine with splitter blades used in a domestic pumped storage power station. The results show that as the guide blade opening increases, the rotor-stator interaction of the pump-turbine intensifies and the magnitude of the runner radial force and its pulsation amplitude as well as the magnitude of the guide blade water moment and its pulsation amplitude also increase. In addition, when the opening degree increases from 9.8° to 17.5°, the influence on the main frequency is mainly reflected in the phase change. While the opening degree increases from 17.5° to 24.8°, the influence on the main frequency is mainly reflected in the amplitude change. Moreover, the amplitude of 5fn at opening 9.8° and opening 24.8° is greater than the optimal opening 17.5°, indicating that deviation from the optimal opening will aggravate the difference of rotor-stator interaction between splitter blades and guide blades. In the paper, the influence of guide blade openings on the rotor-stator interaction between the splitter guide blade is studied, which provides a theoretical reference for the stable operation of the pump-turbine.

scholarly journals Characteristic Analysis and Optimal Regulation of Primary Frequency Regulation Condition in Low Water Head Area Based on Hydraulic-Mechanical-Electrical Coupling Model of Pumped Storage Unit

Complexity ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-17 ◽  
Author(s):  
Cong Lv ◽  
Yanhe Xu ◽  
Xin Wu ◽  
Qing Zhang
Keyword(s):  
Power Grid ◽  
Electrical Coupling ◽  
Frequency Regulation ◽  
Regulation System ◽  
Optimization Strategy ◽  
Power Station ◽  
Storage Unit ◽  
Pump Turbine ◽  
Pumped Storage ◽  
Primary Frequency

Pumped storage power station is an important regulating tool for peak load regulation and frequency regulation of the power grid, especially its primary frequency regulation function, which is of profound significance for the safety and stability of the power grid. As the core equipment of the pumped storage power station, the reversible design of the pump turbine makes it easy to have hydraulic fluctuation and mechanical instability when the unit runs to the “S” characteristic area, which will cause the frequency oscillation of the generator under the condition of primary frequency regulation. Therefore, some innovative work is studied in this paper: (1) an accurate hydraulic-mechanical-electrical coupling system mathematical model of pumped storage unit regulation system (PSURS) is established based on full characteristic curve of the pump turbine and seventh-order synchronous generator and excitation system; (2) the dynamic response characteristics of primary frequency regulation of pumped storage unit (PSU) under different water heads and different frequency disturbances are analyzed by numerical simulation; (3) in view of the unstable condition of the unit under the large frequency disturbance when it operates in the low head and small load area, the objective optimization function considering the ITAE index of hydraulic, mechanical, and electrical factors is proposed; and (4) fractional-order PID controller and the bacterial-foraging chemotaxis gravitational search algorithm (BCGSA) combined optimization strategy is used for PSURS optimization regulation and parameter optimization. The results show that the joint optimization strategy proposed in this paper has smaller objective function value, and makes the PSURS pass through the unbalanced area quickly, with better primary frequency regulation speed and smaller regulation depth.

A Study of Photovoltaic Power Prediction

2015 ◽  
Vol 733 ◽  
pp. 203-206 ◽  
Author(s):  
Yan Long Li ◽  
Jing Xu ◽  
Chong Yuan
Keyword(s):  
Power Generation ◽  
Clean Energy ◽  
Energy Development ◽  
Stable Operation ◽  
Solar Photovoltaic ◽  
Generation System ◽  
Power Prediction ◽  
Photovoltaic Power ◽  
Power Generation System ◽  
System Power

Solar photovoltaic power generation as an inexhaustible, inexhaustible clean energy has become the focus of future energy development. Along with photovoltaic power generation incorporated into the power grid, in order to make power generation plan reasonably, ensure the stable operation of power system, need to forecast the photovoltaic power output. In this paper solar photovoltaic power generation forecasting methods are analyzed and summarized. According to the application of solar photovoltaic power generation and demand, mainly on photovoltaic power generation system power prediction research method has carried on the comprehensive elaboration, hoping for the researches play an important role in promoting and advancing the development of solar photovoltaic prediction methods.

Study of flow characteristics in the S-shaped region of a pump-turbine at Baoquan pumped storage power station

2015 ◽  
Vol 10 (2) ◽  
pp. 242-249
Author(s):  
Jun Li ◽  
Yongmei Cao ◽  
Lei Wang ◽  
Xiaochong Chen
Keyword(s):  
Cfd Simulation ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Modern Society ◽  
Stable Operation ◽  
Power Station ◽  
Pump Turbine ◽  
Research Findings ◽  
Computational Fluid Dynamics Cfd ◽  
Pumped Storage

Pumped storage power plays increasingly important roles in modern society but requires some complex equipment. The characteristics of the S-shaped region of a reversible pump-turbine caused significant difficulties in the stable operation of the unit. In this paper, the 1# pump-turbine at Baoquan storage power station is studied. The basic variations of the internal flow were understood using Computational Fluid Dynamics (CFD) simulation, and the relationship between head variation and the ‘S’ characteristic was analyzed. It was found that the basis of the ‘S’ characteristics was channel congestion caused by vortices. Methods that might be used to eliminate the effects of the ‘S’ characteristic are also given. The authors believe that the research findings in this paper could provide the technical support needed for stable operation of such units, as well as further studies of the ‘S’ characteristic.

Research and Develop on Static Frequency Converter of Pumped Storage Power Plant

2012 ◽  
Vol 608-609 ◽  
pp. 1120-1126 ◽  
Author(s):  
De Shun Wang ◽  
Bo Yang ◽  
Lian Tao Ji
Keyword(s):  
Power Plant ◽  
Control Strategy ◽  
Large Scale ◽  
Frequency Converter ◽  
Position Estimation ◽  
Position Sensor ◽  
Storage Unit ◽  
Rotor Position ◽  
Start Up ◽  
Pumped Storage

A static frequency converter start-up control strategy for pumped-storage power unit is presented. And rotor position detecting without position sensor is realized according to voltage and magnetism equations of ideal synchronous motor mathematics model. The mechanism and implementation method of initial rotor position determination and rotor position estimation under low frequency without position sensor are expounded and validated by simulations. Based on the mentioned control strategy, first set of a static frequency converter start-up device in China for large-scale pumped-storage unit is developed, which is applied to start-up control test in the 90 MW generator/motor of Panjiakou Pumped-storage Power Plant. Test results show that rotor position detecting, pulse commutation, natural commutation, and unit synchronous procedure control of static start-up are all proved. The outcomes have been applied in running equipment, which proves the feasibility of mentioned method.

Cost advantage of adjustable-speed pumped storage unit for daily operation in distributed hybrid system

2021 ◽  
Author(s):  
Chen Feng ◽  
Yuan Zheng ◽  
Chaoshun Li ◽  
Zijun Mai ◽  
Wei Wu ◽  
...  
Keyword(s):  
Hybrid System ◽  
Cost Advantage ◽  
Storage Unit ◽  
Adjustable Speed ◽  
Pumped Storage
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