scholarly journals Optimal control of water level oscillations in surge tank of hydropower station with long headrace tunnel under combined operating conditions

2017 ◽  
Vol 47 ◽  
pp. 260-275 ◽  
Author(s):  
Wencheng Guo ◽  
Bingbao Wang ◽  
Jiandong Yang ◽  
Yangliu Xue
Keyword(s):  
Optimal Control ◽  
Water Level ◽  
Operating Conditions ◽  
Hydropower Station ◽  
Surge Tank ◽  
Headrace Tunnel

scholarly journals A Review of the Transient Process and Control for a Hydropower Station with a Super Long Headrace Tunnel

Energies ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2994 ◽  
Author(s):  
Wencheng Guo ◽  
Daoyi Zhu
Keyword(s):  
Design Optimization ◽  
Transient Process ◽  
Operating Conditions ◽  
Research Progress ◽  
Hydropower Station ◽  
Operation Conditions ◽  
Hydraulic Design ◽  
Headrace Tunnel ◽  
And Control ◽  
Hydropower Stations

The hydropower station with a super long headrace tunnel is a significant development type for hydropower energy. By constructing a super long headrace tunnel, the huge natural water fall head can be utilized to generate more electricity. With the development of hydropower energy, a hydropower station with a super long headrace tunnel becomes more and more competitive. Compared with a hydropower station with a short headrace tunnel, the transient process and control for a hydropower station with a super long headrace tunnel is much more complicated and becomes an intractable challenge. It is well known that the transient process and control is the basis of the design and operation of a hydropower station. To overcome the challenge of the transient process and control, much research has been carried out. This paper provides a systematic review on the latest research progress of the transient process and control for hydropower stations with a super long headrace tunnel. Firstly, two key issues for the transient process and control, i.e., hydraulic design optimization of the surge tank and operation control of unit, are illuminated. Secondly, for both single surge tanks and surge tanks with special types or combinations, the hydraulic design optimization methods are described. The most disadvantageous design and advantageous operation of surge tanks under combined operating conditions are discussed. Thirdly, the stability and regulation quality of the hydro-turbine governing system under isolated and grid-connected operation conditions are presented. Finally, some trends and recommendations for future research directions are made. A research thought for establishing the complete theory and application system of the transient process and control for hydropower stations with a super long headrace tunnel from the perspective of multi-slice and multi-scale is proposed.

Critical superposition instant of surge waves in surge tank with long headrace tunnel

2011 ◽  
Vol 38 (3) ◽  
pp. 331-337 ◽  
Author(s):  
XiaoDong Yu ◽  
Jian Zhang ◽  
Arash Hazrati
Keyword(s):  
Numerical Simulation ◽  
Flow Rate ◽  
Analytical Formula ◽  
Hydropower Station ◽  
Surge Tank ◽  
Initial Water ◽  
Initial Flow ◽  
Headrace Tunnel ◽  
Fundamental Equations ◽  
Computational Basis

Superposed mass oscillation that often occurs in a throttled surge tank with a long headrace tunnel is studied. The instant of the worst superposition of mass oscillation in a surge tank is analysed. The analytical formula predicting the worst superposition instant is derived exactly and verified (1) with a numerical solution to the fundamental equations for the surge tank and (2) with a numerical simulation of hydraulic transients in an actual hydropower station. It is shown that the superposed oscillation provides the highest upsurge at the instant that the initial flow rate in the headrace tunnel and initial water level in the surge tank satisfy the judgement formula. The conclusion provides a theoretical and computational basis for the numerical simulation of maximum upsurge in a surge tank.

Mechanism of air-trapped vertical vortices in long-corridor-shaped surge tank of hydropower station and their elimination

2017 ◽  
Vol 29 (5) ◽  
pp. 845-853 ◽  
Author(s):  
Fang Cai ◽  
Yong-guang Cheng ◽  
Lin-sheng Xia ◽  
Yong-qi Jiang
Keyword(s):  
Hydropower Station ◽  
Surge Tank

Using Sliding Mode Control to Adjust Drum Level of a Boiler Unit With Time Varying Parameters

2010 ◽  
Author(s):  
Hamed Moradi ◽  
Firooz Bakhtiari-Nejad ◽  
Majid Saffar-Avval ◽  
Aria Alasty
Keyword(s):  
Water Level ◽  
Transfer Functions ◽  
Sliding Mode ◽  
Operating Conditions ◽  
Model Parameters ◽  
Feed Water ◽  
Time Varying ◽  
Boiler Unit ◽  
Varying Parameters ◽  
Time Varying Parameters

Stable control of water level of drum is of great importance for economic operation of power plant steam generator systems. In this paper, a linear model of the boiler unit with time varying parameters is used for simulation. Two transfer functions between drum water level (output variable) and feed-water and steam mass rates (input variables) are considered. Variation of model parameters may be arisen from disturbances affecting water level of drum, model uncertainties and parameter mismatch due to the variant operating conditions. To achieve a perfect tracking of the desired drum water level, two sliding mode controllers are designed separately. Results show that the designed controllers result in bounded values of control signals, satisfying the actuators constraints.

scholarly journals Curvature Dependent Electrostatic Field in the Deformable MEMS Device: Stability and Optimal Control

2020 ◽  
Vol 11 (1) ◽  
pp. 35-54
Author(s):  
Paolo Di Barba ◽  
Luisa Fattorusso ◽  
Mario Versaci
Keyword(s):  
Optimal Control ◽  
Electrostatic Field ◽  
Stable Equilibrium ◽  
Micro Electro Mechanical System ◽  
Operating Conditions ◽  
Electric Voltage ◽  
External Voltage ◽  
Device Stability ◽  
Equilibrium Configurations ◽  
Mems Device

AbstractThe recovery of the membrane profile of an electrostatic micro-electro-mechanical system (MEMS) device is an important issue because, when applying an external voltage, the membrane deforms with the consequent risk of touching the upper plate of the device (a condition that should be avoided). Then, during the deformation of the membrane, it is useful to know if this movement admits stable equilibrium configurations. In such a context, our present work analyze the behavior of an electrostatic 1D membrane MEMS device when an external electric voltage is applied. In particular, starting from a well-known second-order elliptical semi-linear di erential model, obtained considering the electrostatic field inside the device proportional to the curvature of the membrane, the only possible equilibrium position is obtained, and its stability is analyzed. Moreover, considering that the membrane has an inertia in moving and taking into account that it must not touch the upper plate of the device, the range of possible values of the applied external voltage is obtained, which accounted for these two particular operating conditions. Finally, some calculations about the variation of potential energy have identified optimal control conditions.

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