Experimental Investigation of a Francis Turbine during Exigent Ramping and Transition into Total Load Rejection

Trivedi, Chirag; Agnalt, Einar; Dahlhaug, Ole Gunnar

doi:10.1061/(asce)hy.1943-7900.0001471

Cited by 19 publications

(8 citation statements)

References 53 publications

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“…In practice, load disturbance is a frequently met operation requiring high-level flexibility and robust regulation capability to maintain grid stability [6,39]. Considering 30% load shedding as the case, PSO-PID governor gains are tuned as: k p = 25.8528, k i = 52.2091, k d = 4.464 while SMC governor parameters are given as: λ p = 11, λ i = 8, λ d = 2.5, η = 0.6, δ = 0.02, k = 10.…”

Section: Load Disturbance Response Testingmentioning

confidence: 99%

Feedback Linearization and Reaching Law Based Sliding Mode Control Design for Nonlinear Hydraulic Turbine Governing System

Guo

Jiang

2019

Energies

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Hydropower as renewable energy has continually expanded at a relatively high rate in the last decade. This expansion calls for more accurate scheme design in hydraulic turbine governing system (HTGS) to ensure its high efficiency. Sliding mode control (SMC) as a robust control method which is insensitive to system uncertainties and disturbances raises interest in the application in HTGS. However, the feature of highly coupled state variables reflects the nonlinear essence of HTGS and SMC studies on the related mathematical model under certain fluctuations are not satisfied. In this regard, a novel SMC design with proportional-integral-derivative manifold is firstly applied to a nonlinear HTGS with a complex conduit system. In dealing with certain fluctuations in speed and load around the rated working condition, the proposed SMC is capable of driving the system to the desired state with smooth and light responses in aspects of the key state variables. The exponential reaching law and introduced boundary layer fasten the speed of converging time and suppress chattering. A necessary integral of sliding parameter added to manifold successfully reduces the latency caused by the anti-regulation feature of HTGS. Three operating scenarios are simulated compared with the PSO-PID method, and results imply that the proposed SMC method equips with accurate trajectory tracking ability and smooth responses. Finally, the strong robustness against system uncertainties is tested.

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Section: Load Disturbance Response Testingmentioning

confidence: 99%

Feedback Linearization and Reaching Law Based Sliding Mode Control Design for Nonlinear Hydraulic Turbine Governing System

Guo

Jiang

2019

Energies

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“…Only a few transition experiment tests have been conducted on the reduced-scale model test rigs. 14–16 Therefore, the 3 D computational fluid dynamics (CFD) method has been gradually adopted to simulate the various transitions in hydro-power engineering. A key issue in runaway transition simulations is providing accurate time-varying boundary conditions.…”

Section: Introductionmentioning

confidence: 99%

Mechanism and influence factors of hydraulic fluctuations in a pump-turbine

Wang

et al. 2021

Proceedings of the Institution of Mechanical Engineers, Part A:

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Pumped-storage power technology is currently the only available energy storage technology in the grid net, and its reliability is receiving attention increasingly. However, when a pump-turbine unit undergoes runaway transitions, hydraulic fluctuations intensively affect the reliable operation of a pumped-storage power station. To reduce hydraulic fluctuations, this study investigated the formation mechanism of hydraulic fluctuations and explored its influence factors. In this study, a developed one-dimensional and three-dimensional (1 D-3D) coupling simulation method was adopted. Transient runaway transitions of a pump-turbine with three different inertias (0.5 J, 1 J, and 2.0 J) at three different guide vane openings (21°, 15°, and 12°, respectively) were simulated and compared. The results suggest that, at smaller guide vane openings (15° and 12°), water hammer owing to the increase in rotational speed is the primary unstable issue compared to the pulsation of radial hydraulic exciting forces on the runner. However, at a larger guide vane opening (21°), the latter owing to the back-flow near the runner inlet is the primary unstable issue. Moreover, it is found that a sufficiently large inertia improves the hydraulic fluctuations of the pump-storage power station, particularly in reducing the pulsation of radial hydraulic exciting loads on the runner. The findings of this study provide a valuable reference for determining suitable rotor inertia.

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“…When a turbine is operated outside its best operation point, erosive cavitation may occur. Additionally, quick ramping cannot always be avoided and it can lead to extremely high loads and cavitation effects (Chirag et al 2018). Some erosion might be tolerated, and some may be avoided, for example, by aerating the areas prone to cavitation (Penghua and James 2018;Gangfu and Hubert 2018), but in-situ knowledge of the actual erosion rate is limited.…”

Section: Introductionmentioning

confidence: 99%

Estimation of Cavitation Pit Distributions by Acoustic Emission

et al. 2020

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Cavitation erosion in hydraulic machinery, such as in turbines and pumps, often leads to significant reduction of the service life of the affected components, with serious consequences for their maintenance costs and operation efficiency. In this study, the potential contribution of acoustic emission (AE) measurements to the assessment of cavitation damage is evaluated from experiments in a cavitation tunnel. Stainless steel samples were exposed to cavitation and damage was characterized from pitting tests carried out on mirror-polished samples. The pits were measured using an optical profilometer and cavitation damage was characterized by pit diameter distribution. In parallel, AE time signal was measured directly from behind the samples. A dedicated signal-processing technique was developed in order to identify each burst in the AE signal and determine its amplitude. The AE amplitude distribution compares well with PVDF and pressure sensor measurements from literature. It is concluded that AE signal analysis can be used to monitor the formation of pits without visual examination of the damaged surface. This provides a basis for possible future applications of nonintrusive cavitation erosion monitoring in hydraulic machines, provided the findings remain true in a more complex environment.

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Experimental Investigation of a Francis Turbine during Exigent Ramping and Transition into Total Load Rejection

Cited by 19 publications

References 53 publications

Feedback Linearization and Reaching Law Based Sliding Mode Control Design for Nonlinear Hydraulic Turbine Governing System

Feedback Linearization and Reaching Law Based Sliding Mode Control Design for Nonlinear Hydraulic Turbine Governing System

Mechanism and influence factors of hydraulic fluctuations in a pump-turbine

Estimation of Cavitation Pit Distributions by Acoustic Emission

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