Sensitivity analysis of transient flow of two parallel pump-turbines operating at runaway

Rezghi, Ali; Riasi, Alireza

doi:10.1016/j.renene.2015.08.059

Cited by 67 publications

(19 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In general, the water head of a pump-turbine during transient process were main influenced by the discharge change rate dQ/dt and the hydraulic loss [12]. In order to identify the cause of above distinctive differences on dynamic trajectories between large GVOs and 6 • GVO, the transient variations of discharge Q, the discharge change rate dQ/dt, the total pressure, and static pressure for the GVOs at 15 • and 6 • are shown in Figure 8.…”

Section: Influence Of Discharge Change Rate On Runaway Stabilitymentioning

confidence: 99%

“…Generally, the oscillation stability of a pump-turbine during runaway processes is associated with many parameters of the hydraulic system, such as rotational inertia, water elasticity, and friction loss in the pipe system; however, the slope of the characteristic curve at the runaway point is the most important influence factor [11]. Various one-dimensional mathematical models based on the static characteristic curves of model pump-turbines have been developed to study the dynamic stability mechanism and the influences of different factors [12][13][14][15]. Some methods, such as partly closing the main inlet valve [16] and misaligning guide-vane openings [17,18], have been proposed to stabilize runaway processes.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Internal Mechanism and Improvement Criteria for the Runaway Oscillation Stability of a Pump-Turbine

2018

View full text Add to dashboard Cite

The runaway oscillation process of the pump-turbine in a high head pumped-storage power plant is usually unstable. The root cause of its instability is still unclear. In this paper, its internal mechanism and the improvement method were studied in depth. First, the flow characteristics in a model pump-turbine during the runaway process at four guide-vane openings (GVOs) were investigated by 3D transient numerical simulations. Then, the energy dissipation characteristics of different types of backflow vortex structures (BFVSs) occurring at the runner inlet and their impacts on the runaway stability were investigated by the entropy production theory. The results show that the location change of BFVSs between the hub side and the mid-span of the runner inlet around the no-load point leads to the sharp change in the energy dissipation rate, which makes the slope of dynamic trajectory positive and the runaway oscillation self-excited. If the occurrence of BFVSs at the hub side is suspended, the runaway process will be damped. Finally, the pump-turbine runner was improved to obtain a wider stable operating range.

show abstract

Section: Influence Of Discharge Change Rate On Runaway Stabilitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Internal Mechanism and Improvement Criteria for the Runaway Oscillation Stability of a Pump-Turbine

2018

View full text Add to dashboard Cite

show abstract

“…Li et al introduced Hamiltonian theory to investigate transient stability of a HGS [6]. Riasi et al made sensitivity analysis of transient flow and numerical analysis of the hydraulic transient response [7,8].…”

Section: Introductionmentioning

confidence: 99%

Mathematical model and parametric uncertainty analysis of a hydraulic generating system

Chen

Patelli

et al. 2019

Renewable Energy

View full text Add to dashboard Cite

Conversion efficiency and unit vibration are two important indexes in evaluating the stability of hydraulic generating systems (HGSs). Most of related studies have been carried out in the deterministic theory framework. As running times of HGS increased, understanding uncertainties and limitations of model parameters are important for accurate modeling and stability evaluation. In this study, first, we establish an integrated model of a HGS by proposing unbalanced hydraulic forces based on the Kutta-Zhoukowski assumption. Second, global sensitivity and parametric interactions for conversion efficiency and unit vibration are investigated based on this model. Finally, the novel unified model is verified with two conventional models. This integrated and accurate mathematical model is a major advance in the diagnosis and prediction of failures in hydropower operation. *Revised Manuscript-Clear Click here to download Revised Manuscript-Clear: 20180520-a clear manuscript.docx Click here to view linked References

show abstract

“…In his work, the model was verified by experiments and did indeed improve energy efficiency. Other authors have focused on the hydraulic transient of the parallel pumps system; for example, the sensitivity of the transient conditions during runaway efficiency of the power plant, as in [3,4]. They have even analyzed the differences of operational time for a pump-valve system to decrease the transient pressure, as in [5].…”

Section: Introductionmentioning

confidence: 99%

A Numerical Investigation of the Influence of Geometric Parameters on the Performance of a Multi-Channel Confluent Water Supply

Zhao¹,

Li²,

Zhu³

2019

Energies

View full text Add to dashboard Cite

Transportation efficiency is a problem of particular interest in multi-channel confluent water supply engineering. Transportation efficiency depends not only on the system control strategy but also on the pressure loss (pressure difference between the inlet and outlet) and pressure drop (amplitude of outlet pressure fluctuations) of its structure. In this article, sensitivity analyses of the pressure loss and pressure drop to changes in multi-channel confluent water supply geometry are presented. An experimental set-up was established to validate computational fluid dynamic (CFD) predictions and obtain the boundary conditions for two-channel synchronous switching. The influences of the geometric structure varies by the clustered pipe diameter (40 mm < Dc < 80 mm), main pipe diameter (30 mm < Do < 80 mm), channel pitch (60 mm < L < 400 mm) and number of channels (2 ≤ n ≤ 4); those variables were investigated with the help of CFD simulations. The results showed that configuration “C” can be considered a costless method of decreasing pressure loss (βC(2.05) < βA(2.42) < βB(2.64)) and that the different configurations are insensitive to pressure drop. The variations of the influence of channel pitch and clustered pipe diameter on pressure loss have extremes at L/d = 5 and Dc/d = 2.5, respectively, but the effect on pressure drop is not obvious. The main pipe diameter and the inlet velocity have more significant influences on efficiency. The results can be used to choose the proper geometry of multi-channel confluent water supply to enable energy savings.

show abstract

Sensitivity analysis of transient flow of two parallel pump-turbines operating at runaway

Cited by 67 publications

References 2 publications

Internal Mechanism and Improvement Criteria for the Runaway Oscillation Stability of a Pump-Turbine

Internal Mechanism and Improvement Criteria for the Runaway Oscillation Stability of a Pump-Turbine

Mathematical model and parametric uncertainty analysis of a hydraulic generating system

A Numerical Investigation of the Influence of Geometric Parameters on the Performance of a Multi-Channel Confluent Water Supply

Contact Info

Product

Resources

About