Pump as Turbine: Dynamic Effects in Small Hydro

Abstract

This work focuses on the hydraulic aspects of a Pump as Turbine (PAT) when subjected to different working conditions, including accidental situations. This will provide useful information for the choice of the most adequate solution and will ensure a co rrect design and safe operation of the installed equipments. This work is supported by experimental data obtained in a series of tests performed at the university's laboratory and by calibrated computational modelling. The obtained data was used to perform a sensitivity analysis on t he relation between discharge variation, runaway time and rotational speed and make inferences about the expected peak overpressure in an accidental situation. Based on the results, the hydropower system may be characterized by a r elevant set of calculated parameters that are of extreme utility in the construction and calibration of a computational model capable of accurately predicting different scenarios and alternatives.

Mathematic Modelling of a Reversible Hydropower System: Dynamic Effects in Turbine Mode

“…Several simulations were performed while varying mass inertia (I) and specific speed (n s ). Figure 6 displays the maximum relative absolute pressure head at the upstream part of the turbine for different combinations of a set of pairs composed by I and n s [34,35].…”

“…Several simulations were performed while varying mass inertia (𝐼) and specific speed (𝑛 𝑠 ). Figure 6 displays the maximum relative absolute pressure head at the upstream part of the turbine for different combinations of a set of pairs composed by 𝐼 and 𝑛 𝑠 [34,35]. A decreasing trend in the water flow resulting from low specific-speed turbines operating in runaway conditions with small inertia turbines, associated with small sizes, generates an important overpressure with propagation along the all-conveyance system.…”

“…Three experimental set-ups were used to obtain results from the models' calibration: (i) Classical turbines of Francis and Kaplan (with fixed blades) or propeller [14][15][16]23,24]; and PATs (ii) radial and (iii) axial [21,[28][29][30]34,35,37]. However, a brief description of them is provided (Figure 10).…”

Διαχείριση Υδατικών Πόρων Σε Περιβάλλον Ασαφούς Λογικής

“…Επομένως, στην προκειμένη περίπτωση ως μέγιστη αναπτυσσόμενη πίεση, η οποία ονομάστηκε πίεση ασφαλείας, θεωρήθηκε η αναπτυσσόμενη λόγω του μανομετρικού φορτίου πίεση αυξημένη κατά 20%. Για περισσότερες λεπτομέρειες όσον αφορά το πλήγμα κριού σε υδροηλεκτρικούς σταθμούς ο αναγνώστης μπορεί να ανατρέξει στη βιβλιογραφία (Τζιμόπουλος, 1975;Ni et al, 1996;Calamak & BOZKUŞ, 2012 a,b;Morgado & Ramos, 2011;Hillgren, 2011;Morgado & Ramos, 2010;Karadžić et al, 2009;Ramos & Almeida, 2002).…”