A control system for low-head diversion run-of-river small hydro plants with pressure conduits considering the tailwater level variation

Abstract

This paper presents a control system for low-head

diversion run-of-river small hydro plants with pressure

conduits. Since these hydropower plants usually have low or

null water storage capacity, the water discharged through the

turbines should be adapted to the possible extent to the natural

river inflow. For this purpose, a control scheme aimed at

maintaining a constant water level in the head pond is normally

used in these cases. As an alternative, the option of maintaining

a constant water level in the surge tank is studied in this paper.

Furthermore, since in low-head hydro plants the tailwater level

variation may represent a relatively important contribution to

total head losses, it has been explicitly considered in the

proposed control system. A small-perturbation stability analysis

has been carried out in order to analyze the influence of the

plant design and controller parameters in the plant dynamic

response. Finally, in order to illustrate the applicability of the

proposed control system, several simulations have been carried

out using data gathered from a real hydro plant.