Control of dynamic effects in small hydro with long hydraulic circuits

Lab tests in a long hydraulic circuit were developed to analyse hydrotransients induced by waterhammer effects under runaway conditions. The definition of suitable design criteria in hydraulic systems is of utmost importance and has become a priority for good design implementation. The dynamic behaviour of turbo-generators of small reaction turbines and the interaction with long hydraulic circuits are the major constraints for design criteria. In small reaction turbines, runaway conditions may cause significant discharge variations and consequently pressure fluctuations. A benchmark analysis based on the hydrodynamic behaviour of the system through computer simulations and experimental tests was developed. Specific unconventional protection devices were selected to control overpressures induced by runaway conditions in small hydropower systems with lesser environmental impacts. A spectral analysis was used in order to identify the influence of each type of disturbances in the system response.