Run-off-river plant with Kaplan turbine

Run of river hydroelectric plants are often integrated into larger rivers, and do not incorporate any energy storage: they often work with large water volumes but small differential pressures. They use the natural fall of the accumulated water. In order to ensure that there is enough water entering the penstocks and to increase the level difference between upstream water and downstream water usually small dams are build. Hydroelectric turbines, usually of the Crossflow or Kaplan type, convert the kinetic energy of the flowing water into electricity. Water levels in the head pond or reservoir are controlled by weirs, an overflow via a spillway and in the intake flow by valves integrated into the penstock. Penstocks can be buried as part of a dam or regular pressure pipes.

Level measurement and the precise forecasting of the upstream and downstream water body is essential for a safe and efficient operation of the power plant. Installed at multiple points on the upstream and downstream water body the contactless OPTIWAVE 5200 FMCW radar level transmitter accurately and reliably measures water level. OPTIBAR DP7060 C differential pressure transmitters are used to monitor the pressure drop across the intake grating, within the penstock and across the hydro turbine. KROHNE OPTISONC ultrasonic inline flowmeters can be factory calibrated and cover a diameter of up to 3,000 mm. Other clamp-on and hot/cold tapping versions are available for bigger sizes, for installation on site onto existing pipework. The sophisticated KROHNE Penstock Leak detection system (PLDS) is based on several different field proven leak detection models. It produces zero false alarms and triggers emergency shutdown in case of pipe rupture or any turbine over-speeding, plus has also a low level leak detection capability. It can be used on the data from existing flowmeters and takes into consideration the characteristics of the different flowmeters installed.